Car Mechanics Expert Issue 2

Solving common problems on

EXPERT

MODERN ENGINES

CAR MECHANICS EXPERT SERIES  SOLVING COMMON PROBLEMS ON MODERN ENGINES

PROFESSIONAL ADVICE FOR DIY MECHANICS  UNDERSTANDING ENGINE OIL

 OVERHAULING CRANKSHAFTS

 CHANGING TIMING BELTS & CHAINS

 REBUILDING STARTER MOTORS

 EXPLORING VARIABLE VALVE TIMING

 LOOKING AFTER FUEL INJECTORS

 FRONTEND AUXILIARY DRIVE SYSTEMS

 REMOVING STUCK INJECTORS

 RECONDITIONING ALTERNATORS

 DECOKING CLOGGED ENGINES

LEARN NEW SKILLS

RENEWING TIMING BELTS & CHAINS CHOOSE THE CORRECT OIL FOR YOUR ENGINE

ALTERNATOR REPAIRS

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Contents 4

Top 10 most common mechanical faults Experts in the breakdown and insurance trades reveal the most common causes of engine failure and their solutions.

10 Understanding engine oil Getting your engine oil choice right has become increasingly difficult, leading us to investigate how it can be done.

20 Working on timing belts It’s the job that everyone dreads, but we offer a step-by-step guide, plus show how to perform a timing chain conversion.

30 Working on timing chains

From the editor  Working on your own car not only saves you money, but can also provide you with that feelgood factor of knowing that you have successfully completed a task yourself.

For me, I really enjoy getting stuck into vehicle repairs at home, taking my time over a problem and thinking methodically about a solution. Being able to work at my own pace makes tinkering with cars a real pleasure rather than a chore.

Even with just a basic toolkit, you should be able to perform many of today’s most complicated repairs, as well as keep on top of your vehicle’s servicing requirements.

In this book, we delve into the common jobs you’ll come across in everyday vehicle servicing.

Plus we take a look at the critical components found on a range of engines, explaining why they’re fitted and what happens if they go wrong.

Many motorists prefer timing chains to cambelts, but they can present their own set of problems.

38 Exploring variable valve timing Revealing the common faults and fixes for the various VVT systems incorporated by carmakers.

46 Front-end auxiliary drive systems How the FEAD system enhances drivebelt performance, plus a guide to replacing the overrunning alternator pulley.

50 Reconditioning alternators As the alternator is critical to a vehicle’s electrical system, we advise on repairs to the most common types.

58 Repairing starter motors With a ready supply of spares, you can save a huge amount of money by repairing a faulty starter motor at home.

66 Overhauling crankshafts There has been a recent resurgence in crankshaft issues and ‘bearing knock’. Here’s how to resolve any problems.

Martyn Knowles EDITOR martyn.knowles@kelsey.co.uk Car Mechanics, Kelsey Media, The Granary, Downs Court, Yalding Hill, Yalding, Maidstone, Kent ME18 6AL. Tel: 01959 543747

Email: cm.ed@kelsey.co.uk Car Mechanics is published 12 times a year, on the 3rd Friday of each month, by Kelsey Publishing Ltd. Subscription hotline: 0845 241 5159 (UK) or +44 1959 543747 (overseas).

Chief Executive Chief Operating Officer Managing Director Advertising (Tel: 01233 228753) Grateful thanks to our feature writers › Ian Cushway › Rob Marshall

Steve Wright Phil Weeden Kevin McCormick Peri Smith › Chris Randall

KELSEYmedia Kelsey Media 2021 © all rights reserved. Kelsey Media is a trading name of Kelsey Publishing Ltd. Reproduction in whole or in part is forbidden except with permission in writing from the publishers.

The views expressed in the magazine are not necessarily those of the Editor or the Publisher.

Kelsey Publishing Ltd accepts no liability for products and services offered by third parties.

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74 Looking after fuel injectors They live in one of the engine’s harshest environments, so here’s how to extend their life and improve operation.

82 How to remove stuck fuel injectors A seized injector can write-off an otherwise sound vehicle. We show how the experts deal with the situation.

87 Modern-day decoking methods We reveal methods of cleaning a heavily clogged-up engine that don’t involve an expensive stripdown.

96 Fuel saving technology We explore the technological advances being introduced to make every drop of fuel stretch that much further.

Car Mechanics

MODERN ENGINES

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Top 10 most common mechanical faults

Top 10 most commo MECHANICAL FAULT No one can predict when their car is going to develop a fault, but there are a number of issues that affect the same cars over and over again.

Ian Cushway asked his trade contacts to come up with the worst 10 offenders.

A

ccording to Warranty Direct, specialist in extended car warranties, more than one in two used cars on UK roads break down as soon as they reach 60,000-70,000 miles, the point at which most manufacturers’ warranties expire.

The average cost to repair these faults is £420, but if you factor in the cost of parts and labour, the bill can easily run into thousands of pounds. According to research, axle and suspension issues are responsible for almost a quarter of all problems, followed by electrical gremlins, which account for 19.6%.

While some manufacturers have introduced five- or seven-year policies, most still provide a standard three years and virtually all manufacturer policies are subject to mileage limitations, typically 60,000 miles. Duncan McClure Fisher, former managing director at Warranty Direct, says: “You shouldn’t expect a new car to break down in its first three years, but there is a reason that manufacturers, for the most part, limit their warranties 4

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to three years/60,000 miles and our research highlights that reason.”

According to Warranty Direct, engine issues are nowhere near as common as axle, suspension and electrical woes, but the cost of repairs are usually significantly higher because of the work involved. More worrying, its database of information shows that prestige German cars from the likes of VW and Audi, as well as brands such as MINI, are the most likely to go wrong, with Japanese products remaining the most reliable.

Shrewd motorists, of course, will inevitably make their own minds up about which cars are reliable and which are not, based on hearsay, reviews and reliability surveys. But these reports only tell half the story and often the best authorities are the dealers and mechanics who see the same problems on a day-to-day basis.

These industry insiders have supplied most of the information for this feature.

These, in their opinion, are the 10 most common mechanical faults.

1

The DV6 diesel engine

 The DV6 1.6 PSA Group common-rail turbodiesel engine has seen service in a number of different cars, including various Peugeots and Citroëns, as well as the Ford Focus TDCi, where it seems to cause the most headaches. Problems occur when carbon deposits, usually caused by lack of servicing and using the wrong type of oil, block oilways, filters and breathers, resulting in the engine being starved of proper lubrication.

Issues also stem from the contamination of engine oil by combustion residuals caused by incomplete combustion due to contaminated and leaking fuel injectors (number 3 injector is the worst culprit).

The combination of contamination, sludging-up and restricted ventilation and oil flow has catastrophic consequences, most crucially turbo failure. However, the engine can also suffer cylinder bore wear and damage to the big end bearings and crankshafts, rendering the vehicle a write-off.

Prevention and cures The key to avoiding DV6 engine woes is to carry out frequent oil changes,

using the correct specificatio the engine, and to watch out firing injectors. However, th not always be enough – case where turbo bearings have fa oil contamination don’t mak reading. In one example, an with 107,800 miles on the cl replacement turbo fitted, on subsequent turbo failure aft miles and a further terminal failure just 350 miles later, d undergoing two engine flush the first incident.

The problem appears to be sludge and the possibility th having had a full main deale history where the correct gra was used, servicing was only every 30,000 miles.

Some reconditioned turbo now offer limited guarantee stipulate a comprehensive ra precautions to prevent subse turbo failure, which include requirement to carry out a f replace banjo bolts, fit new t and conduct a thorough clea sump, oil strainer, intercoole diesel particulate filter, as w checking that the correct spe dipstick is fitted to ensure a oil level is maintained.

The DV6 1.6-litre turbodiesel unit installed here in the second-generation Ford Focus.

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Top 10 most common mechanical faults

t common AL FAULTS

he DV6 iesel engine

.6 PSA Group common-rail ngine has seen service in different cars, including ots and Citroëns, as well ocus TDCi, where it seems most headaches. Problems arbon deposits, usually k of servicing and using the oil, block oilways, filters , resulting in the engine of proper lubrication. em from the contamination by combustion residuals omplete combustion due to and leaking fuel injectors ector is the worst culprit). ion of contamination, nd restricted ventilation as catastrophic , most crucially turbo ver, the engine can also r bore wear and damage bearings and crankshafts, vehicle a write-off.

on and cures

oiding DV6 engine woes t frequent oil changes,

using the correct specification oil for the engine, and to watch out for badly firing injectors. However, this might not always be enough – case studies where turbo bearings have failed due to oil contamination don’t make pleasant reading. In one example, an engine with 107,800 miles on the clock had a replacement turbo fitted, only to suffer subsequent turbo failure after just 937 miles and a further terminal turbo failure just 350 miles later, despite undergoing two engine flushes following the first incident.

The problem appears to be residual sludge and the possibility that, despite having had a full main dealer service history where the correct grade of oil was used, servicing was only carried out every 30,000 miles.

Some reconditioned turbo suppliers now offer limited guarantees and stipulate a comprehensive range of precautions to prevent subsequent turbo failure, which include the requirement to carry out a flow check, replace banjo bolts, fit new turbo pipes and conduct a thorough cleaning of the sump, oil strainer, intercooler and diesel particulate filter, as well as checking that the correct specification dipstick is fitted to ensure an accurate oil level is maintained.

tre turbodiesel unit installed cond-generation Ford Focus.

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Inside of the turbocharger showing the vanes that can get clogged with combustion residue.

2

Variable nozzle turbos (VNT)

 The introduction of variable nozzle turbos (VNT) led to reductions in turbo lag. This was achieved by fitting a turbo housing which could change its internal configuration through the use of vanes to adapt to changes in the engine’s boost requirements. Such turbos produce full boost from as low as 1500rpm, yet remain as efficient as much larger turbos at higher revs. At low engine speeds, the vanes stay closed, narrowing the gap between them, which effectively accelerates the exhaust gas onto the turbine wheel. At high engine speeds, the vanes open up, slowing the exhaust gases and preventing the turbo from overboosting.

The problem is that the vane mechanism frequently clogs, jamming them in the closed position and causing a spike in boost. The ECU is fed information via the manifold absolute pressure (MAP) sensor and, to counter the overboost situation, shuts everything down to prevent damage, eventually putting the engine into ‘limp-home’ mode. A huge number of turbodiesels are susceptible to this.

3

rearing its ugly head on modern diesels.

Usually what starts off as an innocent misfire turns into an ongoing nightmare as mechanics struggle to remove stubborn injectors that have effectively cemented themselves into the cylinderhead. An electrolytic reaction between

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Specialists often blame extended oil change regimes for VNT failures and certainly cars that only get serviced once in a blue moon are most at risk.

Ones that have been used for stop-start journeys or have been fed poor quality oil are particularly prone to problems.

Our advice is to ignore longlife regimes and schedule fixed service intervals every 8000-10,000 miles using oils that meet manufacturer specifications. Some motorists have successfully cleaned a VNT by spraying turbo cleaner into the turbocharger.

Revive produces a Turbo Cleaner Starter Kit (petrol or diesel) that appear to work well, so it might be worth giving this a try (www.revivecleaner.com).

Otherwise it will be a case of buying a replacement turbo, usually at a cost of £400-500 plus fitting. Be sure to follow the supplier’s instructions before fitting a replacement unit otherwise you risk invalidating your guarantee.

Stuck injectors

 This is something that’s increasingly

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Prevention and cures

materials bonds the injector, with harsh underbonnet conditions of heat, cold and moisture (sometimes as a result of inadequate drainage) only adding to the problem.

It’s the entire length of the injector that sticks, necessitating the use of a specialist hydraulic puller to get them

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MODERN ENGINES

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Top 10 most common mechanical faults out. Some can be done in situ, others can only be removed with the engine on the workshop floor. And it’s not just injectors that cause problems – with the Citroën C8 and Peugeot 807, the injectors have to come out to undo the inlet manifold in order to replace the cambelt, and any work on the timing gear, valves and head gasket means whipping out the injectors.

The so-called Black Death that particularly affects Mercedes and Peugeot units is where the seals let go, allowing engine gases to pass between the seal and the injector seat, covering the surrounding area in a sticky, black substance. Needless to say, if left, this makes the injectors even more difficult to remove.

Injectors can stick in virtually any modern common-rail engine, but the worst offenders are the Vauxhall Vivaro, Renault Trafic, Nissan Primastar (all models with 1.9, 2.0 and 2.5-litre engines, including 9R, FQ9 and G9U), Citroën C8, Fiat Ulysse, Peugeot 807 with 2.0 HDi, Freelander Td4, Rover 75, Mercedes Vito, Sprinters, Fiat JTD, Peugeots and Citroëns with 1.6 HDi, Mercedes A-Class, Volvo V70 and BMW M57.

Prevention and cures

Prevention and cu

There’s very little you can do to prevent injectors sticking and you’ll only realise they are stuck when it comes to getting them out. That said, if oily deposits are allowed past the seals then this can cement an otherwise removable injector in place if ignored. Removing a stubborn injector will invariably involve the use of a puller and, in the worst cases, the services of a specialist with the necessary kit. Don’t butcher the top of the injector by attempting to remove it yourself with pry bars as this will reduce the chance of success by other methods and possibly result in the injector having to be drilled out.

Expect to pay a specialist in the region of £60 to remove each injector, assuming there’s enough underbonnet access. If they have to mill it out in situ, expect the bill to rise to £180 per injector.

Expensive, but money well spent when the only other alternative would be to remove the engine and renew the head.

With the old injector out of the way, you can apply white ceramic grease to help prevent it getting stuck again.

For many VAG owners, clean debris from the plenum cha cars becomes a weekly ritua the autumn and winter mon Others choose to remove th bungs altogether to allow be evacuation. If water does ge cabin and soak the carpets, be lucky and catch it before the BCM. Otherwise it will b having to buy a replacement Audi A6, it costs around £20

Injectors can get stuck in the cylinder-head.

On certain models it’s almost impossible to remove them without damage to the injector.

Swirl flaps can be blanked off with blanking plates made specially to accomplish the task.

Prevention and cure To avoid the issue, many drivers opt to remove the swirl flaps completely, with the only consequence of this being a slight increase in emissions at idle. When running, the flaps are open anyway, so there’s no effect on how the car drives.

To remove the swirl flap arrangement on BMW engines it’s simply a case of taking off the strut brace, loosening the manifold and EGR tube, then undoing the two screws which hold the flaps in place (as well as the actuator rod which is no longer needed). You will need to block the holes created by removing the flaps and spindles, and companies such as Chelmsford-based PMW (www. pmwltd.co.uk) produce special blanking plates for this purpose. The blanking plates start at only £5 each if you do the job yourself, while a specialist will charge in the region of £200 to remove the old swirl flaps and blank the holes.

On the Vectra, the only real solution is to replace the entire manifold, which will cost around £180 from independents.

5 4

Manifold swirl flaps

 The inlet manifold design on many of BMW’s common-rail diesel engines made from 2000-2008, as well as the Vauxhall Vectra/Saab 9-3 from around this era, features butterfly flaps, commonly known as swirl flaps. These effectively vary the length of the manifold subject to load and anticipated demand for optimum performance and minimum emissions. The engine normally runs with the flaps open, giving a shorter tract.

Unfortunately, the flap arrangement regularly fails and, when it does, the flap, fixing screws and spindles get eaten by the engine. Although the flaps themselves are usually made from plastic, so they disintegrate and pass through 6

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without harm, the metal fixings can be ingested into the cylinders, wrecking the piston, valves and cylinder-head. And that’s not all – on the way out, the tiny bits of metal will ruin the turbo and, as a final act of destruction, damage the catalytic converter. BMW addressed the issue in 2004 by introducing beefier flaps and larger diameter spindles, but there have been reports of these failing as well.

BMW models affected include the E46 320d, 330d, 530d, X3 2.0d, X3 3.0d, X5 3.0d, E60/E61 525d, 530d, 535d and the E65 730d. On the Vauxhall, it’s the 1.9 CDTi that’s affected. The petrol-engined Ford Mondeo built between 2000 and late 2003 also had swirl flaps.

Body control module (BCM)

 It’s strange that prestige manufacturers such as VW and Audi can make such a fundamental design error with the drainage of the plenum chamber: when the bungs clog, the chamber can fill with water, which then has access to the interior via the pollen filter, soaking the fragile Body Control Module that sits in the passenger footwell. And it’s not just VAG cars that are affected – according to our trade contacts, various other makes suffer from the problem, including the MINI, Peugeot, Ford Fiesta and Citroën Berlingo.

Faults with the BCM usually occur when it gets damp, with tell-tale symptoms ranging from various warning lights staying on to the loss of central locking. Snapped wires that prevent the necessary signal from getting through can cause similar problems. shop.kelsey.co.uk/subscription/CME 11/09/2021 21:35

6

Plastic-b water pu impeller

 Numerous manufacturers late 1990s, including BMW, Jaguar, used a water pump w impeller and the result has b of cooling and overheating i What usually happens is t impeller comes loose on its especially when it gets hot, up with catastrophic conseq spotted by the driver in tim might survive a potential ov

Prevention and cu

The only means of preventio an old, outdated plastic-blad pump with a pressed-steel r Fitting a new pump is a bit o and best done at the same t cambelt change, but it will u be time well spent. Be sure t the mating surfaces and app Castrol LM grease around th achieve a perfect seal.

For peace of mind, water pump plastic impellers should be cha replacements.

7

Electric p steering

 With the vast majority of cars now fitted with electron steering, it’s no surprise mo are being reported. One of t we’ve included it in our ‘wor list is because of problems c diagnosis. It seems many ow

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n be blanked off g plates made ccomplish the task.

Top 10 most common mechanical faults Prevention and cures For many VAG owners, cleaning leaf debris from the plenum chamber of their cars becomes a weekly ritual throughout the autumn and winter months.

Others choose to remove the drain bungs altogether to allow better water evacuation. If water does get into the cabin and soak the carpets, you might be lucky and catch it before it damages the BCM. Otherwise it will be a case of having to buy a replacement – for the Audi A6, it costs around £200.

on and cure

ssue, many drivers opt to wirl flaps completely, with equence of this being a e in emissions at idle. When flaps are open anyway, so ect on how the car drives. the swirl flap arrangement nes it’s simply a case of strut brace, loosening the EGR tube, then undoing s which hold the flaps in as the actuator rod which eeded). You will need to es created by removing spindles, and companies msford-based PMW (www. k) produce special blanking purpose. The blanking only £5 each if you do the while a specialist will charge of £200 to remove the old d blank the holes. tra, the only real solution is entire manifold, which will 180 from independents.

ody control module (BCM)

that prestige s such as VW and Audi can undamental design error age of the plenum chamber: gs clog, the chamber can r, which then has access to ia the pollen filter, soaking dy Control Module that ssenger footwell. And it’s cars that are affected o our trade contacts, makes suffer from the uding the MINI, Peugeot, nd Citroën Berlingo. the BCM usually occur damp, with tell-tale nging from various warning on to the loss of central ped wires that prevent the nal from getting through ilar problems.

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6

Plastic-bladed water pump impellers

 Numerous manufacturers from the

late 1990s, including BMW, VAG and Jaguar, used a water pump with a plastic impeller and the result has been a legacy of cooling and overheating issues.

What usually happens is that the impeller comes loose on its shaft, especially when it gets hot, then breaks up with catastrophic consequences. If spotted by the driver in time, the engine might survive a potential overheat.

Prevention and cures The only means of prevention is to swap an old, outdated plastic-bladed water pump with a pressed-steel replacement.

Fitting a new pump is a bit of a fiddle and best done at the same time as a cambelt change, but it will undoubtedly be time well spent. Be sure to clean up the mating surfaces and apply a smear of Castrol LM grease around the O-ring to achieve a perfect seal.

Watch for these too!  Some VW Polos and smaller-engined Golf MkIVs featured a reverse acting thermostat which can be broken by the impeller pressing against the housing. This, in turn, causes the thermostat to stay shut, increasing the risk of overheating.  With the proliferation of speed bumps, anti-roll bar link bush wear has become a common issue. On cars such as the Audi TT, the brackets can rust and this can also become a problem. Listen out for any tell-tale knocks.  Like injectors, glow plugs can get stuck in the head and become difficult to remove.

Because the threads are often so small (with some as little as 8mm) they frequently shear off completely.  EGR valves can be problematic on most makes of car. There are two types: valves operated by means of a vacuum and others that work electronically. The latter are particularly problematic on Vauxhalls. You can try to clean them out with carb cleaner (the rod that pushes the valve open often becomes sticky), but otherwise it’s a case of buying a replacement and they’re not cheap at around £230.  Steering rack problems are a common weakness on the MINI, resulting in the steering wheel feeling rough or notchy when turned. Power steering pump failure is also common on early cars – you’ll notice the steering suddenly feeling heavy or see dash warning lights that may eventually prevent the car from starting.  Still on the MINI, the Rover-derived M65 fivespeed Midland gearbox fitted to 2001-2004 Ones and Coopers is prone to failure. If it begins to whine or loses synchromesh, the cheapest solution is to buy a reconditioned replacement, which will cost £400-700. You can convert to a more reliable Getrag unit, but you’ll also need to replace the driveshaft, flywheel, engine mount ends, gear selector and cables, and airbox, which can be pricey and is unlikely to be worthwhile on a car of this age.

For peace of mind, water pumps with plastic impellers should be changed to steel replacements.

7

Electric power steering

 With the vast majority of new cars now fitted with electronic power steering, it’s no surprise more problems are being reported. One of the reasons we’ve included it in our ‘worst offenders’ list is because of problems concerning diagnosis. It seems many owners are shop.kelsey.co.uk/subscription/CME

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Electric power steering systems rely on a healthy 12V battery to operate correctly.

plagued by problems, some of which start when the car is virtually new, which are either intermittent or simply can’t be traced by a main dealer.

In most cases, there’s a partial or total loss of assistance and there are numerous possible causes, including problems with the motor, torque converter or angle position sensor. Some of the worst

affected models include small Fiats such as the Punto and Panda. Fiat owners driving on the open road with the ‘City’ setting engaged don’t help matters. The EPS on the Vauxhall Corsa C also receives a number of complaints; here the most common symptom is the steering feeling lighter when turning the steering wheel in one particular direction.

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Top 10 most common mechanical faults Prevention and cures The EPS system requires a healthy 12V battery, so a weak alternator or dying battery are the cause of many problems.

If problems disappear once a car is warm, check the integrity of the electrical system first. Following this, if any error messages are showing, carry out a fault code reading in an attempt to pinpoint exactly where the problem lies. Often it’s possible to replace sensors, ECUs, torque converters, motors and racks separately, although fitting a complete column

assembly with the ECU and motor attached and already calibrated as a plug ’n’ play replacement can be a far more cost effective solution.

Regarding the Corsa, most issues seem to originate from the torque sensors going out of balance and there are fixes outlined on the internet that can sometimes redress this. However, the problems will usually reoccur, in which case replacing the column is the best solution – they’re £240 from specialists Western Power Steering (www.westernpowersteering.co.uk).

What stops cars most?

Who better to report back on the most common faults than the RAC, which rescues thousands of stricken motorists from the roadside each year.

According to its most recent data relating to breakdown jobs, this is the top 10 by volume of incidents (in brackets).

1. Non-serviceable battery (229,503) 2. Puncture – wheel change (177,515) 3. Battery – flat (152,026) 4. Unknown (140,356) 5. Puncture – no spare (96,839) 6. Tyre related (76,304) 7. Alternator (61,599) 8. Road traffic accident (59,446) 9. Clutch assembly (55,247) 10. Starter motor (50,090)

8

Broken coil springs

 Snapped suspension coil springs

have always been an issue, but as manufacturers have started to use thinner metal, the incidence of broken springs seems to be on the increase.

Usually what happens is that road salt gets into tiny fissures in the spring and cracks from which will eventually lead to the spring failing. It affects all makes of car, but when the spring breaks on the Ford Fiesta/Renault Laguna and a wide variety of other vehicles it can drop the strut and damage the tyre.

Prevention and cures Regular inspection is the obvious way to identify problems early on, although it’s worth carrying this out while the car is up on a two-post lift because fractures can be difficult to spot. Knocks while driving over a lowered kerb or pothole, and the car listing very slightly on one side are also giveaways that something is wrong.

Replacing a road spring is a relatively straightforward and inexpensive affair, but be sure to replace springs as a pair and not individually. Consider a quality replacement spring kit from the likes of Eibach, which will give all four corners a new lease of life. Lowering springs are another option.

As for top claims under the RAC’s warranty scheme, it’s various electrical components that account for four out the top five most claimed-for parts.

Rank Part 1.

Alternator

2.

Coil

3.

Sensor

4.

Starter motor

5.

Water pump

6.

Lambda sensor

Internal or wiring failure causing loss of vehicle electrics

£342

Internal or wiring failure causing engine running faults

£125

Internal or wiring failure causing engine running faults

£206

Internal or wiring failure causing non-starting issues

£256

Internal failure causing overheating

£258

Internal or wiring failure causing engine running faults

£189

Gearbox

Internal fault causing loss of drive

£1000

8.

EGR valve

Sticks or gets jammed causing engine running faults

£285

Internal fault causing the windows to stop working

£243

Gasket fails causing overheating and other engine faults

£486

Window motor

10.

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Average pay-out

7.

9.

8

Description & most common fault

Cylinder-head gasket

Car Mechanics

MODERN ENGINES

The BMW 1-Series has seen hig of ABS warning light problems.

Prevention and cu

Replacement units were orig region of £1200 but, having r problem, BMW has done the thing and reduced the price affordable £159.55. It’s an u and takes approximately tw hours to fit once the fault co been cleared and the system

10

Dual ma flywhee

 Every second vehicle buil now has a dual mass flywhe They are fitted to help isola of the drivetrain as possible vibration and add refineme ones were introduced in 198 BMWs, and as torque and co

JL

There are reports of high MOT failures on cars these days due to broken springs.

9

ABS control module

 From early on in BMW 1-Series production there was a problem with the ABS control module and it’s an issue that continues to blight ownership. In a nutshell, the valve block fails, which brings on the ABS warning light – now an MOT fail point. Some MINIs also suffer from the same problem. shop.kelsey.co.uk/subscription/CME

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For more informati

web: www.jlm email: info@ka tel: 01273 8

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Top 10 most common mechanical faults

roken oil springs

uspension coil springs een an issue, but as s have started to use l, the incidence of broken s to be on the increase. happens is that road salt fissures in the spring and which will eventually lead to ling. It affects all makes of the spring breaks on the enault Laguna and a wide er vehicles it can drop the mage the tyre.

on and cures

ction is the obvious way to ems early on, although it’s g this out while the car is up lift because fractures can spot. Knocks while driving d kerb or pothole, and the y slightly on one side are s that something is wrong. road spring is a relatively rd and inexpensive affair, o replace springs as a pair idually. Consider a quality spring kit from the likes of h will give all four corners f life. Lowering springs are n.

The BMW 1-Series has seen high volumes of ABS warning light problems.

Prevention and cures Replacement units were originally in the region of £1200 but, having recognised the problem, BMW has done the honourable thing and reduced the price to a more affordable £159.55. It’s an uncoded unit and takes approximately two-and-a-half hours to fit once the fault codes have been cleared and the system bled.

10

Dual mass flywheels

 Every second vehicle built in Europe now has a dual mass flywheel (DMF).

They are fitted to help isolate as much of the drivetrain as possible, to reduce vibration and add refinement. The first ones were introduced in 1985 on diesel BMWs, and as torque and compression

It’s not just diesel engines that have dual mass flywheels. The torsion springs inside the DMF will become weak over time and the whole unit has to be changed.

outputs of modern engines has improved, so has the design of the DMF. That said, bad driving habits such as letting a car labour in the wrong gear will quickly shorten the life of the flywheel, resulting in a hard clutch pedal, clutch slip and annoying rattles. Of course, the tolerances that manufacturers build into a DMF can be challenged by ECU remapping, so as more turbodiesels are being remapped on the aftermarket, the incidence of ruined DMFs is becoming increasingly common.

Overloading a car by towing a heavy trailer or ignoring ignition problems

Prevention and cures The obvious way to prevent DMF issues is to keep your car as the factory intended and improve your driving style by ensuring you are always in the right gear at the right time.

The average cost of a replacement DMF is £300 (plus clutch kit, if required).

But before you go ahead and order a replacement, it is worth using a special tool to check for free play and rocking.

Solid flywheel conversion kits are available and, for a shorter term solution, this could represent a small saving.

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Car Mechanics

MODERN ENGINES

9

11/09/2021 21:35

Understanding ENGINE OIL

ENGINE OIL Getting your engine oil choice right has become increasingly difficult, leading Rob Marshall to investigate how it can be done, while unpicking the latest developments.

We are all told that regular oil changes reduce motoring costs in the long run but making the wrong choice can be counterproductive.

E

ven in today’s supposed ‘ecofriendly’ world, the link between the modern motor car and the petrochemical industry remains unbroken. From most interior plastics to the fuel that still powers over 98% of cars registered on our roads, perhaps the most obvious link to fossil-fuel is the engine oil.

Planes, trains and automobiles Whether mineral oil, intended for a fourpot classic, or a sophisticated synthetic lubricant for a modern direct-injected turbocharged triple, the ‘base stock’ originates from crude oil. Yet, while nature provides the raw material, humans deliver the development. Petroleum-based mineral oil was less prone to solidifying when cold and leaving fatty deposits

While manufacturers have bespoke specifications that you should not ignore, this does not mean that you are limited to main dealer parts counters. There are many quality options but buy a recognised brand, or one that can justify its assertions.

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MODERN ENGINES

behind at higher temperatures, compared to animal and vegetable oils, making it more suited to the harsh environment of an internal combustion engine. Yet, the raw product remains far from perfect.

One of the notable pioneers of lubricating oil in the UK was Charles Cheers Wakefield, a publicity-conscious entrepreneur, whose business diverted from railway lubricants to supplying engine oils for motor vehicles in the early twentieth century. While supplying buses initially, the Wakefield Motor Oil company became an engine oil sponsor for more exciting competitive events

to prove its engineering prowess. This successful publicity campaign began not with motorcars but monoplanes, possibly looking to cash-in on the notoriety of Louis Bleriot, a French car accessory manufacturer, who flew to England over the English Channel in under 40 minutes.

By adding a small proportion of castor oil to Wakefield’s mineral lubricant, the result was a superior oil film: the Castrol brand was born. Understandably, it was not long before attention moved to motorsport. Consequently, the 1911, 1912 and 1913 Isle of Man Senior TT races were all won by motorcycles using

Multigrades for classic cars tend to be mineral-based with minimal detergent additives. If your classic tends to work its oil to a very high temperature, or you drive frequently at motorway speeds, consider upgrading to an oil with a superior high-temperature capability.

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NEW OIL S

 While API standards ar for European and British means of addressing pro introduced ‘SN Plus’ in M ‘SN’ specification, which g result is API SP, introduce Interestingly the ACEA were intended to be intro receive an explanation. A an oil based only on the If you own (or maintain see oil recommendations Committee (ILSAC), whic compatible, with superio (for 0W-16 oils only) spec May 2020, which provide Pre-Ignition (LSPI) preven

Castrol oils. Development ac during hostilities, where the topping Castrol R (‘Racing’) tactical advantages for fight due to the oil being able to r lubricating properties at the ambient temperatures that those experienced at high al During the inter-war peri continued to be the engine l of choice for British record b land, water and air. Howeve cars were becoming more po they had different demands strung race winners. Additiv the answer. In the mid-1930 research department discov adding tin and chromium el helped to alleviate engine co internal sludging and oil agei oxidisation. These issues we noticeable on cars undergoin and remain relevant today. E engine design and better qua played essential roles since b additives keep combustion d

Oil vapour enters the inlet thro positive crankcase ventilation ( Check that the hose(s) between and crankcase (including any fi vapour separator) are unblocke

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OIL

ngineering prowess. This blicity campaign began not rs but monoplanes, possibly sh-in on the notoriety of a French car accessory r, who flew to England over hannel in under 40 minutes. mall proportion of castor eld’s mineral lubricant, s a superior oil film: the was born. Understandably, g before attention moved t. Consequently, the 1911, 13 Isle of Man Senior TT won by motorcycles using

al detergent additives. If your ve frequently at motorway ature capability.

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Understanding ENGINE OIL

NEW OIL STANDARDS  EUROPE LAGS BEHIND  While API standards are general indicators of quality, they are not intended for European and British markets, unlike those of the ACEA. To provide a temporary means of addressing problems that were afflicting GDI engines in particular, API introduced ‘SN Plus’ in May 2018, as an update to the pre-existing ‘SN’ specification, which gave breathing space to develop a new standard. The result is API SP, introduced formally in May 2020.

Interestingly the ACEA has delayed introducing similar specifications; they were intended to be introduced during 2018. We contacted the ACEA and did not receive an explanation. All we can recommend for GDI engines is that you choose an oil based only on the manufacturer’s recommendations.

If you own (or maintain) a very young car, especially a hybrid vehicle, you may see oil recommendations from the International Lubricant Specification Advisory Committee (ILSAC), which the API adopts. ILSAC GF-6A (which is backward compatible, with superior performance over API SN Plus) and ILSAC GF-6B (for 0W-16 oils only) specifications are the latest technologies, available since May 2020, which provide extra protection for timing chains, Low-Speed Pre-Ignition (LSPI) prevention and fuel economy advantages.

Castrol oils. Development accelerated during hostilities, where the rangetopping Castrol R (‘Racing’) oil provided tactical advantages for fighter planes, due to the oil being able to retain its lubricating properties at the extreme low ambient temperatures that are typical of those experienced at high altitude.

During the inter-war period, Castrol R continued to be the engine lubricant of choice for British record breakers on land, water and air. However, passenger cars were becoming more popular but they had different demands to highlystrung race winners. Additives provided the answer. In the mid-1930s, Castrol’s research department discovered that adding tin and chromium elements helped to alleviate engine corrosion, internal sludging and oil ageing, caused by oxidisation. These issues were becoming noticeable on cars undergoing short trips and remain relevant today. Enhanced engine design and better quality fuels have played essential roles since but dispersant additives keep combustion deposits

Oil vapour enters the inlet through the positive crankcase ventilation (PCV) valve.

Check that the hose(s) between the valve and crankcase (including any fine gauze oil vapour separator) are unblocked.

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suspended in the lubricant. Ultimately, this saves the car owner from having to dismantle the engine and scrape away the carbon residues, in favour of a simple and relatively inexpensive oil change.

While racing lubricants provide oil brands with a degree of credibility, they were unsuited to everyday motoring. Excessive thickening at low temperatures makes the engine very difficult to turn-over and start from cold, especially for early motorists that had to wield a starting handle first thing in the morning. If the oil was specified to be thinner at lower temperatures, the compromise was excessive thinning when hot, courting engine damage.

Additives came to the rescue, once more. While lighter oils were introduced to the British motoring public by the 1940s, defined by their viscosity (‘thickness’), polymer-based viscosity index improver additives provided a solution to the lubricant thinning-out excessively at higher temperatures. Another additive, designed to suppress the pour-point and

Viscosity is only part of the story and most modern cars rely on synthetic oils. Seek-out the appropriate ACEA/API standards but prioritise manufacturer ratings.

reduce the oil’s tendency to thicken at low temperatures, inhibits the oil’s wax molecules tendency to link together as they become colder. By adjusting the viscosity improvers and pour-point suppressant additives, therefore, engine oils could adopt different viscosity characteristics at set temperatures. This important invention laid the foundations for multigrade oils and the resultant Society of Automotive Engineers (SAE) classification remains in force today.

The environmental role The internal combustion engine has always been extraordinarily wasteful and lubricants have become increasingly more important to reduce fuel consumption. Since the 1970s, engineers found that thinner (or less viscous) engine oils reduced resistance within the engine, wasting less energy. Engineers could use this to their advantage by improving performance, enhancing fuel consumption and reducing tailpipe emissions.

 PCV valves themselves can become clogged with sludge, resulting in the crankcase pressurising, which forces oil past the various rubber seals, causing oil leaks.  This PCV valve is part of the cam cover, dictating that the entire moulding be replaced.

Car Mechanics

MODERN ENGINES

11

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Understanding ENGINE OIL

WHAT ENGINE OIL DOES

ROB’S TOP TIP Consult your handbook for oil recommendations.

 Without a suitable lubricant, an internal combustion engine would not last for long. A complete loss of oil pressure results in the heavilyloaded metallic components to contact, overheat and seize. Many parts of an engine have different lubrication demands than others and the main practical issues affect classic car owners, where certain anti-wear additives that protect older engines are either reduced, or removed, for environmental reasons. However, this does not always mean you should On this older engine, the stated API recommendation pay a premium for oils with these additives put back in: ZDDP (Zinc has become obsolete. Therefore, seeking an API rating DialkylDithiophophate) is a typical example. that is back-compatible (API SJ onwards) would be a Aside from preventing metal-to-metal contact, the oil must also satisfactory solution, provided that the recommended transfer and shed heat effectively. However, this and lubrication are not viscosity is maintained. its only roles. Certain components rely on the pressurised oil to provide an hydraulic function, such as valve lifters, variable timing variators and even timing chain tensioners. Some of these components can boast small filters that might block, especially if the car’s service history is patchy.

As petrol and diesel are a complex mixture of compounds, they do not burn entirely cleanly. The engine oil must remove these deposits and keep them in suspension, so that they do not build within the crankcase. The deposits are one reason why the attractive golden hue of fresh oil turns black as it ages, especially on diesel engines. However, should the engine have a fault, or the oil has not been changed on time, the lubricant reaches a saturation point; the deposits can then fall-out of the oil and can start to build within the engine. The most common example is a sticky, plastic-type sludge that can not only block the oil galleries and affect the valve lifters (causing a loud rattling from the top of the engine) but it also compromises the oil’s protective qualities.

Besides, modern engines also require chemical protection. While burning a litre of petrol produces, approximately, a litre of water that promotes rusting, addressing acidity is a further challenge. Ethanol-laced fuels, for example, lower the pH value of the oil, which is why the latest oil blends include extra additives that can resist petrol containing up to 20% ethanol.

Oils also keep rubber seals supple, reducing hardening and, therefore, the opportunity for leaks to develop. The lubricant must also maximise the life of the anti-pollution systems, including catalysers and DPFs.

Naturally, motorsport provided an ideal testbed and BP’s introduction of a 10W-30 oil in its Formula Three racing car during the early 1970s raised eyebrows, when many motorists were used to using 20W-50 in their vehicles.

The subsequent promotional material, to educate the public that engine oil choice can reduce fuel costs, started in the fuelcrisis era of the 1970s. Yet, legislation to limit carbon dioxide emissions especially has accelerated development. Five years ago, CM reported that Shell Lubricants had modified a Mitsubishi engine to run on an engine with an amazingly-low prototype 0W-12 viscosity oil, which has since become a production reality on some latest hybrids. In some instances,

the oil is so thin that the engine internals are coated from new with special antifriction coatings to help tolerate potential extra metal-to-metal contact. Even so, 5W-30 is the most popular engine oil viscosity used by today’s car parc, supplanting the older 10W-40 grade.

As engines have become increasingly sophisticated, faster revving, hotter running and more powerful, mineral oil alone was no longer adequate.

Synthetic oils maintain viscosity at high temperatures more effectively than mineral types, although (ironically) they are made from components that originate from crude oil. Unsurprisingly, modern chemical additive packs have also become increasingly complex.

Elderly oil seals harden and lose their sealing abilities. Quality engine oils contain additives to keep them supple. However, seal swell additives may help extend worn seal life, when dosed into the sump separately.

Sludge deposits result, when the oil becomes contaminated. This can restrict oil galleries and increase mechanical wear. While flushing additives help, severe cases may require dismantling and mechanical cleaning. Image courtesy of Wynn’s

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MODERN ENGINES

Yet, when catalytic converters became commonplace in the 1990s, which reduce toxic emissions by passing spent exhaust gases over a honeycombed structure of exotic catalysts, oil formulations changed again. As all engines burn oil to an extent, some of the anti-wear additives become deposited on the catalyst materials, rendering them ineffective.

The problem was highlighted again in the 2000s, when diesel particulate filters (DPF) were blocking prematurely from anti-wear additives. This led to low sulphated ash, phosphorus and sulphur (SAPS) lubricants that must be used on engines that are equipped not only with DPFs but also Gasoline Particulate Filters (GPF).

Continued on page

14

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10/09/2021 12:50

16/08/2021 11:20

Understanding ENGINE OIL Incorrect oil has such a negative influence on engine life that warranty companies tend to test samples of the engine oil before honouring (or rejecting) claims.

Image courtesy of Millers Oils

ROB’S TOP TIP

Prioritise car manufacturer specifications over viscosity alone.

OIL TEMP

Many modern cars, especially those fitted with turbochargers, possess oil-to-water heat exchangers, or oil coolers. Check them for leaks: this one is oozing both oil and coolant. Regular anti-freeze changes reduces internal corrosion, which risks engine oil mixing with the coolant.

 Even the latest design efficiency, which is why t pumps to speed the warm gauge, many drivers do n temperature – of around Oil temperature is dep involves high RPMs and h viscosity can drop excess constituents within the o On many modern cars, lamp (such as that pictur into the car’s cooling syst problem for everyday dri turbocharged vehicle esp Short journeys, or thos its ideal temperature, the A consequence is oil thic the less efficient combus the additive and deterge time. It also justifies why substitute that has had in

The latest challeng

Premature timing chain wear is becoming a noticeable problem on certain modern GDI engines especially and the latest oil specifications are evolving to provide extra protection to these parts.

Modern engine oil pumps have their role to play with reducing power demands. The pictured BMW pump is of the volume-control design to ensure that no surplus quantities of oil are delivered under low-load operating conditions. Not only does this reduce fuel consumption but it also slows oil ageing.

HOW ENGINE OIL DETERIORATES  Oil does not last indefinitely within the hostile environment of an engine.

Its molecular structures are torn apart by the oil being squeezed constantly between moving metal surfaces, such as the crankshaft bearings/crank pins and the cylinder bores/pistons. Eventually, this reduces the viscosity so that the oil film strength is compromised. Heat also destroys the lubricant’s effectiveness on a molecular level. With modern petrol engines running at higher temperatures, the oil risks premature oxidisation and certain elements vapourising under the intense heat. Additionally, just as oxidisation causes food to go bad, oil’s natural interaction with atmospheric oxygen causes chemical degradation that not only affects the viscosity but also leads to reduced protection against deposits.

While the engine oil is designed to become dirty, the contamination must not drop-out of suspension. As the various additives packs are sacrificial, the lubricant’s effectiveness drops, once they are depleted. Blow-by gases that seep past the piston rings and into the crankcase, allied to any moisture from the closed-circuit breathing system, raise the oil’s acidity, accelerate oxidisation and cause the engine oil to thicken. The resultant internal resistance raises fuel consumption but does not enhance the lubrication properties. More common on cars used on short trips, one that is ill-maintained, or where an injector fault exists, fuel can also wash past the piston rings and contaminate the oil, which elevates the risk of sludging and varnish accumulations. Most diesel models are designed so that the fuel raises sump levels, as part of the DPF regeneration process. Should you find an excessive oil level, there might be a problem with the anti-pollution equipment.

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MODERN ENGINES

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The current generation of pe especially, demands new gen These small capacity, directturbocharged units deliver i torque figures but require ve viscosity lubricants and extr to cope with the higher tem increased deposits and exten intervals. Unfortunately, cer anti-wear additives, present the oil, are responsible for ig fuel/air mixture within the c prematurely. As the conditio to be prevalent at low engin (<2500rpm) but high-load c LSPI (Low-Speed Pre-ignitio latest challenge to overcome (‘pinking’) is just as damagin engines as earlier units that advanced engine manageme

The fine filtration channels on d blocked by certain anti-wear ad complies with the ACEA C grade

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cars, especially those fitted gers, possess oil-to-water heat oil coolers. Check them for leaks: ng both oil and coolant. Regular nges reduces internal corrosion, gine oil mixing with the coolant.

e to play with reducing power the volume-control design to are delivered under low-load reduce fuel consumption but

rops, once they isture from the il to thicken. The es. More common on sh past the piston rings l models are designed so ve oil level, there might

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Understanding ENGINE OIL

OIL TEMPERATURE  Even the latest design of engine has an ideal operating temperature for optimum efficiency, which is why the latest cooling systems boast sophisticated on-demand water pumps to speed the warming process. While most cars possess a coolant temperature gauge, many drivers do not appreciate that the oil takes longer to heat up to its ideal temperature – of around 80°C. Oil temperature is dependent on load. Sustained long motorway runs, or driving that involves high RPMs and hard acceleration make it run hotter. Should the oil overheat, its viscosity can drop excessively, risking increased metal-to-metal contact, as well as various constituents within the oil vapourising and depositing residues within the crankcase.

On many modern cars, most of which lack either an oil temperature gauge/warning lamp (such as that pictured right), an oil cooler sheds excessive heat from the lubricant into the car’s cooling system and so excessive oil temperatures are rarely a significant problem for everyday driving. Even so, the mechanically-sympathetic motorist that runs a turbocharged vehicle especially must still be sensitive of localised oil overheating.

Short journeys, or those where the oil cannot attain 80+°C, present problems. Should the lubricant be unable to attain its ideal temperature, the moisture content cannot evaporate thoroughly and exit the crankcase via the breathing circuit.

A consequence is oil thickening. As the engine also consumes more fuel when cold, it produces more deposits because of the less efficient combustion, which hastens the downward spiral, by further deteriorating the base stock and depleting the additive and detergent packs. These reasons explain why oil change intervals are dependant not merely on mileage but time. It also justifies why a well-maintained high-mileage engine can be in better mechanical condition than a low mileage substitute that has had infrequent maintenance.

The latest challenges The current generation of petrol engines, especially, demands new generation oils.

These small capacity, direct-injection, turbocharged units deliver impressive torque figures but require very low viscosity lubricants and extra additives to cope with the higher temperatures, increased deposits and extended service intervals. Unfortunately, certain calcium anti-wear additives, present within the oil, are responsible for igniting the fuel/air mixture within the cylinders prematurely. As the condition tends to be prevalent at low engine speed (<2500rpm) but high-load conditions, LSPI (Low-Speed Pre-ignition) is the latest challenge to overcome. Pre-ignition (‘pinking’) is just as damaging on these engines as earlier units that lacked advanced engine management that could

retard the ignition automatically. Yet, because the ignition source is oil deposits on the cylinder wall, electronics cannot intervene. Violent explosions replace the intended smooth burning, the long-term consequence of which is severe mechanical harm, including damaged pistons and valves. While it is unclear whether the engine makers, or their lubrication partners, are to blame for this serious oversight, new oil standards are being introduced to help combat the challenge.

Apart from LSPI, the desire to reduce weight and carbon dioxide emissions has seen sump capacities reduce. While oil change intervals have not increased dramatically (if at all) within the last decade, many technicians and engineers concur that a biennial, or 20,000-miles, change interval is excessive. Various engine oil blenders have also revealed to CM that producing an engine oil that protects an

The fine filtration channels on diesel particulate filters become blocked by certain anti-wear additives. They require low SAPS oil that complies with the ACEA C grades, at the very least.

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engine throughout these extended drain periods is a significant challenge.

Identifying oil The Society of Automotive Engineers (SAE) determines the viscosity measurement for mono and multigrade oils. Yet, the ‘weight’ scales for engine lubricant viscosities are not comparable to those used for EP (Extreme Pressure) lubricants, such as gear oils.

A lower number denotes thinner oil and an easier pour point. For multigrades, the ‘W’ denotes ‘winter’ and indicates the limit at which the oil ceases to flow properly.

0W will flow down to -30°C 5W up to -25°C 10W (-20°C) 15W (-15°C) 20W (-10°C)

Overfilling an engine sump can be just as damaging as allowing the level to fall too low. If your sump capacity is less than that of your oil filling can, do not add all the contents anyway. A clean measuring jug is a useful cheap purchase for this task.

Car Mechanics

MODERN ENGINES

15

12/09/2021 01:56

Understanding ENGINE OIL Most turbocharger failures are caused by oil breakdown, degradation or starvation. The pictured turbine shaft rotates at hundreds of thousands times per minute and is both cooled and lubricated by an oil supply that is dependent wholly on the much slower engine speed. The blueing marks on this shaft (arrowed) shows localised overheating, caused by the oil pressure being cut, while the shaft was still spinning in its soft bearings at high speed.

ROB’S TOP TIP Where you are unsure, check the advice of several online oil databases, or ask your manufacturer.

NB: Older sequences SA wary of any oils claiming Category Service

Many turbocharger suppliers will not honour warranty claims, unless you can prove that specified parts of the lubrication system have either been cleaned, or renewed.

The second figure denotes the viscosity at 100°C. Therefore, a multigrade with a 5W-30 viscosity flows like a 5 weight oil from cold, and so can tolerate down to -25°C, but it will not thin any more than a monograde 30 weight oil would at 100°C. An interesting aside is that the greater the gap between weightings, the higher the viscosity improver additive content.

Therefore, a 5W-50 oil will contain more of this polymer than a 10W-40 multigrade.

The downside to this is that viscosity improvers influence deposit build within intakes. As a consequence of modern inlet manifolds carrying oil residue from the crankcase breather and exhaust gases from the exhaust gas recirculation valve(s), the viscosity improver element sticks to the surface and attracts soot particles. This results in a deposit build that reduces the

inlet’s diameter, strangling the engine gradually of air. Car manufacturers specify that intake manifold contamination is one of the many parameters that its lubrication development partners consider and highlights the importance of heeding manufacturer specifications on later engines, an issue that will be expounded later.

As oils have had to become more sophisticated, the American Petroleum Institute (API) established oil performance standards, with the European Automobile Manufacturers’ Association (ACEA) following in 1996.

These not only check that the claimed viscosities are maintained but also include extra tests that consider other factors, which influence engine life.

These include abilities to resist foaming

(where the aerated oil causes the lubrication protective film to collapse), plus evaporation, sludging, ageing, bio-fuel degradation implications and the preservation of anti-pollution devices, such as DPFs and catalysts.

In the case of the ACEA, its A/B sequence is for petrol and diesel cars/ vans and C relates to light-duty vehicles that employ exhaust after-treatment devices, such as particulate filters. The E grade is for heavy-duty types of diesel engines that are not considered within this feature. While they hail from North America, do not consider API ratings to be an irrelevance, because the API seems to have been more reactive in recent years to establish oil standards to help tackle the problems associated with modern GDI petrol engines.

TO FLUSH, OR NOT TO FLUSH?

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MODERN ENGINES

SP

Introduced in wear, excessi stringent slu

SN Plus

For 2020 and

SN

For 2020 and

SM

For 2010 and

SL

For 2004 and

SJ

For 2001 and

Selecting engine o

As viscosity does not indica do not base your purchasing upon that single factor. The of Lubrication Specification comments that the ACEA’s o sequences, in particular, ha from being a standard for E engines to now being a star result of this has seen car m demand variations on the A sequences to meet the requ their specific engines. This huge variety of 5W-30 oils a the market, with Ford, Gene PSA Groupe, and more, calli standards that suit their ne but not those from other m The VLS’s chairman, Andr advises CM readers to be on and expounds: "As space in motor factors, wo and even petrol stations come greater pressure, there is a tem

ACEA seque

 Adding a flush additive to old engine oil, before draining it out, remains controversial between DIYers. The primary purpose is to remove sludge deposits from the engine’s internal surfaces. Good quality flush additives contain extra detergents that dissolve the semi-solid impurities and keep them suspended in the oil.

Apart from freeing-up oil galleries, piston rings and hydraulic lifters from sludge that impedes their operation, flushes help to prevent contamination of the new oil, which shortens its life. The problem is not helped by some engines possessing sump drain plugs that are not located at the pan’s lowest point. For example, certain Vauxhall Astra drain plugs are cited approximately 30mm from the base, meaning that up to 15% of the aged oil remains, ready to contaminate and reduce the life of the fresh lubricant. While a flush helps to reduce the chance of this happening, sucking the remaining oil from the sump via the dipstick tube, using a suitable extraction tool, is another option.

Some DIYers argue that the dislodged deposits wreak havoc. Perhaps influenced by old stories of Ford CVH engines from the 1980s and 1990s, which were especially prone to sludging, this is not much of a worry on modern engines, unless contaminated severely. For such applications, there are professional options that are offered by garages.

As with all additives, follow the instructions closely on the bottle. Some flushes contain sufficient lubrication aids so that the car can be driven, although most types recommend that the engine is run with no load at either idle speed, or slightly faster, for a set period. Developments are continuous. Last issue, for example, we reported that Castrol has launched its all-new ‘Engine Shampoo’ flush that claims to remove 85% of petrol engine sludge.

16 Car Mechanics

API sequence

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12/09/2021 01:56

The ACEA has A/B grad The C grade covers veh

Category Overview A3/B3 For petrol an the engine m A3/B4 For petrol an as defined b A5/B5 As A3/B4 bu

Category Overview C1 Lowest SAPS Suitable for C2 Mid-SAPS ca Suitable for C3 Mid-SAPS ca Suitable for C4 Low-SAPS ca Suitable for C5 Mid-SAPS ca economy oil

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Understanding ENGINE OIL

ROB’S TOP TIP Where you are unsure, check the advice of several online oil databases, or ask your manufacturer.

rger suppliers will not honour s, unless you can prove that of the lubrication system en cleaned, or renewed.

rated oil causes the rotective film to collapse), ion, sludging, ageing, adation implications and ion of anti-pollution as DPFs and catalysts. of the ACEA, its A/B or petrol and diesel cars/ lates to light-duty vehicles exhaust after-treatment as particulate filters. The heavy-duty types of diesel are not considered within While they hail from North not consider API ratings to nce, because the API seems more reactive in recent blish oil standards to help oblems associated with petrol engines.

sh lubricant. While a e dipstick tube, using a

f Ford CVH engines modern engines, unless rages. t lubrication aids so that er idle speed, or slightly strol has launched its

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API sequences (petrol) NB: Older sequences SA, SB, SC, SD, SE, SF, SG and SH are all obsolete, so be wary of any oils claiming compliance.

Category Service SP

Introduced in May 2020, for protection against LSPI, timing chain wear, excessive deposits for pistons and turbochargers, and more stringent sludge and varnish control

SN Plus

For 2020 and older automotive engines with extra LSPI protection

SN

For 2020 and older automotive engines

SM

For 2010 and older automotive engines

SL

For 2004 and older automotive engines

SJ

For 2001 and older automotive engines

Selecting engine oils As viscosity does not indicate quality, do not base your purchasing decision upon that single factor. The Verification of Lubrication Specifications (VLS) comments that the ACEA’s oil sequences, in particular, have moved from being a standard for European engines to now being a start point. The result of this has seen car manufacturers demand variations on the ACEA sequences to meet the requirements of their specific engines. This has seen a huge variety of 5W-30 oils appearing on the market, with Ford, General Motors, PSA Groupe, and more, calling for standards that suit their new vehicles but not those from other manufacturers.

The VLS’s chairman, Andrew Goddard, advises CM readers to be on their guard and expounds: "As space in motor factors, workshops and even petrol stations comes under greater pressure, there is a temptation for

lubricants marketers to adopt a ‘one size fits all’ approach, making multiple claims on individual lubricant products. Yet, modern engines require a precise balance of chemistry to keep them working at their best. Using the wrong oil can cause accelerated wear in gears and bearings leading to increased maintenance costs and, if left unchecked, eventual engine failure."

This advice highlights especially why you must not consider even toppingup with a different sequence oil to that specified by the manufacturer, even if it possesses the same viscosity. For example, using a ACEA A3/B3 oil on a diesel engine that requires an ACEA C2 specification will reduce particulate filter life, at the very least. Should you run an older car, its stated ACEA and API preferences might have become obsolete.

Do not presume that all ratings are always backward compatible; you may not be improving engine protection by adding the latest specification lubricant.

API sequences (diesel) NB: Older sequences CA, CB, CC, CD, CD-II, CE, CF, CF-2 are all obsolete.

Category Overview CK-4

2017 model year onwards with DPF protection. Backward compatible with API CJ-4, CI-4 with CI-4 PLUS and CH-4 service categories.

CJ-4

From 2010 model year onwards and backward compatible where API CI-4, CI-4 PLUS, CH-4, CG-4 and CF-4 are specified.

CI-4

2002 model year onwards. Formulated to sustain engine durability where exhaust gas recirculation (EGR) is used. Can be used in place of CD, CE, CF-4, CG-4, and CH-4 oils.

Some CI-4 oils may also qualify for the CI-4 PLUS designation.

CH-4

Introduced in 1998 Can be used in place of the obsolete CD, CE, CF-4, and CG-4 service categories.

ACEA sequences (petrol & diesel) The ACEA has A/B grades for petrol and diesel cars and vans.

The C grade covers vehicles possessing sophisticated exhaust after-treatment devices.

Category Overview A3/B3 For petrol and diesel engines with extended drain intervals/severe operating conditions as defined by the engine manufacturer.

A3/B4 For petrol and direct-injection diesel engines with extended drain intervals/severe operating conditions as defined by the Engine Manufacturer. Back compatible with A3/B3.

A5/B5 As A3/B4 but especially suitable for extended drain intervals for vehicles designed for low viscosity oils.

Category Overview C1 Lowest SAPS catalyst compatible for vehicles with extended drain intervals.

Suitable for modern after-treatment systems for petrol/diesel applications. Low viscosity oils C2 Mid-SAPS catalyst compatible for vehicles with extended drain intervals.

Suitable for modern after-treatment systems for petrol/diesel applications. Low viscosity oils C3 Mid-SAPS catalyst compatible for vehicles with extended drain intervals.

Suitable for modern after-treatment systems for petrol/diesel applications.

C4 Low-SAPS catalyst compatible for vehicles with extended drain intervals.

Suitable for modern after-treatment systems for petrol/diesel applications.

C5 Mid-SAPS catalyst compatible for vehicles with extended drain intervals using very low viscosity fuel economy oils. Suitable especially for GPFs.

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Understanding ENGINE OIL

ROB’S TOP TIP Protect your skin, when handling both new and old engine oils.

Old screw-on oil filters can be tricky to remove but you can buy various tools to help. Use hand pressure alone to fit the replacement.

Oil passes through the oil filter, before it goes anywhere else. Quality filters respect carmakers’ technical specifications, including filtration requirements, anti-drain values and bypass valve pressures. Never risk undermining your car’s lubrication system with unmarked, generic filters.

OIL ADDITIVES  Unlike engine oils, additives do not have to meet any technical standards. Does this give credence to the argument that you are wasting your money by dosing extra chemicals into your oil? Quite possibly. Yet, consider this: while your vehicle handbook might warn that the use of additives is either not recommended, or prohibited, we have heard from additive companies that certain carmakers use some of their products within their UK dealer networks. Unfortunately, we cannot elaborate on our sources of this information due to confidentiality, but it gives credence that you cannot dismiss all additives as ‘snake oils’. Additionally, with an increasing number of independent workshops and CM readers experiencing issues caused by ‘contamination’, additives have a more prominent role to play now than before.

According to Wynn’s, its oil additives contain viscosity index improvers, to aid stability especially at high temperatures, as well as containing extra detergents and dispersants to prevent combustion deposits from linking together to form sludge. Further claims include reducing oil ageing, plus controlling oxidisation and the resulting oil thickening and an increase in oil filter life. The brand highlights that these qualities benefit modern engines with extended service intervals and small capacity sumps in particular.

Yet, there is an argument that modern engine oils contain these additives already and dosing new additives can interfere with the delicate chemistry balance, potentially putting it out of specification. Shell Lubricants is one such company that adopts this stance. However, certain companies produce both engine oils and additives. LIQUI MOLY is a notable example, which claims that its additives are fully compatible with every common engine oil and cannot affect the chemistry of the engine oil negatively, if added correctly and as directed.

The more discerning motorist can also choose additive packages as protective measures. Most engine wear occurs immediately following a cold start, where internal metal-to-metal contact ensues between the engine firing and the oil arriving at its destinations. You can tell if this is occurring, should your oil light remain illuminated, or you notice a change in engine note within a few seconds after starting. Therefore, you might wish to consider an

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anti-wear additive, especially on an engine that is prone to this ‘dry start’ scenario, or one subjected to short runs and regular stop-start motoring. Yet, even with just this single aim, you can find a variety of different chemistries employed, dependent on your budget. LIQUI MOLY told us that its anti-wear additives range starts with Oil Additiv, which utilises molybdenum disulphide particles that cling to the engine’s surfaces. Alternatively, its Motor Protect product offers a chemical alternative that uses friction modifiers to smooth the metal surfaces, instead of physical protection. Cera Tec is a combination of both methods but it used more costly ceramic particles for its solid lubricant instead of molybdenum disulphide. When we questioned whether this makes any difference to the performance of a modern lubricant, the company revealed that tests at the automotive engine test centre, APL in Germany, showed that the wear protection level for engine oil doubles, when fortified with Cera Tec. While diesel engines tend to run at cooler temperatures, their oils tend to contain extra detergent additives to combat the higher quantities of soot produced. Diesel oil deterioration remains a significant problem and is one of the leading causes of oil starvation in specific applications, such as the Ford/Peugeot/Citroën/MINI 1.4 and 1.6-litre turbodiesels. It is unsurprising, therefore, that diesel-specific additives are available. BG Products, for example, highlights that its Diesel Oil Conditioner (DOC) maintains the oil’s viscosity, improves soot control, reduces friction and sludging and reduces oil breakdown and evaporation effects.

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GDI COMP

 While Low-Speed Pre-Ig afflicts turbocharged dire models, consider other iss lightweight but highly-str reduce internal friction fo and CO2 benefits, low ten up to 60% less force again compared to older indirec while compression has in 50%. This places the pisto strain to prevent the gase them and into the crankc Even in normal use, a sm oil collects behind the pis the high temperatures in restricts ring tension. The by gases increase, pressu excessively and contamin soot and fuel. This proble that are far from worn ou a field test in North Amer found that compression h in three cylinders of a For only 11,000 miles. It also t which experienced up to compression after 36,000 in employing a good qua dissolved the deposits be followed by a suitable oil the lubricant’s high-temp act as a preventative.

Renew any crushable washers, plug appears worn in such a wa consider that new replacement factors hold the most common washer, where needed.

As engines have become in fussy about their lubricant c best advice is to consult you The manufacturer’s specific should be listed, which inclu requirements for that partic over and above the proprieta standards. The VLS told us th see these standards printed packaging, where the lubrica suitable for use, meet the re

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Understanding ENGINE OIL

ROB’S TOP TIP Protect your skin, when handling both new and old engine oils.

ality filters respect carmakers’ rain values and bypass valve with unmarked, generic filters.

engine that is prone bjected to short runs t, even with just this different chemistries get. LIQUI MOLY told e starts with Oil Additiv, hide particles that cling ely, its Motor Protect ve that uses friction aces, instead of physical on of both methods but es for its solid lubricant . When we questioned to the performance of a vealed that tests at the in Germany, showed ngine oil doubles, when

at cooler temperatures, rgent additives to ot produced. Diesel oil problem and is one of in specific applications, MINI 1.4 and 1.6-litre efore, that diesel-specific , for example, highlights ) maintains the oil’s uces friction and sludging aporation effects.

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GDI COMPLICATIONS  While Low-Speed Pre-Ignition (LSPI) afflicts turbocharged direct-injection petrol models, consider other issues that afflict these lightweight but highly-strung units. In order to reduce internal friction for fuel consumption and CO2 benefits, low tension piston rings exert up to 60% less force against the cylinder walls, compared to older indirect injection engines, while compression has increased by as much as 50%. This places the piston rings under greater strain to prevent the gases from leaking past them and into the crankcase.

Even in normal use, a small quantity of engine oil collects behind the piston rings and, due to the high temperatures involved, it hardens and restricts ring tension. The result is that blowby gases increase, pressurising the crankcase excessively and contaminating the oil with soot and fuel. This problem affects engines that are far from worn out. When conducting a field test in North America, BG Products found that compression had reduced by 8% in three cylinders of a Ford 2.0-litre GDI’s after only 11,000 miles. It also tested a Mazda3, which experienced up to 14% reduction in compression after 36,000 miles. The solution lay in employing a good quality engine flush that dissolved the deposits behind the piston rings, followed by a suitable oil fortifier to enhance the lubricant’s high-temperature stability and act as a preventative.

Renew any crushable washers, prior to refitting the sump plug. If your plug appears worn in such a way that removal could be made difficult, consider that new replacements tend to be inexpensive and most motor factors hold the most common types on the shelf, which include the washer, where needed.

As engines have become increasingly fussy about their lubricant choices, the best advice is to consult your handbook.

The manufacturer’s specific standards should be listed, which includes requirements for that particular engine over and above the proprietary API/ACEA standards. The VLS told us that you might see these standards printed on the oil packaging, where the lubricant might be suitable for use, meet the requirements shop.kelsey.co.uk/subscription/CME

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When you have completed an oil change, pour the oil into your original can and take it to your nearest household refuse/recycling site, most of which have facilities for old engine oil’s safe disposal.

of, or might have passed (and paid for) the carmaker’s formal approval process. Yet, look at the wording on the bottle carefully, because ‘suitable for use’ is rather different to a formal car manufacturer sanction.

Who to trust?

While oil companies must ensure that the statements and specifications on their packaging are true, minimal

independent testing checks that engine lube is to its stated description. In the UK, the VLS acts on receiving complaints and has a procedure in place for testing and enforcement. More recently, the organisation has established a more proactive means of operating but it cannot test every oil grade from every brand.

Therefore, our best advice is to buy from a trusted brand from a trusted source.

The same advice applies to oil filters.

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Working on TIMING BELTS

Working on

Timing belts WWW.GSFCARPARTS.COM

Despite being the bane of many motorists’ lives, Rob Marshall argues that timing belts can be better than chains. He discusses their development, DIY replacement and the latest applications.

T

hings were much simpler in the old days. At one time, vital parts of the engine were prevented from smashing together, by being synchronised with a dependable chain. Buried within the bowels of the engine, it was intended to last the life of the car and, even if worn, the driver was alerted by a tell-tale rattle long before chain failure could cause the engine’s vital internals to become violently and expensively intertwined.

Replacing timing belts and their associated parts is a fiddly task, which is why garage labour rates are so high.

gears were used instead of timing chains, but even they could suffer from stripped teeth as the engine bearings became worn. Most OHV engines linked the camshaft and valves together through a series of rods and rockers, hence their description of ‘push-rod’, which required tappet adjustment at every major service.

Push-rod engines lasted until relatively recently, one of the most famous being Ford’s Endora-E; its lineage can be traced to the 1950s Kent unit, which ended its

days powering certain 1300cc variants of the first-generation Ford Ka. With the desire for more power, improved refinement and greater efficiency, overhead camshaft (OHC) engines replaced the push-rod’s valvegear, by placing the camshaft over the valves. This created a problem for the humble timing chain. With the camshaft positioned further away from the crankshaft, not only did it have to be longer, which dictated more elaborate

Never fit the timing belt alone. Install a kit that includes, if appropriate, a tensioner and idler roller. Depending on your car, you may need other parts – such as a water pump – if it’s driven by the timing belt.

Consider other parts that may be required.

Pictured on the top left of this Mitsubishi engine is a balance shaft belt, which must be replaced at the same time as the main timing belt. Note also the hydraulic belt tensioner, which utilises engine oil pressure in this dry belt application (circled).

WHAT GOE

u Timing belts rarely snap. M commonly, the fibre teeth w or else the belt simply falls f pulleys. Naturally, leaving th reasonable replacement inte to excessive deterioration o Yet, as a timing belt tends to the camshaft but also other the oil/water/high-pressure or the balance shafts, any w items, including within their will place the belt under add The belt is likely to be route and tensioner pulleys, with bearings on those compone belt longevity also. Should t fail, for example, the slack b come away from its pulleys.

As belt life is linked so dir health of those other compo wise to not replace the belt reason, most timing belts ar part of a kit that should incl and idler at the very least. H should consider taking the o step further, by renewing ot Water pumps, for example, t replacing at least every othe

tensioning mediums, but al of elongation from wear (ch ‘stretch’) increases the chan only failure but the engine’s also being affected. The solu mount a toothed belt outsid block, where it could not de oil contact. The timing belt, had arrived. Compared to a belts were more efficient, qu cheaper for car-makers to in As many readers will testi main disadvantage with tim the need for routine replace which the professional labou

Progress – back & forth An advantage of early side-valve and pre-1960s overhead-valve (OHV) engine designs was that their cam and crankshafts sat fairly close together within the engine block, meaning that the interlinking chain’s length was kept relatively short. On some engines, such as Ford’s Cologne V4 and V6 units, solid

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As assessing belt wear is almos never refit a used belt. This one missing teeth, the most commo

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elts

g certain 1300cc variants of ration Ford Ka. esire for more power, inement and greater erhead camshaft (OHC) ced the push-rod’s valveng the camshaft over the reated a problem for the ng chain. With the camshaft rther away from the ot only did it have to be dictated more elaborate

parts that may be required. e top left of this Mitsubishi ance shaft belt, which must be same time as the main timing the hydraulic belt tensioner, engine oil pressure in this dry n (circled).

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS WHAT GOES WRONG? u Timing belts rarely snap. More commonly, the fibre teeth will shred, or else the belt simply falls from its pulleys. Naturally, leaving the belt past a reasonable replacement interval can lead to excessive deterioration of its structure.

Yet, as a timing belt tends to not only drive the camshaft but also other items, such as the oil/water/high-pressure fuel pumps, or the balance shafts, any wear of those items, including within their bearings, will place the belt under additional stress.

The belt is likely to be routed around idler and tensioner pulleys, with deteriorating bearings on those components affecting belt longevity also. Should the tensioner fail, for example, the slack belt can simply come away from its pulleys.

As belt life is linked so directly to the health of those other components, it is wise to not replace the belt alone. For this reason, most timing belts are supplied as part of a kit that should include a tensioner and idler at the very least. However, you should consider taking the operation one step further, by renewing other items.

Water pumps, for example, tend to require replacing at least every other belt change

and this gives you the opportunity to refresh the coolant, renewing the cooling system’s anti-corrosive properties that diminish naturally with time.

Consider the condition of any parts that might fail and get tangled within the timing belt. Auxiliary, or balance shaft, belts can come off their pulleys and be dragged into the timing belt cover. Linked to this is a crankshaft pulley, many of which incorporate an internal damper (see Torsional vibration dampers – TVD).

As externally-mounted timing belts operate ‘dry’, the presence of oil, in particular, will degrade their structure, so attending to any coolant and oil leaks must be a priority. Obviously, no rotating belt should be allowed to abrade against anything and a part that has been fitted correctly should run freely – although missing bolts on the cover can cause the belt to rub through the plastic casing.

Belt life can also be shortened by incorrect fitting and careless handling.

Never crimp or twist a belt, because you can break the internal reinforcing fibres.

Never contaminate the belt with dirt or oil either – so keep your hands clean.

Getting the tension right is not always easy and methods differ between engines.

Some tensioners are spring-loaded. The one pictured here is not and requires a force of 30 newtons to be applied to the belt and its deflection checked as being 7.5mm at a specific point with the engine cold.

Apart from handling issues, getting the tension wrong is the most common mistake. Misaligning and overtightening the belt can be just as damaging as not tensioning it sufficiently. A belt that it too tight might promote a whining sound with the engine running; eventually, its teeth can strip. Over-tensioning also places an additional strain on other components, such as the high-pressure diesel pump bearings.

tensioning mediums, but also the risk of elongation from wear (chains do not ‘stretch’) increases the chance of not only failure but the engine’s timing also being affected. The solution was to mount a toothed belt outside the engine block, where it could not degrade from oil contact. The timing belt, or cambelt, had arrived. Compared to a chain, the belts were more efficient, quieter and cheaper for car-makers to install.

As many readers will testify, the main disadvantage with timing belts is the need for routine replacement, for which the professional labour cost alone

can run easily into many hundreds of pounds. When cambelts appeared first on mainstream cars, manufacturers tended not to be bothered too much about issues that would affect a car that was likely to be out of warranty by the time replacement was required. Nevertheless, timing belts still gave them more than a few headaches. Exaggerated renewal intervals on the service schedules meant that failing belts caused catastrophic engine damage. Interestingly, this issue appears not to have gone away entirely.

In the 1980s, belt change intervals tended to be quoted at between 40,000-

60,000 miles, but breakage could happen well before then. Today, official belt change quotations tend to be between 100,000-150,000 miles, or 10-15 years, but many experienced mechanics advise that 80,000 miles, or eight years, is a far more realistic interval. Even so, according to Andrew Vaux, Technical Training and Support Team Specialist for the Gates Corporation, a major belt manufacturer, modern timing belts may look very similar to those made in the 1960s but many unseen material changes have been made, including to the cord, jacket and tooth profile.

As assessing belt wear is almost impossible, never refit a used belt. This one exhibits missing teeth, the most common failure.

When fitting the timing belt for the first time, the belt may need to be placed in a specific position. On this Renault F-Type engine, two marks on the belt must align with the notches on both the crankshaft (pictured) and camshaft. The socket, incidentally, is holding the belt in place temporarily.

If removing the water pump, its condition will give you an idea of the cooling system’s soundness. This one was clean, due to regular coolant changes. Interestingly, this pump’s bearings were starting to stiffen after 80,000 miles of being driven by the belt, the official change interval of which was 150,000 miles.

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CAR PARTS, ACCESSORIES & TOOLS PREPARATIONS:

RESEARCH & TOOLS u As engines have become more sophisticated, the importance of not disturbing manufacturer-set timing has become even more critical.

Keith Anderson, technical writer at Laser Tools, notes that timing belt changing tools evolve all the time.

It is worth noting that some motor factors operate tool hire schemes.

Keith says also that obtaining the correct tools is the easy part, but obtaining specific manufacturer data can be more difficult and that DIYers should factor in the extra potential expense of sourcing data along with parts and tool costs.

For some basic engines, you may be able to use a long bolt of the correct diameter to lock the cam and/or crankshaft, instead of a dedicated locking pin. Be wary that a drillbit could fall into the crankcase.

More modern engines will require more advanced locking tools. It’s worth investing in the correct equipment, rather than risk the cam and crankshafts moving when the timing belt has been removed.

Certain examples of the latest generation three-cylinder units are utilising BIO technology. Pictured is Ford’s Fox EcoBoost engine, with the timing belt shown clearly as being situated within the engine block.

Realising that many fleet customers – responsible for more than 80% of new car sales in the UK – were factoring maintenance costs as part of their purchasing decisions, car-makers reacted by redesigning OHC engines to accept internal chains instead of timing belts. Except in very rare cases, there was no replacement interval, meaning that fleet car managers could trim a useful maintenance cost from their running calculations. Unfortunately, the traditional disadvantage with using long chains in an OHC application remained, not helped by modern considerations that include the quality of recycled metal, the need to reduce weight, very lengthy oil change intervals and, of course, manufacturing costs.

The result was that the supposed fitted-for-life timing chains were either rattling, or even failing, at very low mileages. As they were not designed to be replaced, some cars (such as those fitted with BMW’s N47 and N57 engines, which locate the timing chain between the engine and transmission) require the engine to be removed just to gain access.

This has become such an issue that certain car manufacturers, including the Volkswagen Group, have performed yet another volte-face, by replacing certain engines’ chains with belts. Thus, it may not be worth paying extra for a car fitted with a timing chain, because the unscheduled cost of replacing it can be far more involved and expensive, when compared to a timing belt.

The latest development – belt-in-oil More than a decade ago, in response to car-manufacturers’ demands to reduce weight and exhaust emissions wherever possible, Dayco introduced the belt-in-oil (BIO) timing belt. Presented first on the Ford Lynx 1.8-litre TDCi, the BIO timing belt replaced earlier engines’ Duplex chains, tensioners and sprockets with a special oil-resistant belt that comes pre-assembled with its own tensioner and pulleys. Unfortunately, customer experience with this specific application has not been as positive, compared to the earlier maintenance-free chain. As with dry timing belts, the teeth are prone to stripping but, as the BIO belt is situated

TORSIONAL VIBRATION DAMPERS  TVD u Essentially an upmarket term for a crankshaft pulley that incorporates a rubber damper, that is sandwiched between a pair of metal sections – these should be inspected for their condition after removal. As TVDs absorb vibrations from the crankshaft, they enhance the life of the auxiliary belt that, in recent years, has been responsible for driving an increasing number of components, from the alternator to the air-conditioning compresssor.

Apart from increasing the risk of the auxiliary belt failing and wrapping itself around the timing belt, vibrations that are caused by a failing TVD can cause the timing belt to delaminate – for this reason, it is inadvisable to fit solid pulleys if a TVD was fitted originally. Worse still, the TVD can break apart and introduce fragments into the timing belt housing.

For further information about inspecting a worn TVD, please make reference to http://bit.ly/2uzRaRp

Note that other parts of the auxiliary belt system, including any idlers, tensioners and even alternator overrun pulleys, should be inspected for rough movement and/or seizure.

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS within the engine, the fragments can work their way into the oil pump, or else block the oil pump strainer within the sump.

Any low oil pressure warnings, or difficulty in building pressure immediately following a cold start, might indicate a BIO problem.

Our technical partner for this article, TLC Ford of Wolverhampton, reports that many customers insist on making a belt-to-chain conversion to provide a life-long solution. Best of all, this task is simply a bolt-on conversion that is detailed later in this feature.

Given their drawbacks, one might presume that BIO belts are classed as an expensive mistake never to be repeated, but you would be wrong. The Ford EcoBoost 1.0 Fox engine, for example, has a timing belt running in 0W-20 oil, while both Peugeot-Citroën and the Volkswagen Group have adopted BIO systems also in their small-capacity engines. However, these units are relatively new and only time will tell whether BIO timing belts are as dependable as claimed, especially given long service intervals and the proliferation of Stop-Start systems, both of which place extra strain on the belt. Speaking to the motoring press, Herman Schulte, head of timing belt development at ContiTech, said that BIO technology was necessary to help car-makers meet 2020 CO2 targets of 95g/km, as well as making the timing gear lighter and more

If working on cars with variable valve timing, be wary of any extra work required, such as additional instructions to unload the hubs. Consider also replacing any worn hubs, while the timing belt is being renewed.

compact. Comparing both the original Duplex chain design with the BIO belt for Ford’s 1.8-litre TDCi, the latter is considerably lighter and likely to be much cheaper to produce.

DIY REPLACEMENT  Replacing a timing belt for the first time, or on an unfamiliar engine, can be daunting.

The key is research. Find out if there is sufficient space for you to undertake the operation at home without a four-post ramp. While some cars are straightforward, others might require significant dismantling before the belt can be accessed.

Also establish if any special tools are required to lock the camshaft or crankshaft, or to tension the new belt, before you start dismantling. In some cases, you can improvise, such as substituting the correct-diameter bolt to lock the crankshaft, for example, but this is not always possible, especially on newer cars. Buying the correct tools is an investment and their cost is a small price to pay considering the labour charges saved by doing the job yourself.

As labour tends to be the largest cost of a professional timing belt change, it is not worth cutting corners on parts. Insist on brand-new, original equipment (OE) quality parts from proven suppliers, such as GSF Car Parts, and not a cheap online purchase that might have been sitting on a damp garage shelf for five years. As it is almost impossible to assess the condition of a timing belt accurately by sight, it is not worth the risk.

Never forget the importance of torque wrench settings for all bolts that secure pulleys, tensioners and idlers to the engine. Should any bolt loosen, catastrophic engine damage is likely to result.

WET TIMING BELT REPLACEMENT FORD 1.8-litre TDCi  To improve access for photography, this engine was removed from the car, although belt changes can be performed in-situ, despite being considerably fiddlier.

1

 The top timing belt cover is secured by a selection of bolts.

Unscrew and store them carefully, then remove the moulding and check it for damage.

2

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& TOOLS

CAR PARTS, ACCESSORIES & TOOLS  Accessing the hole, through which the crankshaft locking pin is inserted, is difficult if airconditioning is fitted, necessitating further dismantling (see Step 5).

3

 Remove the rocker cover, including its gasket.

Have a fresh gasket to hand, ready for refitting, once the procedure has been completed.

4

 The single camshaft on this engine is locked after rotating and locking the crankshaft (see Step 3) prior to fitting another locking tool in the provided slot.

5

ming, be wary of any extra work to unload the hubs. Consider timing belt is being renewed.

nal Duplex chain design e TDCi, the latter is much cheaper to produce.

portance of torque wrench that secure pulleys, tensioners ine. Should any bolt loosen, damage is likely to result.

 To release the tension on the top belt, undo the single bolt that holds the tensioner to the engine block.

Retain the bolt and discard the tensioner.

6

 The top timing belt can be removed from its pulleys.

It’s usually not worth refitting a used belt, if you have removed it to conduct other repairs.

7

 On this engine, the top timing belt drives the camshaft via the diesel pump; remove the pump pulley’s bolts and detach it from the pump shaft.

8

TDCi

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 Undo and retain the nuts that secure the metal diesel pump engine oil seal cover to the engine face.

Discard the old part.

9

 Remove the camshaft pulley bolt. In the absence of a Woodruff key, note that this pulley is tapered, so it will require levering gently and evenly from the shaft.

10

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS WET TIMING BELT REPLACEMENT FORD 1.8-litre TDCi continued

Unscrew the fixings that hold the front engine cover to the engine block and lift it away, ensuring you avoid distortion.

11

The water pump is driven by the auxiliary belt and not the cambelts on this engine, but its pulley is removed anyway, to improve access.

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Even if this engine were fitted to the car, it would require supporting from beneath and the offside upper engine mounting would have been removed.

13

 The crankshaft pulley nut can be very tight – although this one came undone easily.

The pulley can then be inspected (see Torsional vibration dampers – TVD).

14

 The front aluminium engine cover also houses the oil pump and is removed by unscrewing its bolts (see Steps 18 and 19).

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The replacement wet be just the belt on its own.

 The wet belt has shredded its teeth, causing the timing between the crankshaft and diesel pump (and, therefore, the camshaft) to become out of sync.

16

 Remnants of teeth can also be seen within the wet belt assembly. TLC Ford also advises that the sump be removed and the oil pump strainer checked.

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WET TIMING

 The stray belt teeth can also find their way into the oil pump and result in oil pressure being lost. Remove the Torx screws that hold the cover in place...

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 ...and lift out the pump’s meshing gears. Clean the remnants of the damaged timing belt, refit the pump components and bolt the cover back into position.

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If you prefer not to repla does not require periodi

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS

& TOOLS

 Remove the oil pressure-fed timing belt tensioner by unscrewing it from the engine block. You may decide to replace it, if its condition is unknown.

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TDCi continued

 The complete wet belt assembly can be lifted from the engine, which includes the belt, the plastic guide rail and its pair of pulleys.

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his engine were fitted to it would require supporting and the offside upper engine ld have been removed.

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The belt must be fitted so that the red marks on the belt align with the notches on the pulley. One is provided for the crank sprocket, two on the diesel pump.

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The replacement wet belt assembly is supplied from Ford as a complete kit and not just the belt on its own.  Fit the wet belt assembly. One dowel is supplied on the crankshaft (see Step 29). In the inset pic, the diesel pump alignment mark must point to the 12 o’clock position.

24

 Screw-in the tensioner, not forgetting to replace the crushable copper washer between the tensioner and the engine block.

Reassembly continues from Step 33.

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WET TIMING BELT CONVERSION TO CHAIN 1.8-litre TDCi

26

If you prefer not to replace the wet belt, a chain kit is a simple bolt-on conversion that does not require periodic replacement.

You will also need to buy a hub assembly so that you can fit the chain sprocket to the diesel pump shaft.

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS  The hub assembly is a taper fit onto the diesel pump shaft. Fit and tighten the securing nut to hold it in place.

28

 Fit the complete chain cartridge assembly, noting that the crank dowel (inset pic) must locate within the bottom sprocket’s drilled hole.

29

Fit the dry timing belt’s b onto the diesel pump sp assembly. The bolt hole pattern it can be installed one way only

36

 The circled pair of Torx screws retain the chain guide to the engine block. Ensure that they are tight before proceeding.

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 You will need to turn the hub behind the pump sprocket by rotating the nut – also pictured as being tightened in Step 28 – to reveal the threads.

31

Fit a new timing belt ten should come as part of th might wish to use a thread-lock bolt threads, but do not tighten

39

Fit the 32  tensioner (see Step 25) and insert the bolts that retain the sprocket. Note that the square hole should be aligned at the 12 o’clock position.  Fit the oil pump cover with a new gasket, noting that the slots on the crankshaft nose must align with those of the oil pump drive (as pictured).

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 Once the securing bolts are tightened evenly, it is advisable to replace the crankshaft oil seal, prior to refitting the front cover plate and crankshaft pulley.

34

With the timing chain te loose, the plate is turned alignment mark corresponds w peg (circled), then the bolt is re

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CHANGE IN

 Be extremely cautious abou all timing belts are able to rea replacement requirements, wi timing belts tend to be placed that the timing belt on a low-m sooner than one on an identic If you are looking to buy an mileage is too low to justify a

The diesel 35  pump seal is supplied with its new outer case. Once fitted over the sprocket end, remove and discard the plastic tool and tighten the locating nuts.

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Working on TIMING BELTS

CAR PARTS, ACCESSORIES & TOOLS

Fit the dry timing belt’s bottom pulley onto the diesel pump sprocket/pulley assembly. The bolt hole pattern ensures that it can be installed one way only.

Once fitted, the two indented timing marks (highlighted white in the picture above) should align and point at the 12 o’clock position.

Ensuring that the camshaft is still locked securely (see Step 5), refit the top timing belt pulley and tighten its fixing bolt.

Fit a new timing belt tensioner, which should come as part of the belt kit. You might wish to use a thread-lock solution on the bolt threads, but do not tighten the bolt yet.

Note that the pictured arrow on the tensioner should point towards the rear of the engine and indicates that its adjuster must be turned anti-clockwise (see Step 42).

Thread the belt onto the pulleys. Never crimp a new belt and ensure that the embossed arrows run in the same direction as the pulleys with the engine running.

With the timing chain tensioner bolt loose, the plate is turned until the alignment mark corresponds with the square peg (circled), then the bolt is retightened.

After removing the locking plate/pins, the crankshaft is rotated two complete revolutions and the timing marks are rechecked for correct alignment (see Step 37).

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CHANGE INTERVALS  Be extremely cautious about following official change intervals to the letter, because not all timing belts are able to reach them. Car-makers supply both time and mileage-based replacement requirements, with the important proviso of ‘whichever comes first’. This is because timing belts tend to be placed under greater stress in stop-start motoring conditions, so it’s likely that the timing belt on a low-mileage car that has been used exclusively for urban trips will fail sooner than one on an identical vehicle that has covered similar mileage on long motorway runs.

If you are looking to buy an older low-mileage car, disregard the vendor’s assurance that the mileage is too low to justify a timing belt change, when its age indicates otherwise.

The ancillaries are replaced, starting with the timing belt cover, then the rocker cover, the water pump pulley, the engine mounting, etc.

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THANKS TO TLC Ford, Parkfield Road, Wolverhampton, West Midlands WV4 6EL. www.tlcford.co.uk Tel: 01902 402274 Email: info@tlcford.co.uk

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Working on TIMING CHAINS

Timing Chains With car owners running scared of timing belts, chains have experienced a resurgence. However, Rob Marshall says that choosing a car with chain-driven valvegear might not be your best option after all.

F

or many people, swapping the once reliable timing chain with a flexible belt was a serious error of judgment. After all, old-fashioned chains often outlasted the engine, whereas a timing belt is another perishable service part. In addition, the owner has to bear the considerable routine cost of renewing not only the belt but also its tensioner and, possibly, the water pump, just in case the parts fail without warning and wreck the engine.

Why belts and the change of heart?

Contrary to the views of many sceptics, timing belts were not introduced to maximise dealer workshop and parts’ sales profits, although this might have been a welcome by-product for some manufacturers. As overhead valve engines (such as the type pictured in Steps 1-15) had their camshafts situated beneath the cylinder bores, the timing chain’s length was kept relatively short. Although the ensuing overhead cam (OHC) designs SHACKLE PLATE

SLEEVES/ROLLERS

PINS Steel wire

Steel strip Conventional stamping Recutting Precision blanking Hardening & tempering Barrel finishing

Steel strip Winding Calibration Barrel finishing Case hardening Shot peening Assemble rollers

Cut Mould Grind

The process of making a good quality chain is complex, but it is difficult to differentiate it from a low-grade, low-cost alternative that has not been hardened.

Always buy from a reputable supplier that offers a warranty.

Heat treatment chromisation or gas nitriding barrel finish

Inner shackle plate Press in sleeves

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Press in pins

Assemble - Rivet - Oil - Check

u Timing chains and belts with its valves, via the cams efficiency and longevity. Th Tensioners can operate i simple strip of sprung stee between the sprockets. Oth within the casing of which engine’s lubrication system poor maintenance and inco We have also heard of th against the chain, breaking is also promoted by poor in results in the chain not run Sprocket teeth can also w are made from either a soft Especially important for lon about, nor jump from its sp whenever the chain and te

Generally, two chain designs are (at the top of the photo) reduce on the sprockets, but is noisier i compared with a silent type (pictured below).

The timing chain links the crankshaft to the camshaft.

On this Volkswagen TSI engine, timing chain problems are common complaints. Note the presence of a second chain, which drives the oil pump.

positioned the camshaft above the pistons and valves, ridding the engine of power-sapping, maintenance-intensive and noisy rockers and pushrods, the timing chain had to extend from the bottom to the top of the engine.

Ensuring adequate lubrication, to reduce the chance of the timing chain wearing out or breaking prematurely, gave engine designers plenty to think about. Although wear is referred to as ‘stretch’, the term can be misleading; the chain’s pins and holes wear and develop slack, with the resulting elongation causing the camshaft’s

How timing

rotation to lag behind that of the crankshaft. Due to its increased length in OHC applications, a potentially greater increase in dimensions is likely to affect both valve and ignition timing more acutely. Some OHC designs were fitted with chains, including those fitted to various Jaguars, certain fourcylinder Saabs, plus early attempts in the old four- and six-cylinder E-series range from BMC, the Maserati-engined Citroën SM and Triumph’s Stag V8, but those particular engines weren’t noted for chain reliability and ease of repair.

Timing belts, however, require no external lubrication and tend to be not only virtually silent, but also efficient in operation. They have become ubiquitous in the UK since Vauxhall first fitted them to its 1.6- and 2.0-litre Victor FD engines. Nevertheless, timing belts developed a poor reputation very quickly. Early lifespans were short, sometimes less than 30,000 miles.

Even today, many belts and their shop.kelsey.co.uk/subscription/CME 12/09/2021 09:40

components struggle to reac stated replacement interval technicians advise that they prematurely. Practical issues the parts within a cramped bay, plus early confusion ab tension the belt correctly, di Somewhat unfairly, the au repair trade does not enjoy a reputation, with suspicious, mechanically minded motor taking kindly to receiving a bill for replacing component seem to make any discernib to how the car drives afterw pressure to reduce both run servicing costs (mainly to ap fleet sector), manufacturers new generation of cam-chai rid their customers of the de

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ains

g behind that of the Due to its increased length cations, a potentially ase in dimensions is likely h valve and ignition timing Some OHC designs were hains, including those ous Jaguars, certain fours, plus early attempts in and six-cylinder E-series MC, the Maserati-engined nd Triumph’s Stag V8, but lar engines weren’t noted ability and ease of repair. ts, however, require no ication and tend to be not silent, but also efficient They have become the UK since Vauxhall em to its 1.6- and 2.0-litre gines. Nevertheless, timing ed a poor reputation very lifespans were short, ss than 30,000 miles. many belts and their

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Working on TIMING CHAINS

How timing chains work u Timing chains and belts synchronise the engine’s pistons, via the crankshaft, with its valves, via the camshaft(s), which is vital to ensure proper performance, efficiency and longevity. The chains must be kept taut.

Tensioners can operate in several ways. On older engines, they can be a simple strip of sprung steel, which bears against a portion of chain that runs between the sprockets. Other types involve a piston that acts indirectly on the chain, within the casing of which is a strong spring. Alternatively, pressurised oil from the engine’s lubrication system can be used but a cracked tensioner housing, worn seals, poor maintenance and incorrect oil will reduce its effectiveness.

We have also heard of the rubber/plastic tensioner ends, which bear directly against the chain, breaking up in some cases, due to poor quality control. Chain wear is also promoted by poor installation, such as fitting a sprocket incorrectly, which results in the chain not running true.

Sprocket teeth can also wear and reusing worn gears, especially if they are made from either a soft metal, or nylon, to reduce noise, is a false economy.

Especially important for longer chains, the guides, or rails, help to ensure the chain can neither vibrate, flap about, nor jump from its sprockets. Most modern engine guides are made from plastic and should be renewed whenever the chain and tensioners are replaced.

Generally, two chain designs are favoured. A roller chain (at the top of the photo) reduces friction and wear on the sprockets, but is noisier in operation compared with a silent type (pictured below).

components struggle to reach their stated replacement intervals and most technicians advise that they be replaced prematurely. Practical issues of accessing the parts within a cramped engine bay, plus early confusion about how to tension the belt correctly, didn’t help.

Somewhat unfairly, the automotive repair trade does not enjoy an enviable reputation, with suspicious, nonmechanically minded motorists not taking kindly to receiving a large repair bill for replacing components that do not seem to make any discernible difference to how the car drives afterwards. Under pressure to reduce both running and servicing costs (mainly to appease the fleet sector), manufacturers developed a new generation of cam-chain engines to rid their customers of the derided belt.

Not so perfect While it is reasonable to presume that modern design, engineering and manufacturing techniques have solved the timing chain’s foibles in an OHC application, many modern cars can experience problems. As the chain, tensioner and guides are located inside the engine and cylinder-head castings, significant dismantling is required to access the parts and some models might even require the engine to be removed.

As with timing belts, however, certain specialists view timing chains as a service part, even if the manufacturer did not intend them to be so. For example, the 2.8-litre VR6 design, used on many Volkswagen models, includes several chains and the unofficial recommendation is to have them all

Some kits may include extra items, including bolts, gaskets, guides, tensioners and sprockets, such as this full kit for Ford’s 2.0-litre diesel engines, which are fitted to Transits and Mondeos from 2000-2007.

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ROB’S TOP TIP

Be wary if your engine possesses balancer shafts – ensure that they are timed correctly.

changed every 100,000 miles, presuming that they have not failed earlier.

Some engine designers have been accused of underrating timing chain specifications. Yet, packaging, weight, longevity, efficiency and cost tends to influence engineers into making a compromise, which is why heavy-duty duplex chain layouts are not used in all cases. Should your car experience timing chain issues, do your research carefully to see if any updated parts are available from either the carmaker’s franchised outlets or through aftermarket suppliers. When purchasing parts, be aware that many main dealerships tend to price components individually, whereas quality aftermarket suppliers are more likely to supply a kit of parts that might include the chain, gaskets, tensioners, guides and sprockets, depending on the application. You may find that a split-link timing chain option might be available, but you will need to obtain the appropriate tool to crimp the chain’s links. Many engineers advise you to remove the entire assembly and inspect it for other worn parts that

When buying parts, be aware that many kits for vehicles with variable valve timing are different and may include the variable valve timing sprocket/hub assembly.

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Working on TIMING CHAINS

Identifying timing chain failure

u As with a broken timing belt, should the chain fail completely, the engine will not only stop running but the valves and pistons are also likely to collide, which could cause major mechanical damage.

Identifying impending chain failure should be your priority. As chain elongation/‘stretch’ (and/or inadequate tension) tends to precede breakage, look for tell-tale signs such as a scraping and rattling noise emanating from the timing chain area, which may be more noticeable on start-up and at tickover.

As timing chain ‘stretch’ affects the timing settings, poor running might result, but this can be masked by sophisticated self-learning engine management systems that compensate for the mechanical wear. Some cars might display an engine fault warning light on the dashboard panel, but the fault codes generated are unlikely to point directly to a worn timing chain.

Should you drain your oil at home, the presence of any plastic ‘pips’ might indicate a disintegrating chain guide, meaning that the affected components must be checked immediately. In some cases, removal of the sump could be necessary, to check for a clogged oil pump strainer.

could shorten the life of a replacement chain. Plus, the risk of dropping something inside the engine accidentally could land you with even more work.

Looking for quality Even original equipment (OE) suppliers do not always get the quality right. In a 2012 interview with Germany’s AUTO BILD magazine, Volkswagen Group’s head of quality control assurance attributed timing chain failure on the 1.4-litre TSI petrol engine to a supplier using worn tooling.

Perhaps undermining that conclusion, the report also highlighted improved timing chain tensioners that were available for other engines in the TSI range, although the journalist did not provide a definitive answer as to why chain failure was so widespread.

Stop-start driving (not helped by eco Stop-Start technology), city conditions and poor oil quality were mentioned, all of which put the chain under extra strain. Interestingly, more recently-built TSI direct-injection petrol engines are fitted with timing belts.

Even though other manufacturers are experiencing issues with timing belt longevity, official recalls for free timing chain replacements are unusual, because they tend not to be safety-critical.

For example, even after experiencing complaints that attracted the eyes of BBC Television’s Watchdog consumer affairs programme in 2013, BMW UK’s press office took almost three weeks to confirm to Car Mechanics that it had not issued any kind of recall for the N47 2.0-litre diesel timing chain. However, CM understands that BMW has issued what it calls “a quality enhancement measure” for the N47 timing chain, but the company insists that this “must not be seen as an indication of a fault 32 Car Mechanics 30-37.indd 6

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OVERHEAD

A worn sprocket will wear a new timing chain prematurely. Not replacing it can be a false economy.

or inherent defect with this particular engine.” Nevertheless, the sheer number of problems encountered by owners might lead a reasonable person to conclude otherwise, especially as repair entails the engine being removed from the car and reports indicate that the cost can reach £8000 or more.

Manufacturers also tend to state

Although an engine warning lamp may indicate a cam sensor fault, it’s possible that the real issue lies with the timing chain.

DIY prospects uReplacing a timing chain at home can vary from being mildly challenging to almost impossible, especially if the engine needs to be removed and special tools are required. To illustrate how the procedures differ, the following stages show the timing chain replacement on an old-style overhead valve engine, which is relevant for the Ford Kent-based HCS and Endura-E family of 1300cc engines, compared to a BMW E87 1-Series, which is fitted with a double overhead camshaft 2.0-litre N46 petrol engine. Despite being a 2006 model with approximately 30,000 miles recorded, it was suffering from poor running that was mainly due to an elongated timing chain.

The crankshaft pulley bol tight and tricky to remove someone has applied a threadin the past. Inspect the pulley’s renew the bolt if necessary.

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ROB’S TOP TIP

Regular engine oil and filter changes will ensure better lubrication of the chain, reducing the rate of wear.

that timing chains are engineered to last for the life of their engines, thus failure must be down to neglect. Infrequent oil changes will not only wear the chain physically, but could also affect the ability of a tensioner to work properly, especially if it relies on a steady supply of clean oil. Should your car be within its manufacturer’s warranty period and serviced outside of the main dealer network, including at home, you must ensure that you retain all records relating to not only the oil change mileage, but also the exact type of oil and filter used, both of which must be to OE specifications.

The vehicle manufacturer is not obliged to provide goodwill gestures once the warranty period has expired, and if they are offered, they tend to be more generous to those customers who have invested in main dealer servicing.

Generally, the burden of proof is on the owner to demonstrate a manufacturing defect, and although this is sometimes possible, using the services of an independent parts inspection expert (such as Dekra, www. dekra-expert.co.uk), it will require that the part be removed from the car for analysis, which may involve the vehicle being off the road for some time.

If legal action is taken, you may have to seek judgement against the vehicle manufacturer, which may not be the same as the importer.

While ascertaining the quality of timing chains and kits is not easy, do not be tempted by the cheapest parts available. Although our independent sources did not wish to be named, concerns were voiced about the grade of metal used for timing chains, in general. The best advice is to always buy parts from a reputable retailer that offers a reasonable warranty. shop.kelsey.co.uk/subscription/CME 12/09/2021 09:40

Check that the timing ma usually when piston 1 is a centre (TDC). Here, dot marks a onto the engine plate and both rotate the crankshaft until they

4

On this engine, the timing slackness is controlled by metal tensioner that bears agai tensioner is fitted to the chain c must be cleaned and degreased

7

Also check the condition Although penetrative co unlikely, the ends of some spru can wear through the cover, wh in a severe oil leak.

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Working on TIMING CHAINS

g chain false economy.

OVERHEAD VALVE ENGINE

The crankshaft pulley bolt/nut can be tight and tricky to remove, especially if someone has applied a thread-lock solution in the past. Inspect the pulley’s condition and renew the bolt if necessary.

The timing chain cover tends to be secured by a variety of bolts, screws and nuts. Remove them carefully, but note that the cover can be made from thin metal and can distort if too much pressure is applied.

With the cover off, the camshaft and crankshaft gears, chain and oil thrower are all accessible. Clean away any old gasket material, ensuring that remnants cannot fall into the sump.

Check that the timing marks line up, usually when piston 1 is at top dead centre (TDC). Here, dot marks are punched onto the engine plate and both sprockets; rotate the crankshaft until they are aligned.

On this engine, the camshaft gear is held in place by two bolts, with a rectangular locking plate that prevents them from unscrewing. Once removed…

…the camshaft sprocket can be freed (with its Woodruff key, if fitted), along with the timing chain. Here, the oil thrower and crankshaft gear simply pull away from the crankshaft nose.

On this engine, the timing chain’s slackness is controlled by a sprungmetal tensioner that bears against it. The tensioner is fitted to the chain cover, which must be cleaned and degreased.

Assuming that any other consumable parts are easy to access, it might be foolish not to replace them. Here, the crankshaft oil seal was levered from the housing and a new one pressed into place evenly.

When replacing the timing chain, always renew a worn tensioner. You can make a rough assessment of its condition by inspecting the wearing surface for obvious grooves – as shown here.

Also check the condition of the cover.

Although penetrative corrosion is unlikely, the ends of some sprung tensioners can wear through the cover, which can result in a severe oil leak.

The tensioner on this engine is held to the cover by a pin that is retained by several circlips. The pin must not exhibit wear grooves or be twisted out of shape – any circlips must be renewed.

Inspect the timing gears’ teeth for any wear. Note that the unused crankshaft sprocket possesses sharp teeth (pictured at right) compared with the blunt ones on the removed part.

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ROB’S TOP TIP

2

3

Regular engine oil and filter changes will ensure better lubrication of the chain, reducing the rate of wear.

o last for the life of their failure must be down to quent oil changes will not e chain physically, but could e ability of a tensioner erly, especially if it relies upply of clean oil. Should ithin its manufacturer’s iod and serviced outside ealer network, including must ensure that you ords relating to not only e mileage, but also the oil and filter used, both t be to OE specifications. manufacturer is not obliged odwill gestures once the iod has expired, and if ed, they tend to be more hose customers who have main dealer servicing. the burden of proof er to demonstrate a ng defect, and although mes possible, using of an independent parts pert (such as Dekra, www. t.co.uk), it will require be removed from the car which may involve the off the road for some time. n is taken, you may have ment against the vehicle r, which may not be the mporter. rtaining the quality of s and kits is not easy, do ed by the cheapest parts hough our independent ot wish to be named, e voiced about the grade d for timing chains, in best advice is to always m a reputable retailer reasonable warranty.

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OVERHEAD VALVE ENGINE continued

Reassemble and refit the timing sprockets, oil thrower, chain assembly and gasket with new parts, where appropriate.

Double-check that the timing marks align before tightening any retaining bolts.

13

As this engine’s chain is oiled by splash lubrication (and it was being rebuilt), the chain is treated with an engine assembly lubricant. Oiling the chain is not always necessary – check your workshop manual.

14

When fitting the cover, the tensioner is levered out of the way, so that it bears against the chain and holds it under tension when released. The retaining nuts/bolts must be tightened evenly.

15

Rotate the engine until th piston is at TDC. A dedica tool must be used, which is inse the engine block and flywheel crankshaft into position (see al

9

OVERHEAD CAM ENGINE

An economical repair is impossible without proper diagnosis. Apart from chain rattle and a loss of power, a diagnostic check reveals other unrelated issues with the variable valve lift mechanism (Valvetronic).

u To access the rocker cover, wiring is disconnected and a number of plastic covers, including the scuttle panel beneath the windscreen, are either removed or manoeuvred away from the work area.

Multiple retaining bolts are unscrewed (see also Step 38), before the rocker cover, its gasket and sensor plug are removed and stored in a safe place. It is prudent to also take out the spark plug tubes.

Although this feature concerns the chain specifically, it is worth inspecting the camshafts and variable valve timing mechanism for any obvious faults, including fractures and broken springs.

Remove the bolts and brackets. Carefully pull the pair of solenoids, which control the VANOS (valve overlap timing), from the cylinder-head, ensuring that you do not damage the rubber O-ring seal (see Step 36).

Alternatively, you can sim the centre of the pulley, Allen key bolts tend to be eithe corroded, meaning that it is be the complete pulley.

Dirty oil not only affects timing chain life, it can also damage the variable valve timing. Here, the solenoid’s gauze has prevented abrasive particles from causing additional damage – they can clog completely.

Inspect the chain’s condition. This one appeared to be tight, until the engine was turned over slightly, then the true state of the slack was revealed; this particular chain had also jumped a tooth, ruining the timing.

Remove the undertray, prior to unhooking the auxiliary belt, by manipulating the sprung tensioner. If you find fraying or splits, consider renewing it (and the alternator’s one-way clutch, if fitted).

Another of the aforemen is adjacent to the soleno but the camshaft sensor’s wirin to be disconnected to improve bolts behind the plugs can then

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Situated low down on th front of this engine, the tensioner can be unscrewed an from the block. This unit does n pressure, but utilises the streng

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Working on TIMING CHAINS

Rotate the engine until the number 1 piston is at TDC. A dedicated locking tool must be used, which is inserted into the engine block and flywheel to fix the crankshaft into position (see also Step 35).

To check if the camshafts are in their correct position, a timing tool is mounted to the VANOS hubs’ stator plates. As the hole on the inlet camshaft does not engage, the timing requires resetting (see Step 16).

The crankshaft pulley, chain sprocket and the balance and oil pump gears rely on the main bolt (pictured in Step 30) being tightened to 300Nm. Locking the flywheel is prudent, because the timing pin could break.

Situated low down on the offside front of this engine, the timing chain tensioner can be unscrewed and removed from the block. This unit does not work by oil pressure, but utilises the strength of…

…an internal spring. Once the tensioner is removed, it can be compared with a brand-new part. Note that the original’s plunger is retracted partially, meaning that replacement is required.

Remove the crankshaft pulley very carefully, because you risk dislodging the balance shaft and oil pump sprockets inside the engine (also see Step 28). Here, the customer did not want the sump to be removed.

the bolts and brackets. Carefully pair of solenoids, which control ve overlap timing), from the ensuring that you do not bber O-ring seal (see Step 36).

Alternatively, you can simply take off the centre of the pulley, although the Allen key bolts tend to be either very tight or corroded, meaning that it is best to remove the complete pulley.

The technician slackens the VANOS hub bolts and rotates the cams, until they mesh with the dedicated locking tools in position. Pictured is the rear cam locking tool – this verifies that the timing has been reset.

The fixings, which retain the chain and guide assembly, are hidden beneath three Allen key-headed plugs. One of them is situated behind the engine lifting eye on this engine; another is to the left of the crankshaft pulley.

the undertray, prior to ng the auxiliary belt, by he sprung tensioner. If you find s, consider renewing it (and the e-way clutch, if fitted).

Another of the aforementioned plugs is adjacent to the solenoid apertures, but the camshaft sensor’s wiring may need to be disconnected to improve access. The bolts behind the plugs can then be loosened.

Another securing bolt can be found at the top of the guide – on some engines in this family you might find there are more than one. Remove the bolt, but do not drop it!

After double-checking that they cannot move, unscrew the bolts – one of which is employed for each camshaft – which hold the VANOS hubs and sprockets in place.

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tting the cover, the tensioner is out of the way, so that it bears ain and holds it under tension . The retaining nuts/bolts must venly.

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Working on TIMING CHAINS

OVERHEAD CAM ENGINE continued

The combined timing chain and guide assembly can be manipulated out of the block/cylinder-head and onto a suitable surface for closer inspection. Nothing must be allowed to drop into the engine.

Refit the crankshaft pull retaining bolt (as shown that the flywheel is locked as p applied. Resist using a thread-l on the bolt’s thread and tighten

Always buy parts that match at least OE quality. Main dealers usually price parts individually, whereas the aftermarket tends to offer kits that include guides, tensioners and the chain.

The front camshaft lockin shown in place, indicatin positions as being correct, comp 10. Obviously, the tool must be correctly so that it engages with

You will have to assemble the new kit, adding the old sprockets (if appropriate). On this example, care must be taken to ensure that the bottom sprocket is fitted the correct way round.

The solenoids are cleane sure that the rubber O-ri cylinder-head are not pushed in as the solenoids are inserted. R solenoids, their securing bracke

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The bolts that secure the guide and chain assembly are accessed through the plug holes and are removed next. It’s possible that they are of different lengths; if so, do not mix them.

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Inspect the removed guide assembly closely and compare it against a new part to verify that no plastic has broken off. If it has, you should remove the sump to retrieve the remnants.

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Comparing the removed chain against a new part shows how much the original has elongated. Here, the difference is considerable; further ‘stretch’ could have ruined the engine.

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Should you find that any part of the guide has broken, it must be retrieved by removing the sump. It is advisable to clean the oil pump strainer, but inspect the timing chain housing for fragments in any case.

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Verify that the sprockets for both the oil pump and balance shafts have not dropped into the sump. Here, a finger is inserted through the crank pulley’s aperture to check that all is well.

28

The replacement timing chain guide assembly, chain and bottom sprocket is then positioned inside the engine. The guide securing bolts are tightened and the plugs refitted.

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As this car’s ECU is self-le needs to be reset with di equipment, so that it can adjus controlling an engine that is ru corrected mechanical timing.

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Working on TIMING CHAINS

de assembly can be manipulated d onto a suitable surface for ed to drop into the engine.

Refit the crankshaft pulley and retaining bolt (as shown), ensuring that the flywheel is locked as pressure is applied. Resist using a thread-lock compound on the bolt’s thread and tighten it to 300Nm.

The VANOS hub and sprocket assemblies are refitted in their original positions and the central bolt is hand-tightened. To prevent them from being mixed, BMW marked the hubs to indicate inlet or exhaust.

The replacement tensioner is fitted with a new washer and tightened to 65Nm. If reusing the original tensioner, replace the crushable washer, to reduce the chance of a future oil leak.

ast OE quality. Main dealers hereas the aftermarket tends ers and the chain.

The front camshaft locking tool is shown in place, indicating the timing positions as being correct, compared with Step 10. Obviously, the tool must be positioned correctly so that it engages with the hubs.

With the camshafts locked, use a torque wrench to tighten the VANOS hub securing bolts to 20Nm, followed by two clockwise turns of 90°.

The camshaft locking tools are removed and the pin is extracted from the engine block/flywheel (as shown). The engine is then rotated several times by hand and the timing is rechecked.

w kit, adding the old sprockets care must be taken to ensure rrect way round.

The solenoids are cleaned first. Make sure that the rubber O-rings inside the cylinder-head are not pushed into the engine as the solenoids are inserted. Refit the two solenoids, their securing brackets and bolts.

Prior to refitting the rocker cover (not forgetting the plug tubes), check the timing again, by inspecting the position of both the camshafts and the crankshaft pulley, when the locking pin is reinserted.

Reconnect all removed electrical connections, including those for the camshaft position sensors (the photograph shows one situated on top of the rocker cover), coil earths, leads, etc.

acement timing chain guide y, chain and bottom sprocket ned inside the engine. The bolts are tightened and ed.

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With thanks to:

Stourbridge Automotive Ltd 6 Gainsborough Trading Estate Rufford Road Stourbridge DY9 7ND. enquiries@stourbridgeautomotive.co.uk Tel: 01384 377792 stourbridgeautomotive.co.uk

As this car’s ECU is self-learning, it needs to be reset with diagnostic equipment, so that it can adjust quickly to controlling an engine that is running with corrected mechanical timing.

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Once the fault codes are cleared and the engine started, the various plastic panels can be refitted beneath the bonnet, prior to the car being road-tested and rechecked diagnostically, to verify that all is well.

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Variable Valve Timing (VVT)

UNDERSTANDING VVT

Variable Valve Timing A vital contribution to modern motoring or an unnecessary complication?

Rob Marshall explores the many permutations of variable valve timing and reveals how the most common faults can be identified and eradicated.

Variable valve timing optimises valve opening, closing, lift and duration, depending on engine speed and load.

W

ith motorists demanding more power from less fuel, as well as ever-increasing restrictions on tailpipe emissions, variable valve timing (VVT) is equipped to the majority of today’s vehicle engines. As its name implies, VVT alters the valve timing from an otherwise fixed setting, depending on engine speed and load. It also alters lift on some systems, which is how much the valve head is lifted from its seat.

There are several methods of achieving VVT and valve lift control, thus carmakers’ marketing departments went into overdrive to coin a bewildering list of names, abbreviations and acronyms to differentiate their versions, including AVCS/AVLS (Subaru), CVTCS/N-VCT (Nissan), VarioCam (Porsche), VCT (Ford), VVC (MG Rover), VVTi/VVTLi (Toyota), VTEC (Honda) and VANOS/ VALVETRONIC (BMW).

Why has VVT become necessary?

Although a form of VVT was in use during the age of steam, then adopted later by fighter aircraft, it took the motor industry far longer to incorporate systems that circumvented the restrictive nature of fixed valve 38 Car Mechanics

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timing. Just like turbochargers, the first automotive applications of VVT were introduced to increase output. More recently, the aims have been to enhance engine flexibility, maximise fuel efficiency and minimise pollution. Aside from a very few production applications (Mitsubishi’s post-2010 turbodiesel 1.8-litre is a notable example) VVT tends to be used in spark ignition (petrol) vehicles, which are the focus of this feature.

By its very nature, the basic four-stroke Otto Cycle is restrictive. In essence, for each cylinder, the inlet valve opens on the piston’s downstroke, permitting an air and fuel mixture (or just air in a directinjected engine) to enter, then closes at around the Bottom Dead Centre (BDC) position. Both the inlet and exhaust valves remain shut as the piston rises and compresses the mixture, prior to the spark plug firing. The resulting burning gases expand and drive the piston back down the cylinder, after which time the exhaust valve opens on the upward stroke, to evacuate the spent gases.

ROB’S TOP TIP Do not be confused by a throttle valve being fitted to an engine with VALVETRONIC – it tends to be fitted as a back-up.

As car engines operate under a variety of speeds and loads, this non-adjustable sequence delivers compromised efficiency, flexibility and emissions.

While old-style tuners, who swapped their stock camshafts for replacements that possessed different lobe profiles, were happy with the power increases at elevated engine speeds that their high-lift cams provided, the unfortunate downside included deterioration in both low-speed torque and idle-speed quality.

VVT helps to overcome these compromises. To achieve a non-lumpy idle, the inlet valve can be opened and closed later but this is not desirable, when full power is required. To achieve optimum volumetric efficiency for maximum torque at lower engine speeds, shop.kelsey.co.uk/subscription/CME

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What goes w

u Considering the harsh en in which its components op fairly reliable overall, with s afflicting certain engines.

However, when problems be tricky to resolve and, as w faults, it is forgivable (even be an expensive mistake) to VVT mechanism is at fault, w culprit lies elsewhere. A stre chain, for example, may cau issues and even a diagnosti code might point to a VVT p something else is to blame.

As an electrical solenoid regulate the flow of hot, pre they can fail internally. Thei will also be affected by the of a defective engine senso an ECU problem. For examp Renault Scénic IIs require an update to shut down the po to the solenoids, when the running, to avoid flattening The main issue tends to a dephaser pulleys. Initial ratt cold engine start can be cau worn internal seals, which d as the system pressurises. E the dephaser will not be eff adjusting the timing, which power drop, especially at lo speeds. An engine manage

the inlet valve can be opene slightly earlier, for example.

In certain situations, it is to keep both exhaust and in open simultaneously, a cond known as ‘overlap’. This can scavenging effect, whereby t gases are driven from the cy often promoted by the flow air from the inlet. More fres enter the combustion chamb therefore, more oxygen is av the following compression a strokes. In low-power situat can also be manipulated to n

LOWLIFT CAMS 1

2

Early Honda VTEC systems used conditions. When full power wa pin that passes through the roc

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ing

used by a throttle ted to an engine ONIC – it tends to ack-up.

nes operate under a variety loads, this non-adjustable vers compromised xibility and emissions. le tuners, who swapped mshafts for replacements d different lobe profiles, ith the power increases ngine speeds that their s provided, the unfortunate luded deterioration in both rque and idle-speed quality. to overcome these . To achieve a non-lumpy valve can be opened and ut this is not desirable, wer is required. To achieve umetric efficiency for rque at lower engine speeds,

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Variable Valve Timing (VVT)

What goes wrong? u Considering the harsh environment in which its components operate, VVT is fairly reliable overall, with specific issues afflicting certain engines.

However, when problems strike, they can be tricky to resolve and, as with all engine faults, it is forgivable (even though it can be an expensive mistake) to think that the VVT mechanism is at fault, when the real culprit lies elsewhere. A stretched timing chain, for example, may cause running issues and even a diagnostic warning code might point to a VVT problem, when something else is to blame.

As an electrical solenoid tends to regulate the flow of hot, pressurised oil, they can fail internally. Their function will also be affected by the presence of a defective engine sensor, or even an ECU problem. For example, certain Renault Scénic IIs require an ECU software update to shut down the power supply to the solenoids, when the engine is not running, to avoid flattening the battery.

The main issue tends to affect the dephaser pulleys. Initial rattling on a cold engine start can be caused by worn internal seals, which disappears as the system pressurises. Eventually, the dephaser will not be effective in adjusting the timing, which will cause a power drop, especially at lower engine speeds. An engine management lamp

the inlet valve can be opened and closed slightly earlier, for example.

In certain situations, it is beneficial to keep both exhaust and inlet valves open simultaneously, a condition known as ‘overlap’. This can create a scavenging effect, whereby the exhaust gases are driven from the cylinder, often promoted by the flow of incoming air from the inlet. More fresh air can enter the combustion chamber and, therefore, more oxygen is available for the following compression and firing strokes. In low-power situations, VVT can also be manipulated to not only

Picture kindly supplied by

PSA Groupe

This cutaway shows how a typical camshaft dephaser operates internally. In total, there are eight chambers. Solenoid valves direct pressurised oil into either chamber (P) or (Q), to either advance, or retard the timing. The difference in pressure between the chambers offsets the camshaft. Part ‘a’ is a pin that locks the dephaser, when the oil pressure is less than 0.5 bar on this Peugeot/Citroën EW9A engine. Part ‘b’ is the supply and return channel for chamber Q and ‘c’ is the supply and return channel for chamber P.

may not illuminate at this point. If fitted, worn gears on dephasers that are not connected directly to the camshaft can also be responsible for the racket.

Some units are known to not last the life of the engine – Italian car specialists, for example, recommend dephaser (or variator) replacement is conducted at the same time as a timing belt change on Alfa Romeo Twin Spark engines.

As oil quality is vital to VVT longevity,

optimise air motion (swirl) but to also permit a pre-determined quantity of exhaust gas to remain within the cylinder. Provided that the fuelling is adjusted accordingly, reduced fuel consumption and in-cylinder temperatures also result in lower NOx emissions. In some cases, this situation can negate the need for a separate exhaust gas recirculation (EGR) valve.

While James Atkinson’s pioneering Atkinson Cycle of 1882 was not only impractical but also expensive to massproduce, therefore failing to usurp that of the aforementioned Nicolas Otto, VVT

HIGHLIFT CAM

regular lubrication maintenance is essential. With many failing VVT dephasers causing a gradual decrease in performance, a real-time diagnostic check is worthwhile, to identify if the camshaft timing is being altered sufficiently under load. Should you suspect problems with the system, consider consulting a specialist that is experienced with your type of car and engine. As with all diagnostics, start with the simplest (and cheapest) solution.

CAMSHAFT

VTEC MECHANISM VTC DEPHASER

Some later VTEC systems combine the original VTEC with a VTC camshaft dephaser to provide greater accuracy of valve timing control and a more progressive power delivery.

Early Honda VTEC systems used low-lift ‘eco’ camshaft lobes (1 and 2) for most running conditions. When full power was needed, the centre high-lift cam (3) was activated by a pin that passes through the rockers, controlled by hydraulic oil pressure.

lies at the heart of making the Atkinson system viable, more than 100 years after the invention was patented. Atkinson’s engine relies on slightly different valve timing characteristics that delay the inlet valve’s closing during the compression stroke, which forces some air back into the inlet. While this situation reduces the cylinder’s displacement, the full expansion ratio in the combustion phase is retained. Aside from the piston encountering less resistance, another reason for Atkinson’s increased efficiency is due to the residual pressure inside the cylinder, post-power stroke,

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LOWLIFT CAMS 1

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Variable Valve Timing (VVT) being as close to atmospheric pressure as possible. The downside includes a narrower rev range and limited power output, although these can be overcome by using a supercharger (creating Miller Cycle engines); some production cars use this method to great effect. Hybrid cars tend to employ Atkinson Cycle engines, which masks the engine’s limitations with electric motor assistance.

VVT in the real world While the exact VVT specification varies between carmakers and engine families, only a comparative handful of layouts have been used, although expect to find many subtle variations. Aside from being fitted to several production Italian cars, Japanese manufacturers have been at the forefront of popularising VVT, making reliable small-displacement passenger car engines that boast impressive power outputs. Early iterations switched between two camshaft profiles, one for ‘eco’ running and the other lobe featuring higher lift profiling for enhanced engine speed performance. Perhaps the most famous example of these systems is Honda’s Variable Valve Timing and Lift Electronic Control (VTEC) that was fitted first to a production car in 1989. With VTEC, each pair of valves is operated by

ROB’S TOP TIP Never exceed manufacturer oil change intervals and always use good quality oil to the correct specification.

two lobes but, at a predetermined point, the engine ECU activates a solenoid that permits pressurised engine oil to activate a locking pin. This passes through and locks the rocker arms, so that they are all operated by the single larger ‘performance’ lobe, located between the two smaller lobes on the camshaft.

The result is a noticeable power boost at a pre-determined engine speed.

Like early VTECs, the initial VVT applications were non-linear in their operation, such as Toyota’s VVT and Mitsubishi’s first-generation MIVEC. Gradually, the systems were refined to make the change in valve timing more progressive. Generally, this has been achieved by fitting cam dephasers (also called phasers or variators) to the end of the camshaft. When oil is pumped through the assembly, the camshaft is rotated accurately by set degrees, while the pulley/sprocket drive position remains fixed. Many carmakers fitted dephasers to the inlet cams only, but now they are being used to vary exhaust valve timing, too. Some even replace the hydraulic element with electric motors, to enhance low engine VVT control, an example of which is Toyota’s VVT-iE (Intelligent Electronic) system.

Fiat Group vehicles were the first production cars credited with introducing dephaser-style VVT systems in the 1980s

and this layout has been adopted since by numerous other manufacturers, which operate also on an electro-hydraulic principle. Taking input from a variety of sensors, the engine ECU operates a solenoid that diverts pressurised oil to the dephaser unit. Early Italian applications tended to have dephasers mounted indirectly to the camshaft with gears, but many later systems that are used on more modern cars utilise dephasers that are connected to the camshaft.

To make engines even more efficient, engineers are investigating removing camshafts altogether.

While no production engines have succeeded entirely, Fiat’s MultiAir technology from 2009 replaces the more usual electromechanical means of controlling the inlet valves. Instead, each one is operated by a hydraulic chamber, through which the flow of oil is controlled by a solenoid valve. When this solenoid valve is opened, some oil can ‘bleed’ off, so the valve is opened less. The chamber is fed with oil from a pump that is activated by a lobe on the exhaust camshaft.

To find out the variations that can exist with even a single manufacturer, we examined BMW’s VVT systems, one of the most prolific types on UK roads, as well as one of the least understood.

 Despite Valeo’s E-Valve being available, we are unaware of any production engines that have dispensed with camshafts completely. One problem with such a system might be ensuring reliable operation of the exhaust valves, which run considerably hotter than the inlets.

Variable No

u Despite being only one man answer to VVT, BMW’s VANOS s been fitted to the majority of i made within the last 30 years. I adopted by certain MINIs and s Citroëns that inherited the cofour-cylinder Prince series of p On BMWs, several different l been introduced, with numero changes, depending on the ag and its engine type. Even so, th using the same principles and pressure to change the fixed re between the sprocket and the a result, any problems with oil prevent the VANOS from work as will a stretched timing chain be a common failure.

An internet search might lea assume that all VANOS system time-bombs, ready to fail at an

BMW VANOS

u The single VANOS unit incremental timing chang not very reliable, with subsequ gaining an unfortunate reputa being troublesome.

2

Fiat’s MultiAir technology replaces the inlet camshaft and dephaser with a pump and solenoid that operates the inlet valves hydraulically, using pressurised engine oil.

 The later double VANO offers a variable adjustm range on both inlet and exhaus cams. As with the preceding images, the pictured part is fro a six-cylinder engine.

3

The 471bhp V8 engine of the Lexus RC F uses VVT to switch the engine from an ‘eco’ Atkinson Cycle to the Otto Cycle, when full power is required, then back again afterwards.

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ut has been adopted since by her manufacturers, which on an electro-hydraulic king input from a variety e engine ECU operates a diverts pressurised oil to the t. Early Italian applications ve dephasers mounted he camshaft with gears, er systems that are used on cars utilise dephasers that d to the camshaft. ngines even more efficient, investigating removing ogether. roduction engines have tirely, Fiat’s MultiAir om 2009 replaces the ectromechanical means of he inlet valves. Instead, each ed by a hydraulic chamber, h the flow of oil is controlled valve. When this solenoid ed, some oil can ‘bleed’ off, opened less. The chamber is om a pump that is activated he exhaust camshaft. the variations that can en a single manufacturer, BMW’s VVT systems, one rolific types on UK roads, of the least understood.

technology replaces the t and dephaser with a pump hat operates the inlet valves using pressurised engine oil.

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Variable Valve Timing (VVT)

Variable Nockenwellensteuerung (VANOS) u Despite being only one manufacturer’s answer to VVT, BMW’s VANOS system has been fitted to the majority of its models, made within the last 30 years. It has also been adopted by certain MINIs and some Peugeot/ Citroëns that inherited the co-developed four-cylinder Prince series of petrol engines.

On BMWs, several different layouts have been introduced, with numerous detail changes, depending on the age of the car and its engine type. Even so, they operate using the same principles and utilise oil pressure to change the fixed relationship between the sprocket and the camshaft. As a result, any problems with oil pressure will prevent the VANOS from working correctly, as will a stretched timing chain, which can be a common failure.

An internet search might lead you to assume that all VANOS systems are ticking time-bombs, ready to fail at any moment

and bankrupt you through repair costs.

“This is not necessarily true,” insists BMW specialist Sam Saharan of i6 Automotive in Sheffield. “We have many people who bring cars to us, stating that the VANOS has failed, when the real cause lies elsewhere, such as a failing coil pack or a vacuum leak.”

Sam says that identifying a faulty VANOS can be difficult, as performance may drop gradually, which might not be detected by the driver, or else a new owner may be unfamiliar with the true performance potential of the engine. Sam quotes, “This, alongside the extremely poor knowledge of these units at both main dealer and independent network levels, makes VANOS a very overlooked item. When it is at fault, instead of replacing expensive parts, repairs can be extremely affordable, provided that you contact a knowledgeable specialist.”

Speaking to CM, several other specialists

backed up Sam’s assertions, but every one of them emphasised that poor servicing, especially neglected oil changes or using the incorrect lubricant, are root causes of VANOS problems.

Nigel Crooks, director of independent BMW used parts supplier Midland BM, admits that the first VANOS applications were not up to expected Teutonic standards of dependability.

Nigel told CM that demand for replacement VANOS parts has declined considerably since his company started trading more than 20 years ago, which suggests that later Double VANOS systems are more reliable on the more common engines. While BMW’s iteration of VVT is better than its reputation suggests, several common problems plague many of the designs. These include weak rubber seals that can leak oil after as few as 30,000 miles have been covered, which prevents VANOS from functioning properly.

BMW VANOS INVESTIGATION

ROB’S TOP TIP

Exercise the utmost caution with the engine timing, should you desire to remove a VANOS dephaser.

 The earliest example was a single VANOS system, fitted to certain six-cylinder petrol engines, which varied only the inlet valve’s timing.

1

u The single VANOS unit offered only incremental timing changes and was not very reliable, with subsequent systems gaining an unfortunate reputation for being troublesome.

2

 The later double VANOS offers a variable adjustment range on both inlet and exhaust cams. As with the preceding images, the pictured part is from a six-cylinder engine.

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Four-cylinder BMW engines do not employ a VANOS unit on top of the cylinder-head; the dephasers are accessible once the rocker cover is removed.

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Variable Valve Timing (VVT)

Variable Nockenwellensteuerung (VANOS) continued A vocal rattle is a further complaint, caused by either broken retaining bolts or wear within the internal bearings and gears.

With VANOS being the single term used to describe several different designs and specifications of a system that performs the same basic task, faults and repair techniques also vary.

While the following pictorial is not intended to be a comprehensive repair description, it provides an overview of the various systems that may be encountered on the most prolific BMW models.

For specific advice about an engine, especially a high-performance variant, you need to consult a specialist, if you suspect the VANOS really is at fault.

While BMW dealers will insist that the entire unit is renewed, the aftermarket has developed upgraded parts that address many of the common problems.

Again, this depends on your engine’s age and type.

Since its introduction in 1992, BMW’s VANOS variable valve timing system has been refined continually, meaning that layouts differ with engine type and age.

As all VANOS units are ol operated, it is wise to ins loose or broken wiring, prior to any in-depth investigations.

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BMW VANOS INVESTIGATION continued u On four- and some six-cylinder units, conventional-type variator/dephasers are employed, similar to those found on other cars. Pictured is a dismantled unit.

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 While solenoids direct the oil flow, their positions vary, even on VANOS units with separate pumps. Pictured is a four-cylinder unit being removed.

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One of the effects of neglected servicing is blocked solenoid filters, which restrict oil flow to the VANOS unit.

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Some VANOS designs have a separate pump that is positioned on top of the engine. These systems are fitted with a camshaft position sensor.

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Many cylinderhead-mou units are reputed to have which cause an internal oil leak reduction in performance.

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Should VANOS be positioned on top of the engine (not the four-cylinder types), the solenoids may be mounted to the unit – such as the pair on this V10 (M5) motor.

7

Check for signs of external leaks around VANOS components. When refitting solenoids, avoid dislodging the rubber seals in the cylinder-head, if fitted.

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Some radial sprocket fix protruding tabs, which e can also break off and fall into

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Variable Valve Timing (VVT)

nued

ANOS be positioned on top of e (not the four-cylinder types), may be mounted to the unit air on this V10 (M5) motor.

or signs of external leaks VANOS components. When oids, avoid dislodging the the cylinder-head, if fitted.

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As all VANOS units are oleo-electrically operated, it is wise to inspect for any loose or broken wiring, prior to commencing any in-depth investigations.

Unfortunately, the solenoid pack is in contact with a circuit board, which can be damaged by the heat and vibration from the engine.

This S54 (Z3/M3) VANOS requires a high-pressure (approx 1200psi) oil feed and has its own oil pump. The solenoid is the black unit bolted to the underside.

Many cylinderhead-mounted VANOS units are reputed to have weak seals, which cause an internal oil leak and a gradual reduction in performance.

The seals can be replaced with upgraded parts from specialists.

Pictured is a pair of piston seals removed from their housing (see also Step 14).

Some specialists can supply a kit to alleviate a ‘chattering’ VANOS, which can result from wear in the gear teeth or internal bearings.

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Some radial sprocket fixing bolts can snap. Certain designs’ protruding tabs, which engage with the VANOS oil pump drive, can also break off and fall into the sump.

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Pictured on the left is the pump drive. The two cut-outs on the disc engage with the sprocket’s tabs on this S54 engine; the disc can be damaged if these tabs break.

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Variable Valve Timing (VVT)

BMW VANOS INVESTIGATION continued

If you decide to remove the VANOS unit, be aware that the timing and hubs’ positions may need resetting and that you may require dedicated camshaft locking tools.

19

Bear in mind that most double VANOS applications tend to be reliable, so check first for other issues, such as timing chain/ sprocket wear.

20

BMW VALVETRONIC

After checking that the re motor matches the origin can be bolted to the engine by the method of removal.

G

Active Cylin

As VANOS does not vary valve lift, BMW developed the VALVETRONIC system, which negated the restrictive throttle valve, enhancing efficiency by around 10%.

A

VALVETRONIC was used with VANOS systems from 2001. Although it also acts on the valve gear, most repairs can be carried out independently.

B

These images show how the VALVETRONIC’s parts interact under minimum and maximum valve lift conditions. Note that the system is fully-variable.

D

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E

The system works using a stepper motor that acts on a secondary eccentric shaft, featuring rocker arms that control the degree of inlet valve lift.

C

u Although various system introduction of ACT on its p engine in 2012, they were u not sold in the UK, or surviv numbers. The self-diagnosi one of the most common m roads, in which the valves a cylinders under certain run While the system is a form independent of the VVT me and three are activated, the conventional way, using lob instead of being integral wi fixed and is mounted on a s

Whenever the rocker cover has been removed, it is worth checking that none of the VALVETRONIC mechanism’s springs have broken.

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Variable Valve Timing (VVT) ROB’S TOP TIP If replacing a VALVETRONIC motor, ensure that the appropriate gaskets/seals are replaced, to reduce the chance of oil leaks.

If the motor has failed, disconnect its electrical connector and remove the nuts that hold it to the cylinder-head casting. A four-cylinder engine is pictured.

F

THANKS TO: Midland BM Midland House, Stone Street, Oldbury, West Midlands B69 4JL. Tel: 0121 544 9444.

Stourbridge Automotive 6 Gainsborough Trading Estate, Rufford Road, Stourbridge DY9 7ND. Tel: 01384 377792 stourbridgeautomotive.co.uk enquiries@stourbridgeautomotive.co.uk BMW UK

PSA Groupe

Volkswagen UK

NOS applications tend to be sues, such as timing chain/

m works using a stepper at acts on a secondary featuring rocker arms that ree of inlet valve lift.

After checking that the replacement motor matches the original part, it can be bolted to the engine by reversing the method of removal.

G

Should a new motor not resolve the problem, the ECU may have developed a fault. Either a replacement can be sought, or else the unit can be repaired by a specialist.

I

Active Cylinder Management (ACT) u Although various systems preceded Volkswagen’s introduction of ACT on its production 1.4-litre TSI EA211 engine in 2012, they were usually in production on cars not sold in the UK, or survivors tend to be in very small numbers. The self-diagnosing VAG ACT system remains one of the most common modern examples on our roads, in which the valves are used to shut down a pair of cylinders under certain running conditions.

While the system is a form of valve timing control, it is independent of the VVT mechanism. When cylinders two and three are activated, their valves are operated in the conventional way, using lobes on the camshaft. However, instead of being integral with the shaft, the lobe is not fixed and is mounted on a spline.

The system works by moving the appropriate lobe, permitting the valve to run on an alternative that possesses zero lift, therefore the valve does not open and the cylinder is deactivated. The sliding cam lobes move across the shafts, thereby disconnecting (or reconnecting) the appropriate valves, and are activated by four electronic actuators that contain metal pins that lock into the appropriate sliding groove.

The ‘reset ramp’ forces the metal pins back into the actuators, when changing between the lobes. While the actuators can be replaced, mechanical problems with the ACT mechanism or camshaft dictates renewal of the entire cylinder-head assembly.

emoved, it is worth checking anism’s springs have broken.

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Once the electrical connection is reattached, the motor ‘learns’ its positions during a diagnostic session. Related fault codes should not reappear.

H

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Front end auxiliary drive systems

FEAD me The front end auxiliary drive system enhances drive belt longevity and refinement; Rob Marshall gives an overview of the overrunning alternator pulley (OAP) and how to replace it using a minimum of special tools.

FEAD belt suffixes (Courtesy of Dayco)

 ‘S’ belts Higher performance compound used. For example, 6PK1836S Fiat 1.9 JTD and 5PK1745S Mercedes-Benz A- & B-Class diesel.  ‘EE’ belts Elastic or stretch belts.

You should see an ‘ELABELT’ logo.

For example, 6PK1059EE Ford Focus 1.6 petrol.  ‘K’ belts Internal cord reinforced with aramid fibres. For example, 5PK1121K Volvo 2.0 & 2.4 D.  ‘DT’ belts Fabric material used on rear belt surface. For example, 6PK1080DT for PSA’s 2.0 HDi Hybrid (Peugeot 508 RXH)  ‘PM’ belts White fabric on ribs.

For example, 6PK1041PM and 6PK848EEPM, both for PSA 1.2 three-cylinder range.

All work must be performed in a clean environment and safety must always be a priority. The vehicle’s battery on conventional engines must be disconnected. Hybrid systems must be isolated, so that there is no risk of the engine starting while you are working on the pulleys. Do not wear loose clothing, and long hair should be tied back.

FEAD systems involve more than just the auxiliary drivebelt. Pictured is an automatic tensioner and an overrunning alternator pulley (OAP).

T

he humble fanbelt has come a long way. Fitted originally to run the fan that cools the engine and drive the alternator, it is used now to transmit power from the crankshaft pulley to an increasing number of ancillary components. For this, the belt has had to evolve: improved design has seen multi-ribbed auxiliary belts (sometimes called serpentine belts) and pulleys become universal.

Materials have changed, too. Most conventional vehicles from the last 10-15 years use belts made from ethylene propylene diene monomer (EPDM). This is relevant, because a DIYer must consider that the traditional method of identifying wear at service time, such as checking the running surfaces for cracks, or perishing, is not as relevant as it once was.

Additional components have been added to reduce vibration, plus enhance belt life and efficiency, such as tensioners and idler pulleys. The alternator pulley may be either an overrunning alternator pulley (OAP) or an overrunning alternator decoupler (OAD), both of which are designed to protect the belt drive components from premature wear. While there are different ways of detecting pulley wear, which differs between OAP and OADs, should you notice that the tensioner oscillates excessively when the 46 Car Mechanics

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engine is running, then the alternator OAP/OAD will need replacing as well. Unless official maintenance intervals state otherwise, check the FEAD system at 60,000 miles and change all components at 90,000 miles, regardless of their condition.

The auxiliary belt should not be thought of as a single component, but as one part of a front end auxiliary drive (FEAD) system. Rather than change the belt on its own, you should replace all of the components that make up the FEAD system at the same time. Quality suppliers have developed kits of FEAD parts for particular makes and models.

This feature details the fitting of a kit of OE-quality components, using specialist Laser tools from The Tool Connection.

The FEAD system on this 2006 Citroën C5 2.0 HDi diesel had covered 108,000 miles. Many technicians recommend that the change interval coincides with that of the timing belt. Check your car’s manual for recommended replacement intervals, or follow our earlier replacement advice.

1

FEAD systems can, sometimes, be difficult to access, due to being positioned very close to the inner wing. Laser Tools sells a slimline toolkit (part number 3757) for £60.65 to make the task considerably easier (see Step 5).

2

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Front end auxiliary drive systems  On this car, turning the pulley bolt (shown in Steps 4 and 21) clockwise raises the spring-loaded tensioner, which relieves the pressure on the belt so that it can be unhooked. Make a note of how it is routed round the pulleys.

3

belt suffixes

ayco)

Higher performance nd used. For example, S Fiat 1.9 JTD and S Mercedes-Benz ass diesel.

 For clarity, we have removed the plastic pulley from the tensioner.

This particular one has a lefthand thread; turning the bolt clockwise unscrews it. It would be ordinarily unnecessary to remove it unless access is especially difficult.

s Elastic or stretch belts. uld see an ‘ELABELT’ logo. mple, 6PK1059EE Ford 6 petrol.

4

Internal cord reinforced mid fibres. For example, K Volvo 2.0 & 2.4 D.

s Fabric material used belt surface. For example, DT for PSA’s 2.0 HDi Peugeot 508 RXH)

 We removed our pulley to improve access to the tensioner retaining bolt (see inset pic as removed).

This one has an 8mm Allen key head – the Laser slimline tool proved invaluable here to gain sufficient leverage.

5

ts White fabric on ribs. mple, 6PK1041PM and EPM, both for PSA 1.2 inder range.

 Should a lack of access mean you have to take off the alternator, remove parts that might obstruct the work area. In this case, the diesel fuel filter moulding had to be disconnected, taking care not to drip fuel over the alternator, which could damage it.

ust be performed in a clean and safety must always The vehicle’s battery nal engines must be . Hybrid systems must be hat there is no risk of the ng while you are working on o not wear loose clothing, should be tied back.

6

 Remove protective cover(s) and disconnect all wiring from the alternator.

Manipulate any wiring clips from the alternator body and tuck the wiring safely out of the working area, where it cannot be damaged.

7

 Undo the alternator fixing bolts. Thanks to the automatic spring-mounted belt tensioner, even tension is applied continually, should the belt stretch. This was not the case on older cars, where the alternator was bolted solidly to a bracket.

8

D system on this 2006 Citroën Di diesel had covered 108,000 chnicians recommend that erval coincides with that of . Check your car’s manual for replacement intervals, or er replacement advice.

 Extract carefully the alternator from the engine bay and check it visually for a cracked casing, or any evidence of damage. If a new/ remanufactured alternator is to be fitted, ensure that a fixed pulley has not been used to save costs.

9

 While OAP and OAD alternator pulleys differ mechanically, the replacement procedure is the same.

OAPs (and some but not all OADs) are protected by a plastic cap. A fixed pulley (pictured left) will not have one fitted.

10

being positioned very close to ber 3757) for £60.65 to make

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Front end auxiliary drive systems

A worn belt, made from E identified by perishing. T (left) has had its grooves cut de metal pulleys and the ribs have has narrowed their shape. Some offer a gauge for assessment of

20

plastic pulley cover (if fitted) can 11 The be prised away and discarded. A new one should be supplied with your replacement part. Should oil be seen leaking out, it is a sign that the pulley needs replacing.

Should an INA pulley be fitted, identify it by the ‘F’ number printed behind the cover (circled). Several replacement kits may be specified, depending on the car’s alternator manufacturer; the original ‘F’ number on your alternator provides a definitive answer.

12

Special tools are required to replace alternator pulleys. Laser Tools provides DIY-orientated answers to the professional tools. This is part number 6750 and costs £27.74 including VAT.

13

 On this Mitsubishimanufactured alternator, the splined section of the special tool engages with the pulley, through which a Hex bolt extension passes to slot into the alternator shaft. Never use an impact wrench, only hand tools.

14

 The Hex bolt is used to hold the alternator shaft while the pulley is rotated anticlockwise. Once loosened, the tools can be dismounted and the alternator pulley unscrewed from the shaft by hand, prior to being discarded.

15

 Check that the alternator shaft is in good order, prior to confirming that the replacement pulley is fitted the correct way round. Screw the new pulley along the threads by hand until it locks into place.

Again, using hand tools 17  only, fit the special tools as described in Step 14. As with Step 15, a ring spanner is preferable to the open-ended spanner, pictured. Final tightening should be performed with a torque wrench – the specification should be provided with your kit. For ours, the figure is 85Nm.

16

 Finally, fit the plastic protective cover. Do not be tempted to reuse the old one – the lifespan of the alternator pulley will be reduced, or damaged considerably should you elect not to fit a new plastic cover.

18

Fit a replacement belt of the same specification.

Never fit a cheaper and incompatible belt, if the original part had specific technical requirements (see page 46).

This one matches the old one’s specifications: 6 ribs of 1217mm length.

19

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MODERN ENGINES

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tools are required to replace or pulleys. Laser Tools provides answers to the professional art number 6750 and costs ng VAT.

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Front end auxiliary drive systems

A worn belt, made from EPDM, is not identified by perishing. The old belt (left) has had its grooves cut deeper by the metal pulleys and the ribs have worn, which has narrowed their shape. Some belt suppliers offer a gauge for assessment of wear.

20

Pictured are the old (left) and new automatic tensioners. The pulley centre bolts that are used to manipulate the tensioner to remove pressure on the belt are pictured more clearly. The bolt on the new part must not be unscrewed.

21

 The new tensioner is offered up to the engine block, with any locating pins that form part of the casting being fitted to the appropriate recess. The fixing Allen key bolt on this tensioner is then fitted and tightened.

22

 The centre pulley bolt (shown in Step 21) is manipulated to position this tensioner, enabling a locking pin (a 4mm diameter drillbit will suffice if one is not available) to be inserted into the recesses.

23

 The alternator is then refitted, mounted to a fixed point (unlike many older cars, where alternator positioning dictated belt tension). Obviously, this negates the old practice of levering against the alternator after the belt has been installed.

24

 With the alternator in place, the locked tensioner allows the new belt to be positioned loosely around the metal multi-ribbed crankshaft, alternator, airconditioning and the plastic tensioner pulleys.

25

 Step 23 is repeated, this time with the locking pin removed. The torque on the tensioner pulley bolt is relieved gradually, as the tensioner applies pressure to the new belt. Check that the belt is aligned correctly on the pulleys.

26

 Refit any removed parts, such as the alternator’s connections and the battery. Start and stop the engine, then check that the belt is still routed correctly.

Press on the belt to confirm the tensioner moves freely and that its end stops are not touching.

27

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Reconditioning alternators

Alternators heated rear windows, halogen headlights and variable-speed demister fans and wipers, a more reliable and efficient means of electricity generation was required. Although alternators had previously been used in industrial applications that required an alternating current (AC), they were unsuitable for automotive use until the invention of the transistor in the 1950s, which made it possible for the AC to be converted into a more usable direct current (DC) form. The main advantage of early alternators compared with dynamos is that they produced a third more power and could charge the battery at engine idle speeds.

most popular alternators, fi British and European cars u mid-1980s. It had a built-in and possessed a maximum o ranged from 30-50 amps, de on the vehicle’s make, mode level. In the ensuing decade accessories have multiplied to either enhance comfort a (heated seats, mirror/winds demisting elements, LCD sc multiple ECUs, etc), or to re driven pumps, such as those and power steering systems of reducing both fuel consum reducing tailpipe emissions. some modern alternators ar to generate 200 amps or mo has changed internally comp the old ACR units.

However, regulating the c changed dramatically. Altho alternators retain their in-b regulators, the voltage feed battery is no longer the sole used to assess battery condi modern vehicles are fitted w charging systems that can co alternator’s output, many of pre-programmed to take int the battery’s exact specificat ECUs are immensely flexible even cut the alternator’s out full acceleration is required, the alternator shaft easier to that maximum engine outpu directed to the wheels.

The system also means th alternators no longer charge rate of approximately 14.5 v battery requires a fast-charg is possible for 17-18 volts to Therefore, on modern cars, voltage reading be noted at terminals with the engine ru might not be an overchargin

Modern developments

DIY prospects

Lucas’s ACR range became one of the

Home alternator testing ten limited. Some smart charger the ability to assess alternat rates, but the check is very b older cars, ensuring that the voltage remains between 13 volts when the engine is run to be the only practical DIY Obviously, for a more moder test is redundant and more equipment is required. Shou suspect a faulty alternator, i best to consult an automotiv for an accurate diagnosis.

Even so, it is easy to confu deteriorating alternator with battery. Lead-acid batteries naturally and their ability to full charge dissipates over ti

The alternator has become increasingly critical to a vehicle’s electrical system.

Rob Marshall probes the latest types and investigates how they are repaired.

P

etrol-powered engines require electricity to keep them running. The high voltage arc that jumps between the spark plugs’ electrodes and ignites the fuel/ air mixture is created by the ignition system, which requires energising. This has traditionally been provided by a battery, although the engine will stall if the power supply is exhausted.

The average pre-1965 British car was fitted with a dynamo that was responsible for powering the rudimentary electrical system and charging the battery. The unit can be thought of as an electric motor in reverse: should power be applied to it, the main shaft onto which the internal rotor is fitted will rotate. If spun, the amount of electrical energy generated is in direct proportion to the speed at which the rotor is turning.

The major disadvantage with dynamos is that hardly any current is produced at engine idle speed and, if the car were stationary in heavy traffic with electrical

wipers and lights activated, the battery might have to make up for the dynamo’s shortfall. The driver would then have to make several choices: either rev the engine antisocially to increase the amount of power produced, or else switch off one of the electrical accessories (with potential safety risks), or risk a breakdown if the battery were to run flat.

As well as undercharging a battery, dynamos could also overcharge, especially on longer journeys at high engine speeds, such as those encountered on the then newfangled motorway network. Although dynamos incorporated externally-mounted regulators elsewhere on the vehicle’s bodywork, they were operated electro-mechanically and required careful setting up prior to use, as well as periodic adjustments as their internal contacts deteriorated.

As consumers demanded more electrically-operated equipment fitted to their new cars, such as energy-sapping

This old Lucas ACR unit has one connection for the electrical system and is not responsible for battery charging – the single connector only serves to power the battery warning light…

…whereas this modern alternator possesses a separate terminal block, which allows full communication with the car’s electrical system, including a smart-charge ECU.

Early days

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While most alternators are air-cooled, some types may be liquid-cooled. This cutaway of a prototype under development shows the cooling channels built into the outer casing.

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ors

Reconditioning alternators

heated rear windows, halogen headlights and variable-speed demister fans and wipers, a more fficient means of electricity as required. Although ad previously been used applications that required g current (AC), they were r automotive use until the the transistor in the 1950s, t possible for the AC to into a more usable direct form. The main advantage nators compared with hat they produced a third nd could charge the battery speeds.

most popular alternators, fitted to many British and European cars until the mid-1980s. It had a built-in regulator and possessed a maximum output that ranged from 30-50 amps, depending on the vehicle’s make, model and trim level. In the ensuing decades, electrical accessories have multiplied further, to either enhance comfort and safety (heated seats, mirror/windscreen demisting elements, LCD screens, multiple ECUs, etc), or to replace enginedriven pumps, such as those for the fuel and power steering systems, for the sake of reducing both fuel consumption and reducing tailpipe emissions. Even though some modern alternators are now rated to generate 200 amps or more, very little has changed internally compared with the old ACR units.

However, regulating the current has changed dramatically. Although modern alternators retain their in-built internal regulators, the voltage feed from the battery is no longer the sole parameter used to assess battery condition. A lot of modern vehicles are fitted with smartcharging systems that can control the alternator’s output, many of which are pre-programmed to take into account the battery’s exact specifications. These ECUs are immensely flexible and can even cut the alternator’s output when full acceleration is required, which makes the alternator shaft easier to turn, so that maximum engine output can be directed to the wheels.

The system also means that alternators no longer charge at a nominal rate of approximately 14.5 volts. If the battery requires a fast-charge boost, it is possible for 17-18 volts to be applied.

Therefore, on modern cars, should this voltage reading be noted at the battery terminals with the engine running, there might not be an overcharging fault.

developments

DIY prospects

ange became one of the

Home alternator testing tends to be very limited. Some smart chargers possess the ability to assess alternator charge rates, but the check is very basic. For older cars, ensuring that the system voltage remains between 13.8-14.4 volts when the engine is running tends to be the only practical DIY check.

Obviously, for a more modern car, this test is redundant and more sophisticated equipment is required. Should you suspect a faulty alternator, it might be best to consult an automotive electrician for an accurate diagnosis.

Even so, it is easy to confuse a deteriorating alternator with a dying battery. Lead-acid batteries degrade naturally and their ability to hold a full charge dissipates over time. If an

ernators are air-cooled, some quid-cooled. This cutaway of der development shows the els built into the outer casing.

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How an alternator works u When a loop of wire is rotated between closely-positioned magnets, electrical energy is created in the wire. This basic physics lies at the heart of how both alternators and dynamos work. Alternators convert mechanical energy to an alternating electrical current (AC), prior to converting it to a direct current (DC). The main moving part is the rotor, which features field windings and is spun via a shaft, onto which is mounted a pulley. Bearings at either side of the shaft support the assembly. One of the ways an alternator can produce high current at low speeds is that the field windings create the internal magnetic field electromagnetically, rather than relying on magnets, and the circuit is fed with power via slip rings and brushes. Thus, alternators consume electrical energy and it is possible for an internal fault to drain the battery when the engine is stationary. The current produced by the alternator is created in the static stator, within which are several layers of windings wrapped around a circular frame; this is fixed to the inside of the outer casings.

As the car’s circuits require DC, the stator is connected to a rectifier, which consists of approximately six diodes that act as valves and switches to convert the incoming AC. The regulator circuitry assesses the voltage of the battery and alters the alternator output by varying the current to the rotor, thus altering the strength of the magnetic field. The diodes are air-cooled by a fan that tends to be mounted to the spinning rotor shaft; older alternators used to possess an external fan mounted behind the pulley. The outer casings tend to be cast from aluminium, due to the material being light, strong and non-magnetic. Newer alternators are fitted with additional circuitry, so that the unit can interpret and transmit communication to and from the vehicle’s electrical system.

REAR COVER BRUSH BOX/ REGULATOR ASSEMBLY

RECTIFIER UNIT

PROTECTIVE CAP

REAR COMMUTATOR END COVER

STATOR REAR BEARING

ROTOR incorporating the field windings and fan) FRONT DRIVE END COVER

FRONT BEARING PROTECTIVE PLATE

FRONT BEARING SPACER FRONT PULLEY

SECURING NUT

incorrect battery is fitted, such as one that possesses a low capacity, or a vehicle equipped with Stop-Start technology has not been furnished with the correct enhanced flooded battery or absorbent glass mat type, the vehicle might be unable to recharge them correctly.

Fortunately, provided there is sufficient space beneath the bonnet, modern alternators can be removed easily at home. Just make sure you note the correct drivebelt routing and establish whether or not the belt and tensioners require periodic renewal.

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Reconditioning alternators

Pulleys

ALTERNATOR DISMANTLING

u While most pulleys were solid castings that lasted indefinitely, the requirement of greater alternator loads, enhanced efficiency, lower noise vibration and an increase in auxiliary belt life (and reduced CO2 emissions and fuel use) has seen one-way clutch and overrunning decouplers being used within the alternator pulley. Both types detach the alternator’s rotating shaft (and rotor) from the belt temporarily, under certain conditions. The main advantage is to isolate the components from shock. Auxiliary drivebelt life can be extended as much as tenfold with these clutch and decoupling systems.

Overrunning alternator pulleys (OAPs) allows the rotor shaft to freewheel as the belt speed drops, so the system disconnects the alternator from the belt during engine shutdown, transmission upshifts and deceleration. The overrunning alternator decoupler (OAD) pulley does not allow the alternator to freewheel fully.

Instead, the pulley isolates the direct drive with the use of a oneway torsion spring, to dampen the shock that results with sudden changes in belt speed.

Bodges that involve welding up a failing OAP/OAD pulley are a false economy.

Failure of both systems results in excessive noise from the drivebelt, possibly accompanied by the belt flapping on its longer runs and spring-loaded tensioners moving excessively. In extreme cases, the belt can jump from the pulleys.

With the belt disconnected, spin the alternator pulley manually; if it feels rough or notchy, suspect a failed pulley. Should the pulley be locked permanently in both directions, it is likely to have failed.

Always replace a failed OAP/OAD pulley with the same type and, if relevant, one with the same spec.

Never cut costs by either welding the pulley or fitting a solid type.

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u Faulty or elderly alternator stock arrives from all over Europe in significant quantities. Although this ‘core’ has a scrap value, it tends to be overshadowed by its worth for reconditioners.

1

A single alternator can po two part numbers, one fo and another for the alternator p Eurolec enters these into its sto

3

 Each unit has to be inspected for damage, before they are racked carefully. Due to the alternator ranges increasing massively over the last three decades, cataloguing is a lengthy process.

2

The stator tends to be sol rectifier, therefore desold separating the connections is v the part being lifted from the a

6

Repaired, reconditioned or remanufactured? u Fortunately, mail-order spare parts are available from a variety of outlets, such as Wood Auto Supplies of Huddersfield (Tel: 01484 439000, woodauto.com), and this makes repairing a troublesome component a practical option. However, as it is difficult to test the internal components of a modern alternator at home, you may as well buy more parts and replace the rectifier, brushes, regulator and bearings, regardless of their condition. Note any part numbers on your alternator and ensure you order the correct parts. If you own an older car, it might not possess its original alternator, therefore be doubly-sure that all parts that ordered are suitable.

The downside with reconditioning is that it remains a rather laborious process, as the step-by-step procedure shows. Therefore, you might decide that buying a professionally-rebuilt unit is a better value option, compared with the risk of refitting a DIY-rebuilt alternator to the car, only to find that it is not working, necessitating removal and stripping down once again.

With increased technology and Asian production capacity opening up, particularly in China, remanufactured copies of OE specification alternators have flooded the UK market for many common models, which even undercut the price of reconditioned original items. However, exercise caution and buy from a supplier that knows about rotating electrics and has been involved with the factory producing them.

The reproduced items might look the same on the outside, but their output might not match that of an OE part, meaning that performance could be compromised. For example, some alternator rotors are magnetised and a maker of a copy might not realise this; the result will be reduced output. However, do not think that all remanufactured alternators are substandard; some wholesalers and retailers are experts in their field and apply strict quality control standards in overseas factories. Therefore, make any purchase from a reliable and knowledgeable supplier, rather than an unknown source, or a ‘cheapy’ from an internet auction site.

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Remove bolts holding the the alternator together (s page 56). A light tap should sep halves, but do not subject them t

9

Concentrating on the oth for the presence of a spa front of the bearing that is pres front cover. It must be reused o

12

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Reconditioning alternators

TLING

A single alternator can possess at least two part numbers, one for the carmaker and another for the alternator producer.

Eurolec enters these into its stock database.

Most alternators possess a protective rear cover, which tends to be held in place by either several nuts or bolts. Once removed, the internals can be accessed.

The brush box and the regulator tend to be amalgamated into a single unit on modern alternators. The pictured part was secured by only a few screws.

The stator tends to be soldered to the rectifier, therefore desoldering and separating the connections is vital, prior to the part being lifted from the alternator.

Although the rectifier may be diagnosed using complicated test equipment, obvious visual clues, such as burnt-out diodes, might indicate the location of the original fault.

The front pulley may be held on with either a nut (on older alternators) or a spline socket might be required. Finally, pull the pulley clear from the shaft.

Remove bolts holding the two halves of the alternator together (see Step 14 on page 56). A light tap should separate the two halves, but do not subject them to heavy blows.

The delicate copper slip rings might be protected by their own dedicated gaiter. Prise it away carefully, without damaging the components beneath.

The stator should pull from its housing. If glued in place, dismantling will be considerably trickier. If you use any tools, be careful not to damage the wiring.

Concentrating on the other half, check for the presence of a spacer, fitted in front of the bearing that is pressed into the front cover. It must be reused on reassembly.

Remove the rotor from the front housing by pulling its nose out of the bearing.

Note that one or more thrust washer shims might be fitted between the stator and housing.

Professional reconditioners remove the rotor bearing by gripping the part to be removed in a bespoke vice, prior to pulling it clear from the rotor shaft.

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 Each unit has to be inspected for damage, before they are racked carefully. Due to the alternator ranges increasing massively over the last three decades, cataloguing is a lengthy process.

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manufactured?

ased technology and tion capacity opening up, n China, remanufactured specification alternators the UK market for on models, which even price of reconditioned s. However, exercise buy from a supplier that rotating electrics and olved with the factory em. uced items might look the outside, but their t not match that of an OE g that performance could ised. For example, some ors are magnetised of a copy might not he result will be reduced ever, do not think that ctured alternators are some wholesalers and xperts in their field and uality control standards ctories. Therefore, make e from a reliable and ble supplier, rather than source, or a ‘cheapy’ net auction site.

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Reconditioning alternators

ALTERNATOR DISMANTLING continued

ALTERNAT u Reassembly can begin, not only after all of the reusable parts are clean and the new components have been received, but also when the rebuilder is sure that they are correct. This alternator is from an early 2000’s Honda Civic.

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The front bearing can be pressed from the housing but its guard plate might require removal first. The part on this alternator is held in place by three screws, accessed from the other side.

Retain the old parts, so that you can compare new components side-by-side. As alternators from the same range can possess many subtle differences, this is vital for a major reconditioning company.

Cleanliness is vital when reconditioning rotating electrics.

Eurolec uses a hot water-based degreasing machine to cleanse all parts that it is reusing for rebuilding.

Most external cast metal parts require grit-blasting to restore an as-new appearance. This includes certain screws, nuts, bolts, outer casings and brackets.

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Deep scores on the slip ring(s) can be rectified by cutting the copper back lightly, with a dedicated lathe. This ensures the rings do not go out-of-round.

Linishing copper slip ring(s) is performed on a lathe, using sandpaper. This removes minor scoring from the wearing surface so the brushes will not wear prematurely.

Although a DIY multimeter might suffice, professional rebuilders use dedicated equipment to test the windings on each stator.

Faulty stators tend to be irreparable.

Should a stator pass the tests, Eurolec tends to fit extra insulation to the exposed wire that is to be soldered to the rectifier, to prevent the risk of an internal short-circuit.

Despite replacement brush boxes being available widely from Asia, the internal regulator quality can be variable.

Experienced rebuilders know which part is better to use as a replacement or…

…if it is better to retain the original regulator and replace the brushes.

On many original regulators, replacement brushes are available and can be soldered into place.

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After the rotor’s original f is pressed out of the drive front plate (see Steps 13-15 of A Dismantling), a replacement is hydraulic press to locate it in po

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Working on the empty re end casing, the rectifier i the moulding. This particular p with a single screw.

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After ensuring that both are aligned, they are sold care not to melt any surroundin

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an compare new components he same range can possess major reconditioning company.

quire grit-blasting to restore des certain screws, nuts, bolts,

h a DIY multimeter might suffice, onal rebuilders use dedicated est the windings on each stator. end to be irreparable.

better to retain the original or and replace the brushes. nal regulators, replacement ailable and can be soldered

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Reconditioning alternators

ALTERNATOR ASSEMBLING u Reassembly can begin, not only after all of the reusable parts are clean and the new components have been received, but also when the rebuilder is sure that they are correct. This alternator is from an early 2000’s Honda Civic.

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Obviously, it is vital that even the smallest part is refitted, to ensure a long life. Should a washer/spacer be fitted to the rotor’s nose, it must be reused or renewed.

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After the rotor’s original front bearing is pressed out of the drive-end’s front plate (see Steps 13-15 of Alternator Dismantling), a replacement is fitted, using a hydraulic press to locate it in position.

If fitted – and referencing Step 15 of Alternator Dismantling – refit the bearing’s protective plate using the original fixings. In virtually every case, the bearings do not require any additional lubrication.

With the drive-end’s cover gripped in a vice, the rotor’s nose is inserted gently, but firmly, into the new bearing. Never strike the rotor in an attempt to force it home – just use firm hand pressure to slide into position.

Working on the empty rear commutator end casing, the rectifier is inserted into the moulding. This particular part is secured with a single screw.

To protect the spring-loaded brushes, you may be able to insert a pin that engages with the holes in both the brushes and the regulator body. Step 23 of Alternator Dismantling shows the brushes fully-forward.

The combined brush box and regulator is then inserted into the rear commutator end housing and secured with screws. Note that the brushes are still held back by the pin.

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After ensuring that both the regulator and rectifier’s connections are aligned, they are soldered together, with the operator taking care not to melt any surrounding plastic.

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After the stator is inserted into the rear housing, its insulated connections will require soldering to the rectifier. Note that, in this picture, the freshly-soldered area from Step 9 is visible.

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Reconditioning alternators

ALTERNATOR ASSEMBLING continued

The stator might fit into a recess within the casing. Hand pressure should ensure that it is located, otherwise reuniting the alternator’s two halves might become difficult.

Fit the new bearing to the commutator end of the armature (or the casing) and reunite the front and rear alternator halves by inserting the rotor carefully into the stator.

Make sure the brackets from both halves align, prior to ensuring that the other end of the stator is pressed firmly into any recess within the front drive-end cover.

Insert the securing bolts and tighten them evenly. Rotate the exposed rotor shaft to make sure that it spins freely, with no ‘tight spots’. Should any be found, the cause must be investigated.

Consult Step 7 on page 55 and note that the pin protrudes from the end of the rear commutator housing. Pull it out and a ‘click’ may be heard, as the brushes make contact with the slip ring(s).

Fit the pulley (including any spacers) using thread-lock on the threads, prior to tightening the securing bolt. Here, the original solid pulley has been reused; other types will require a replacement part.

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 Each alternator that Eurolec reconditions undergoes a testing procedure, which is accompanied by a print-out of results.

Afterwards, the unit is boxed, ready for dispatch.

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Mount any connector extensions, noting if any protective rubber gaiters are used to not only protect the wiring but also help prevent the risk of a short circuit, which could be catastrophic.

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Combined starter/ alternator units are fitted to some Stop-Start models and hybrids.

Currently, there is little aftermarket support for these types. Some hybrid cars lack a dedicated alternator – and battery charging problems might need to be directed to a specialist.

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WITH THANKS TO: Eurolec and Powerlite Rotating Electrics Units 2-4 Northmoor Industrial Park, Moor Street, Brierley Hill, West Midlands DY5 3SU. Tel: 01384 261984 eurolec-components.co.uk

Bosch Automotive Matt Wilkin

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12/09/2021 21:49

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Starter motor overhaul

Starter motor OVERHAUL

Combined starter/alternator un connect to the crankshaft pulle are fitted to certain Stop-Start hybrid vehicles.

As spare parts are so easy to obtain, Rob Marshall says you can save a significant sum by repairing a faulty starter motor at home.

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urprisingly, electric starters have not changed radically since they were first introduced to the car.

The motor operates on a simple brush-type principle and a cog (the pinion gear) resides at the armature shaft’s end. When power is supplied, the pinion meshes with the flywheel’s teeth and the engine is turned over under the motor’s power. When the engine is rotated at sufficient speed to start, the pinion disengages as power to the starter motor is cut. As the pinion is much smaller than the flywheel’s ring gear, the armature has to turn at a faster rate – a ratio of 15:1 is not uncommon on direct-drive types.

Due to the motor having to overcome opposing forces of compression (especially in a diesel) and friction, plus the drag caused by cold oil, starter motors can have a torque rating in excess of 200lb ft. Passing a heavy current through the ignition circuit is impractical – doing so would dictate very heavyweight cabling, otherwise the wiring would melt.

Therefore, a solenoid utilises a low current trigger input from the ignition switch to close a pair of heavy-duty contacts that permit substantial current flow – at least 250 amps – to the starter motor.

inertia-type or Bendix Drive pinions. In virtually every case, the solenoid was mounted separately to the motor, often on the inner wing or bulkhead.

As the motor starts to turn, the pinion gear rides up the armature shaft on a threaded sleeve, until it meshes with the flywheel’s teeth. Once the engine fires, the action of it turning faster than the starter motor causes the pinion to disengage, due to the force of a powerful spring that bears against it. While inertia starter motors are inexpensive to produce, the method of pinion gear engagement is fairly aggressive, meaning that its teeth are prone to being chewed.

Inertia motors became obsolete as the 1980s progressed, but you will still find them on engines that power older cars, boats and other equipment. Electric-start lawnmowers, for example, tend to use inertia motors fitted with fibre pinions.

These days, pre-engaged starter motors serve almost every modern car.

COLLAR

RUN-OFF SPRING

CIRCLIP

They differ from the cheaper inertia-type by having their solenoids mounted on the top of the main motor casing. This serves a dual purpose: not only does it fulfill the switching criteria, but a plunger is operated electromagnetically to engage the pinion when the armature is either not turning or is just rotating very slowly, hence the term ‘pre-engaged’. A one-way clutch, which cannot be rebuilt separately, can be incorporated within the pinion. While pre-engaged motors are more expensive to produce, the pinion has a much longer life expectancy and the motor is significantly quieter.

Direct-drive starters have their pinions attached directly to the armature, while gear reduction starters use several gears internally, allowing the pinion to spin up to five times faster than the armature.

This means a lighter and less bulky motor can be used by the car manufacturer.

THREADED SLEEVE

PINION

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Getting started Starter motors differ in the ways their teeth engage with the flywheel.

Cheaper cars used to employ

Some starter motor desig replace the field coil with a magnet, meaning the batter have to energise both the fi armature simultaneously. H the magnets attract iron pa fragments that find their w bellhousing (caused by, for e failing dual mass flywheel), be sucked into the starter m thereby ruining it.

The introduction of Stopand hybrid technology has s humble starter motor being even greater stress, but any about longevity have been r by strengthened brushes an Combined starter/alternato been introduced, such as Va (Starter Alternator Reversib It operates on the engine no flywheel, but by the alternat

Most starter motor probl internals, especially whe

The inertia starter motor is also known as the Bendix Drive, named after its inventor, Vincent Hugo Bendix.

 An inertia motor can be identified by its simple construction and separate solenoid.  The pre-engaged motor has its solenoid mounted above the motor casing.

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As starter motors are dam excessive heat, on remov bend any shielding out of shap

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Starter motor overhaul

tor

IDENTIFYING PROBLEMS

Combined starter/alternator units, which connect to the crankshaft pulley via a belt, are fitted to certain Stop-Start models and hybrid vehicles.

om the cheaper inertia-type ir solenoids mounted on the in motor casing. This serves e: not only does it fulfill criteria, but a plunger is tromagnetically to engage hen the armature is either r is just rotating very the term ‘pre-engaged’. A ch, which cannot be rebuilt n be incorporated within While pre-engaged motors ensive to produce, the much longer life expectancy r is significantly quieter. e starters have their pinions ctly to the armature, while n starters use several gears owing the pinion to spin up faster than the armature. lighter and less bulky motor y the car manufacturer.

Some starter motor designs also replace the field coil with a permanent magnet, meaning the battery does not have to energise both the field coil and armature simultaneously. However, the magnets attract iron particles and fragments that find their way into the bellhousing (caused by, for example, a failing dual mass flywheel), which can be sucked into the starter motor, thereby ruining it.

The introduction of Stop-Start and hybrid technology has seen the humble starter motor being put under even greater stress, but any worries about longevity have been resolved by strengthened brushes and pinions.

Combined starter/alternators have been introduced, such as Valeo’s i-stARS (Starter Alternator Reversible System).

It operates on the engine not via the flywheel, but by the alternator belt. A

 While fitted to the car, the starter can manifest problems in different ways.

Reluctance for the motor to turn until tapped with a suitable implement can point to a worn solenoid, brushes or armature. It can also indicate a blown fuse or a problem with the car’s wiring.

Intermittent operation can be down to the same components. A poor earth can cause slow starter movement, as can a shorted field coil. A grinding noise can be caused by either a worn pinion or sticky solenoid; do not use the starter motor or else you can damage the flywheel teeth. A high-pitched shriek heard soon after the engine fires is down to worn bushes that support the starter’s armature. However, you should check the battery and alternator before suspecting the starter motor.

conventional starter motor tends to be used as well, for the more difficult cold starts. Few of these units are in circulation and the aftermarket is only just beginning to repair them, because specialist calibration is required. These systems are not included within this feature.

Rebuild costs Should you treat your motor to a basic rebuild – replacing the brushes, their springs and the armature bushes only – the cost of parts is unlikely to exceed £20, which is a significant saving over the cost of a new motor. However, once the motor is disassembled, should you find that the solenoid, armature or field coils need replacing as well, the parts cost will inflate dramatically and might even eclipse the price of a guaranteed reconditioned exchange unit. This is in

addition to the inconvenience of having the car off the road for a longer period.

Starter motors can also be tricky to remove and not all of them are fitted in an accessible location, so check that removing the starter motor is within your capabilities. As carmakers tend to fit starter motors from different manufacturers, even for the same model, identifying which version is fitted to your car, either by registration or chassis number, might not be accurate.

The starter motor being demonstrated is a pre-engaged, direct-drive type, equipped with field coils. In the majority of cases, rebuilding a starter motor is straightforward. Other than a soldering iron and a multimeter, no special tools are required. However, should you run into difficulties, do not be worried about contacting your local auto electrician for assistance.

PINION

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Most starter motor problems are caused by dirt affecting the internals, especially when the unit is submerged in an oil leak.

As starter motors are damaged by excessive heat, on removal, try not to bend any shielding out of shape.

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Some starter motors can be tricky to see, let alone access.

Ensure that removing it is within your capabilities.

Note the wiring’s position before disconnecting anything. Some motors are supported by a rear bracket.

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Here, the starter came out from behind the engine. Some might necessitate taking off a wheel or undertray.

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Ensure that any locating dowels do not drop into the bellhousing. Retain any spacing shims, noting their position.

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Inspect the starter motor for any cracked or damaged casings, especially as the front plate tends to be cast from aluminium.

Degrease the outer case with a solution that cannot dissolve the glues and resins used on the armature.

If not done so already, note the identifiers stamped on the centre casing and inform your spare parts supplier.

While chipped or chewed teeth are unlikely to affect pre-engaged starter motors, always replace inertia pinions.

Disconnect the field coil supply lead from the solenoid, storing the bolt and any washers for reuse.

The small nuts that secure the solenoid to the motor’s front plate can seize and snap easily, so be careful.

Withdraw the solenoid and spring.

Be aware that some types need unclipping from the arm within the motor.

Drive out this steel pin. Try not to damage the soft aluminium front plate casting. See Step 22.

If fitted, remove the rear mount support bracket, retaining all nuts and spring washers for reuse.

If fitted, a dust cover not only protects the rear bush but also supports the brush box. Note if a gasket is fitted.

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A bolt is retaining the en motor from turning by lo

Remove the retaining bo unit together. They can b either internally (as pictured) o

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Ease the armature from out of the front bush. Lif

After lifting the rear plat box is uncovered. Here, t springs are attached to the rear

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racked or damaged casings, to be cast from aluminium.

hipped or chewed teeth are to affect pre-engaged starter replace inertia pinions.

w the solenoid and spring. e that some types need m the arm within the motor.

Starter motor overhaul

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A bolt is retaining the end-float washers here. Prevent the motor from turning by locking the pinion using…

Remove the retaining bolts holding the unit together. They can be mounted either internally (as pictured) or externally.

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After lifting the rear plate, the brush box is uncovered. Here, the brush springs are attached to the rear plate.

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…an implement such as a flat-bladed screwdriver. Remove the bolt and note the position of the end-float washers.

Slowly and carefully, pull the combined front casting and armature away from the centre and rear casings.

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Ease the armature from the front casting by working the nose out of the front bush. Lift off the pinion operating arm.

a dust cover not only protects bush but also supports the e if a gasket is fitted.

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Remove and store the other thrust washers fitted to the rear of the armature – they must be refitted later.

Note the brush positions, prior to removal. Brush boxes can be damaged easily – replacements tend to be available.

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Most units have a rubber gasket and mounting plate between the solenoid and front casing. Lift them away.

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Gently clean away oil and dust residue from all casings and parts, before allowing everything to dry.

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Starter motor overhaul PINION OPERATING ARM

CASING BOLT

SOLENOID

OUTER CASING

FIELD COILS

THRUST WASHERS

REAR PLATE

BRUSH SPRING

PINION RETURN SPRING

DUST COVER

FRONT BUSH

FRONT CASING

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PINION ASSEMBLY

CASING BOLT

ARMATURE

FIELD COIL RETAINING SCREW

BRUSH

REAR BUSH

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The pinion tends to be re Remove it and slide the p

Once all the components have been allowed to dry after being cleaned in a suitable solution, lay them out on a clean surface. Inspect all of the parts for their serviceability and make sure that no major components need to be renewed.

Check the surface, on wh brushes bear, for heavy s commutator lathe can remove t

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As they are inexpensive, renew the carbon brushes regardless.

The length of the new brushes here was 15.2mm.

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As a bare minimum, renew brushes and their springs, as well as the two bushes that support the armature at each end.

A more comprehensive overhaul can include renewing the field coils, armature, pinion and solenoid.

Allow the bushes to soak in engine oil for 24 hours prior to fitting. They absorb the lubricant and will last longer.

Working on the rear cap, press out the old bush using either a small socket or a screwdriver.

The new bush must be pressed into the aperture evenly, using either an old bush or a small socket.

After the replacement bush is in position, replace any brush springs if they are fitted to the end cap.

To renew the front plate’s bush, repeat Steps 32 and 33, taking extra care not to damage the aluminium casting.

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Check also for continuity that no winding is shorti

Should you not renew th cut off the old brushes fr Leave some copper wire expose can solder new brushes to it.

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Starter motor overhaul REAR PLATE

BRUSH SPRING DUST COVER

REAR BUSH

36

The pinion tends to be retained by either a collar or a circlip.

Remove it and slide the pinion from the armature shaft.

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Check your replacement pinion matches that of the original.

Slide it onto the shaft and replace the retaining circlip.

a clean surface. Inspect all of

es and their springs, as well as armature at each end.

g on the rear cap, press out the h using either a small socket or

w the front plate’s bush, repeat 2 and 33, taking extra care not aluminium casting.

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Check the surface, on which the brushes bear, for heavy scoring. A commutator lathe can remove the high spots.

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Check also for continuity between each field coil connection and that no winding is shorting out to the earthed body.

Should you not renew the field coils, cut off the old brushes from the post.

Leave some copper wire exposed, so that you can solder new brushes to it.

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Do not sand the commutator. Polish it with wet-and-dry sandpaper and clean using contact cleaner and a toothbrush.

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Should either fault be detected, renew the field coils (if fitted) by removing the screws on top of the casing.

Solder the new brushes to the exposed wire. In some cases, you’ll find it’s hard to solder directly to the post as the solder just runs off.

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Check the commutator’s individual segments for continuity and for any short circuits.

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Reassemble the solenoid’s pinion operating arm (see Step 22) and locate the armature’s nose into the front housing’s bush.

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Starter motor overhaul

THE COST

Drive the operating arm’s pivot pin back into the casing, but check if it needs to pass through the aperture.

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Position the main casing, which incorporates the field coils/permanent magnets, into the front housing.

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 In the case of this Valeo D9E motor, renewing all the parts at home would cost £92.93+VAT – which is more than a new aftermarket replacement, which Wood Auto Supplies prices at £79.20+VAT. However, replacing the bushes, brushes and one or two major components, if needed, will realise a saving. The component prices below exclude VAT, and, while specific to the unit being dismantled in this feature, give an idea of which parts cost the most.

Solenoid £16.00 Brush set £2.32 Brush spring set £1.12 Armature £25.60 Pinion £12.16 Field coils £35.20 Bushes (x2) £0.53

SPARE PARTS Fit the brushes and, if necessary, secure the brush box. Ensure that the thrust washers are present on the armature.

Refit the bolt or renew the securing washers. Ensure that the other set of thrust washers is refitted.

The rear plate’s bush may be reluctant to locate easily into the armature.

Tighten the locating bolts evenly.

Ensure that any rubber grommets, which surround a protruding field coil lead, are fitted and located correctly.

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Refit or replace the gaskets (see Step 21), solenoid and return spring. Refit the field coil lead to the original terminal, if fitted (see Step 11).

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(MAIL ORDER)

Wood Auto Supplies Limited Colne Road, Huddersfield HD1 3ES Tel: 01484 439000 Email: sales@woodauto.com Web: www.woodauto.com

Consulting Steps 15 and 16, refit the dust covers, their gaskets and the rear supporting bracket.

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Test the starter motor and solenoid before refitting it to the car. Do not connect live power leads directly to the terminals because a high current’s spark will erode the threads. Use a switching medium, such as a jump-pack.

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Crankshaft overhaul

Crankshaft

REGRINDI

OVERHAUL

Crankshaft problems were once banished to the history books, but the distinctive ‘bearing knock’ is becoming more common again.

Rob Marshall looks at how the problem can be resolved.

A

crankshaft is the heart of the engine and is one of the components that comes under the highest stress. Soft-metal shell bearings run between its journals and the connecting rods, with the moving parts separated only by a thin film of oil.

If this film fails, the bearings are sacrificed to avoid costly crankshaft damage.

Lubrication advances, better filtration, tighter engine tolerances and journal toughening methods have helped to virtually eliminate the

Assessing the condition o within the cap) will help t whether or not regrinding is ne

1

once-common big-end knock, or main bearing rumble, which was once typical of a high-mileage engine. However, Greg Healey, proprietor of Bromsgrove Engine Services, reports that crankshaft failure is becoming a pressing issue again. “Not only are motorists extending the already lengthy manufacturer lubrication change intervals,” he says, “but even modern engines consume oil and simple level checks are being forgotten. Some drivers think that an illuminated low-pressure fascia lamp is

Hardened surfaces  Some crankshafts on performance models are heat-treated, to toughen the working surfaces, using special processes such as nitriding or tuftriding (nitrocarburising).

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This hardened surface is removed by the grinding process, so it must be restored. Once the costs are evaluated, it could be more cost-effective to simply buy a new crankshaft.

only a warning, rather than a tell-tale that their engine is being ruined.”

Falling oil pressure, possibly prompted by low sump levels, will cause rapid heat build-up between each crankshaft journal and its bearing, resulting in direct metal-to-metal contact. The softer bearing material will overheat and scrub away first, widening the tolerance between the shell and journal.

“By the time obvious knocking is heard,” says Greg, “the crankshaft journal will have been damaged, possibly becoming oval, as a result of the hammering action of the connecting rod against it. In extreme cases, the metal surfaces will weld together, seizing the engine.”

Even if the motor were stopped in time, replacing the bearings alone might be insufficient and the crankshaft would need removing. Bad driving practices do not help either. Although limiters make accidental over-speeding difficult, revving an engine hard when cold is not advisable. Similarly, a clutch pedal depressed for prolonged periods will wear out the thrust washers, which can lead to excessive crankshaft end-float, which could even damage the engine block.

“In the old days, replacement undersized shell bearings compensated for the material ground from the crankshaft journals during the machining process,” says Greg. “But, as crank failure became rarer, these stopped being made available. Now, undersized bearings have been reintroduced for many engines to meet the demand from customers wanting to save hundreds of pounds by having their crankshafts reconditioned, rather than replaced.” shop.kelsey.co.uk/subscription/CME 13/09/2021 22:08 22:03 13/09/2021

Before any work can com the crankshaft is removed engine, stripped of its ancillarie thoroughly and compressed air through its oil galleries.

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The thrust washers’ toler end-float – are checked. T was unnecessary and new stan

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The operator makes sure is mounted securely and the crankshaft grinding machin radius of each journal is checke

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REGRINDING

Assessing the condition of the shell bearings (pictured above within the cap) will help to establish the state of the journal and whether or not regrinding is needed.

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ng, rather than a tell-tale gine is being ruined.” pressure, possibly prompted levels, will cause rapid between each crankshaft s bearing, resulting in to-metal contact. The g material will overheat and rst, widening the tolerance shell and journal. e obvious knocking is heard,” he crankshaft journal will maged, possibly becoming ult of the hammering action ting rod against it. In s, the metal surfaces will r, seizing the engine.” motor were stopped in ng the bearings alone might t and the crankshaft would ng. Bad driving practices ither. Although limiters tal over-speeding difficult, gine hard when cold is . Similarly, a clutch pedal prolonged periods will wear t washers, which can lead rankshaft end-float, which mage the engine block. days, replacement hell bearings compensated ial ground from the urnals during the ocess,” says Greg. “But, as became rarer, these stopped vailable. Now, undersized e been reintroduced for s to meet the demand from nting to save hundreds having their crankshafts d, rather than replaced.”

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Before any work can commence, the crankshaft is removed from the engine, stripped of its ancillaries, degreased thoroughly and compressed air is blown through its oil galleries.

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A journal tolerance varies between different engines. To decide whether or not regrinding is necessary, the tolerances need to be verified first, by consulting the relevant data…

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The thrust washers’ tolerances – which control the crank end-float – are checked. They’re fine here, so extra machining was unnecessary and new standard thrusts would be fitted.

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The operator makes sure the crankshaft is mounted securely and accurately into the crankshaft grinding machine. Then, the radius of each journal is checked…

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A quick check for a scored journal is possible by running a fingernail across its surface. Should any scores be felt, regrinding will be necessary, prior to more accurate measuring.

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A crankshaft grinding machine is a bespoke lathe that needs to be configured twice by the engineer: one setting suits the bigends, the other is for the main bearing journals.

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…before the grinding stone is chosen and configured to match the appropriate journal’s diameter. Only one journal is worked on at any one time.

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…which is compared with measurements taken from the crankshaft. As the journal had worn to below the stated tolerances for this example, regrinding was needed.

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The crank is set perfectly in line with no run-out and the machine is switched on. The grinding wheel starts to spin and the crank is revolved slowly.

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COSTS

Sample prices supplied by Bromsgrove Engine Serv 35 Sherwood Road, Aston Industrial Estate, Bromsgr Worcestershire B60 3DR. Tel: 01527 559333

www.bromsgroveenginese Regrind & polishing: The first journal to be reground was the big-end with the most scores. The operator has to control the stone skilfully, because excess ground-off metal cannot be added back.

At various intervals, the machine is switched off and the journal diameter checked and measured, to establish how much more material needs to be removed to bring it within its new tolerance.

Journals that have knocked out a bearing can also go oval, the extent of which determines how much material has to be removed. The depth of any scoring is also an influencing factor.

We established that this crankshaft’s journals were not damaged badly and needed only 0.010in of material removing.

0.030in could have been tolerated, dictated by the availability of undersized bearings.

Once the remaining three big-end journals had 0.010in of material removed, the crankshaft grinding machine was reset and steps 7-14 were repeated for the main bearing journals.

Once all grinding is completed, polishing removes any minute grinding marks that might shorten a new shell bearing’s life. First, each journal is lubricated with a lapping oil.

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£18 per jou

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espite being balance factory, a crankshaf stability can gradua due to age, heat, we stress. Achieving a perfect b mass-produced cranks is un even on today’s latest engin that a tolerance is specified. ages, the imbalance can grow those tolerances, and becaus moves the eccentric position bearings slightly, thereby co possible bend, re-balancing the issue. Obviously, should be tuned to increase its max and revs, then the specified will no longer be relevant an precise balancing is advisabl “Many people do not appr extra forces that an imbalanc

BALANCIN

A length of emery cloth is held against the journal’s surface by the operator, and with the crankshaft remaining secured to the grinding machine, it is rotated at a higher speed.

The surfaces on which the crankshaft seals bear are also polished. This removes any light corrosion and provides a better working surface, to reduce the chance of oil leaks.

Inspect any clutch pressu signs of balancing. This H clutch pressure plate had been the factory, because extra weig spot-welded to it…

The crankshaft is removed from the machine and, to ensure that no metal specks from regrinding can reduce the rebuilt engine’s life, its oil galleries are flushed through.

Once it has dried, the reground crankshaft is ready to be balanced, prior to being refitted to the engine with new undersized bearings and stock thrust washers.

The reground crankshaft machine. The unit is spun displayed, in a similar manner t

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COSTS

Sample prices supplied by Bromsgrove Engine Services, 35 Sherwood Road, Aston Fields Industrial Estate, Bromsgrove, Worcestershire B60 3DR. Tel: 01527 559333

www.bromsgroveengineservices.com Regrind & polishing:

s that have knocked out a can also go oval, the extent of nes how much material has to he depth of any scoring is also factor.

grinding is completed, g removes any minute s that might shorten a new life. First, each journal is h a lapping oil.

£18 per journal

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espite being balanced at the factory, a crankshaft’s rotational stability can gradually decline due to age, heat, wear and stress. Achieving a perfect balance on mass-produced cranks is unfeasible, even on today’s latest engines, meaning that a tolerance is specified. As the unit ages, the imbalance can grow outside of those tolerances, and because regrinding moves the eccentric position of the main bearings slightly, thereby correcting any possible bend, re-balancing will redress the issue. Obviously, should an engine be tuned to increase its maximum power and revs, then the specified tolerance will no longer be relevant and more precise balancing is advisable.

“Many people do not appreciate the extra forces that an imbalance generates,”

says Trevor Wilkinson, proprietor of Andrews Precision Engineering in Worcestershire. “In five decades of experience, I have witnessed bottom-end imbalances which create forces that are equivalent to half of the vehicle’s weight!

Obviously, this places the crankshaft bearings under huge additional stress”.

Apart from increasing engine wear, any imbalance will also promote failure of the dual mass flywheel (DMF), because that expensive component is placed under the additional strain by absorbing the unwanted vibration. A technician might arrive at the incorrect diagnosis that the DMF is at fault, when the true cause lies elsewhere.

However, preparing the crankshaft is pointless if the front pulley, flywheel and clutch pressure plate are all out of balance, so failing to have these components attended to is a false

economy. Worryingly, an increasing number of clutch pressure plates, often the cheaper non-OE quality versions, tend not to have been balanced at all, so it is worth paying to have the new part checked before fitting.

Correct balancing starts with the bare crankshaft, prior to its ancillary parts being added one at a time, with the balance rechecked and adjusted at each stage. Some low-cost operators might save time by balancing everything together and drilling or adding weights to one item alone. While this approach might work at the time, problems will occur if any item is replaced at a later date. Additionally, some ‘V’ engine configurations are considerably more complicated – and costly – to balance than an inline crankshaft, because they require more involved preparation, including the use of bespoke balance weights.

…whereas this cheaper non-OE clutch plate had obviously not been anywhere near a balancing machine, not only because weights were absent, but there was no evidence of assymetrical drillings.

Replace any missing parts. Even a simple dowel, which had been lost on this flywheel, would have made it run out of balance. Using his lathe, Trevor remakes and fits a replacement.

BALANCING

haft seals bear are also orrosion and provides a better f oil leaks.

Inspect any clutch pressure plate for signs of balancing. This Honda’s new clutch pressure plate had been balanced from the factory, because extra weights had been spot-welded to it…

ankshaft is ready to be o the engine with new ashers.

The reground crankshaft is weighed and fitted to the balancing machine. The unit is spun and the degree of the imbalance is displayed, in a similar manner to a tyre balancer.

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The production tolerance of this crankshaft is 80.5gm/mm (see Determining forces, page 72), but the actual imbalance was 175gm/mm at the nose and 490gm/mm at the clutch end.

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Balancing more dept

As this crank’s webs were too thin for drilling, Trevor used a bespoke belt sander and innate experience to determine the quantity of material that needed to be removed.

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Trevor repeats steps 6 and 7. The machine’s computer screen highlights the degree of imbalance, its location (yellow dot) and the angle (red lines) at which points material would need to be removed.

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The crankshaft is refitted to the balancing machine and re-spun.

The imbalance had reduced to 34gm/mm and 43gm/mm, thus well within stock production tolerances for a maximum 6000rpm.

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Although the crankshaft has been balanced, its ancillary components also need to be checked. They are added to the crank one at a time, starting with the flywheel, which is weighed first…

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…before being fitted to the crankshaft with bolts that are of identical length and weight. The flywheel and crank are then mounted into the balancing machine and spun.

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 Imbalance is expressed multiplying the weight of a component (mass) by the r its pivot point. Therefore, a that has 10gm of unbalanc mounted at a radius of 50m an imbalance of 500gm/mm Tolerances for all types o are expressed by a ‘G’ grade fixed figure for crankshafts which means 6.3gm/mm p weight. To calculate the tol ‘G’ grade is multiplied by 10 divided by the engine’s ma intended rpm. This figure is multiplied by the compone Thus, the tolerance of a f that weighs 10kg would be by 6.3 x 10,000 ÷ 6000 = 10 is then multiplied by the we 10kg, giving a tolerance of 1 The forces that an imbala creates can be huge. If a fly balanced to 105gm/mm w on the crankshaft by only 0 the imbalance would be 50 – nearly five times the prod tolerance – generating 18k at 6000rpm.

As the structure is highly drilling too much materi one place will weaken it. There ensures that drilling at the cent imbalance is kept to a minimum

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This flywheel exhibited little evidence of being balanced effectively from new. The result of 741gm/mm confirmed it, exceeding its tolerance of 75.6gm/mm by a huge margin.

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To counteract the imbalance, Trevor removes material from the flywheel by drilling at the point that had been indicated by the red line on the computer screen readout (see step 11).

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The front pulley is also d centre point of imbalanc the technician needs to drill a p carefully if it is fitted with a rub damper.

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The result sees the imbalance fall from 741gm/mm to a more acceptable limit. However, Trevor had to repeat steps 10 and 12, before the final figure of 11.8gm/mm was achieved.

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Should the flywheel be removed from the crankshaft, it must be refitted in exactly the same balanced position, otherwise the flywheel will introduce an additional imbalance.

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Crankshaft overhaul  Although it is unnecessary to balance sprockets, the clutch pressure plate needs to be checked, especially as many replacements aren’t inspected when new. As with the other components, this is weighed first, prior to being bolted securely to the flywheel. Ensure that identical bolts are used (ie, none should be longer than the others) and that all spring washers are fitted, if they are required.

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Balancing in more depth

alancing machine and re-spun. m/mm and 43gm/mm, thus for a maximum 6000rpm.

e being fitted to the aft with bolts that are of h and weight. The flywheel and mounted into the balancing pun.

 Imbalance is expressed by multiplying the weight of a component (mass) by the radius from its pivot point. Therefore, a crankshaft that has 10gm of unbalanced mass, mounted at a radius of 50mm, gives an imbalance of 500gm/mm.

Tolerances for all types of balancing are expressed by a ‘G’ grade and the fixed figure for crankshafts is ‘G 6.3’, which means 6.3gm/mm per kilo of weight. To calculate the tolerance, the ‘G’ grade is multiplied by 10,000 and divided by the engine’s maximum intended rpm. This figure is then multiplied by the component’s weight.

Thus, the tolerance of a flywheel that weighs 10kg would be calculated by 6.3 x 10,000 ÷ 6000 = 10.5. The 10.5 is then multiplied by the weight of 10kg, giving a tolerance of 105gm/mm.

The forces that an imbalance creates can be huge. If a flywheel balanced to 105gm/mm was offset on the crankshaft by only 0.05mm, the imbalance would be 500gm/mm – nearly five times the production tolerance – generating 18kg of force at 6000rpm.

As the structure is highly-stressed, drilling too much material from any one place will weaken it. Therefore, Trevor ensures that drilling at the centre point of the imbalance is kept to a minimum…

…but he also scores away material with a mini belt sander so that the pressure plate will not buckle in use. If removed, a balanced pressure plate must be refitted in the same position.

Moving to the crankshaft’s nose, the front pulley and its nut are weighed and bolted to the crankshaft, prior to the imbalance tolerance being calculated and the assembly spun and rebalanced.

The front pulley is also drilled at the centre point of imbalance. However, the technician needs to drill a pulley very carefully if it is fitted with a rubber vibration damper.

It would be pointless balancing the rotating masses if the connecting rods and pistons were to differ in weight. The rods and pistons are removed by pressing out the gudgeon pin.

The weights of the rods are assessed individually using Trevor’s bespoke scale and the lightest one is set as the benchmark. The other connecting rods will be lightened to match the lightest.

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or removes material from the hat had been indicated by the (see step 11).

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from the crankshaft, it me balanced position, additional imbalance.

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 The balancing process is repeated. In this case, the imbalance has leapt to 610gm/mm.

Then, once Trevor had removed material from the pressure plate, the figure dropped considerably to 15.3gm/mm.

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Determining forces generated by imbalance

The heaviest connecting rods have material removed from both their caps and shafts using a belt sander, and Trevor’s experience ensures that not too much metal is shaved off.

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Each connecting rod’s weight is checked to be within 0.2gm of the lightest one. Note that the bearing caps were not removed and that they should never be mixed up.

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RPM ÷ 1000 squared, multipled by gm/mm. Total multiplied by 0.001.

Example: RPM = 6000 Imbalance = 500gm/mm 6000 ÷ 1000 = 6 6 squared = 36 36 multiplied by 500gm/mm = 18,000 18,000 multiplied by 0.001 = 18 kilos of force generated at 6000rpm

COSTS

The pistons’ weights need to be equalised as well. As with connecting rods, the masses vary, so each piston is weighed and the lightest one is taken as the benchmark.

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As an aluminium piston is considerably softer than a steel connecting rod or crankshaft, the belt sander will be too aggressive to remove excess material.

Instead, a lathe is used.

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Sample prices supplied by Andrews Precision Engineering, Unit 10, Wildmoor Mill, Mill Lane, Wildmoor, Bromsgrove, Worcs B61 0BX. Tel: 01527 835005 4-cylinder in-line £144 6-cylinder in-line £192 5-cylinder crankshaft £240 V6 £240 V8 £360 V10 £420 V12 £360

All these parts are balanced but, as crankshaft components have been separated, they must be refitted in the identical positions to which they were balanced.

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Looking after your FUEL INJECTORS

Looking after your

What goes w

Fuel Injectors Fuel injectors are precision instruments that endure one of an engine’s harshest atmospheres. Rob Marshall explains their operation.

All injectors are designed to create a fine spray pattern, which deteriorates as the injector wears and deposits build up both within and outside the injector.

O

f the many refinements made to the internal combustion engine, fuel injection was one of the most important. Fitted initially to fighter aircraft, accurate liquid energy metering is a vital tool in the never-ending quest to not only reduce pollution and noise, but also maximise engine power, economy and flexibility.

de-restrict the air inlet, which results in further efficiency at both high engine revolutions and loads. As a fine mist of petrol is created post-injection, it mixes more effectively with the flowing airstream, making it possible for the engine to be tuned to run at weaker mixtures. This was the premise of lean-burn technology, post-Honda’s revolutionary CVCC expertise, which became popular from the 1980s.

Fitted to the inlet manifold, in most cases, the majority of multi-point set-ups had their injectors situated just behind the inlet valve (port-injection). Due to improvements in injector technology, many petrol engines adopted directinjection, where the injector was placed directly above the piston within the combustion chamber. To refine the higher-compression heavy oil (diesel) engine, indirect-injection was popular

Injector history While not particularly accurate, single-point petrol fuel injection replaced carburettor jets. However, the set-up’s popularity declined markedly from the mid-1990s as legislation demanded more accurate metering. The more precise multi-point fuel injection has become universally accepted, with each cylinder being fed by its own injector, a layout that is applied to the majority of diesel engines.

When Bosch developed its famous Jetronic multi-point petrol fuel injection, internal test data revealed an increase of up to 15% in power, with a corresponding decrease in fuel usage, compared with even a progressive twin-choke carburettor.

Deleting the carburettor body helps to ADJUSTER SPRING

NEEDLE SPRING

CONTROL VALVE

CAP NUT

NOZZLE

Some solenoids are sealed and cannot be removed. On injectors thus equipped, all that can be replaced are the cap nut, nozzle, needle spring, control valve and adjuster spring.

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for passenger cars, in which the injector and pre-heater glow plug tips protruded into a separate chamber, cast into the cylinder-head. The trade-off was a loss in efficiency but later advances in the technology have permitted direct-injection to become tailored for diesel engines.

Early diesel injector breaking (or squirt) pressures tended to be set at around 115bar, but later developments discovered that higher pressures increased engine power and decreased tailpipe emissions.

The 115bar, therefore, rose to around 280bar, prior to the two-stage injector being introduced, which boasted improved atomisation of the fuel, among its other advantages, at around 400bar. Common rail-type diesel injectors took this a step further. First, diesel ‘knock’ and extraneous noise is reduced by several pre-injections that are followed by two main injections, to obtain the desired power output. Finally, a further pair (or more) of post-injections might feature on the exhaust stroke, to regenerate the diesel particulate filter (DPF).

Therefore, modern, direct-type fuel injectors operate at between 1500bar and 2000bar and are built to considerably finer tolerances. Although direct petrol injection systems work at reduced pressures, they can still be as high as 200bar, which is 10 times the inflation pressure of a typical car tyre. shop.kelsey.co.uk/subscription/CME 13/09/2021 22:51 22:45 13/09/2021

u Difficult starting, poor intolerable fuel consump and excessive exhaust em might be caused by a hos issues, not just fuel inject Therefore discount the si cause first, before suspec the most expensive issue investigating fuel injectio especially with commonsystems, it is best to chec any ECU fault codes and c live diagnostic readouts b dismantling commences.

Like any mechanical pa injectors will wear. Notab valves and their seats det with their minute nozzle h enlarging or cracking, esp high-pressure systems. Th either inaccurate atomisa that simply dribbles unre into the cylinder, which m result in either increased exhaust smoke or diluted oil. Thus, poor running or code that indicates exces ‘knock’ (or pre-ignition) a possibly, deteriorated en lubricant condition migh an injector problem.

Other than making visu for fuel leaks around the body, there is not much e you can look for. The exce injector blow-by (or ‘black which is a thick, tar-like su that might be found surro the injector on direct-inje diesel engines. The cause to be the copper end sea at the base of the injecto fails, permitting gases to upwards and squeeze be cylinder-head and injecto prior to exiting through t the injector. A ‘chuffing’ so the top of the engine is a that all is not well. Unfort these conditions, the eng tends to compensate by the fuelling, which can in fuel consumption and ex emissions, as well as crea potential for engine dam Should this stage be re it is wise to remove the in check its condition and re seal. Some diesel engines prone to ‘black-death’ and power units (such as PSA DV6 engine), it is recomm that the injector clamp to checked at every service.

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What goes wrong

ors All injectors are designed to create a fine spray pattern, which deteriorates as the injector wears and deposits build up both within and outside the injector.

cars, in which the injector er glow plug tips protruded te chamber, cast into the d. The trade-off was a loss but later advances in the ve permitted direct-injection lored for diesel engines. injector breaking (or squirt) ded to be set at around ter developments discovered ressures increased engine creased tailpipe emissions. herefore, rose to around to the two-stage injector ced, which boasted improved of the fuel, among its other t around 400bar. Common el injectors took this a step , diesel ‘knock’ and oise is reduced by several s that are followed by two ns, to obtain the desired . Finally, a further pair (or -injections might feature st stroke, to regenerate the late filter (DPF). modern, direct-type operate at between 2000bar and are built to finer tolerances. Although njection systems work at sures, they can still be as ar, which is 10 times the sure of a typical car tyre.

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u Difficult starting, poor running, intolerable fuel consumption and excessive exhaust emissions might be caused by a host of issues, not just fuel injectors.

Therefore discount the simplest cause first, before suspecting the most expensive issues. When investigating fuel injection, especially with common-rail systems, it is best to check for any ECU fault codes and consult live diagnostic readouts before dismantling commences.

Like any mechanical part, fuel injectors will wear. Notably, needle valves and their seats deteriorate, with their minute nozzle holes either enlarging or cracking, especially on high-pressure systems. The result is either inaccurate atomisation or fuel that simply dribbles unregulated into the cylinder, which might result in either increased black exhaust smoke or diluted engine oil. Thus, poor running or a fault code that indicates excessive diesel ‘knock’ (or pre-ignition) and, possibly, deteriorated engine lubricant condition might point to an injector problem.

Other than making visual checks for fuel leaks around the injector body, there is not much else that you can look for. The exception is injector blow-by (or ‘black-death’), which is a thick, tar-like substance that might be found surrounding the injector on direct-injection diesel engines. The cause tends to be the copper end seal, fitted at the base of the injector, which fails, permitting gases to head upwards and squeeze between the cylinder-head and injector body, prior to exiting through the top of the injector. A ‘chuffing’ sound from the top of the engine is also a clue that all is not well. Unfortunately, in these conditions, the engine ECU tends to compensate by increasing the fuelling, which can increase fuel consumption and exhaust emissions, as well as creating the potential for engine damage.

Should this stage be reached, it is wise to remove the injector, check its condition and renew the seal. Some diesel engines are very prone to ‘black-death’ and, on some power units (such as PSA/Ford’s DV6 engine), it is recommended that the injector clamp torques are checked at every service.

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ROB’S TOP TIP Always check the condition of any rubber leak-off pipes.

If made pre-2000, they might be vulnerable to being attacked by the bio-additives present in today’s road fuel.

Keep it clean Other than wear, the majority of problems are caused by low quality, deteriorated or incorrect fuel, plus false economies such as fitting a sub-standard fuel filter or omitting to change it at all. As injector tolerances have become more precise and the fuel pressures have increased, maintaining a high standard of petrol and diesel quality has become vital. ‘Dirty’ gas can also cause problems with LPG and CNG injectors.

For a long service life, modern fuel injectors (as well as other parts of the system) rely on the additives that have replaced the lubricating properties of sulphur in Ultra-Low Sulphur petrol and diesel. Road fuel must also be of a high enough quality, so that any impurities which are small enough to pass through the fuel filter do not abrade the injector internally. Even if deposits do not restrict the nozzle holes, black carbon can grow on the injector ends in sufficient mass to alter the spray pattern.

Further challenges arise with the increasing percentage of bio-fuels being blended with regular petrol and diesel, which can dislodge deposits in the fuel system, resulting in either a clogged fuel filter or damage to both pump and injectors, as well as introducing microbes and sticky deposits.

The percentage blend of up to 5% ethanol in standard unleaded petrol has recently increased in the UK to 10% and this can attract water, then separate and oxidise, which might increase internal fuel injector corrosion rates.

In the case of biodiesel, moisture is held in suspension, which robs the fuel of its lubricator properties, as well as increasing the risk of corrosion in the injector. With the increase of ethanol in fuel, it is likely that fuel injection failure rates will increase.

Greater reliance on cleaning agents has also become more pressing on certain ageing direct-injection petrol engines, such as Mitsubishi’s GDI range. Ignoring manufacturer recommendations, which specify a higher octane fuel than 95 RON petrol, is likely to cause problems. Bear this in mind if you run a car imported unofficially from overseas – particularly Japan – where it might be set up to run on a specific octane rating or fuel with a different means of anti-knock calculation.

All injectors are made to very fine tolerances.

On this indirect injection nozzle, from a classic diesel Land Rover, note that a smaller hole is positioned in the six o’clock position to assist with engine warming. t The unit injector combines the high-pressure diesel pump and the injector. The most well-known application for cars is VAG’s PD (Pumpe Düse) diesel engines, with the plunger pump being driven by the engine’s camshaft.

u The copper washer must always be renewed and the mating surfaces, both on the injector and the seat within the cylinder-head, must be in good condition.

Often, higher octane fuel leaves fewer carbon deposits and some types contain optimised detergent packs to keep injectors clean. Carbon build-up may also be reduced behind the inlet valve, especially where EGR valves are fitted on direct-injection models, because the area is no longer washed clean by passing fuel mist, unlike older port-injection setups. If you’re concerned about excessive carbon build-up, investigate walnut shell decoking, which is more cost-effective than stripping the cylinder-head.

The high cost of injectors means that refubishment is often more economical than a new part – we were quoted £477.30 from Peugeot/Citroën for a new injector for a DV6 engine, compared with £135288 for a same spec refurbished unit from Euro Car Parts. You may find that many main dealers fit refurbished injectors as replacement parts as a matter of course.

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DIY Propositions u If you are unsure about any aspect of working on a fuel injection system, particularly with diesels, leave the work to a trained and experienced technician who possesses the correct tools.

Although all fuel injection systems are pressurised to some extent, be wary of the fire risk should you work on any part yourself. More importantly, because the pressures involved on common-rail diesel systems can exceed those of a water jet cutter, opening up any part of the pressurised circuit could be a potentially lethal move.

Although many DIY mechanics still perform leak-off tests – connecting each injector’s low-pressure return outlet to a bottle to evaluate how much fuel flows back to the tank – some injectors still have their return circuits operating at a significant pressure, such as over 7 Bar (100psi), which might render this operation unsafe in a DIY environment.

Obviously, there is a significant fire risk from exposed fuel when performing leak-off tests on any injector that is fitted to a vehicle.

If excessive fuel is being returned to the fuel tank via the injector’s leakoff pipe, the common-rail might be unable to maintain sufficient pressure, which might cause the ECU to run the engine in ‘limp-home’ mode. The blame could be levelled at a highpressure pump, when one or more injectors might be responsible.

The other problem with modern injectors is that, should they be faulty, you will need to remove them. While this should not present a problem with older, non-direct injection diesel engines, where the injectors are often a press-fit and are not subjected to the high pressures that are encountered within a combustion chamber, the task can still become a nightmare.

Fusing together Apart from the aforementioned ‘blackdeath’ doing its best to ‘weld’ the injectors into place, injector bodies that are made from steel can react electrolytically with the aluminium housing of a typical cylinder-head. As the corrosion occurs along the length of the injector body, the part can become fused into place.

Inspect the top of your power unit (beneath any engine covers) for standing water, which will exacerbate

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COMMON R Fuel injectors vary tremendously in size and spec. Pictured are parts from a small diesel generator and a marine engine.

Old injectors arrive at Car businesses located all ove injector is inspected closely to r or not it can be reconditioned.

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Should combustion gases leak past the injector, they can erode a channel into the injector itself, rendering it useless.

‘Black-death’ in diesels is caused by combustion gases leaking into the engine bay between the injector and the cylinder-head. The resultant tar can be very tricky to remove; if not done so, the refitted injector might not seat correctly and the problem will reoccur.

the problem. Some engines have drain holes, which allow any water to escape. In some cases, the problem can be severe, such as was highlighted by the BBC’s Watchdog report in 2014, which detailed stuck injectors being caused by a front scuttle panel deflecting rainwater from beneath the windscreen and onto the top of 2.0-litre diesel engines, fitted to X83 model Vauxhall Vivaro vans and their Renault- and Nissan-badged sisters.

Do’s & don’ts Should you decide on DIY injector removal, ensure that you can complete the task. Apart from some pipes being for single use only, the delicate plastic return pipes might crumble and, should you encounter a stuck injector, do not be tempted to hammer or chisel it out. A damaged injector body might be rejected by a re-conditioner, meaning you will have to stump up extra cash to fund the surcharge. Special tools are available and further details about the task are shown from page 82.

Once removed, never attempt to

Injectors are cleaned care in a separate degreasing m remove any lingering diesel and Injectors with collars require ex

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Renewing the fuel filter regularly and ensuring that contaminated fuel is not dosed in the fuel tank are the best ways of preserving fuel injectors.

clean the injector nozzles with a wire brush. Trust that work to a specialist.

During refitting, it is vital that you renew the injector’s copper washer and ensure that the seating surfaces on both injector and cylinder-head are clean and even. If they are not, you can purchase injector seat cutters, but this tends to be more of a specialist task. If ‘black-death’ has struck, be especially vigilant. On refitting, smear white ceramic grease (not copperimpregnated grease) lightly along the injector shaft, to make any future removal easier.

Should you renew only one injector, rough engine running might result, because the flow rate of the new part is likely to differ from that of remaining, more worn components.

It is also prudent to trust injector repairs to a specialist, not just to a garage that owns a single item of equipment. Our visit to Carwood of Birmingham shows injector dismantling and reconditioning taking place in almost sterile conditions, which suggests a level of cleanliness that tends to be beyond the means of most DIYers and non-specialist garages.

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…and, when all compartm the tray are full, the parts another sonic and hot bath. Whe is then passed to the rebuilding

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New seals (in this case, t required) are fitted to th is inserted into the injector to l internal seals into the correct p

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Looking after your FUEL INJECTORS

COMMON RAIL INJECTOR OVERHAUL

vary tremendously in size red are parts from a small or and a marine engine.

Old injectors arrive at Carwood from businesses located all over the UK. Each injector is inspected closely to reveal whether or not it can be reconditioned.

Although several companies manufacture injectors, there is a massive range of tolerances. Therefore, old injectors are sorted and racked according to specification.

Cleaning the exterior is vital to prevent contamination. Sand-blasting removes heavy exterior corrosion and a sonic bath breaks down any stubborn deposits.

Injectors are cleaned carefully by hand in a separate degreasing machine, to remove any lingering diesel and encrusted oil.

Injectors with collars require extra attention.

To remove all traces of cleaning solution, the injectors are placed into a hot-wash machine (industrial dishwasher).

The injector’s body now appears as new.

The injectors are dismantled but all parts must kept together, because each one is calibrated individually when new. They are all kept in a separate storage slots…

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stion gases leak past the an erode a channel into the rendering it useless.

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fuel filter regularly and ontaminated fuel is not el tank are the best ways uel injectors.

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BOSCH INJECTOR REBUILD

ctor nozzles with a wire hat work to a specialist. ng, it is vital that you ector’s copper washer at the seating surfaces tor and cylinder-head even. If they are not, you injector seat cutters, but be more of a specialist death’ has struck, be lant. On refitting, smear grease (not coppergrease) lightly along haft, to make any future r. renew only one injector, running might result, ow rate of the new o differ from that of ore worn components. dent to trust injector ecialist, not just to a wns a single item of ur visit to Carwood m shows injector nd reconditioning taking t sterile conditions, which el of cleanliness that eyond the means of most n-specialist garages.

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…and, when all compartments within the tray are full, the parts are treated to another sonic and hot bath. When dry, the tray is then passed to the rebuilding department.

The re-conditioners select the main parts that are to be replaced. In most cases, they are the seals, nozzles and caps. Some injectors can only be stripped partially.

New seals (in this case, two are required) are fitted to the tool, which is inserted into the injector to locate the internal seals into the correct position.

The control valve on this Bosch injector is lubricated with a low viscosity calibration fluid, prior to being inserted into the injector body.

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After checking the solenoid (see Step 2, page 80), a seal setter tool is screwed into the injector’s top, to set the depth at which the internal seals sit.

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Another special tool is screwed onto the injector body, which locates the control valve into the injector and ensures that the internal seal seats correctly.

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BOSCH INJECTOR REBUILD continued

For clarity, the picture above shows the end of an old control valve, the shadow on which outlines clearly the position of the internal seal.

The original, lower shim is inserted back into the valve body. The part is not renewed, because its thickness alters the injector’s specifications.

tiny ball must be placed into its 16 The similarly-sized cup, prior to the pair being placed inside the injector. Again, their sizes differ according to the injector specification.

ball and cup are placed onto the 17 The control valve inside the injector and are seated correctly before work continues.

Cleanliness must be maintained at all times.

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Step 14 is repeated with the upper shim.

If these original parts are faulty, the injector will fail subsequent tests, but renewing serviceable shims is not cost effective.

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Next, the armature base fitted over the springs a by a circlip, which fits into the g base plate (see Step 18),

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The solenoid’s terminal p needs to be set, not only car’s wiring loom can reach it b avoid fouling adjacent parts.

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The armature base plate is then inserted on top of the control valve (not forgetting both the ball and cup)…

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USING INJECTOR CLEANERS u While British road fuel has to comply with specific standards, its changing composition has increased its tendency to both absorb water and leave deposits, as well as reducing its lubrication value. While most premium pump fuels increase the octane/cetane rating, they might also possess stronger detergent and lubricant packs, but the exact formulations remain a closely-guarded secret of the fuel companies.

Aftermarket injector cleaners are designed to optimise the lubricating qualities of the fuel, while reducing oxidation, increasing the octane/cetane, providing a cleaner burn, softening existing carbon deposits and helping to remove biofuel microbes, all for a reduced cost per-litre than the more expensive super-unleaded or enhanced diesel fuel. While the additive makers that we spoke with said that treating the fuel is likely to be a cheaper alternative to ultrasonic cleaning, reconditioned injectors and even when compared to filling with premium fuel, not one of them provided any independent test data of their products’ effectiveness, instead pointing us to both their internal findings and anecdotal evidence, mainly coming from internet review sites.

While injector cleaners might be beneficial, bear in mind that some car companies tend to view fuel or oil additives with suspicion when considering warranty claims.

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The shim is dropped into hole first, followed by th bush, then the thrust member ( is inserted into the guide bush.

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…and its retaining nut is fitted over it, prior to being torqued to its specified figure (40Nm in this case).

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The number of springs (as well as their spring rates) also differs between injectors. Two are fitted in this case, one over the other.

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The nozzle assembly is b compressed air, prior to over the injector ends, ensuring dowels locate correctly.

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Looking after your FUEL INJECTORS

s repeated with the upper shim. original parts are faulty, the subsequent tests, but renewing ms is not cost effective.

Next, the armature base plate cover is fitted over the springs and is secured by a circlip, which fits into the groove of the base plate (see Step 18),

If serviceable, the solenoid on this injector type is renewed. A new rubber seal is fitted, plus the shim (pictured) and spring are refitted to the solenoid.

The armature base plate’s protruding stem must be located correctly within the recess of the solenoid, as it is refitted to the top of the injector.

The solenoid’s terminal position angle needs to be set, not only so that the car’s wiring loom can reach it but also to avoid fouling adjacent parts.

After the solenoid’s securing nut is tightened to its required torque, the injector is turned around so that work can commence on its lower body.

These parts, refitted to the nozzle-end, rarely wear – if they are found to have deteriorated, the injector will fail subsequent tests (see page 81).

The shim is dropped into the centre hole first, followed by the guide bush, then the thrust member (pictured) is inserted into the guide bush.

The locating dowels are placed into the offset side holes, which, importantly, ensure that the nozzle is fitted in the correct position.

The new needle and nozzle are supplied as a matched pair. The needle is lubricated and inserted into the nozzle, while the operator checks for smooth movement.

The nozzle assembly is blown out with compressed air, prior to being located over the injector ends, ensuring that the dowels locate correctly.

The new end cap is fitted, prior to being tightened to its specified torque setting.

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ature base plate is then on top of the control valve both the ball and cup)…

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s retaining nut is fitted over it, being torqued to its specified n this case).

mber of springs (as well as ring rates) also differs ors. Two are fitted in this case, ther.

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Finally, the fuel union is unscrewed and replaced with a new steel washer and torqued to 40Nm. This injector is ready for final testing (see page 81).

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Looking after your FUEL INJECTORS

TESTING AN

HOW INJECTORS OPERATE u Old-type mechanical injectors had their nozzles opened and closed by a poppet valve which was dependant on fuel pressure: the valve opened when the pressure of incoming fuel overcame its spring’s resistance, then once the fuel pressure dropped, the valve closed again. Solenoid-type injectors (pictured B) use electromagnetism to open and close the valve, which is controlled electronically by the ECU. Piezo injectors (pictured A) utilise an internal piezoelectric crystal that expands when electrified. Not only can they react between 4-5 times faster than a solenoid, the injector can be made more compact. Should a fault develop, the crystal cannot be replaced and they tend to be expensive to renew. However, many piezo injectors have been superseded with more advanced solenoid-actuated units.

A B

This injector is ready for t is generated that can be e injector is fitted, prior to the en

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DELPHI INJECTOR REBUILD

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A complete Delphi-type solenoid injector disassembled, showing the reduced number of components compared to its Bosch equivalent.

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First, the solenoid is checked for any current leakage to earth.

If the part is faulty, a new replacement is sourced and fitted.

Some injectors fail the te to replace the componen original shims are the cause, bu

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TUNING

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The solenoid is removed from the injector body and the housing is blown through with compressed air.

After a thread-locking solution is applied to the casting’s outer thread, the control valve and its locating dowels are lowered onto the injector body.

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4

The small pin is dropped into the central hole in the nozzle end.

The spring (pictured) is inserted next.

The adapter plate is placed over the control valve and the spring fits into its top recess. On this injector, dowels are fitted to both the control valve and the adapter plate.

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Step 29 on page 79 is repeated and the new nozzle assembly is fitted to the injector, prior to the securing nut being tightened to its specified torque.

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u Certain tuning method as bolt-on tuning boxes t increase fuel rail pressure also shorten injector life. injection manufacturers a specialists tend not to ad using aggressive techniq that increase both fuel ra pressure and injector spr times. It is also inadvisabl pressure-limiting safegua It is possible to purcha with higher ‘cc’ outputs, w larger nozzle holes permit be injected per cycle. Alw high-flow injectors from a Excess fuel can not on both fuel consumption a emissions, but an overric mixture might also dama engine, by washing the o the cylinder bores and o the catalytic converter.

Uprated injectors shou a package of modification the types that increase th and, possibly, vary the ign so that the additional fue burnt efficiently. Some co

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Looking after your FUEL INJECTORS

TESTING AN INJECTOR

THANKS TO:

Carwood Motor Units Ltd., Units 2-6 Willow Court, Crystal Drive, Smethwick, Birmingham B66 1RD. Tel: 0121 552 9524

B This injector is ready for the testing phase. If it passes, a code is generated that can be entered into the car’s ECU when the injector is fitted, prior to the engine being restarted.

Fuel injectors are tested for excessive leak-back and their performance in a host of engine running conditions. The machines are calibrated according to the type of injector being examined.

Some injectors fail the test and require stripping down again, to replace the components responsible. Occasionally, faulty original shims are the cause, but replacing them is time consuming.

This injector failed the test spectacularly because excessive corrosion on the injector body had caused calibration fluid to spray out once the internal pressure reached 800bar.

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ny current leakage to earth. ment is sourced and fitted.

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Thanks to: United Diesel, Unit 6, Leaton Industrial Estate, Bomere Heath, Near Shrewsbury, Shropshire SY4 3AP. Tel: 01939 291155.

TUNING

entral hole in the nozzle end. ext.

on page 79 is repeated and nozzle assembly is fitted to ior to the securing nut being s specified torque.

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u Certain tuning methods, such as bolt-on tuning boxes that increase fuel rail pressure, might also shorten injector life. Fuel injection manufacturers and specialists tend not to advocate using aggressive techniques that increase both fuel rail pressure and injector spray times. It is also inadvisable to remove pressure-limiting safeguards.

It is possible to purchase injectors with higher ‘cc’ outputs, where the larger nozzle holes permit more fuel to be injected per cycle. Always purchase high-flow injectors from a specialist.

Excess fuel can not only increase both fuel consumption and exhaust emissions, but an overrich fuel mixture might also damage the engine, by washing the oil film from the cylinder bores and overheating the catalytic converter.

Uprated injectors should be part of a package of modifications, including the types that increase the airflow and, possibly, vary the ignition map, so that the additional fuel can be burnt efficiently. Some companies sell

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NOID LIGHT SETS

upgraded nozzles alone, especially for turbodiesels, which can be fitted by a DIYer, but many owners either miss out on the benefits or damage their engines by neither having the injector calibrated by a specialist afterwards, nor taking into account air-flow, ignition maps or even whether or not the clutch, dual mass flywheel, brakes, etc, can tolerate the extra power.

Be aware that nozzles are precision instruments and the quality of some aftermarket types is questionable, particularly if they have been sourced from an unknown maker. Always research the most appropriate tuning options before parting with any money, and also check how any changes might influence your insurance premium.

u A noid light set is made up of various connectors, each used to check for fuel injector signal faults on a variety of engines.

Simply disconnect the injector harness before plugging in the appropriate noid light. Then switch on the ignition and check the injector pulses from the ECU via the lights. No lights, or a steady light, equals a malfunction in the ignition system.

Noid lights can be bought individually if you don’t need a set.

Model featured is a 6pc set from Sealey.

Model No VS213 retails at £23.94 and fits GM PFI, Ford TBI, Geo TBI, Bosch PFI, GM TBI and GM SCPI systems.

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Removing stuck injectors

It’s simple in principle, but di in practice. Hence why works around the country are desp for Tony’s services before en work can commence.

And he’s not the only specialist who’s working fla to remove stubborn injector We visited PCR in Worthing which has also invested in a 20-tonne hydraulic puller to get diesel owners out of trou and hopefully prevent afflic engines having to come out being written-off completel PCR’s investment in a specialist puller was prompt by the number of snapped c they were seeing on French as the Citroën C8 and Peuge largely as a result of the bel water. PCR’s Ryan Mansfiel cambelt snaps on one of the sometimes snaps the rocker bending the valves, but eith have to take out the injecto the inlet manifold. And this the problem started. We jus get them out, so we had to i necessary equipment to hel

Removing

Stuck Injectors Seized or stuck injectors can be a real headache and even write off an otherwise sound vehicle. It’s a growing problem and specialists who have found a solution are in strong demand, as IAN CUSHWAY discovers.

S

uccessfully diagnosing diesel injector issues is one thing, but removing the faulty part is an entirely different matter. This is what prompted Tony Powell at AP Autodiagnostics to buy his first hydraulic puller and set up his own fully mobile injector removal business. However, buying the puller was only the beginning of a long, hard learning curve, which has led Tony to design and manufacture tools that outperform off-the-shelf equipment, and allow him to remove injectors others wouldn’t touch.

That was back in 2010, and, in that time, Tony has successfully removed stuck injectors from thousands of vehicles.

“I had a mobile fault diagnosis business, but when I returned to an independent garage a couple of weeks after identifying an injector problem on a car, I spotted the stricken vehicle shoved in a corner, 82 Car Mechanics Removing Stuck82 Injectors.indd 82 082-086.indd

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Components of the common-rail injection system include the rail with injectors, the pump and the ECU.

untouched,” says Tony. “I quizzed the garage owner, who told me they hadn’t managed to get the old injector out and it went from there. Today, I get calls from independents, main dealers and private owners alike, and travel the length and breadth of the country removing stuck injectors.”

He’s travelled as far as the Channel Islands for one customer and crosses the English Channel and Irish Sea regularly.

Such heavy demand isn’t surprising. On many engines, the injectors have to be removed in order to take off items such as the rocker cover and inlet manifold. Therefore, if you’re doing work on the timing gear, valves and head gasket, the injectors have to be whipped out first.

The top of the injector is disassembled and the hydraulic puller is screwed into the threaded section in order to remove it. shop.kelsey.co.uk/subscription/CME 13/09/2021 23:32 23:24 13/09/2021

First, the top of the injector is r order to reveal the thread.

...before the puller is assembl attached to an air-line or man

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Removing stuck injectors It’s simple in principle, but difficult in practice. Hence why workshops around the country are desperate for Tony’s services before engine work can commence.

And he’s not the only specialist who’s working flat out to remove stubborn injectors.

We visited PCR in Worthing, which has also invested in a 20-tonne hydraulic puller to get diesel owners out of trouble and hopefully prevent afflicted engines having to come out or being written-off completely.

PCR’s investment in a specialist puller was prompted by the number of snapped cambelts they were seeing on French cars such as the Citroën C8 and Peugeot 807, largely as a result of the belt absorbing water. PCR’s Ryan Mansfield says “If the cambelt snaps on one of these engines it sometimes snaps the rockers, instead of bending the valves, but either way you have to take out the injectors to remove the inlet manifold. And this is where the problem started. We just couldn’t get them out, so we had to invest in the necessary equipment to help us.”

Puller kits have got many main dealers, independent garages and private owners out of stuck injector dilemmas.

Injector faults While injectors should last for at least 80,000 miles, that doesn’t mean they will, as poor design and owner abuse can easily spell their early demise. As Tony Powell confirms: “One problem is, instead of using correctly manufactured biodiesels, increasingly I’ve come across diesel owners trying to save money by using unprocessed chip fat in their engines!

Of course it’s not the same thing and the injectors become contaminated by unfiltered particles or suffer excessive internal wear due to high water content or other liquids in the low grade fuel mixture.”

This type of poor fuel, along with misfuelling by putting petrol in the tank by mistake or running on red diesel, which is a lower grade agricultural off-road fuel, can rapidly promote excessive wear in the precision world of common-rail systems, easily destroying in excess of £1000 of fuel injection parts by washing out or failing to supply the required lubrication for the fuel system. A system that measures in microns to tolerances so small that you can’t even see the gaps without specialist tooling can be very unforgiving.

Then there’s the infamous ‘Black Death’ that affects a variety of diesel engines, but specifically Mercedes and Peugeot units.

Here, says Tony, it’s the injector seat seals that let go, allowing engine gases to chuff past the injector and coat the engine in thick tar. “The tar goes rock solid and The puller bit is then screwed in...

write off an ialists who WAY discovers.

says Tony. “I quizzed the , who told me they hadn’t et the old injector out and there. Today, I get calls from s, main dealers and private owners alike, and travel the length and breadth of the country removing stuck injectors.”

He’s travelled as far as the Channel Islands for one customer and crosses the English Channel and Irish Sea regularly.

Such heavy demand n’t surprising. On many es, the injectors have to be d in order to take off items as the rocker cover and inlet manifold. Therefore, if you’re doing work on the timing gear, valves and head gasket, the injectors have to be whipped out first.

The top of the injector disassembled and the aulic puller is screwed into section in order to remove it.

lsey.co.uk/subscription/CME 13/09/2021 23:24

First, the top of the injector is removed in order to reveal the thread.

...before the puller is assembled and attached to an air-line or manual pump.

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Electrolytic reaction between different materials causes injectors to seize along the full length of their shafts. You can clearly see the corrosion near the tip of this Renault Clio injector.

It’s taken from the K9K 1.5 engine – it was too tight for the garage to remove, so they called in Tony Powell.

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Removing stuck injectors What makes them

Access is difficult on models such as the Peugeot 807, requiring the removal of the wiper motor and other items to allow room for the injector puller.

These M9R injectors are buried in corrosion.

An owner’s attempt at removing this injector complicated the extraction process for Tony Powell.

Lack of anything to get hold of made the removal of an injector on this Chrysler Voyager difficult.

Injector types As their name suggests, injectors spray atomised fuel into the combustion chamber as a fine mist. The duration that the injector is open – the pulse width – determines how much fuel is delivered.  Traditional ‘rotary’ diesel engines, such as the Peugeot XUD9 1.9, have mechanical injectors that have a plunger and high-pressure fuel pump driven by the engine crankshaft. Each injector is fed fuel at the correct time in the engine’s combustion sequence. The injectors, which feature a springloaded valve, operate on fuel pressure and ‘pop’ open when a specified pressure is reached, allowing fuel to pass into the combustion chamber at the correct moment. Fuel in an engine with indirect fuel injection is ignited in a separate combustion chamber recessed into the cylinderhead, while direct-injection is fuel injected directly into the cylinder.

Combustion is slowed down on indirect injection engines, and engines are generally quieter and less stressed. They require a glow plug to aid the combustion process until the engine is running and getting warm.  In common-rail diesel engines, injectors are either traditional electromagnetic or piezoelectric.  Traditional electromagnetic injectors employ a solenoid operated by an electronic control unit which results in accurate control of the injector opening times depending on factors such as engine speed and loading, and provides improved performance and fuel economy compared with their mechanical predecessors. If one fails, it’s usually down to the solenoid, in which case the faulty injector can be replaced individually.  Injectors featuring piezo crystals work on the basis that such crystals expand when current is passed through them, which, in turn, regulates the amount of fuel injected. These offer more precision and operate up to pressures of 26,000psi. However, when one piezo injector fails, it’s recommended that the rest are changed at the same time, as chances are they will soon suffer the same fate.

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has to be chipped off first before tackling the injector, which is then usually stuck as well by the tar-like substance.”

Here, says Tony, it’s important to catch the problem early, as he’s seen several cylinder-heads turned into scrap by the deep cuts gouged into the injector seat by the hot, high pressure gases pushing their way past the injector.

Being little more than hand-ti go in, it seems inconceivable take so much persuasion to This is down to an electro between very dissimilar mat namely the steel of the injec aluminium of the cylinder-h the copper seal and, rumour magnesium which is often a alloy to reduce production c harsh underbonnet environ its constant exposure to hot temperatures, along with m poor drainage, doesn’t help “It’s like a recirculating mois system,” says Tony. “Many o I work on have inherent des which allow water to enter a directly on top of the injecto which makes the situation w Given the extent of the el reaction, it’s usually the ent of the injector which sticks, remedies such as Coca-Cola to prove totally ineffective. confirms this: “I’ve come acr using everything from drain sulphuric acid to free them u success of Coca-Cola is just a tale.” Chemicals just cannot distance required to fully fre injector effectively.

Most attempts at removin injectors begin with prybars

Many injectors simply break u complicating matters when it

Injector failure Over time, given the high pressures at which they operate, injectors will eventually wear as well. After all, they often fire two or three times per engine cycle, which effectively doubles the amount of wear they are likely to be subjected to compared with older diesels.

Early symptoms of injector failure usually include a faint misfire initially due to internal electrical failure, which gets progressively worse and escalates into starting problems, when injectors stick open or return excessive fuel so that the pump is unable to build enough pressure for the ECU to allow the engine to fire. This, in turn, results in flashing warning lights and multiple fault codes, sometimes for what appears to be totally unconnected items, an increased thirst for fuel and the ECU triggering ‘limphome’ mode, which can miraculously be reset when the ignition key is cycled off and back on again. shop.kelsey.co.uk/subscription/CME 13/09/2021 23:32 23:24 13/09/2021

This injector from a Mercedes-B

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Removing stuck injectors What makes them stick?

jector Tony Powell.

pped off first before tackling which is then usually stuck tar-like substance.”

Tony, it’s important to blem early, as he’s seen der-heads turned into scrap uts gouged into the injector ot, high pressure gases way past the injector.

Being little more than hand-tight when they go in, it seems inconceivable that injectors take so much persuasion to get out.

This is down to an electrolytic reaction between very dissimilar materials, namely the steel of the injector, the aluminium of the cylinder-head, the copper seal and, rumour has it, magnesium which is often added to the alloy to reduce production costs. The harsh underbonnet environment, with its constant exposure to hot and cold temperatures, along with moisture and poor drainage, doesn’t help matters.

“It’s like a recirculating moist air heating system,” says Tony. “Many of the vehicles I work on have inherent design faults which allow water to enter and sit directly on top of the injector recesses, which makes the situation worse.”

Given the extent of the electrolytic reaction, it’s usually the entire length of the injector which sticks, so alleged remedies such as Coca-Cola are likely to prove totally ineffective. Tony confirms this: “I’ve come across people using everything from drain cleaner to sulphuric acid to free them up, and the success of Coca-Cola is just an old wives’ tale.” Chemicals just cannot travel the distance required to fully free a stuck injector effectively.

Most attempts at removing stuck injectors begin with prybars and

Cleaning injectors  Unlike injectors in petrol engines, diesel injectors aren’t prone to developing build-up that block nozzles or affects fuel atomisation. Indeed, many of the symptoms commonly attributed to dirty injectors – loss of power, missing, poor running, increased fuel consumption and exhaust smoke – are usually related to other issues to do with lack of compression, engine management, blocked air filters and sensor problems, as opposed to a build-up of injector deposits. The reason for this is largely because diesel injectors operate at higher pressures – up to 1800 bar (26,000psi) – and this helps keep them clean, even if it does lead to eventual wear.

So how do you tell the difference between a dirty injector and one that’s worn? The truth is, this can only be determined by specialist testing – and if it does turn out they are dirty, then there are specialists who can clean them. Charges vary, starting at around £25, but as injectors wear anyway, it usually makes more sense to fit a brand new replacement.

Chemical cleaners may work but there’s also the risk of them loosening debris, which can result in ongoing fuel filter blockages.

As for adding a small amount of petrol into the diesel to clean the system – don’t do it! It is risky because it lowers the fuel’s flashpoint, as well as being potentially damaging to the fuel system components because it can strip out the necessary lubrication. This is obviously much more of an issue with common-rail diesel units that operate at very high pressures.

Also bear in mind that most common-rail fuel systems incorporate single-use fuel pipes, and that once the pipes have been loosened, they must be replaced as it is not possible to reliably reseal them due to the high pressures involved. Moreover, electronic injectors are often individually calibrated to the engine management system and must be refitted into their original place. If mixed up, or the injectors refurbished or cleaned, the system will often need to be recalibrated.

In a nutshell, the injector and high pressure diesel fuelling system is a no-go area as far as DIY fixes are concerned. The best advice is to prevent potential issues in the first place by replacing fuel filters as per the manufacturers’ recommendations and avoid putting dirty or poor quality fuel in your engine.

Many injectors simply break up during removal, further complicating matters when it comes to getting them out.

failure

ven the high pressures operate, injectors will ear as well. After all, they o or three times per engine effectively doubles the ear they are likely to be compared with older diesels. toms of injector failure de a faint misfire initially al electrical failure, which ively worse and escalates problems, when injectors return excessive fuel so p is unable to build enough he ECU to allow the engine in turn, results in flashing ts and multiple fault codes, or what appears to be totally items, an increased thirst he ECU triggering ‘limpwhich can miraculously be he ignition key is cycled off again.

This injector from a Mercedes-Benz 220 saloon has a distorted body.

One of four very corroded injectors from a 2.5-litre Vivaro engine. Tony Powell was lucky to get the clamp bolts out without them snapping off.

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The pitting and distinctive groove in this Honda Accord 2.2 injector was caused by continued running with a failed seal.

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Removing stuck injectors screwdrivers, escalating to slide hammers and small mechanical pullers, all of which more often than not prove ineffective and regularly do more harm than good, smashing holes in the paperthin aluminium cam covers. Tony warns against the use of universal pullers because they rarely fit properly and can slip or move, causing damage in the process. Hence why Tony uses hydraulic pullers which have been specially modified to make the job easier and more cost-effective.

With the old injector out and the hole cleaned up, the replacement injector can simply be screwed in, using a white ceramic grease to prevent it seizing again.

Tony strongly advises against using a copper-based grease, as it only increases the amount of copper in the war of dissimilar metals already taking place.

Visit Tony’s website for up-to-date prices and details of other services they provide. We think it’s money well spent, given that the alternatives would be to remove the engine or scrap the cylinder-head.

Which engines?

Injectors can seize in virtually any common-rail diesel engine, although Tony Powell reports that some engines are more affected than others. Here are Tony’s most troublesome contenders.  Vauxhall Vivaro, Renault Trafic and Nissan Primastar – all models and 1.9, 2.0 and 2.5-litre engines from early production models to date including M9R and F9Q.  Citroën C8/Fiat Ulysse/Peugeot 807 with the DW12 2.0 HDi engine, for the whole production life. Also Suzuki Vitara.  Land Rover Freelander (Td4), Rover 75, Mercedes-Benz Vito, Sprinter, ML270 and 220s.  Fiats, Vauxhalls, Alfa Romeo and others with the JTD engine.  The Peugeot-engined Citroëns and Fords with the 1.6 HDi (DV6).  Small vans such as the Citroën Berlingo with the DV6 unit (which can also suffer ‘Black Death’), as well as the 407 and C4.  Peugeot’s Euro engine with the steel liner which comes out with the injector.

This can require a new cylinder-head, although Tony has a fix for this.  SsangYong 2.9.  Mercedes A-Class, Jeep and Chrysler.  Iveco vans and motorhomes.  Mazda6, Lancia and Alfa Romeo diesel units.  Various Volvo (d5252t engine) and BMW (M57 engine) diesels.

Useful contacts AP Autodiagnostics 07799 108594 www.apautodiagnostics.com PCR 01903 767676 This injector was damaged by a poor quality tool that cost more than £1000.

Age makes little difference to whether an injector will stick or not. This engine was only 14 months old.

Many people weld on a nut or extension in the hope that it will aid removal.

A bodge is to shorten the injector clamp bolt rather than clean out the hole correctly.

The infamous ‘Black Death’ caused by leaking injector seals.

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The cause of virtually all M9R piezo crystal injector failures – this is the crystal removed from the injector.

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Decoking modern engines

Decoking MODERNDAY

In making engines cleaner, they have become dirtier. This irony is not lost on Rob Marshall, as he looks at modern decoking techniques that do not demand an expensive engine strip.

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ne might have thought that decoking had been banished to the history books long ago.

At one point, it was normal for engines to require a semi-regular tear-down to remove carbon that had accumulated on the pistons and valvegear. The procedure was necessary because carbon and sludge, both of which are byproducts of combustion, built-up on the engine’s operating parts, restricting either their movement or interrupting efficient airflow. Not only can these issues reduce reliability, efficiency and engine life, but emissions and fuel consumption can also increase.

Is this progress?

Over the years, cleaner fuels, enhanced lubricants and better engine design have negated the need for regular decoking.

At the same time, engine designers have increased engine power, while decreasing

fuel use and overall exhaust emissions.

Heightened complexity is the main cost of these seemingly incompatible achievements, along with a greater tendency for combustion deposits to build within the engine, from its air inlet to the sump. Sadly, the situation even afflicts engines that have been wellmaintained, although neglected units suffer to a greater extent. Consequently, decoking has made a comeback, albeit with several modern twists.

Should you decide to dismantle an engine to deal with other faults, it is prudent to clean the internal components, especially as evaluating their condition will be easier, plus the risk of old contaminants shortening the life of a rebuilt unit will be reduced. Despite decarbonising being a straightforward process, when an engine’s parts are laid out on a workbench, stripping the unit to deal with the issues alone is time-consuming

t EGR valves and inlet manifolds can be cleaned manually, using solvents that can range from inexpensive brake cleaner to aerosols containing bespoke EGR cleaner.

u If cleaning out the intake with solvents, ensure that all traces of the cleansing vapour have been removed before refitting the parts to the car.

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ROB’S TOP TIP

Decoking modern engines

ROB’S TOP TIP

If you are considering having your engine tuned, it might be a pointless exercise, unless you can be sure the engine is clean.

Deposits build behind the intake valve and within the intake port (pictured on this cutaway illustration in light blue).

Viscosity improvers are a vital component of engine oil blends, yet they are responsible for starting the process of inlet valve deposits on many direct-injection engines.

and not cost-effective. Thankfully, a number of recent developments enable you to remove deposits from certain parts of the engine without having to dismantle the engine block and tear down the cylinder-head.

Starting at the top One of the major ways in which engineers have enhanced efficiency in small capacity petrol and diesel engines has been to install direct-injection. In the case of petrol engines, non-direct injection (port injection) relies on the fuel injector being situated behind the intake valve and the continuous contact with the solvent keeps the area clean. Once direct-injection design relocated the injector within the cylinder, this ‘washing’ effect was removed.

Although carbon results from burning

petrol and diesel, engine oil can pose a greater problem. In theory, an engine should not consume its lubricant, but production tolerances, breather design and wear mean that all vehicle engines burn oil to a degree.

As an engine is not permitted to vent toxic crankcase gases into the atmosphere, they are recirculated through the breather system and into the inlet tract. Inevitably, some engine oil vapour is carried along, too. Some enterprising enthusiasts try and negate the issue, by integrating an oil catch tank into the crankcase ventilation circuit, to separate the lubricant from the blow-by gases. Catch tanks (or ‘cans’) tend to have limited success, depending on the make and model of car. The tanks also require periodic emptying, which is another reason why they are not used on mainstream production vehicles.

Valve stem seal wear exacerbates the problem, because oil seeps down the valve stems, then carbonises and builds on the rear of not only the inlet valve but also, potentially, the exhaust valve. Excessive oil consumption will also damage post-treatment devices, including diesel particulate filters (DPFs) and catalytic converters.

Exhaust gas recirculation (EGR) valves pose an additional complication. The system was introduced as a means of increasing engine efficiency (by reducing pumping losses), while driving down NOx emissions. Unfortunately, as hot, untreated exhaust gases flow from the EGR valve and into the inlet manifold, the existing sticky oil film attracts certain exhaust gas deposits, including carbon.

The build-up restricts not only the ports’ diameters but also inlet manifold swirl flap movement, on engines thus fitted.

Fortunately, the deposits can be removed out with a cleaner, which necessitates removing the inlet manifold. Despite being messy and time consuming, the procedure is a straightforward DIY task.

The intake tract, within th head of a typical direct-injec can be even harder to clean. a narrow port present an acc but the higher temperatures also bake the oil deposits on the intake valve, which acts as a ‘fly-catcher’ of unburnt from the incoming exhaust g result is a rubbery accumula incredibly difficult to remov Dr Helmut Leonhardt, She team leader for the developm engine oils in Europe, reveal that inlet valve deposits are problem. He tackled the issu PHD in the mid-1980s: “Ove ago, lead oxide built-up on t of inlet valves, which is a po that absorbed the incoming biggest deposit that I ever re the back of single inlet valve weighed a whopping 4.5 gra Helmut admitted that, wh injection was used in conjun with new additive blends of petrol, the issue of intake va disappeared. However, the a of direct-injection and the v demands to reduce oil visco efficiency and emissions rea seen the problem resurface.

Crushed walnut sh

Dr Leonhardt says: “Today, i valve deposits are caused pr viscosity improvers within t which become baked onto th valve and are burnt subsequ incoming exhaust gases from causing the deposit to carbo trap further deposits. Here a develop lubricants for carma many of those engine oils ha

WALNUT SH

t Poor engine design and excessively long oil change intervals can result in sludge accumulating within the lubrication system, including the sump. u One can remove carbon from pistons and cylinder-heads manually, but the dismantling process is expensive.

TerraClean removes carbon chemically.

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The French direct-injectio Citroëns and Peugeots, is

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ROB’S TOP TIP

Decoking modern engines

ROB’S TOP TIP

If you are considering having your engine tuned, it might be a pointless exercise, unless you can be sure the engine is clean.

overs are a vital component of ds, yet they are responsible for ocess of inlet valve deposits on jection engines.

seal wear exacerbates because oil seeps down ms, then carbonises and rear of not only the inlet o, potentially, the exhaust ive oil consumption will post-treatment devices, sel particulate filters atalytic converters. s recirculation (EGR) valves ional complication. The ntroduced as a means of gine efficiency (by reducing es), while driving down ns. Unfortunately, as hot, haust gases flow from the d into the inlet manifold, ticky oil film attracts certain eposits, including carbon. restricts not only the ports’ t also inlet manifold swirl nt, on engines thus fitted. the deposits can be removed aner, which necessitates inlet manifold. Despite and time consuming, the a straightforward DIY task.

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The intake tract, within the cylinderhead of a typical direct-injection engine can be even harder to clean. Not only does a narrow port present an access problem, but the higher temperatures involved also bake the oil deposits onto the back of the intake valve, which acts subsequently as a ‘fly-catcher’ of unburnt particles from the incoming exhaust gases. The result is a rubbery accumulation that is incredibly difficult to remove.

Dr Helmut Leonhardt, Shell Lubricants’ team leader for the development of engine oils in Europe, revealed to CM that inlet valve deposits are not a new problem. He tackled the issue for his PHD in the mid-1980s: “Over 30 years ago, lead oxide built-up on the rear faces of inlet valves, which is a porous deposit that absorbed the incoming fuel; the biggest deposit that I ever removed from the back of single inlet valve in those days weighed a whopping 4.5 grammes.”

Helmut admitted that, when indirect injection was used in conjunction with new additive blends of unleaded petrol, the issue of intake valve deposits disappeared. However, the advent of direct-injection and the various demands to reduce oil viscosity for efficiency and emissions reasons have seen the problem resurface.

Crushed walnut shells Dr Leonhardt says: “Today, intake valve deposits are caused primarily by viscosity improvers within the oil blend, which become baked onto the hot inlet valve and are burnt subsequently by incoming exhaust gases from the EGR, causing the deposit to carbonise and trap further deposits. Here at Shell, we develop lubricants for carmakers and many of those engine oils have to pass

t Carbon build-up within the cylinder can ignite the fuel/ air mixture at the wrong moment, resulting in poor running and, possibly, damage to the engine.

an intake valve deposit test, to comply with manufacturer-set specifications.”

As intake valve deposits are a consequence of many direct-injection petrol engine designs, knowledgeable owners can reduce the problem. As it is illegal to disable pollution control equipment, we do not recommend removing the EGR valve; even if you were to do this, it would not provide a solution, because oil can still enter the inlet via the breathers. Rerouting the system and venting the gases straight into the atmosphere is also an offence and may lead to unpleasant odours permeating the interior of the vehicle.

A potential option is to select a lubricant with fewer viscosity improvers, the cause of the initial build-up, which will be present in oil with a bigger differential between its cold and hot viscosity grades. For example, this means that a 0W-30 oil is likely to contain more viscosity improvers than one with a 10W-30 grade. This is not an excuse for you to stray outside of the recommended oil viscosity for your engine – always stay within the carmaker’s parameters.

Unfortunately, post-combustion fuel additives, water injection and even solvent cleaning tend to be ineffective.

Firing abrasive particles under pressure into the inlet may also cause damage, especially if grains of the fine grit stray into the combustion chamber.

Fortunately, crushed walnut shells have provided a solution, as they are tough enough to remove the deposits, without scoring the metal surfaces.

While the procedure is not a DIY task, it is a significantly cheaper option than dismantling the engine. As the PSA/ BMW ‘Prince’ series of 1.6-litre directinjection petrol engines seem to be particularly prone to inlet valve coking, this operation is common for MINIs built around the R56 platform – even some main dealers carry out the work.

Given their experience of dealing with the problem on both MINIs and BMWs, we approached SWSS MINI of Cardiff for its insight into what the operation entails and how effective it can be. This is the first time that the photographed 2007 Cooper S had been subjected to the operation in its 75,000 miles of existence.

WALNUT SHELL CLEANING

The blast medium is crushed walnut shells. They are considerably less abrasive than conventional beads, used for shot blasting, so they will remove carbon without damaging soft aluminium castings.

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The French direct-injection petrol engine, used in MINIs from 2006, as well as various Citroëns and Peugeots, is particularly prone to inlet valve deposits.

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Decoking modern engines

WALNUT SHELL CLEANING continued

To gain access, the air filter box has to be removed, along with its associated ducting. If choosing an aftermarket filter (such as this K&N unit), ensure that it is well maintained and do not over-oil…

…because unfiltered contaminants will end up in the inlet, possibly adding to the deposit. Remove any breather pipes carefully. On the MINI, the throttle body also needs to be removed.

Unscrew the bolts and/or nuts that retain the inlet manifold to the cylinder-head. Remove the part from the working area, ensuring that any separate gaskets, if fitted, are discarded.

After the first session of 10 minutes, the technici repeated, because not all of the

Remove the spark plugs (plus the coils, if necessary), which will make the engine easier to turn over by hand.

Store them carefully, so that they cannot be damaged. After engaging a forward gear...

...insert a screwdriver into cylinder No 1 hole. As the offside wheel is rotated, with the nearside chocked, the screwdriver’s highest point indicates when top dead centre has been reached.

Although walnut shells are soft and non-abrasive, precautions are taken at SWSS MINI of Cardiff to reduce the chance of any ingress, by plugging any intake pipes with non-fluffy cloths.

Pictured are particles tha dislodged by the walnut their rubbery consistency, they remove and affect the engine’s

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The tool-end is bespoke to the engine type, because it must form a tight fit inside the cylinder-head’s inlet tract. Fitted to the tool is both an injector and a suction device.

As the walnut shells are fired into the port, the technician will direct the flow, by manipulating the nozzle’s angle. Afterwards, he, or she, will turn off the flow and vacuum out the remaining particles.

The protective rags are r coils refitted. The inlet m cylinder-head, along with the t

After the tool has been removed, the technician will inspect how clean the inlet track has become. Based on this, he or she will decide whether or not the process needs to be repeated.

For comparison, this was the initial state of the MINI’s inlet system. The deposits were fixed firmly to both valves, restricting the incoming airflow within the port.

As the engine ECU is self permit the engine to wo inlet ports have been restored

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Decoking modern engines

After a further five minutes, the deposits had been removed entirely, with the intake restored to as-new condition. It is important to verify that no walnut shell traces are left behind.

the bolts and/or nuts that e inlet manifold to the Remove the part from the ensuring that any separate d, are discarded.

After the first session of blasting, which took approximately 10 minutes, the technician decided that the process had to be repeated, because not all of the deposits had been shifted.

walnut shells are soft and sive, precautions are taken at ardiff to reduce the chance by plugging any intake pipes cloths.

Pictured are particles that were dislodged by the walnut shells. With their rubbery consistency, they are difficult to remove and affect the engine’s performance.

the port, the technician will he nozzle’s angle. Afterwards, um out the remaining particles.

The protective rags are removed and the spark plugs and coils refitted. The inlet manifold can be reunited with the cylinder-head, along with the throttle body (if necessary) and ducting.

Before the engine is restarted, it is checked for error codes.

If any are found, they are reset and checked afterwards for any reappearance. In this case, no codes were found.

al state of the MINI’s inlet rmly to both valves, he port.

As the engine ECU is self-learning, its values must be reset, to permit the engine to work at its factory-set values, now that its inlet ports have been restored to as-new condition.

The engine is run in the workshop for several minutes, while the technician checks for any new fault codes and analyses the live readouts. The car is road-tested afterwards.

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The process is repeated on cylinder No 4, followed by No 3 and No 2. The entire procedure takes approximately four hours, working on a four-cylinder engine.

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Prior to refitting, the inlet manifold gasket must be renewed. On the MINI, these consist of replaceable rubber rings that locate into the moulding’s recesses.

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Decoking modern engines Chemical combustion chamber cleaning Evaluating the many fuel and oil additives on the market is an almost impossible task. To investigate a more concentrated, direct and quicker cleaning procedure for fuel injectors and the combustion chamber (including the piston crown), both of which tend to be inaccessible without major engine dismantling, we turned to TerraClean, a Canadiandeveloped product that is promoted to the UK’s motor trade by Randstad of Cramlington, Northumberland.

The procedure involves disconnecting the engine from its fuel supply and reconnecting it to a dedicated machine that contains a mix of the appropriate fuel and the company’s cleansing solutions. For commercial reasons, one can understand why Randstand does not reveal the exact composition of TerraClean’s cleaning mixtures, preferring to use the vague explanation that the car is run on “negatively charged, highlyrefined fuel… which will collide with the positively-charged particles, normally found in the combustion process.” At the time of writing, the description on the importer’s website of how the procedure works is even more elusive.

ROB’S TOP TIP

Keep the engine’s breather system in order, including cleaning out any breather gauzes.

When CM looked first at TerraClean’s claims, shortly after its UK debut in March 2013, contributor Steve Hole provided evidence of an approximate 20% reduction in smoke opacity emissions on his tuned 2003 BMW X5 3.0 diesel.

In the case of my own car – a wellmaintained 2007 Citroën C5 2.0 16v HDi in stock specification and with 80,000 miles – I consider a smoke emission test as not being a very accurate means of assessing the treatment’s effectiveness, because the car is fitted with a DPF, which would trap any freed carbon. Also, it is easy to fall victim to a placebo effect, when assessing any real-world performance difference. Nevertheless, I found an obvious difference post-treatment, in that my car’s clutch started to slip on full-throttle applications immediately on my return journey, which I can only theorise was caused by the slight increase of torque being liberated. While this is a good thing, be wary that the

TerraClean treatment could highlight mechanical deficiencies after its cleaning process has worked its ‘magic’, despite not being the root cause.

My own experience, like that of many others, is non-scientific, so we requested that Randstad provide independent evidence to confirm TerraClean’s claims. At the time it could not supply us with any independent, substantive evidence to back up the claims further.

Despite this magazine’s positive past and current findings, we advise that you weigh up the anecdotal evidence and come to your own conclusions.

To demonstrate the procedure, we approached Scotlands Ash Garage in Didcot, Oxfordshire, to treat my Citroën HDi and a 2003 Volkswagen Passat 1.9 PD diesel, which had over 220,000 miles recorded. TerraClean recommends that the treatment is carried out every 15,000 miles as a preventive measure.

The cost of having the work done at each or every second service represents a big increase in maintenance costs, which many people would (understandably) find hard to swallow. It could be argued that the procedure would be more worthwhile as a preventive measure on a vehicle that covers a low annual mileage, primarily in urban conditions.

TERRACLEAN PROCEDURE

With the engine switched off, the plastic covers are removed to give full access to the fuel system. As it requires a power supply, the TerraClean machine is connected to the car’s battery.

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The car’s fuel injection system must be isolated from the fuel tank. The lowpressure pipes are disconnected and plugged, where necessary, to prevent any external contaminants from entering the fuel system.

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As our Citroën does not employ an in-tank lift pump, only a single diesel pump on the engine, there is no need to create a return circuit; only connections to the machine’s inlet and return are necessary.

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This VW PD engine employs a lowpressure lift pump, immersed within the diesel tank. To separate the car’s fuel tank from the injection system, the intake and return pipes from the tank are connected together.

Ensuring that the engine i its speed is held at a const for 15 minutes, to allow carbon, tar deposits to be loosened from pump and combustion chamber

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…to allow the turbocharg its heat to dissipate. The e switched off for a further 15 min ‘soak’ period utilises the last un pulse to loosen carbon from the

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With the pipes connected to the TerraClean machine, the operator ensures that the internal operating pressure matches that of the vehicle fuel line, negating the risk of the vehicle generating a fault code.

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TerraClean has develope gas recirculation (EGR) v to the EGR cooler, which drives

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Post-treatment, the EGR carbon, without any dism can extend the part’s life, it will n

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eatment could highlight eficiencies after its ess has worked its ‘magic’, eing the root cause. perience, like that of many n-scientific, so we requested d provide independent onfirm TerraClean’s e time it could not supply ndependent, substantive ack up the claims further. magazine’s positive past indings, we advise that you anecdotal evidence and own conclusions. trate the procedure, we cotlands Ash Garage in rdshire, to treat my Citroën 03 Volkswagen Passat , which had over 220,000 d. TerraClean recommends ment is carried out every as a preventive measure. aving the work done at each nd service represents a big aintenance costs, which would (understandably) wallow. It could be argued edure would be more s a preventive measure on a overs a low annual mileage, urban conditions.

Decoking modern engines

Ensuring that the engine is warmed fully, its speed is held at a constant 2000rpm for 15 minutes, to allow carbon, varnishes and tar deposits to be loosened from the injectors, pump and combustion chambers.

During this process, some tailpipe smoke may be emitted on cars without DPFs. The engine coolant temperature is also monitored continually, to ensure that overheating does not result.

…to allow the turbocharger to slow and its heat to dissipate. The engine is then switched off for a further 15 minutes. This ‘soak’ period utilises the last unburnt injection pulse to loosen carbon from the piston crowns.

The operator restarts the engine and runs it at 2000rpm for a further 15 minutes, before allowing the unit to idle again, prior to switching it off. The TerraClean machine is then disconnected from the vehicle. The car is road-tested. On DPF-equipped vehicles, the released carbon can become lodged within the filter, making it necessary for the vehicle to be treated to a long run at a sustained speed and load, to allow the filter to regenerate.

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The exact cycle time can vary, depending on the vehicle make, model and engine size. When the engine has completed its 15-minutes run, it returns to idle for a further two minutes…

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PD engine employs a lowlift pump, immersed within the separate the car’s fuel tank from ystem, the intake and return tank are connected together.

TerraClean has developed other processes, including exhaust gas recirculation (EGR) valve cleaning. Here, the tool is attached to the EGR cooler, which drives cleansing fluid towards the valve.

An EGR valve prior to being treated. This one is not especially dirty, although some units can coke up significantly, restricting the valve’s operation and resulting in an illuminated engine warning light.

raClean machine, the operator pressure matches that of the vehicle generating a fault code.

Post-treatment, the EGR valve appears completely cleansed of carbon, without any dismantling being necessary. While cleaning can extend the part’s life, it will not prevent solenoid failure, for example.

TerraClean has also developed its own DPF cleaning, which drives fluid into the filter, by attaching the pictured insert into one of the pressure differential sensor pipes.

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Decoking modern engines decontamination/detox process (it prefers not to use the term ‘flush’) provides an answer to the last point, mainly because its cleansing solution is sucked out of the engine. Arguably, the success of this depends on the sump drain hole location, which is not always at the lowest point on the pan. Even in this case, EDT Automotive reports that any remaining cleansing fluid, which is both non-acidic and non-toxic, will be negligible and in a far smaller quantity than that of the old oil and flush.

In 2015, EDT Automotive won a Green Apple Environment Award for its technology, which pulses the engine’s lubrication system with a pre-heated, soya-based cleansing fluid. Since its UK introduction in 2013, the company has treated thousands of vehicles and, while a 2012 Mercedes-Benz SLK 250 2.2 diesel is the vehicle we are using for this feature, the oldest vehicle that EDT has treated is a 1974 MGB, while the highest-mileage example was a London Taxi TX1 with 470,000 miles.

As with Terraclean, many positive reviews exist, but where is the proof?

CM has intercepted a batch of independent MOT emissions data, which backs up the company’s claim of substantial pollutant reductions, based on pre- and post-treatment results. However, we also have to consider that new oil will also make a positive contribution to those results.

Even so, the figures are impressive. A 10-year-old Jaguar S-TYPE diesel saw its average smoke opacity reduced from

The ‘wet’ side To look after the lubrication system, all you need to do is change the oil and filter regularly, a function of which is to hold many of the by-products of combustion in suspension, preventing them from being deposited within the engine and causing damage. As modern oils have a greater tendency to ‘stick’ to the internal parts – which is desirable to reduce the rate of component wear on cold start-ups – as the oil pressure builds, the suspended contaminants are less likely to fall into the sump. The problem is exacerbated, thanks to long service intervals making the oil more likely to become oversaturated with deposits, leading to the formation of sludge that can build-up not only on the exposed metal surfaces but also within the lubrication system’s innards. Furthermore, the greater effort that is needed to pump the oil around the engine is one way by which efficiency decreases and running costs rise as a car ages.

Although many people use oil flush additives to resolve the problem, some owners believe they might free-up deposits to wreak havoc in other parts of the engine, especially in a poorly maintained unit. Furthermore, a proportion of the flush will, inevitably, remain inside the castings after the sump plug is replaced. While not wishing to become embroiled too deeply in this debate, EDT (Engine Decontamination Treatment) Automotive of Ashford, Kent, argues that its US-developed

0.66m(-1) to 0.07m(-1), while a 10-yearold, 81,000-mile Ford Puma 1700cc petrol saw its carbon monoxide levels reduce from 0.08% (still within MOT pass limits) to 0.02%. A more detailed emissions test found the hydrocarbon emissions of a 1995 BMW 318, with 132,000 miles, drop from 307ppm (parts per million) to 25ppm, although its CO2 emissions rose slightly by 1.25%. EDT Automotive also showed us independent dynamometer readings, revealing a 2.4% increase in horsepower, after a 1997 Alfa Romeo 2.0 Twin Spark was treated.

A 2003 Chrysler Crossfire 3.2 also realised a 3.1% increase. Fuel economy differences are only based on anecdotal feedback from customers, however.

EDT Automotive also claims that customers have reported other unofficial benefits, including reduced (or cured) cold-start top-end and timing chain rattle. While main dealer rates for the operation tend to be higher, independent garage quotations start from £99 inc VAT. Like the Terraclean treatment, however, this can raise the cost of a typical service significantly and EDT Automotive recommends retreatment intervals at 20,000-25,000 miles. We must also highlight that an EDT treatment treats the lubrication system only and not the pre-, post- or ‘dry’ sides of the engine.

Additionally, because our demonstration Mercedes SLK 250 is fitted with a DPF, conducting our own smoke opacity test would have been pointless, because the pre-test figures would have been too low to give an accurate comparison.

The machine is equipped filters. A non-replaceable the machine (pictured), two can of five microns thickness (one u treatments, another for diesels renewed every 40 treatments.

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As separate soya fluid tan for petrol and diesel, the selects the appropriate cycle. To machine pulses the solution, he through the engine at 40psi for

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EDT TREATMENT PROCEDURE As well as independents, certain main dealership groups have adopted EDT machines. We are grateful to Inchcape Mercedes of Stratford-UponAvon, which demonstrated the procedure on one of its sales cars. The EDT procedure pumps warm, pressurised fluid via the oil filter housing. More recent vehicles rely on cartridge-type filters, of which there are many types, but EDT Automotive has made adapters suitable for most engines.

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Older cars that are fitted with cartridge-type filters are not left out; they require a different adapter and threaded collar.

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The three stages are rep cleaned. After the replac allowed to drain, trapped parti see the difference between a us

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Once the oil flow has ceased, a special threaded adapter is screwed into the sump, connected in turn to an extension pipe, through which the cleansing solution returns to the EDT machine for filtering.

Note the difference in di EDT treatment, after the might not be the case if not all reached, such as oil coolers; thi not sufficiently hot to open the

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The engine must be warmed, prior to the oil filter being removed, the sump bolt unscrewed (note the plastic pan on this Mercedes) and the old lubricant captured in a suitable receptacle for recycling.

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Decoking modern engines

0.07m(-1), while a 10-yearmile Ford Puma 1700cc carbon monoxide levels 0.08% (still within MOT o 0.02%. A more detailed t found the hydrocarbon a 1995 BMW 318, with s, drop from 307ppm (parts o 25ppm, although its CO2 e slightly by 1.25%. EDT lso showed us independent r readings, revealing a 2.4% orsepower, after a 1997 .0 Twin Spark was treated. ler Crossfire 3.2 also % increase. Fuel economy e only based on anecdotal m customers, however. motive also claims that ve reported other unofficial uding reduced (or cured) p-end and timing chain main dealer rates for the d to be higher, independent ions start from £99 inc VAT. aclean treatment, however, the cost of a typical service and EDT Automotive retreatment intervals at 0 miles. We must also t an EDT treatment treats n system only and not the ‘dry’ sides of the engine. because our demonstration K 250 is fitted with a DPF, ur own smoke opacity test een pointless, because the es would have been too low urate comparison.

Older cars that are fitted with cartridge-type filters are not left out; they require a different adapter and threaded collar.

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ial threaded adapter is screwed o an extension pipe, through he EDT machine for filtering.

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The machine is equipped with four filters. A non-replaceable gauze within the machine (pictured), two canister filters of five microns thickness (one used for petrol treatments, another for diesels), that are renewed every 40 treatments.

Finally, another five micron filter (a typical oil filter is around 25 microns) is renewed by the technician after each treatment. The machine also contains two canisters of soya-based cleaner, one for petrol, the other for diesel engines.

The soya fluids last for 40 treatments, before they have to be renewed. The filters have to be of such fineness to ensure that one engine’s contaminants cannot affect others. An oil filter adapter is fitted and connected to the machine.

As separate soya fluid tanks are used for petrol and diesel, the operator selects the appropriate cycle. To start, the machine pulses the solution, heated to 42°C, through the engine at 40psi for 90 seconds.

As the soya-based solution is sucked out via the sump plug, it passes immediately through the single use filter (pictured), then the gauze, prior to returning to the main tank.

After all of the cleansing fluid is sucked...

...from the engine, the soak stage sees 4.5 litres of fluid passing through the appropriate canister filter into the sump, which soaks for a minute, before being sucked out in the third stage.

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The three stages are repeated twice and the machine’s hoses are cleaned. After the replaceable five-micron filter is removed and allowed to drain, trapped particles are evident. In the photo you can see the difference between a used and new filter.

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The machine’s adapters are removed from the car, the sump plug is re-torqued, a new oil filter is installed and fresh lubricant added. The engine is run for a minute, before being switched off and the oil level re-checked.

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COSTS WALNUT SHELL DECOKE Cost provided by SWSS Saab, BMW & MINI, Unit 2 Lewis Court, 50 Portmanmoor Road, Cardiff CF24 5HQ. swssmini.co.uk 029 2047 3040. MINI petrol and diesel – £259.00 inc VAT BMW 6-cylinder diesel and petrol – £299.00 inc VAT

TERRACLEAN TerraClean treatment costs vary. To find your local agent, visit terraclean.co.uk or call 01670 706203.

RRP: Cars up to 2.0-litres £108.00; Cars above 2.0-litres £126.00.

Note the difference in dipstick cleanliness, both pre- and postEDT treatment, after the engine had run for 60 seconds. This might not be the case if not all parts of the lubrication system are reached, such as oil coolers; this is because the cleansing solution is not sufficiently hot to open their thermostats.

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EDT TREATMENT EDT treatment costs vary, depending on local labour rates. Prices usually start at £99.00 inc VAT, plus oil and filter change cost.

For more information, see edtautomotive.com

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Fuel saving technology

Fuel saving tec Every motorist wants to save money on fuel, so it’s fortunate that plenty is being done to help us. Chris Randall looks at some of the latest developments.

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ince Car Mechanics was first published in 1958, articles on saving money on fuel have been a regular feature of the magazine. From handy driving tips to advice on maintaining your car so it runs as efficiently as possible, we’ve strived to help you spend less of your hard-earned cash at the pumps.

When it comes to carmakers, ever more stringent legislation has meant their focus on improving economy and emissions has never been greater. Right now they are having to get to grips with new testing regimes – the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) is far stricter than the previous New European Driving Cycle test – and, in 2021, an EU target demanding a corporate average of just 95g/km of CO2 will present further challenges.

The recent demonisation of diesel

Integrated Starter Generator (ISG)

cars hasn’t helped, plus there’s the proliferation of electric and hybrid models on the market.

So where does that leave things for the internal combustion engine? Let’s take a look at what’s being done to make every gallon go further.

Weight-watching Weight is one of the arch-enemies of fuel economy. As cars get bigger and more buyers are tempted by an SUV, making vehicles lighter is crucial. One of the biggest advances is in the materials used for bodyshells, with many carmakers opting for a multi-material mix that

ensures excellent strength and rigidity while being much lighter in weight.

Combining the likes of high-strength and ultra-high-strength steel (both hot- and cold-formed), aluminium, magnesium and composites such as carbon-fibre reinforced plastic can yield significant savings.

For example, at the launch of the current Astra, Vauxhall claimed that it was up to 200kg lighter than its predecessor, with the body-in-white saving of around 20% (280kg instead of 357kg), while the current Audi Q7 SUV reputedly saved a whopping 325kg overall. The 2018-on Ford Focus’s 88kg reduction compared to the outgoing model is helped by lighter window regulators that are reinforced with glassfibre fabric.

Streaming service Streamlining isn’t exactly a new area in car development, but it is worth noting how much work is being done on mainstream cars to reduce drag. Taking the latest Ford Focus as an example, the manufacturer’s data reckons that aerodynamic improvements (along with the weight reduction) contribute to a 10% improvement in fuel efficiency.

This affordable family vehicle now has a coefficient of drag of 0.273 and benefits from features such as an Active Grille Shutter, which closes to reduce drag when less cooling is required, as well as ‘air curtains’ that guide airflow across the front wheels to reduce turbulence and enhancements to underbody airflow due to panelling over the central tunnel, fuel tank and rear axle.

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Becoming common on a wid premium and bread-and-bu an ISG combines the functi starter motor and alternato known by different names – it a belt alternator starter – engines also retain a conven starter motor for use durin but they all work in essenti way. Connected to the engin it has a number of benefits a quicker-acting Stop/Start and the ability to recover en braking which is then fed b car’s electrics. That ability t ‘free’ energy and provide el assistance to the powertrain to fuel economy.

Mild-hybrid system

ISG is also a key componen hybrid systems. These diffe hybrids by not actually driv wheels directly, but can stil useful savings. Audi and Me are keen employers of such but they aren’t confined to brands. For example, Suzuk same technology to save fu Smart Hybrid Vehicle by Su set-up. Using an ISG and a lithium-ion battery to store energy, the system can harv from regenerative braking ( in the case of Audi’s system that can then be used to ass engine during take-off from during acceleration.

More complex systems als incorporate ‘coasting’ functi in conjunction with 48-volt systems, and when combine smaller-capacity, more effici it’s easy to see how mild-hyb boost economy.

48-volt electrics

Although pretty much limit more expensive models at p this technology will be filte down to more affordable ca next few years. Able to prov times the power of current systems that are considered

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Fuel saving technology

ng technology Integrated Starter Generator (ISG)

lent strength and rigidity much lighter in weight. the likes of high-strength h-strength steel (both -formed), aluminium, nd composites such as reinforced plastic can ant savings. e, at the launch of the , Vauxhall claimed that 00kg lighter than its with the body-in-white und 20% (280kg instead hile the current Audi Q7 y saved a whopping 325kg 2018-on Ford Focus’s 88kg mpared to the outgoing ed by lighter window at are reinforced with ric.

ng service

isn’t exactly a new area pment, but it is worth much work is being done on cars to reduce drag. Taking d Focus as an example, urer’s data reckons that improvements (along with duction) contribute to a ment in fuel efficiency. le family vehicle now has a drag of 0.273 and benefits s such as an Active Grille h closes to reduce drag oling is required, as well as that guide airflow across eels to reduce turbulence ments to underbody airflow ing over the central tunnel, rear axle.

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Becoming common on a wide range of premium and bread-and-butter models, an ISG combines the function of the starter motor and alternator. It can be known by different names – Audi calls it a belt alternator starter – and some engines also retain a conventional starter motor for use during cold starts, but they all work in essentially the same way. Connected to the engine by a belt, it has a number of benefits, including a quicker-acting Stop/Start system and the ability to recover energy under braking which is then fed back to the car’s electrics. That ability to supply ‘free’ energy and provide electrical assistance to the powertrain contributes to fuel economy.

Smart Hybrid Vehicle

by Suzuki (SHVS) is a mild hybrid that recovers energy from braking, storing it in a lithium-ion battery to assist the petrol engine later.

Mild-hybrid systems ISG is also a key component in mildhybrid systems. These differ from full hybrids by not actually driving the wheels directly, but can still produce useful savings. Audi and Mercedes-Benz are keen employers of such systems, but they aren’t confined to premium brands. For example, Suzuki uses the same technology to save fuel with its Smart Hybrid Vehicle by Suzuki (SHVS) set-up. Using an ISG and a separate lithium-ion battery to store recovered energy, the system can harvest power from regenerative braking (up to 12kW in the case of Audi’s system), power that can then be used to assist the engine during take-off from rest and during acceleration.

More complex systems also incorporate ‘coasting’ functions, often in conjunction with 48-volt electrical systems, and when combined with smaller-capacity, more efficient engines, it’s easy to see how mild-hybrids can boost economy.

48-volt electrics Although pretty much limited to more expensive models at present, this technology will be filtering down to more affordable cars in the next few years. Able to provide four times the power of current 12-volt systems that are considered to be at shop.kelsey.co.uk/subscription/CME Fuel Saving Technology.indd 97 096-098.indd 97

48-volt systems are already fitted on high-level models. The technology should filter down to affordable vehicles in the not-too-distant future.

the limit of their capabilities, it’s seen as a crucial development to support technology such as mild-hybrid systems and autonomous driving, as well as powering electric turbos or superchargers and climate control compressors. Combining 48-volt systems with starter-generators also means quicker engine restarting and allows higher levels of brake energy recuperation. And being capable of higher voltages with a lower current draw, there’s less need for heavy-duty electrical components, so wiring can be thinner and lighter.

Coasting Popping the gearbox into neutral and coasting – or freewheeling – was once frowned upon because you were deemed to not be in full control of the vehicle. However, in conjunction with sophisticated automatic and dual-clutch transmissions, it has become an essential part of saving fuel. Essentially, the electronics put the gearbox into coasting mode, decoupling it from the engine and disengaging clutches to reduce mechanical drag, in some cases switching off the engine at the same time.

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BMW’s ECOPRO electric system helps achieve fuel savings of up to 20%.

During this operation, the battery (sometimes a separate lithium-ion unit) supplies power to electrical equipment and the engine is restarted almost instantaneously via an ISG. In Audi’s system, the mode can be activated at speeds between 34mph and 99mph.

Assistance systems It’s not just mechanical improvements that save fuel. Electronics are playing an ever greater role and nowhere is that more true than with systems that help you drive more efficiently.

Audi’s Predictive Efficiency Assistant claims to reduce fuel consumption on country roads by up to 10%. It works by pulling together a number of different technologies, including adaptive cruise control, satellite navigation and traffic sign recognition (plus coasting functions in some models), taking into account factors such as speed limits, the traffic ahead and route topography. Able to adjust speed to road conditions and alert the driver to slow down for corners, junctions and roundabouts, it promotes smoother, more efficient driving.

BMW’s ECOPRO system works in a similar fashion, using a gearshift indicator and the Stop-Start system, as well as coasting and a route aheadassistant, to achieve fuel savings of up to 20%.

Downsizing You could find cars fitted with three-cylinder engines back in the 1980s, but they’ve made a strong comeback over the last few years. With the improvements that have taken place in turbocharging and electronic management systems, a wide range of carmakers see three-cylinder engines as an ideal 98 Car Mechanics Fuel Saving Technology.indd 98 096-098.indd 98

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Ford’s three-cylinder engine has the ability to shut down a cylinder when circumstances allow.

way of offering decent performance with impressive economy.

In the Vauxhall Astra 1.0 ECOTEC, for example, you get 0-60mph in 10.5 seconds plus a claimed 64mpg. And if you think these engines are only suitable for urban runabouts, you couldn’t be more wrong. In fact, around a dozen manufacturers offer models with threecylinder engines, in everything from the sporty MINI to SUVs and the usefully large Ford Mondeo.

Cylinder shutdown Shutting down individual cylinders to save fuel isn’t a new idea, having been found on mainstream cars since the early 2000s.

Often applied to larger, multi-cylinder units, it has become more widespread in recent years with Volkswagen the first to introduce Active Cylinder Technology on four-cylinder engines back in 2012.

Taking VW’s current 1.5-litre TSI petrol unit as an example, the system operates between 1400-3200rpm under low-load conditions and at speeds of up to 81mph.

It’s the two inner cylinders that are deactivated (the changeover almost

imperceptible, with the driver notified by ‘2 cylinder mode’ appearing in the instrument display) as a pair of actuators disengage the cam lobes from the inlet and exhaust valves for those cylinders, so the valves remain closed and fuelling is cut. VW claims the 130PS version of this engine is 10% more fuel-efficient than a comparable petrol engine.

Ford has got in on the act: the company’s process of cylinder deactivation on three-cylinder units is a world-first, with its EcoBoost unit able to disengage or re-engage a cylinder in just 14 milliseconds – as they point out, that’s 20 times faster than the blink of an eye!

Spark Controlled Compression Ignition (SPCCI) This latest technological advance was launched in Europe in June 2019.

Developed by Mazda for its Skyactiv-X engine, it combines the spark ignition of a petrol engine with the compression ignition of a diesel, flipping seamlessly between the two. It works by switching from the stoichiometric 14.7:1 air/fuel ratio to a lean-burn mixture of 29.4:1.

When the engine is cold or operating at high revs, conventional spark ignition is used; in lean-burn mode (around 80% of the time, according to Mazda), the spark plug ignites a small amount of fuel-rich mixture injected directly into the cylinder during the compression stroke.

Compression ignition then takes over, resulting in a more complete and powerful burn of the mixture for a stronger power stroke. It promises efficiency gains of 20-30% compared to Mazda’s current Skyactiv-G petrol range.

Mazda’s Skyactiv-X engine combines the spark ignition of a petrol with the compression ignition of a diesel.

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