INTRODUCTION TO AUTOMOTIVE ENGINE MAINTENANCE

INTRODUCTION TO AUTOMOTIVE ENGINE MAINTENANCE

Khairi Ali

Syahrizal Nawawi

Muslim Mamat

Soffi Manda

Mohd Khairi Bin Ali Mohd Soffi Bin Manda Md Syahrizal Bin Nawawi Muslim Bin Mamat

1

Politeknik Sultan Haji Ahmad Shah Published by POLITEKNIK SULTAN HAJI AHMAD SHAH SEMAMBU 25350 KUANTAN

Copyright ©2021, by Politeknik Sultan Haji Ahmad Shah Materials published in this book under the copyright of Politeknik Sultan Haji Ahmad Shah. All rights reserved. No part of this

publication

may

be

reproduced or distributed in any form or by means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of the publishers.

2

Table of Content

1. Introduction to Automotive Engine Maintenance

(1)

2. Automotive Engine Cooling System

(7)

3. Automotive Engine Lubrication System

(23)

4. Automotive Engine Ignition System

(39)

5. Conclusion to Automotive Engine Maintenance

(67)

1

2

Introduction to Automotive Engine Maintenance

Chapter 1

Introduction To Automotive Engine Maintenance

1

Introduction to Automotive Engine Maintenance Introduction to Maintenance

Maintenance is a process of retaining or restoring an equipment, machine or system into its optimum working condition. Without proper maintenance, an equipment, machine or system may gradually fail before the expiry of its guaranteed useful life. This condition may cause waste of money due to severe failure which is not economic and efficient to be repaired.

2

Introduction to Automotive Engine Maintenance There are many advantages of maintenance. First of all is to prolong the useful life of the equipment. In addition to that, by doing maintenance, premature failure may be noticed in its early stage and recovery action may be taken quickly to prevent further severe damage. Other than that, maintenance may also increase safety and reliability of an equipment, machine or system. Improperly maintained equipment may cause unexpected failure which could cause time loss because the consumer was not ready to face the situation. In worst case, accident may also occur due to neglecting the importance of maintenance and could results in casualties to its consumers.

Automotive Engine Maintenance Engine is a heart of an automotive machine. Without an engine, any automotive machine will become useless and invaluable. Therefore, maintenance of an automotive engine should always be given attention by its consumer. There are several important aspects on an engine which require attention in maintenance point of view. Those aspects are engine cooling system, lubrication system and ignition system.

3

Introduction to Automotive Engine Maintenance Properly planned maintenance procedure always produced after a brief understanding on how the equipment works. For instance, a gear drive system and a brake system are two component which works differently. Gear drive does not require friction because it can cause wear, but brake on the other hand need higher friction so that it can effectively works. So, it is incorrect to apply lubricant on the brake but the gear must be lubricated.

Therefore, in order to effectively practicing on automotive engine maintenance, one should understand how automotive engine works.

This e-book will cover basic theoretical knowledge on engine cooling, lubrication and ignition systems. The areas involve are types, functions and working principles of cooling, lubrication and ignition systems together with brief explanation on its components. For instances, in cooling system, this ebook will cover coolant or anti-freeze, in lubrication system, this e-book will cover about synthetic engine oil and in ignition system, this e-book will cover timing advance mechanism. Other than that, there are also many other important item that will be explained in subsequent chapter.

Automotive Engine Cooling System

4

Introduction to Automotive Engine Maintenance

Automotive Engine Lubrication System

Automotive Ignition System

5

Introduction to Automotive Engine Maintenance

6

Automotive Engine Cooling System

Chapter 2

Automotive Engine Cooling System

7

Automotive Engine Cooling System Introduction to Engine Cooling System

A car engine produces a lot of heat when it is running, and must be cooled continuously to avoid engine damage. Generally this is done by circulating coolant liquid usually water mixed with an antifreeze solution through special cooling passages. Some engines are cooled by air flowing over finned cylinder casings. Cooling system is important to ensure that the engine will work effectively. Excessive heat may cause the engine to over expand either on engine block parts or piston parts. When the engine metal parts expand, the reciprocating motion will get interrupt and jammed. Among the purposes of an engine cooling system are as the following: a. To maintain engine temperature at best operating temperature. b. To remove excessive heat that is not desired. c. To prevent from engine overheating.

A typical water-cooling system with an engine-driven fan: note the bypass hose taking off hot coolant for the heater. The pressure cap on the expansion tank has a spring-loaded valve which opens above a certain pressure.

8

Automotive Engine Cooling System Generally there are two types of automotive engine cooling system namely; a water-cooled cooling system and an air-cooled cooling system.

The name implies how the cooling system works.

Water-cooled Cooling System A water-cooled engine block and cylinder head have interconnected coolant channels running through them. At the top of the cylinder head all the channels converge to a single outlet. A pump, driven by a pulley and belt from the crankshaft, drives hot coolant out of the engine to the radiator, which is a form of heat exchanger.

Unwanted heat is passed from the radiator into the air stream, and the cooled liquid then returns to an inlet at the bottom of the block and flows back into the channels again. Usually the pump sends coolant up through the engine and down through the radiator, taking advantage of the fact that hot water expands, becomes lighter and rises above cool water when heated. Its natural tendency is to flow upwards, and the pump assists circulation.

The radiator is linked to the engine by rubber hoses, and has a top and bottom tank connected by a core a bank of many fine tubes. The tubes pass through holes in a stack of thin sheet-metal fins, so that the core has a very large surface area and can lose heat rapidly to the cooler air passing through it.

On older cars the tubes run vertically, but modern, low-fronted cars have crossflow radiators with tubes that run from side to side. In an engine at its ordinary working temperature, the coolant is only just below normal boiling point. The risk of boiling is avoided by increasing the pressure in the system, which raises the boiling point.

The extra pressure is limited by the radiator cap, which has a pressure valve in it. Excessive pressure opens the valve, and coolant flows out through an overflow pipe. In a cooling system of this type there is a continual slight loss of coolant if the engine runs very hot. The system needs topping up from time to time.

Later cars have a sealed system in which any overflow goes into an expansion tank, from which it is sucked back into the engine when the remaining liquid cools.

9

Automotive Engine Cooling System

The radiator needs a constant flow of air through its core to cool it adequately. When the car is moving, this happens anyway; but when it is stationary a fan is used to help the airflow. The fan may be driven by the engine, but unless the engine is working hard, it is not always needed while the car is moving, so the energy used in driving it wastes fuel.To overcome this, some cars have a viscous coupling a fluid clutch worked by a temperature sensitive valve that uncouples the fan until the coolant temperature reaches a set point.

Other cars have an electric fan, also switched on and off by a temperature sensor. To let the engine warm up quickly, the radiator is closed off by a thermostat, usually sited above the pump. The thermostat has a valve worked by a chamber filled with wax. When the engine warms up, the wax melts, expands and pushes the valve open, allowing coolant to flow through the radiator.

When the engine stops and cools, the valve closes again. Water expands when it freezes, and if the water in an engine freezes it can burst the block or radiator. So antifreeze usually ethylene glycol is added to the water to lower its freezing point to a safe level. Antifreeze should not be drained each summer; it can normally be left in for two or three years.

10

Automotive Engine Cooling System Components of Water Cooling System

Water cooling system mainly consists of: (a) Radiator (b) Thermostat valve (c) Water pump (d) Fan (e) Water Jackets (f) Antifreeze mixtures

Radiator

11

Automotive Engine Cooling System

It mainly consists of an upper tank and lower tank and between them is a core. The upper tank is connected to the water outlets from the engines jackets by a hose pipe and the lover tank is connect to the jacket inlet through water pump by means of hose pipes.

There are 2-types of cores: (a) Tubular (b) Cellular as shown.

When the water is flowing down through the radiator core, it is cooled partially by the fan which blows air and partially by the air flow developed by the forward motion of the vehicle. As shown through water passages and air passages, wafer and air will be flowing for cooling purpose. It is to be noted that radiators are generally made out of copper and brass and their joints are made by soldering.

Thermostat Valve

It is a valve which prevents flow of water from the engine to radiator, so that engine readily reaches to its maximum efficient operating temperature. After attaining maximum efficient operating temperature, it automatically begins functioning. Generally, it prevents the water below 70°C. Bellow type thermostat valve which is generally used. It contains a bronze bellow containing liquid alcohol. Bellow is connected to the butterfly valve disc through the link. When the temperature of water increases, the liquid alcohol evaporates and the bellow expands and in turn opens the butterfly valve, and allows hot water to the radiator, where it is cooled.

12

Automotive Engine Cooling System Water Pump

It is used to pump the circulating water. Impeller type pump will be mounted at the front end. Pump consists of an impeller mounted on a shaft and enclosed in the pump casing. The pump casing has inlet and outlet openings. The pump is driven by means of engine output shaft only through belts. When it is driven water will be pumped.

13

Automotive Engine Cooling System Fan

It is driven by the engine output shaft through same belt that drives the pump. It is provided behind the radiator and it blows air over the radiator for cooling purpose.

Water Jackets Cooling water jackets are provided around the cylinder, cylinder head, valve seats and any hot parts which are to be cooled. Heat generated in the engine cylinder, conducted through the cylinder walls to the jackets. The water flowing through the jackets absorbs this heat and gets hot. This hot water will then be cooled in the radiator.

Antifreeze Mixture In western countries if the water used in the radiator freezes because of cold climates, then ice formed has more volume and produces cracks in the cylinder blocks, pipes, and radiator. So, to prevent freezing antifreeze mixtures or solutions are added in the cooling water.

The ideal antifreeze solutions should have the following properties : (a) (b) (c) (d)

It should dissolve in water easily.

It should not evaporate.

It should not deposit any foreign matter in cooling system.

It should not have any harmful effect on any part of cooling system. (e) It should be cheap and easily available. (f) It should not corrode the system.

14

Automotive Engine Cooling System No s i n g l e a n t i f r e e z e s a t i s f i e s a l l t h e r e q u i r e m e n t s .

Normally following are used as antifreeze solutions: (a) (b) (c) (d) (e)

Methyl, ethyl and isopropyl alcohols.

A solution of alcohol and water.

Ethylene Glycol.

A solution of water and Ethylene Glycol.

Glycerin along with water, etc.

Advantages of Water Cooling System (a) Uniform cooling of cylinder, cylinder head and valves. (b) Specific fuel consumption of engine improves by using water cooling system. (c) If we employ water cooling system, then engine need not be provided at the front end of moving vehicle. (d) Engine is less noisy as compared with air cooled engines, as it has water for damping noise.

Disadvantages of Water Cooling System (a) It depends upon the supply of water. (b) The water pump which circulates water absorbs considerable power. (c) If the water cooling system fails then it will result in severe damage of engine. (d) The water cooling system is costlier as it has more number of parts. Also it requires more maintenance and care for its parts.

Engine cooling system The cooling system is a key to efficient engine operation. An internal combustion engine only uses one-third of the power produced. One-third heats oil or goes out the exhaust and one-third must be controlled by the water cooling system.

1. An engine wears out four times faster if it continually operates at a low temperature.

2. A tractor doing the same work will use 3.8 gallons of fuel per hour at 400 and only 2.8 gallons of fuel per hour at 1800.

Warm up your engine before putting under load.

15

Automotive Engine Cooling System

3. Too much heat can damage an engine, increase oxidation to the oil, and reduce the effectiveness of the additives in the oil.

4. Excessive heat may attack seals, liners, gaskets, and sealants.

5. A thin (1/16") layer of calcium carbonate build-up on an engine is equal to 4" of solid cast iron in heat transfer.

Antifreeze 1. Antifreeze should be changed every year unless you add chemical inhibitors to reinforce the rust inhibiting ability.

2. Diluting antifreeze one-third to one-half with water is usually recommended. More than two-thirds antifreeze is too much. It offers less freezing protection rather than more.

3. Distilled or rain water is better than plain water because of the corrosion deposits.

4. Ethylene-Glycol antifreeze in the cooling system raises the boiling temperature substantially. This makes for greater heat dissipation.

5. Antifreeze is not a waste of money if you consider risk factor alone. It is insurance that makes sense.

16

Automotive Engine Cooling System Air-cooled Engine Cooling Systems In an air-cooled engine, the block and cylinder head are made with deep fins on the outside. Frequently a duct runs all around the fins, and an engine-driven fan blows air through the duct to take heat away from the fins.

A temperature-sensitive valve controls the amount of air being pushed around by the fan, and keeps the temperature constant even on cold days.

Air cooled system is generally used in small engines say up to 15-20 kW and in aero plane engines. In this system fins or extended surfaces are provided on the cylinder walls, cylinder head, etc. Heat generated due to combustion in the engine cylinder will be conducted to the fins and when the air flows over the fins, heat will be dissipated to air.

The Basic Principle of this type of system is to allow a flow of current through the parts from which heat is to be dissipated, which depends upon the surface area of metal in contact rate of flow of air, a temperature difference between hot surface and air. Surface area of the metal will be increased by providing the fins around the cylinder which is made of copper or steel (high heat conductivity material).

17

Automotive Engine Cooling System Advantages of Air Cooled System Following are the advantages of air cooled system : (a) Radiator/pump is absent hence the system is light. (b) In case of water cooling system there are leakages, but in this case there are no leakages. (c) Coolant and antifreeze solutions are not required. (d) This system can be used in cold climates, where if water is used it may freeze.

Disadvantages of Air Cooled System (a) Comparatively it is less efficient. (b) It is used in aero planes and motorcycle engines where the engines are exposed to air directly.

Air cooling Cars and trucks using direct air cooling (without an intermediate liquid) were built over a long period from the very beginning and ending with a small and generally unrecognized technical change.

Before World War II, water-cooled cars and trucks routinely overheated while climbing mountain roads, creating geysers of boiling cooling water. This was considered normal, and at the time, most noted mountain roads had auto repair shops to minister to overheating engines.

ACS (Auto Club Suisse) maintains historical monuments to that era on the Susten Pass where two radiator refill stations remain (See a picture here). These have instructions on a cast metal plaque and a spherical bottom watering can hanging next to a water spigot. The spherical bottom was intended to keep it from being set down and, therefore, be useless around the house, in spite of which it was stolen, as the picture shows.

During that period, European firms such as Magirus- Deutz built aircooled diesel trucks, Porsche built air-cooled farm tractors, and Volkswagen became famous with air- cooled passenger cars. In the USA, Franklin built air-cooled engines. The Czechoslovakia based company Tatra is known for their big size air-cooled V8 car engines, Tatra engineer Julius Mackerle published a book on it. Air-cooled engines are better adapted to extremely cold and hot environmental weather temperatures, you can see air-cooled engines starting and running in freezing conditions that stuck water-cooled engines and continue working when water-cooled ones start producing steam jets.

18

Automotive Engine Cooling System Cooling System Maintenance Ignoring routine car maintenance or ignoring minor engine problems will add significant wear and tear on your vehicle and lessen engine life. This is especially true when it comes to the cooling system in your vehicle. Despite the fact that maintaining the cooling system holds such importance in engine performance, 28% of vehicles have inadequate cooling protection. If you can’t recall the last time you had the coolant (also known as antifreeze) flushed and replaced, you fall into that category. It’s time to take care of the cooling system and here’s why.

The cooling system is designed to remove the heat generated when a spark ignites the fuel/air mixture in the engine. It’s a circular process that starts in the radiator. When the engine reaches a certain operating temperature, the water/coolant flows to the engine, removes the heat. The coolant then flows back out to the radiator where the air flowing through the grill cools it down so it can go back through the cycle again. The coolant is designed to keep the engine from overheating and it also protects vital parts within the cooling system from corrosion. When the coolant gets old, it can no longer adequately do its job and you run the risk of an overheating engine, which could lead to a blown head gasket or worse.

Signs You Have a Cooling System Problem As with any engine component, there are some signs to look for that will alert you to a problem. When it comes to the cooling system watch for these:

a. The engine overheats. As mentioned above, an overheating engine should not be ignored. There are any number of things that can be causing the engine to overheat – like a bad water pump, and a broken hose or belt to name a couple. If the engine temperature light warning light comes on or you notice the engine is overheating, safely pull over and call for a tow. Continuing to drive could lead to fatal engine damage.

b. You can smell antifreeze when you drive. The smell of antifreeze when driving or right after you stop your vehicle is an indicator of a leak in the system. The smell is caused by the antifreeze dripping onto the hot engine. Like an engine that is overheating, this should be fixed right away.

19

Automotive Engine Cooling System c. You notice antifreeze under the front of your vehicle. If you notice a puddle of coolant under your vehicle, have your vehicle checked out right away. Any time there’s a leak in the cooling system, it can’t properly protect the engine from overheating.

d. The coolant level is always low. If you have to add coolant to the radiator on a regular basis, there’s a leak in the system.

Proper Cooling System Maintenance The cooling system should be maintained as follows: a. Regularly check the radiator, belts and hoses and have them replaced when they show signs of excessive wear or aging.

b. Replace the drive belt (also known as the serpentine belt) before it breaks. Check the owner’s manual to see when it should be replaced.

Our technicians will also let you know when it is prudent to change the belt.

c. Have a cooling system service performed. During this service the old fluid will be drained, the system flushed and new coolant added. This service should be performed at least once every two years. We can also complete a quick test of the coolant to let you know if it can adequately protect.

20

Automotive Engine Cooling System Common Cooling System Maintenance Items There are a few ways to maintain your cooling system and ensure that it’s working its best. A clean cooling system also helps avoid accumulation of dirt and debris that can lead to blockage and corrosion. Take these following steps to guarantee a reliable cooling system: a. Check your coolant level often and top-up if necessary

b. Check for leaks and coolant consumption — possible signs of head gasket wear or failure

c. Have your coolant tested, especially if you have cold winters

d. Watch for rust or discoloration in your coolant — an indication of corrosion

e. Have your cooling system flushed every 5 years or 30,000 miles

f.

If you have detected any leaks in your cooling system or suspect you have a blown head gasket (detectable as increased coolant consumption with no visible leaks as well as white smoke coming from your tailpipe), it’s time to act. Using one of our industryleading cooling system or head gasket leak products can help seal leaks before they become a major problem and cause costly engine damage.

21

Automotive Engine Cooling System

22

Automotive Engine Lubrication System

Chapter 3

Automotive Engine Lubrication System

23

Automotive Engine Lubrication System Introduction to Engine Lubrication System

When two metallic surfaces under direct contact move over each other, they create friction which generates heat. This causes excessive wear and tear of those moving parts. However, when a film of lubricating matter separates them from each other, they do not come in physical contact with each other. Thus, lubrication is a process that separates the moving parts by supplying a flow of a lubricating substance between them. The lubricant could be liquid, gas or solid. However, engine lubrication system mainly uses liquid lubricants.

24

Automotive Engine Lubrication System You may know about maintaining your car that is you have to change the Engine lubrication oils time to time. What you may not know is where the oil goes, what does it do? and why it needs to be changed time to time? The first task of oil in the engine is to keep the things oily so they could not get dry. Just think for a while if the eardrum-piercing sounds of metal pistons screeching up and down inside a dry cylinder. It will be so annoying, isn’t it?

There are pleasant effects of keeping the engine lubricated with automotive lubricants. There is little friction, which makes a sense that engine has to make little effort to keep it running. So, it means that it is able to skate on less fuel can run at the lower temperature. And this means that less wear and tear on the engine parts. Engine needs to fill with clean oil so it can perform well.

Never get confused by the term “lubrication”, sometimes when you go to the local quick lube work shop, they recommend you are supposed to have a “lube job”. That is certainly not an oil change. That absolutely means oiling the chassis and suspension system. None of them shares the oil with lubrication system in engine.

Lubrication system The Engine lubrication system is considered to give a flow to the clean oil at the accurate temperature, with a appropriate pressure to each part of the engine. The oil is sucked out into the pump from the sump, as a heart of the system, than forced between the oil filter and pressure is fed to the main bearings and also to the oil pressure gauge. The oil passes through the main bearings feed- holes into the drilled passages which is in the crankshaft and on to the bearings of the connecting rod. The bearings of the piston-pin and cylinder walls get lubricated oil which dispersed by the rotating crankshaft. By the lower ring in the piston the excess being scraped. Each camshaft bearing is fed by the main supply passage from a branch or tributary. And there is another branch which supplies the gears or timing chain on the drive of camshaft. The oil which is excesses then drains back to the sump, where the heat is being transferred to the surrounding air.

25

Automotive Engine Lubrication System Journal Bearings

If the crankshaft journals get worn, the engine will be having very low oil pressure and will throw oil all over inside the engine. The unnecessary splash will overcome the rings and can cause the engine to use that oil.

Simply replacing the bearing inserts can restore the worn bearing surfaces. In well maintained engine, bearing wear take places instantly after a cold start because there is less or no oil film between the shaft and bearing. At the time that enough automotive lubricants is dispersed through the hydrodynamic lubrication system apparent and stops the bearing wear progress.

Piston rings – cylinder

A sliding seal avoiding leakage of the air mixture or fuel is provided by piston rings. It gets weaken into the oil sump while combustion and compression from the combustion chamber. On other hand, from leaking into the combustion area they keep oil in the sump, where it will be burned and lost. Those cars that burn oil and have to be added, a quart at every 1,500 miles are flaming it because the rings get no longer to be sealed properly.

26

Automotive Engine Lubrication System Hydrodynamic lubrication prevails in the center of the cylinder wall and the piston rings of the good maintained car, essential for the very lower wear and friction. The thickness of the film becomes assorted and minimal lubrication may exist where the piston will stop to redirect on the top and bottom of the dead centre.

To analyze or realize well head transfer from the piston to the cylinder, a finest sealing, a minimal thickness of film and a minimum of oil burning is desirable. Oil controlling ring keeps minimal the thickness of film.

This is ring is located after the piston rings so that the surplus oil directly scraped down to the sump. To lubricate the following ring the oil film left on the cylinder wall by the passage of this ring will be available.

Oil degradation results by the air mixture or leakage of the fuel which exhaust from the combustion chamber into the oil sump. That is why, frequent replenish of oil despites, oil change will remain essential or it can also become more essential.

The Purposes of Engine Lubrication System: a. Minimizes power loss by reducing the friction between the moving parts. b. Reduces the wear and tear of the moving parts. c. Provides cooling effect to the hot engine parts. d. Provides cushioning effect against vibrations caused by the engine. e. Carries out the internal cleaning of the engine. f. Helps piston rings to seal against high-pressure gases in the cylinder.

Engine lubrication system supplies the engine oil to the following parts: a. b. c. d. e. f. g. h. i. j.

Crankshaft main bearings Big end bearings Piston pins and small end bushes Cylinder walls Piston rings Timing Gears Camshaft and bearings Valves Tappets and push-rods Oil pump parts 27

Automotive Engine Lubrication System k. l. m. n. o.

Water pump bearings In-Line Fuel Injection Pump bearings Turbocharger bearings (if fitted) Vacuum pump bearings (if fitted) Air-compressor piston and bearings (in commercial vehicles for airbrake)

Types of Engine Lubrication System: There are mainly four types of lubrication systems used in automotive engines which are: a. b. c. d.

Petroil System Splash System Pressure system Dry-Sump System

Petroil Engine Lubrication System

28

Automotive Engine Lubrication System

Splash Engine Lubrication System

Pressure Engine Lubrication System

29

Automotive Engine Lubrication System

Dry Sump Engine Lubrication System

Components of Engine Lubrication System: a. b. c. d. e. f. g.

Oil Sump Engine oil filter Piston cooling nozzles Oil Pump The Oil Galleries Oil Cooler The Oil pressure indicator/light

Oil Pan / Sump: An Oil Pan / Sump is just a bowl-shaped reservoir. It stores the engine oil and then circulates it within the engine. Oil sump sits below the crankcase and stores the engine oil when the engine is not running. It is located at the bottom of the engine in order to collect and store the engine oil. The oil returns to the sump by pressure/gravity when the engine is not in use.

Bad road conditions could cause damage to the Oil Pan / Sump. So, the manufacturers provide a stone guard/sump guard underneath the sump.

The sump guard absorbs the hit from the uneven road and protects the sump from any damage.

30

Automotive Engine Lubrication System Oil Pump: An Oil Pump is a device which helps to circulate the lubricant oil to all the moving parts inside the engine. These parts include crankshaft & camshaft bearings as well as valve lifters. It is generally located at the bottom of the crankcase, close to the oil sump. The oil pump supplies the oil to oil filter which filters and sends it onward. The oil then reaches different moving parts of the engine through oil galleries.

Even, small particles can choke the oil pump and galleries. If oil Pump gets blocked, then it can cause the severe damage to the engine or even complete seizure of the engine. To avoid it, the oil pump consists of a strainer and a by-pass valve. Hence, it is necessary to change the engine oil and filter at regular intervals as recommended by the manufacturers.

Oil Galleries: In order to get better performance and longer engine life, it is essential that the engine oil quickly reaches the moving parts of the engine. For this purpose, manufacturers provide oil galleries within the engine. The Oil Galleries are nothing but series of interconnected passages which supply the oil to the remotest parts of the engine.

Oil galleries consist of big and small passages drilled inside the cylinder block. The bigger passages connect to the smaller passages and supply the engine oil upto the cylinder head and overhead camshafts. The oil galleries also supply the oil to the crankshaft, crankshaft bearings and camshaft bearings thru holes drilled in them as well as to valve lifters/tappets.

31

Automotive Engine Lubrication System Oil Cooler: The Oil Cooler is a device which works just like a radiator. It cools down the engine oil which becomes very hot. Oil cooler transfers the heat from the engine oil to the engine coolant through its fins. Initially, manufacturers used the oil cooler only in the racing/high-performance vehicles. However today, most vehicles use oil cooler system for better engine performance.

Oil cooler which helps to maintain the engine oil temperature also keeps its viscosity under control. Additionally, It retains the lubricant quality, prevents the engine from overheating and thereby saving it from wear and tear.

32

Automotive Engine Lubrication System Understanding The Different Types Of Engine Oil If you’ve ever gone to your local auto parts store and walked down the motor oil aisle, you’ve probably been shocked or even overwhelmed at the number of different choices you have. There are different brands, different quantities, different weights, and even different types of oil. How in the world could you possibly know which one is right for you?

It’s actually not nearly as difficult as it seems. If you consult your vehicle’s owner’s manual, you’ll find what weight of oil, how often you should change it, and how much oil you should put in every time you do. These are all important figures to know, but your manual may not include what type of oil to get. This is perhaps the most important choice when selecting your new oil, as it could have a pretty significant impact on your engine’s health.

Are all oils the same? Not at all. On this blog, our auto repair experts cover different types of motor oil, including conventional, synthetic, synthetic blend, and high-mileage and help you determine which one is right for your vehicle.

Conventional Oil Conventional oil is your standard motor oil. It’s manufactured from crude oil that’s pulled from the ground and then refined in a factory. Different additives and processes are done to improve its viscosity (thickness) and engine protective properties, and it’s then bottled and sold for use in your engine. Simple as that.

There are up and downsides to this. The biggest upside: cost.

Conventional oil is an extremely budget-friendly option for keeping your engine protected and your car running smoothly. It’s also fairly effective— there aren’t really any bad motor oils on the market these days; as long as you get the right weight and quantity, you can expect reasonable performance. However, their downsides are greater than other types.

Because of the naturally-occurring materials, they tend to be less refined.

They also offer a lower degree of protection than other types as well.

33

Automotive Engine Lubrication System Full-Synthetic Oil Synthetic motor oil is manufactured entirely in a factory, or lab.

Because of this, they tend to be far more consistent; it’s easier to control manufacturing processes when all of your materials are held to much more stringent standards. Thus, these oils are more refined, and are overall better for your engine But this comes at a cost—literally. Full-synthetic motor oil is more expensive than conventional oil. Not by a lot, mind you, but generally you can expect to pay anywhere from an extra $20 to $40 for your oil change if you use a full-synthetic oil, depending on how much your car takes. Synthetic oils also tend to last longer, going for longer periods of time and distance than conventional oils do before needing to be changed.

Synthetic Blend Oil Synthetic blend oils are a kind of hybrid oil manufactured from both synthetic and natural materials. In other words, it’s a blend of both conventional and synthetic oils to try to capture some of the benefits of both while reducing their drawbacks.

The results are pretty much exactly what you’d expect: they provide better protection and performance than a conventional oil, but not quite as good as a full-synthetic oil. They last a little bit longer than conventional oils, but not as long as full-synthetic. When it comes to cost, they’re a little bit more expensive than a conventional oil, but not as much as a full-synthetic.

Overall, they’re an okay middle ground for those looking to keep costs down, but want to give their car a little more help.

34

Automotive Engine Lubrication System High-Mileage Oil High-mileage oil is a somewhat unique branch of oil that’s entirely on its own. These products have a blend of unique additives included which are designed to help protect engine seals, which in turn helps prevent oil evaporation and improves overall performance. For cars that are getting a little long on the odometer, this extra protection is key as oil burn-off becomes a little bit more common of a problem, contributing to more engine wear and a decreased lifespan. If you drive a car over 75,000 miles, it’s strongly advised that you use high-mileage oil.

Lubricating System Servicing Common Problems a. Higher Oil Consumption.

The main factors affecting oil consumption are engine speed and engine wear. Engine temperature increases at high speed due to which the oil viscosity decreases. The low viscosity oil can pass at higher rate through piston rings into the combustion chamber where it is burned. High speed can cause ring shimmy or ring float. Under this condition the oil control rings cannot function effectively. Crankcase ventilation at higher speeds causes more air to pass through the crankcase due to which more oil is lost in the form of mist. At high speeds more oil is fed through the crankcase to the connecting rod journals. Oil consumption increases with engine parts wear. Worn bearings throw more oil on the cylinder walls. Oil control rings do not perform perfectly on the worn cylinder wall and hence more oil is admitted into the combustion chamber where it burns and fouls spark plugs, valves, rings, and pistons. Worn intake-valve and exhaustvalve guides increase oil consumption. Therefore worn parts are to be repaired or replaced accordingly to bring down the oil consump•tion to the recommended level.

35

Automotive Engine Lubrication System b. Erratic Oil Pressure Indication If sometime light glows, or the gauge shows low pressure reading, then either there is less oil in the crankcase or the oil pickup is inconsistent. If light stays on all the time, or the pressure gauge constantly reads low, then the causes may be: i.

A weak relief-valve spring, ii.

A defective sender unit or oil pressure indicator, iii.

A worn oil pump, iv.

Obstructed or cracked or broken oil lines, v.

Insufficient or excessively thin oil, and/or vi.

Worn bearings, which pass more oil than the pump, can deliver. c. Excessive Oil Pressure Indication Excessive oil pressure indication may be due to: i.

A clogged oil line, ii.

Excessively viscous oil, (Hi) stuck relief valve, and/or iii.

Excessively strong valve spring.

Lubrication System Maintenance and Trouble-Shooting To keep your machines operating at their peak it is important to keep your lubrication system in tip-top shape too. Having a routine lubrication system maintenance program will help insure service problems are kept to a minimum. To help prevent clogs in the system, proper lubricant storage and correct filling procedures should be followed. Also, proper lubrication system maintenance requires regular cleaning and replacement of filters, screens and strainers. Visual inspections should be performed periodically to detect leaks that can be repaired before they become serious problems. With routine lubrication system maintenance many common problems can be avoided. Here is a check list to help you implement a lubrication system maintenance program that will keep your machines operating smoothly.

36

Automotive Engine Lubrication System Lubrication System Maintenance Check List • • • • • • • • •

•

Clean lubrication reservoir periodically but do NOT use cotton or fiber rags.

Inspect suction filter and screens: filter should be replaced and screens should be cleaned annually.

Remove and clean strainer regularly.

Change line filter (pressure filter) annually.

Inspect flexible hoses for cracks, punctures and wear.

Check tubing/pipe for flattening or breaks.

Check for leaking or “weeping” at all connections; check tightness of connections but avoid over-tightening.

Monitor system for unusual drops or increases in operating pressure.

Only recommended lubricants should be used. Lubricants with additives that could clog filters or flow apportioning devices should be avoided.

To avoid introducing air and contaminants into the system, follow recommended lubricant storage and filling procedures. Lubricant should be stored in a sealed container at all times. A permanently sealed container with a sump pump to pump out lubricant as needed is recommended. Contaminated lubricant will certainly cause problems.

Lubrication System Trouble-Shooting: Installation and Commissioning • •

Low/No Pressure – Pump not primed; improper loading of lubricant into reservoir; air pocket in line at gauge location.

High Pressure – Improper grade of lubricant; improperly installed hose; contaminants introduced during assembly.

37

Automotive Engine Lubrication System Lubrication System Trouble-Shooting: System Malfunctions •

• • •

High Pressure – Clogged line filter. Take pressure gauge reading upstream and downstream of filter. Visually inspect filter. Replace filter. Other causes of high pressure could be smashed tube/kinked hose or incorrect flow apportioning units.

Low Pressure – Pump failure; leak in system/ lubricant has “thinned out.”

Decrease in amount of lubricant dispensed – Change in operating speed of machine (power take off actuates lubricator); worn pump.

Increase in amount of lubricant dispensed – Incorrect flow apportioning unit.

38

Automotive Ignition systems

Chapter 4

Automotive Ignition systems

39

Automotive Ignition systems Introduction to Automotive Ignition systems

Automotive ignitions systems have seen many transitions over the years. Historically, the designs have matured from a magneto to today’s coilover-spark plug designs. The progression follows the emergence of solid state electronics as well as the phasing out of mechanical components in favor of electrical components.

The goal of the ignition system is to fire a spark plug. In order to do so, a large voltage must be pulsed to the spark plug to make a spark fire across the spark gap. The basic spark plug remains the same. However, the firing circuit has gone through many changes.

40

Automotive Ignition systems The early magnetos are still in use today in many small engines such as those commonly found in lawn mowers. This style of ignition circuit generated energy by having magnets move past an armature. A magnet in motion creates an electrical current in the armature passing the current through a primary coil. The basic operation of an inductor is not to rapidly change current. When the points open [or the field ceases providing current in some designs], the inductor voltage reverses as the inductor keeps the current flowing. The voltage on a secondary coil is amplified by the turn’s ratio between the primary and secondary. This voltage is then ported through the spark plug wire causing the plug to fire. The locations of the magnets are such that the cylinder fire slightly before the piston reaches top dead center on the compression stroke.

As engines gained more cylinders, the magneto became impractical to locate on the flywheel, so an electromechanical device called a distributor was invented. A distributor uses gearing from the engine to fire a signal from a central connector outward to a perimeter connector in the distributor cap. A spinning rotor carries the electrical pulse from the coil input in the center connector to the spark plug connection on the outer connector. On a V8 engine, the wires coming from a distributor resemble the eight tentacles of an octopus.

41

Automotive Ignition systems

Inside the distributor is a set of points. The points are closed and build up current on the coil during a portion of the engine rotation cycle. In a V8 engine, an octagon ring on the center distributor shaft mechanically separates the points opening them and interrupting the current in the coil causing the aforementioned flyback of the inductor and generation of the spark.

Points had difficulty handling 12 volt circuits so a ballast resistor was used to prolong the life of the points. Often times, the ballast resistor was bypassed during starting for maximum firing power.

42

Automotive Ignition systems

As solid state electronics became more robust, high voltage transistors replaced the mechanical points. At first bipolar junction transistors [BJTs] were used. Later on, insulated gate bipolar junction transistors [IGBTs] were used as they require less drive current.

43

Automotive Ignition systems Solid state electronics solved many problems for ignition systems.

Unlike mechanical systems, there were no moving parts to wear out.

Triggering could be accomplished by magnetic sensing of a location on the distributor shaft. The assembly could be located within the distributor or moved to a control box or “brain box” for creating pulses. Solid state ignitions were more immune to shorting from moisture. A famous car commercial during the 1970’s showed an engine starting even though fire hoses were pouring water under the hood directly on the distributor.

Ignition modules often failed. Furthermore, routing the high spark energy through long wires resulted in losses due to resistance. As a result, coil packs were created. The first coil packs were located near the spark plugs and fired two plugs. Now the spark was more direct and could be on longer as the coil powered on two cylinders in the same time period the distributor fired eight cylinders. With the loss of the distributor, the timing system no longer was linked to the engine via gearing. Designers went back to sensing the camshaft or directly on the flywheel like the magneto.

However, sensing required much less energy than the ignition power of a magneto. The sensed signal is sent to the ignition control module for processing and creating the spark trigger pulses that are in turn sent to the coils.

44

Automotive Ignition systems Today’s engines have the coil mounted directly on the spark plug.

This offers the shortest path for the energy to traverse. Also, the high power signals of spark plugs generate a lot of noise and EMI. By routing low level signals directly to the coils, interference is greatly reduced.

Ignition System Timing The ignition system on your car has to work in perfect concert with the rest of the engine. •The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.

When the fuel/air mixture in the cylinder burns, the temperature rises and the fuel is converted to exhaust gas. This transformation causes the pressure in the cylinder to increase dramatically and forces the piston down.

In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke. Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success.

45

Automotive Ignition systems There is a small delay from the time of the spark to the time when the fuel/air mixture is all burning and the pressure in the cylinder reaches its maximum. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.

To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke, so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful work. The timing of the spark is important, and the timing can either be advanced or retarded depending on conditions.

The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance: The faster the engine speed, the more advance is required.

Other goals, like minimizing emissions, take priority when maximum power is not required. For instance, by retarding the spark timing (moving the spark closer to the top of the compression stroke), maximum cylinder pressures and temperatures can be reduced. Lowering temperatures helps reduce the formation of nitrogen oxides (NOx), which are a regulated pollutant. Retarding the timing may also eliminate knocking; some cars that have knock sensors will do this automatically.

Spark Plug The spark plug is quite simple in theory: It forces electricity to arc across a gap, just like a bolt of lightning. The electricity must be at a very high voltage in order to travel across the gap and create a good spark. Voltage at the spark plug can be anywhere from 40,000 to 100,000 volts.

The spark plug must have an insulated passageway for this high voltage to travel down to the electrode, where it can jump the gap and, from there, be conducted into the engine block and grounded. The plug also has to withstand the extreme heat and pressure inside the cylinder, and must be designed so that deposits from fuel additives do not build up on the plug.

46

Automotive Ignition systems

Spark plugs use a ceramic insert to isolate the high voltage at the electrode, ensuring that the spark happens at the tip of the electrode and not anywhere else on the plug; this insert does double-duty by helping to burn off deposits. Ceramic is a fairly poor heat conductor, so the material gets quite hot during operation. This heat helps to burn off deposits from the electrode.

Some cars require a hot plug. This type of plug is designed with a ceramic insert that has a smaller contact area with the metal part of the plug.

This reduces the heat transfer from the ceramic, making it run hotter and thus burn away more deposits. Cold plugs are designed with more contact area, so they run cooler.

The carmaker will select the right temperature plug for each car.

Some cars with high-performance engines naturally generate more heat, so they need colder plugs. If the spark plug gets too hot, it could ignite the fuel before the spark fires; so it is important to stick with the right type of plug for your car.

47

Automotive Ignition systems Ignition System Coil

The coil is a simple device -- essentially a high-voltage transformer made up of two coils of wire. One coil of wire is called the primary coil.

Wrapped around it is the secondary coil. The secondary coil normally has hundreds of times more turns of wire than the primary coil.

Current flows from the battery through the primary winding of the coil.

The primary coil's current can be suddenly disrupted by the breaker points, or by a solid-state device in an electronic ignition.

If you think the coil looks like an electromagnet, you're right -- but it is also an inductor. The key to the coil's operation is what happens when the circuit is suddenly broken by the points. The magnetic field of the primary coil collapses rapidly. The secondary coil is engulfed by a powerful and changing magnetic field. This field induces a current in the coils -- a very high-voltage current (up to 100,000 volts) because of the number of coils in the secondary winding. The secondary coil feeds this voltage to the distributor via a very well insulated, high-voltage wire.

48

Automotive Ignition systems Ignition System Distributor The distributor handles several jobs. Its first job is to distribute the high voltage from the coil to the correct cylinder. This is done by the cap and rotor. The coil is connected to the rotor, which spins inside the cap. The rotor spins past a series of contacts, one contact per cylinder. As the tip of the rotor passes each contact, a high-voltage pulse comes from the coil. The pulse arcs across the small gap between the rotor and the contact (they don't actually touch) and then continues down the spark-plug wire to the spark plug on the appropriate cylinder. When you do a tune-up, one of the things you replace on your engine is the cap and rotor -- these eventually wear out because of the arcing. Also, the spark-plug wires eventually wear out and lose some of their electrical insulation. This can be the cause of some very mysterious engine problems.

Older distributors with breaker points have another section in the bottom half of the distributor -- this section does the job of breaking the current to the coil. The ground side of the coil is connected to the breaker points.

49

Automotive Ignition systems A cam in the center of the distributor pushes a lever connected to one of the points. Whenever the cam pushes the lever, it opens the points. This causes the coil to suddenly lose its ground, generating a high-voltage pulse.

The points also control the timing of the spark. They may have a vacuum advance or a centrifugal advance. These mechanisms advance the timing in proportion to engine load or engine speed.

Spark timing is so critical to an engine's performance that most cars don't use points. Instead, they use a sensor that tells the engine control unit (ECU) the exact position of the pistons. The engine computer then controls a transistor that opens and closes the current to the coil.

Distributorless Ignition In recent years, you may have heard of cars that need their first tuneup at 100,000 miles. One of the technologies that enables this long maintenance interval is the distributorless ignition.

The coil in this type of system works the same way as the larger, centrally-located coils. The engine control unit controls the transistors that break the ground side of the circuit, which generates the spark. This gives the ECU total control over spark timing.

Systems like these have some substantial advantages. First, there is no distributor, which is an item that eventually wears out. Also, there are no high-voltage spark-plug wires, which also wear out. And finally, they allow for more precise control of the spark timing, which can improve efficiency, emissions and increase the overall power of a car.

50

Automotive Ignition systems Maintenance of Ignition Systems The complete or partial failure of an ignition system, was the most common cause of vehicle breakdowns in past. This could have been prevented if the recommended maintenance schedule had been carried out at the appropriate time. With the use of modern breakerless systems, many maintenance activities have been reduced, like breakdown due to faulty adjustment. Neverthe•less more complicated and sophisticated systems, incorporating extra devices also increase the risk of breakdown unless a high level of quality control of the components is assured. Since maintenance tests of breakerless systems require special techniques, the conventional Kettering system is considered first.

Maintenance of a Conventional Ignition system Many manufacturers recommend that the ignition system should be checked after every 10,000 km use and the following activities are recommended during the checking, (a) Contact breaker is replaced and adjusted. (6) Spark plugs are cleaned and tested, (c) Wiring is checked for condition and security.id) Dirt and moisture is removed from the coil and any other surface, exposed to HT charges.(e) Lubrication of the cam face and also the moving parts of the automatic advance system is carried out.

Contact Breaker.

Burning of the contact surfaces takes place due to constant use over a period of time, which increases the electrical resistance. In addition, pitting and piling of the contacts changes the gap, which alters both the dwell angle and the ignition timing. Lack of servicing the contacts causes poor engine performance, high fuel consumption and difficult starting. Also low secon•dary voltage, along with incorrect timing of the spark, increases the exhaust emission. To check the condition of the contacts, the voltage drop across the contacts is measured with the contacts fully closed. To conduct this test the wiring from the coil to the contact breaker is necessary. The voltmeter is connected to earth and to the LT coil terminal (normally marked ‘-’), which is connected by a lead to the contact breaker. The allowable voltage drop varies with the make of distributor. The typical maximum limiting values are :

51

Automotive Ignition systems Nowadays it is uncommon to clean or reground the contact points; rather a new contact set is fitted at the appropriate time. However, it must be ensured that the insulated lead from the coil makes proper contact with the alttjdailit to the movable contact, but not with the casing. The correct contact gap is set by using•*’HiMer gauge or dwell meter.

Feeler Gauge Method In this method, the cam is rotated until the contacts are full open to check the gap with a clean feeler gauge. A typical gap is 0.35—0.412 mm.

This gap is set by slightly loosening the contact set clamp screw and moving the contact plate until the correct setting is obtained. After tightening the contact adjusting screw and checking the gap once again, a smear of high melting-point grease is applied to the cam face before refitting the rotor arm and distributor cap. The correct contact gap is essential.

Dwell Meter Method This method accounts for the wear on the distributor bushes and cam eccentricity. Due to wear the cam takes up a different position when it is in motion. This cannot be clearly observed in the static condition during adjustment with the feeler gauge. Dwell is expressed either as an angle or as a percentage, which indicates the time that the contacts are closed.

52

Automotive Ignition systems A dwell meter is similar to a voltmeter, and when connected between the contact-breaker lead and earth, it shows the average voltage. As the voltage fluctuates when the contacts quickly open and close, the instrument needle is made to indicate a steady reading, which depends on the ratio between the open and closed periods, with the engine in slow-running condition dwell measurement is taken. If incorrect reading is shown the dwell meter can be used while the engine is being cranked and the contacts are being adjusted.

Spindle wear and other drive defects can also be identified by observing the change in dwell angle as the engine speed is increased from 1000 to 3000 rpm. Normally the dwell variation should be less than 3 degrees.

Spark Plugs Once the plug is used for a long period, erosion increases the plug gap, and carbon, oil or petrol additive deposits on the internal surfaces decrease the plug’s resistance to misfire. Any shunt path to earth decreases the energy available for the spark. Alternation of the spark gap changes the voltage supplied by the coil for a given compression pressure. When gap is too small, low-voltage spark may be insufficient to fully ignite the air-fuel mixture. This effect is felt when cold-starting, slow-running and when the engine is cruising with weakened moisture. If gap is too large, high-voltage spark may demand more voltage than that produced by the coil.

Consequently high-speed and cold-starting performances are poor, and erosion of the distributor and spark plug electrodes is severe. For removing the plugs first the HT leads are removed by withdrawing the connectors. Then plug is removed by using a suitable plug socket. Care must be taken to avoid 53

Automotive Ignition systems cranking of the ceramic insulator. Inspection of the plug before cleaning often provides information to the state of tune of the engine. Figure below indicates the plug appearance for the following conditions.

Normal The core nose is lightly coated with a gray brown deposit and the electrode is not unduly eroded. Normal erosion wear increases the gap by about 0.016 mm per 1000 km.

Carbon Fouling The core nose gives a matt black sooty appearance due to which the HT charge may short to earth without jumping the spark gap. This deposit starts from an over-rich mixture. Also it occurs when the vehicle is engaged on short journeys as well as when the engine operates below its normal running temperature.

Split Core Nose Initially a hair line crack appears which soon causes a part of the insulator to break away. This failure is often caused by detonation.

54

Automotive Ignition systems Overheating This condition is promoted by any factor that causes overheating of the combustion chamber. Plug temperature increases with ignition advance, so plug failure results due to over-advance.Cleaning of the plug is carried out normally by sand-blasting, followed by air-blasting. A contact file is used to remove deposits on the electrodes at the spark gap and then the gap is reset to the recommended value by bending the earth electrode. A wire-type feeler gauge is more accurate for setting of the gap because a flat feeler blade does not allow for the contour of the earth electrode when it is eroded. Care must be taken to clean all sand from the threads and deposits from the external surface of the insulator. Manual cleaning by a wire brush is an inferiormethod than a sand blast. Using a bruhs may cause damage to the insulate but sufficient pressure is to be applied to remove all deposits.Testing of the plug is carried out in a chamber having the arrangement for the variation of the air pressure while the plug is connected to the source of an HT current at a predetermined maximum voltage. This voltage is sufficient for a new plug to provide good regular sparking up to a given pressure. The plug is screwed into the chamber and left finger tight to allow slight escape of air to improve ionization. The switch is then operated and the air pressure is gradually increased. Sparking is noticed through a window in the chamber and the pressure registered on the gauge is recorded. A good plug should give regular sparking at the electrodes up to the set pressure.When refitting a plug to the engine the correct torque should be applied especially with plugs having a taper seat. In absence of a torque wrench for plug with gasket seat, first tighten finger-tight and then rotate the plug 1/4 turn with a plug spanner.

Similarly for taper seat, tighten finger-tight and then use a plug spanner to rotate the plug 1/16 turn.

Ignition Timing Static Timing. The need for correct timing is inevitable since incorrect spark timing can cause many problems. When a distributor unit is refitted to an engine the following method may be used for timing (assuming detailed manufacturer’s instructions are not available).(i) Set No. 1 piston to TDC compression.(ii) Connect the drive to have the contacts just opening when the rotor arm is pointing to the distributor segment feeding No. 1 cylinder. The contact position can be determined by using a lamp as shown in Fig. 16.74.(Hi) Connect HT leads to the distributor in the order that the cylinders fire. (iv) Start engine and make final adjustments with timing light. This method is also called static timing an^ manufacturers often provide the 55

Automotive Ignition systems crankshaft position at which the spark should occur when the timing is set in this way. A static timing of 4 degrees means “hat when the crankshaft is set to 4 degrees before TDC, the test lamp should indicate that the contact points have just opened.

Stroboscopic Timing Strobe-type timing light provides a sudden flash of light precisely when the spark occurs. The high-intensity, short-duration flash is triggered by the HT impulse from No. 1 plug lead. When the lamp is held close to the member that carries the timing marks, the instantaneous flash illuminates the marks and freezes the motion to enable the spark timing to be ascertained figure below. It may be noted that the timing light illumination provides a false impression of the moving parts as stationary and hence care must be taken.

To set the timing the recommended advance at a certain speed should be known. Set the engine at that speed, and disconnect the vacuum advance pipe. The mark on the crankshaft pulley (or flywheel) should then show the recommended advance if the timing is correct. If the timing is incorrect, the distributor is slackened and the distributor body rotated until the correct setting is obtained. Slight rotation of the distributor body in the same

56

Automotive Ignition systems direction as the movement of the rotor arm retards the ignition. When the correct timing is obtained, the distributor is clamped securely, the timing rechecked and finally the vacuum pipe reconnected. The automatic advance mechanism can be tested with this method. After setting the normal timing, the engine speed is raised through set increments. At each speed the timinglight control is varied to make the original timing marks coincide, the angle of advance is observed on the meter. Special timing light are available, which uses a control to provide the flash at a set time after the spark is produced.

The extent of this delay is indicated to the operator by an analogue-type meter or digital read out.

Ignition Circuit Testing An engine incorporated with conventional ignition system, if fails to start, the following checks can be made :(a) Visual Check. Ensure that the battery is in good condition and check all cable and connector for security. (b) Coil Output. Remove king lead from distributor cap and fit extension (e.g. center electrode from old spark plug). Hold lead with insulated pliers so that the end of the extension is about 6 mm from a good earth location such as the engine block. Switch-on ignition and crank the engine. If a good spark is observed, but the fault is present in the secondary circuit beyond the coil HT lead, then proceed to Test (g). (c) Contact Breaker. If no spark, or a poor spark from the coil HT lead, examine the contact breaker for the condition of the surfaces and the gap setting.

The surface condition is best checked with a voltmeter. Alternatively a 12 V, 3 W test lamp can also be used in parallel with the contacts and the lamp should go out when the contact is closed.(d) Primary Circuit. A high resistance in the primary circuit can be located by measuring the p.d. at various parts of the circuit (Fig. 16.77). The contact breaker is kept closed for the flow of current in the circuit. If the contacts are not set in this position the voltage at three points 1-4 in Fig. 16.77 corresponds to the battery emf unless 57

Automotive Ignition systems the circuit is completely broken between points 1 and 4.(c) Capacitor. In absence of the special test equipment, the capacitor condition is found out by substituting a test capacitor. Alternatively, contact breaker can be observed with the engine being cranked and the distributor cap removed so as to assess the degree of arcing. If arcing is severe, the capacitor should be changed.(/) Ignition Coil. A visual inspection of the insu•lated surfaces should be made for any tracking.

Breakdowns of insulation, internal and external, often visible when the coil is loaded. The resistance of each winding can be known by an ohmmeter.

Typical resistances for a conventional coil are 1.2 – 1.4 Q for primary winding and 5-9 kQ for secondary winding.(g) HT Leads. The coil HT lead is reconnected and the HT lead is removed from the spark plug. An extension is added to the end of the lead and the extension is held about 6 mm from a good earth while the engine is cranked. If a sound spark is obtained, then the spark plugs may be faulty. When no spark is observed, the HT circuit between the coil and the spark should be checked.(h) Rotor Arm. The coil king leads are held about 3 mm from the rotor arm blade and the engine is rotated or the contacts are opened manually with an insulated screwdriver. If regular sparking occurs, then the insulation of the rotor arm is faulty.(i) Distributor Cap. The cap is examined visually for any cracks and tracking.

The sign of crack is a thin carbon line due to which the HT current takes an easier path than that required. Tracking can cause misfiring, but normally the engine starts with the cap in this condition. Complete breakdown of the king lead does not permit the engine to start whereas a similar failure of a plug causes regular misfiring under load or poor engine performance in general.

An ohmmeter should be used to check the resistance of the HT lead, which, in the case of a suppression lead, has a value of 13,000 – 26,000 Q/m.

Diagnostic Equipment – Engine Analyzers Modern electronic equipment helps for quick and accurate diagnosis of engine faults. This equipment is capable to pin point common and unknown faults in the engine and associated systems, and also to provide the driver with information on the condition of the engine. A number of analyzers for this purpose are available, which can be categorized broadly into two main groups:(i) Oscilloscopes for the display of test patterns.(ii) Computers for the test of the engine systems and display the results on a visual display unit (VDU).

58

Automotive Ignition systems

Oscilloscope A Crypton Diagnostic equipment comprising of a cathode-ray oscilloscope (CRO) along with analogue and digital meters is used for testing and adjusting the following:• Ignition circuits and components.• Spark timing.• Relative output from cylinders (cylinder balance).• CO emission from exhaust.• Electrical equipment involving the use of basic test meters.

59

Automotive Ignition systems CRO Display The pattern formed on the screen is obtained by a spot of light, which sweeps horizontally across the screen in step with the engine speed. Each time a given spark plug fires, the pot is made to return to the left-hand side of the screen. Vertical deflection of the line corresponds with the voltage sensed at a given point in the ignition system. As the phosphorous coating on the inside of the cathode-ray tube retains the image for a short time, the human eye observes a continous line formed on the screen instead of a moving spot of light. Switches are available to select various meter scales and voltage pick-up points in the circuit, which help the operator to analyse the complete process of ignition.In this form the CRO represents a high-speed voltmeter and displays the actual voltage at all stages of the operating cycle, whereas the sluggish movement of an analogue meter needle provides a mean value of the voltage. Before using a CRO for examining ignition patterns, the primary circuit is normally tested with a voltmeter to eliminate the basic circuit faults, which affects the patterns.

Primary Pattern The trace in Figure below represents an ignition system in good order and indicates the voltage variation in the primary circuit for the production of one spark.

At point (1) the contacts open and voltage increases due to selfinduction. The oscillations at (2) are due to the charge-discharge action of the capacitor. A good capacitor should provide four or five oscillations at this stage. This rise in the voltage at point (3) indicates the end of the sparking period, after which the energy remaining in the primary winding is dissipated as shown in phase (4). Four or five oscillations take place as the energy fades away. The contacts close at point (5) and the trace shows a clean line joining the two horizontal lines. Normally preliminary tests pinpoint a dirty contact condition, but the CRO represents this condition as a hash at the point where the contacts closed.

60

Automotive Ignition systems

Part of primary pattern, diagram shows two common faults. No large separation in the patterns should be visible when the patterns for each cylinder are superimposed on the original trace. However, if the cam or spindle is worn, the dwell angles vary. This appears as presented in Fig. 16.80B. This is called dwell overlap. For greater accuracy of dwell measurement; modern analyzers incorporate a digital meter, which directly indicates the dwell angle. Also this equipment measure the individual dwell given by each cam lobe. After having the values of each dwell angle, the smallest angle can be subtracted from the largest angle to find the dwell overlap.

Secondary Patterns A normal pattern shown in Figure represents the voltage variation in the secondary circuit. When the contact is opened at (1) the voltage rises until a spark is produced. Point (2) represents the voltage during the sparking process. Once sparking stops, the voltage rises (point 3) followed by the dissipation of energy in the secondary widning, which is seen as four or five surges before dying away. At point (5) the closure of the contacts and the start of the current flow in the primary winding mutually induce a small emf into the secondary winding. If the pattern at point (5) is inverted, it indicates 61

Automotive Ignition systems incorrect, coil polarity. To correct this LT coil connections are interchanged.

Defect in coil windings and poor HT leads provide an unstable pattern and broken trace respectively. Most modern analyzers measure the length of the spark line in milliseconds (Fig. 16.81C). Conventional systems show a spark line of length 0.75- 1.5 ms. Breakerless systems of the inductive discharge type give a 2 ms spark line, whereas capacity discharge systems have a very short line of length 0.15 ms or less.

Parade Order Secondary output is represented by each secondary trace, side by side, and the vertical trace lines are broadened to ease the measurement.

Normally the pattern is displayed in the order of the spark plugs firing. This trace provides the voltage initially needed to fire each spark plug. A vertical scale, which can be set at a maximum of either 20 kV or 40 kV measures the voltage applied to each plug and under normal condition the height of each of the prominent verticals is similar. At 1000 rpm the voltage should be 8 – 14 kV, but if the variation exceeds 3 kV, the cause should be determined.

Shorting a plug to earth provides the voltage required to overcome the HT lead resistance and the rotor gap. Normally this voltage should be less than 5 kV. The performance of the spark plugs under load can be assessed by snapping the throttle open and the voltage increases to about 16 kV during this assessment. To measure the maximum voltage output of the coil, the HT lead is removed from the spark plug and is held clear of the engine using an insulated plier. Since most of the coils fitted to vehicles develop a maximum output of at least 28 kV when supplied with a 14 V input, the 40 kV scale is

62

Automotive Ignition systems selected during measurement. This test is not recommended on a breakerless system unless a special lead is used to limit the voltage.

Engine Diagnostic Computer To meet present demands for accurate testing and efficient fault diagnosis, many engine analyzers use a computer. Information on the condition of the engine is displayed on a VDU, which can also be printed.

Detachable memory pods {e.g. EPROM) are installed to store data, which include test procedure, printer commands for presenting information on the customer’s report form, and the specifications for the engines to be tested.

The computer compares actual information with the specified values of a particular system pin-pointing any faults. The computer also guides the operator through the test program to carry out a health-check of the basic engine systems. Identification of the cause of a fault in a particular system can be found out using the computer. Ignition patterns of the form associated with conventional CROs are not displayed, instead values such as maximum ignition voltages, are shown as bar chart below.

Maintenance of a Breakerless Ignition System Since several different systems are in use, the manufacturer’s service manual should be referred for the specific information. Appropriate precaution must be taken while checking breakerless systems to avoid an electric shock.

In some systems like CD systems a high-voltage charge is still stored even after the ignition is switched-off. The specific tests applied to a breakerless system depend on the type of system. However the basic principles are presented in the following descriptions.

63

Automotive Ignition systems

General Maintenance Since checks on dwell angle and spark timing are not required, very little routine main•tenance is necessary with this system. Also spark plug service intervals are extended. During initial timing of the distributor by the manufacturer, a mark is stamped on the flange to indicate its correct position.

If a mechanical advance system is used, timely lubrication of the system should be provided. Timing light may be used to check the operation of the mechanism during servicing.

Ignition Circuit Testing If an engine does not start the following two basic checks are carried out before conducting detailed tests on the control module and pulse generator.(a) Visual Check. Ensure that the battery is in good condition, and check all cables and connectors for security. (b) Coil Output. Remove king lead from distributor cap, fit extension to the end of the lead and hold with insulated pliers to keep the end of the extension about 6 mm from the engine block. Switch-on ignition and crank the engine. A good spark indicates that the fault is beyond the coil HT lead and then the maintenance procedure as for a conventional system is to be followed. It may be noted that damage occurs to the control module if the engine is cranked and the king lead is held at a gap, which is too large for a spark to jump to earth.

Constant-energy Ignition System After performing the basic checks the following addi•tional checks are done. (a) Pulse Generator Gap. The gap depends on the type of engine but a typical gap is 0.2-0.4 mm. A plastics feeler gauge blade is used during checking of the gap between the reluctor tooth and pick-up limb.

64

Automotive Ignition systems Static Check. A voltmeter check at the two points as shown in Fig. 16.85 indicates if the voltage drop across the module is too large or if the module has a poor earth.Cranking Test. The voltmeter is connected between the positive battery terminal and the negative terminal of the coil. If the voltage does not increase when the engine is cranked, then Test (C) should be carried out.

The pick-up leads from the pulse generator are disconnected at the harness connector and an ohmmeter is used to measure the resistance of the pick-up coil. The resistance value depends on the application (a typical value is 2 – 5 kQ). An integral control module is removed from the distributor to carry out this test. If the reading is incorrect then the pick-up may be faulty, but if the resistance value is between the limits recommended, then the control module should be changed.(d) Other Components. The remaining parts of the system are checked in a manner similar to that used for a conventional ignition system. A typical fault is shown in the diagnosis chart.

65

Automotive Ignition systems Hall-effect Generator Control module and wiring should be checked with a voltmeter similar to the method described earlier. Meter readings at the various points are compared with the specified values, which indicate if the module and generator are serviceable.

Digital System The multi-plug connector is removed from the ECU. To measure the voltage at the appropriate terminals the voltmeter tests are carried at the cable end of the connector. Voltage checks are also made to the pulse generator and the ignition coil similar to other breakerless systems. The flow of current from an ohmmeter to the Electronic Control Module (ECU) can damage the module, and hence should be avoided. Spark advance given by the ECU is ckecked in the normal manner with a strobe light.

66

Conclusion to Automotive Engine Maintenance

Chapter 5

Conclusion To Automotive Engine Maintenance

67

Conclusion to Automotive Engine Maintenance Conclusion to Automotive Engine Maintenance

An engine is like the heart of a car. It needs to run smooth in order to keep your car moving. We can’t emphasize more on how important it is to keep the engine fit and functioning efficiently. In this conclusion chapter, several tips are explained to practice proper automotive engine maintenance.

68

Conclusion to Automotive Engine Maintenance 10 Engine Maintenance Tips – Must For A Good Car Care Here are 10 engine maintenance tips that’ll help your engine run forever:

#1. Change engine oil at regular intervals New engine oil being put in the vehicle

This is the least you can do. The engine oil keeps all moving parts well lubricated so that wear and tear is minimal. Also, it traps all the dust, dirt, and sediments, keeping them out of places they shouldn’t be. Check oil levels every month and top up if the level is low. Oil grade and change intervals are subject to the manufacturer’s recommendations. The oil filter is equally important as it filters all the junk from the oil and stops regulation back into the engine. This will ensure that you engine runs smooth and cool.

69

Conclusion to Automotive Engine Maintenance

#2. Keep check on the cooling system Coolant being poured in the vehicle

Even though we have come a long way in terms of efficiency of a car engine, a lot of energy is lost during combustion in the form of heat. Metals and alloys, which your car engine is made out of, are not very good friends with heat. Always ensure there is ample coolant in the tank as it is very important for heat dissipation. A 1:1 ratio of coolant and distilled water is ideal. Also, it’s a good thing to look at the engine temp gauge on a hot sunny day and shut your car down in case it’s close to overheating.

70

Conclusion to Automotive Engine Maintenance #3. Let it breathe A used air filter taken out of the vehicle

Short of breath? Feeling tired? Your car’s engine needs oxygen as much as you do. A constricted air flow can cause the fuel to not burn completely, in turn increasing emissions and reducing mileage. Check the air filter and get it cleaned/ changed whenever you feel there is too much dirt and debris stuck to it. Your engine needs to breathe properly to function well and keep going.

71

Conclusion to Automotive Engine Maintenance #4. Look for leaks Oil leaking out of a car

When you pull out of the driveway, stop and look at the parking spot for any fluids on the ground. If the fuel is leaking, you should visit the nearest mechanic and get it checked. You can also check under the hood to see or smell something leaking. Engine oil and antifreeze are fluids you should look out for when checking for leaks.

72

Conclusion to Automotive Engine Maintenance #5. Don’t keep going on reserve fuel Fuel meter showing reserve fuel level

Petrol contains sediments which settle at the bottom of your tank.

Years of running and there will be definitely a layer of crap which shouldn’t reach the engine. Running on low fuel pulls this junk into the fuel pump which could cause a lot of wear. Instead of just praying it doesn’t reach the engine, top up your tank and save yourself repair/ replacement cost of the fuel filter and pump.

73

Conclusion to Automotive Engine Maintenance

#6. Check your belts A used timing belt in the engine

Rubber belts are essential links to keep everything in tune when an engine runs. If you hear a squeal coming from under the hood, it is time to replace them. You should check your belts for cracks and signs of wear even though they last a long time. But if they break while the engine is running, it can cause serious damage to engine components, “expensive engine components”!

74

Conclusion to Automotive Engine Maintenance #7. Don’t ignore the check engine light Car meter showing engine warning light

This light is your car’s subtle scream for help. Never ignore this and immediately get the car inspected by your local mechanic. We did an article earlier on what it could possibly mean – Check Engine Light Popping Up? Here Is What It Means. It’s basically a self-diagnosis which is put in place to protect your engine. It’s not necessarily serious every time but you’ll never know unless you get it checked.

75

Conclusion to Automotive Engine Maintenance

#8. Replace your fuel filter A used fuel filter taken out of the car

It’s similar to the oil filter but filters out junk from the fuel, prohibiting entry into the combustion chamber. A new filter means free flow of clean fuel to the fuel pump and engine. This ensures there is less build-up inside the engine and its thirst for fuel is quenched.

76

Conclusion to Automotive Engine Maintenance

#9. Replace spark plugs and wires A used spark plug taken out the car

The spark plug acts as a fire starter. It ignites the air-fuel mixture in the cylinders and requires little maintenance owing to its long life span.

Regular maintenance will ensure that the engine retains its spark. At times, they don’t even need replacement. Some cleaning can be of great help as a lot of soot gets accumulated around the electrode over time.

77

Conclusion to Automotive Engine Maintenance

#10. Your engine doesn’t like revving just to come to a complete halt Engine revving at high speeds

Engines are engineered to run at constant speed. This is when they perform the best. Too much variation in the revs tires it out and this takes a toll. City driving, where you constantly move and come to a stop is really hard on the engine. Try not to rev too hard. Instead, be sure footed and don’t overaccelerate when you know you have to stop again. Try sticking to the highway whenever possible. This will give you better mileage (now you know why driving on the highway results in less fuel consumption) and keep that engine running for longer.

78

Department of Mechanical Engineering POLISAS