7A ENGINE SERVICE–540 LOADER (KOHLER)

7A–1 TROUBLESHOOTING

The following troubleshooting chart is provided as an assistance in locating and correcting problems which are most common. Many of the recommended procedures must be done by authorized Bobcat Service Personnel only.

Problem Cause

7A–1 TROUBLESHOOTING (Cont’d)

1.Battery capacity low.

2.Bad electrical connection.

3.Faulty starter motor.

4.Incorrect grade of oil.

5.Low cranking speed.

6.Fuel tank empty.

7.Ignition system has damage.

8.Plugged fuel line.

9.Faulty fuel lift pump.

10.Plugged fuel filter.

11.Restriction in the air cleaner.

12.Wrong starting procedure.

Key To Correct The Cause

25.Incorrect valve tappet adjustment.

26.Sticking valves.

27.Spark plug gap not correct.

28.Worn cylinder bores.

29.Worn valves and seats.

30.Broken, worn or sticking piston rings.

31.Worn valve stems or guides.

32.Worn or damaged bearings.

33.Not enough oil in the oil pan.

34.Gauge is not correct.

35.Oil pump is worn.

36.Pressure relief valve is open.

13.Choke not completely closed.

14.Choke not completely opened.

15.Carburetor is dirty or has a defect.

16.Incorrect valve timing.

17.Poor compression.

18.Plugged fuel tank vent.

19.Dirt or water in the fuel.

20.Sticking or restricted throttle.

21.Exhaust pipe restriction.

22.Cylinder head gasket leaking.

23.Overheating.

24.Governor adjustment not correct.

37.Pressure relief is sticking closed.

38.Broken relief valve spring.

39.Faulty suction pipe.

40.Plugged oil filter.

41.Piston seizure.

42.Damaged fan.

43.Faulty engine mounting.

44.Plugged breather pipe.

45.Valve stem seals damaged.

46.Plugged oil pump pipe strainer.

47.Broken valve spring.

7A–2 CHECKS & ADJUSTMENTS

7A–2.1 Oil Pressure

When the engine is operating at normal temperature, with the correct weight oil and at idle speed, the oil pressure must be within 40–50 PSI (276–345 kPa). If the oil pressure is higher than specified, it will notcause damage, but it could indicate that it is operating with the oil weight too thick. If the oil pressure drops suddenly, this could indicate that the oil pump is faulty or the check valve is not working correctly and has debris in it.

If the oil pump is faulty, do not attempt to disassemble and repair the pump. Replace the oil pump with a new pump. There is an external oil pressure adjustment available.

Check the engine oil pressure using the following procedure:

Warning

Lift the loader and put jackstands under the loader frame so there is no danger of the loader falling and causing personal injury.

1.Stop the engine. Open the rear door.

2.Remove the oil pressure sender from the engine and install a pressure gauge (Fig. 7A–1).

3.Start the engine and run it until it is at operation temperature.

4.Check the oil pressure at full engine RPM. The pressure must be 40–50 PSI (276–345 kPa).

5.Make the adjustment of the oil pressure by loosening the jam nut under the No. 1 cylinder (next to the flywheel) and turn the adjustment bolt in or out to get the correct oil pressure (Fig. 7A–2).

7A–2.2 Valve Clearance

Make the valve adjustment with the engine stopped and cold.

Put the correct size feeler gauge between the tappet and the valve stem and turn the adjustment bolt in or out to get the correct clearance.

The correct clearance for the intake is 0.008–0.010” (0,203–0,254 mm) and the exhaust is 0.017–0.020” (0,432–0,508 mm) (cold) (Fig. 7A–3).

*Early Models Have Acorn Nut

Valve–Tappet Clearance

Use the following procedure to set the valve clearance:

1.Remove the covers from the valve chambers.

2.Turn the crankshaft until there is maximum clearance between the valve stem and tappet.

3.Check the clearance with a feeler gauge (Fig. 7A–3).

4.If the clearance is wrong, turn the bolt at the end of the tappet until the clearance is correct.

7A–2.3 Compression

1.Make sure the engine is at operating temperature.

2.Remove both spark plugs.

3.Open the throttle and choke fully.

4.Disconnect the high voltage wire from the coil.

5.Install the compression gauge in the cylinder to be checked.

6.Turn the engine several times with the starter. Check the gauge. The compression must be 100–120 PSI (689–827 kPa).

7A–2.4 Throttle and Governor Linkage

Warning

Lift the loader and put jackstands under the loader frame so there is no danger of the loader falling and causing personal injury.

Speed Control Bracket

1.Stop the engine. Disconnect the throttle linkage (Fig. 7A–4, Item 1) between the carburetor and the governor arm (Fig. 7A–4, Item 2).

2.Hold the throttle on the carburetor fully open. Put the governor arm against its stop. Adjust the length of the throttle linkage (Fig. 7A–4, Item 1) so it will fit.

3.Push the throttle control fully forward. The speed stop bolt (Fig. 7A–4, Item 3) must be against the stop. If not, make the adjustment at the stop bolts at the throttle lever (Fig. 7A–5, Item 1).

4.Start the engine and run it at idleRPM. Turn the idle adjustment (Fig. 7A–6, Item 1) to get the fastest idle RPM. Then make an adjustment to the idle fuel adjustment (Fig. 7A–6, Item 2) for correct low RPM.

5.Run the engine at full throttle. Put a load on the engine(engage the auxiliary or tilt the Bob–Tach all the way back). Turn the main fuel adjustment (Fig. 7A–6, Item 3) in or out to get a smooth engine operation.

6.Disengage the load. Check the high–idle RPM. Turn the speed RPM stop bolt to get the correct RPM.

7.Engage and release the load at full engine RPM. If the governor action for the engine RPM changes is not smooth, connect the governor spring (Fig. 7A–4, Item 4) to a lower hole on the governor arm. If the engine RPM becomes slower, move the spring to a higher hole in the governor arm.

8.If the location of the spring was changed, check the high–idle RPM again.

7A–2.6 Ignition System

Warning

1.Stop the engine. Open the rear door.

2.Remove the cover from the points at the governor.

3.Remove the old points.

4.Install the new points. Turn the engine until maximum point gap is reached.

5.Adjust the point gap to 0.020” (0,51 mm) (Fig. 7A–7).

6.Remove the cover for the timing hole (Fig. 7A–8, Item 1). Turn the flywheel until the “SP” mark is in the timing hole. Put a chalk mark on the “SP” mark.

7.Start the engine and run it at 1200 RPM.

8.If the timing mark is not correct, loosen the two (2) governor bolts and move the governor until the “SP” mark shows in the timing hole.

9.Stop the engine.

10.Check the adjustment of the idle RPM.

11.Remove the jackstands from under the loader frame.

7A–2.7 Spark Plugs

Every 100 hours of loader operation, remove the spark plugs,check the condition and set the gap. Good operating conditions are indicated if the spark plugs have a light coat of gray or tan deposit. A dead white, blistered coating could indicate overheating. A black (carbon) coating may indicate an “over–rich” fuel mixture caused by clogged air cleaner or the carburetor adjustment is not correct. Replace the spark plugs as needed.

7A–3 CARBURETOR & FUEL SHUT–OFF SOLENOID

7A–3.1 Removing the Carburetor

1.Stop the engine. Open the rear door.

2.Disconnect the air cleaner hose.

3.Disconnect the fuel line.

4.Disconnect the linkage fromthe carburetor.

5.Remove the bolts and nuts which hold the carburetor to the manifold.

NOTE:To install the carburetor, use the above procedure in reverse. Make sure to check adjustment of the linkage for the governor (See Paragraph 7A–2.4). Always use new gaskets.

7A–3.2 Disassembly and Inspection of the Carburetor (Fig. 7A–9)

1.Remove both mixture screws and springs.

2.Remove the plug from the float bowl. Remove the bowl from the carburetor body.

3.Remove the float pin, float and needle.

4.Remove the seat from the carburetor body.

5.Clean all parts. Do not remove the throttle and choke plates unless they are damaged.

6.Check the float for bends or damage.

7.Check the end of the mixture needles for damage.

7A–3.3 Assembly of the Carburetor (Fig. 7A–9).

NOTE:Use new gaskets and float valve and seat when assembling the carburetor.

1.Install the new float valve seat in the carburetor.

2.Put a new bowl gasket and baffle in position.

3.Install the needle on the float. Install the float on the carburetor body.

4.Turn the carburetor so the bottom is up. The float must be parallel to the gasket surface of the carburetor body. If not, bend the tab on the float to adjust the float level.

5.Install the bowl. Install the fuel bowl plug and tighten.

6.Install the mixture needles in the carburetor.

7A–3.4 Fuel Shut–off Solenoid

The loader is equipped with a fuel shut–off solenoid (Fig. 7A–10). The shut–off solenoid shuts the fuel off when the ignition switch is turned to the “OFF” position to prevent the engine from running on (dieseling).

NOTE:There is also an electrically operated shut–off located in the carburetor fuel inlet.

7A–4 GOVERNOR

7A–4.1 Removing the Governor

1.Stop the engine. Open the rear door.

2.Disconnect the linkage from the governor.

3.Disconnect the hose from the governor.

4.Remove the engine shrouding from the right cylinder to reach the lower governor bolt.

5.Remove the governor bolts.

6.Remove the crankcase breather.

7.Remove the governor from the engine.

NOTE:The governor must be replaced as an assembly and can not be repaired. Remove the ignition point cover, ignition points (Fig. 7A–11), push rod and linkage from the governor. Install these parts on the new governor.

7A–4.2 Installing the Governor

1.Remove the plug from the top of the governor adapter and ignition timing hole (Fig. 7A–12).

2.Turn the flywheel so the “D.C.” mark can be seen.

3.Install the governor so the bevel on the gear is in alignment with the hole in the governor adapter (Fig. 7A–12).

4.Check the adjustment of the timing and governor linkage.

7A–5 ENGINE AND HEAT SHIELD

7A–5.1 Removing the Engine

Lift the loader and put jackstands under the loader frame so there is no danger of the loader falling and causing personal injury.

1.Remove the rear door (See Paragraph 5–4.1 or 5–4.2, Page 5–9).

2.Remove the battery (See Paragraph 6–3.1, Page 6–3).

3.Remove the muffler clamps (both sides) (Fig. 7A–13).

4.Remove the muffler from the engine (Fig. 7A–14).

5.Disconnect the fuel line from the carburetor (Fig. 7A–15, Item 1).

6.Move the clamp on the choke cable away from the heat shield.

7.Disconnect the choke cable at the carburetor (Fig. 7A–16).

8.Disconnect the throttle linkage at the pivot shaft on the heat shield.

9.Remove the air cleaner hose from the carburetor (Fig. 7A–17).

10.Remove the nuts and bolts at the starter solenoid (Fig. 7A–18). Remove the starter solenoid with the engine.

11.Remove the bolts which hold the engine to the hydrostatic pumps.

12.Remove the engine mounting bolts (both sides) (Fig. 7A–19).

13.Remove the bolts and nuts (both sides) from the heat shield whichhold it to the engine mounting brackets.

14.Install the engine removal table (Fig. 7A–20, Item 1) at the rear of the loader.

15.Slide the engine out of the rear of the loader on the table (Fig. 7A–20).

7A–5.2 Installation of the Engine

1.Slide the engine into the loader until the crankshaft is in contact with the drive coupler. Make alignment of the drive coupler to the splines on the engine.

2.Install the engine mounting bolts and tighten (both sides) (Fig. 7A–19).

3.Install the bolts in the heat shield and the engine mounting brackets. Install the nuts and tighten.

4.Install the bolts which hold the engine to the hydrostatic pump and tighten to 65–70 ft.–lbs. (88–95 Nm) torque.

5.Install the bolts and nuts in the starter solenoid and tighten (Fig. 7A–18).

6.Install the air cleaner hose (Fig. 7A–17).

7.Connect the choke cable and the throttle linkage at the carburetor (Fig. 7A–16).

8.Connect the fuel line (Fig. 7A–15).

9.Install the muffler (Fig. 7A–14) and tighten the clamps (Fig. 7A–13).

10.Install the battery in the loader (See Paragraph 6–3.3, Page 6–4).

11.Install the rear door (See Paragraph 5–4.1 or 5–4.3, Page 5–10).

7A–20 Engine Removal

7A–5.3 Removing the Heat Shield

1.Remove the engine from the loader (See Paragraph 7A–5.1).

2.Remove the drive coupler from the hydrostatic pump (Fig. 7A–21).

3.Remove the clamp from the choke cable (Fig. 7A–22).

Fig. 7A–21 Drive Coupler

B–05203

B–05205

Fig. 7A–22 Choke Cable Clamp

4.Remove the four (4) bolts and nuts for the mounting bracket for the throttle jackshaft (Fig. 7A–23).

5.Remove the throttle jackshaft and the throttle mounting bracket (Fig. 7A–24).

6.Using a long pry bar, lift the hydrostatic pump up (Fig. 7A–25) and slide the heat shield out and away from the hydrostatic pump.

7A–5.4 Installing the Heat Shield

1.Lift the hydrostatic pumps with a long pry bar. Slide the heat shield up and on the hydrostatic pump (Fig. 7A–25).

2.Install the throttle mounting bracket and tighten the bolts and nuts (Fig. 7A–23).

3.Install the throttle jackshaft into the heat shield and the throttle mounting bracket.

4.Put the choke cable through the hole in the heat shield and install the choke cable clamp (Fig. 7A–22).

5.Install the drive coupler on the splines of the hydrostatic pump (Fig. 7A–21).

6.Install the engine in the loader (See Paragraph 7A–5.2).

7A–6 RECONDITIONING THE VALVES

7A–6.1 Repair of the Valves and Guides

1.Remove the engine from the loader (See Paragraph 7A–5.1).

2.Remove the shrouding, cylinder heads and the valve chamber covers.

3.Turn the crankshaft and check the amount of valve lift. If not enough, the cam is worn and needs to be replaced (See Section 8 for the Specifications).

4.Use a valve spring compressor to remove the valve springs (Fig. 7A–26).

NOTE:There are valve rotators under the exhaust valve springs. The exhaust valve springs are shorter. The close coils of the springs go toward the cylinder heads.

5.Check the clearance between the valves and guides. If over maximum, remove the guides and install new guides.

6.Use a reamer, of the correct size, in the new guides to make them fit the valve stems.

7.Check the exhaust valve seat for wear, distortion or cracks. Use a valve seat tool to remove the old seats, if needed.

NOTE:The exhaust valve seat is the only seat that can be replaced.

8.Grind the valves and seats. Use a grinding compound to check that the valves are fitted correctly and the seat is at the correct width.

Carefully inspect the valve mechanism parts. Check valves and valve seat areas or inserts for a condition of deep pitting, cracks or distortion. Check the clearance of the valve stems in the guides.

If the valve seat insert is badly worn, warped, damaged or if seating surface is badly pitted, the insert must be replaced. The inserts are a tight press fit in the cylinder head. A valve seat removal tool is used for this job. Since the insert removal causes loss of metal in the insert borearea in the head, use only service replacement inserts which have a knurled edge to provide proper fit in the cylinder head. Make sure the service inserts are properly startedand pressed into the bore to prevent the insert from seating at an angle.

7A–7 TIMING COVER, TIMING GEARS AND CAMSHAFT

7A–7.1

Timing Cover

1.Remove the air housing for the flywheel.

2.Remove the bolts which hold the timing cover in position and slide it off the crankshaft.

3.When installing the timing cover, make note of the two special bolts (Fig. 7A–27). Install and tighten these two bolts first.

7A–7.2 Timing Gears

While the timing cover is off the engine, the gears can be removed. The camshaft gear is removed by putting a block of wood between the gear teeth and removing the nut from the camshaft. Then remove the gear from the camshaft. Remove the snap ring from the end of the crankshaft and remove the crankshaft gear.

NOTE:If the oil pump gear needs replacement, you must replace the oil pump assembly.

Make sure the timing marks are in correct alignment when installing the gears (Fig. 7A–28). PI–01909

7A–28 Timing Marks Alignment

7A–7.3 Camshaft and Tappets

The gear cover must be removed to remove the camshaft gear. Remove all of the bolts which hold the gear cover plate in place. Remove the cylinder heads and valves. Turn the camshaft to push the tappets out of the way and remove the camshaft from the engine.

NOTE:If the camshaft is replaced, the tappets must also be replaced. To replace the tappets, you must remove the oil pan.

7A–8 OIL PUMP AND RELIEF VALVE

7A–8.1

Relief Valve

The relief valve for the oil pressure is under the No. 1 cylinder (Fig. 7A–29, Item 1). The oil pressure is adjusted by loosening the jam nut and turning the screw in or out (See Paragraph 7A–2.1).

7A–8.2 Oil Pump

If the oil pump has a defect, you must replace the oil pump as an assembly.

To remove the oil pump, remove the oil panand remove the oil pump screen. Then remove the flywheel and gear cover. Replace the two (2) bolts which hold the oil pump to the engine block and lift it out of the engine (Fig. 7A–30).

7A–8.3 Adjusting Gear Clearance for the Oil Pump

When installing the oil pump on the engine, it is important to adjust the clearance between the oil pump gear and the crankshaft gear. The clearance between the gears is 0.005–0.009” (0,127–0,228 mm). A feeler gauge or a dial indicator can be used.

To set the clearance with a feeler gauge:

1.After the oil pump is installed, do not tighten the bolts.

2.Use a 0.007” (0,177 mm) feeler gauge and adjust the clearance between the oil pump and crankshaft gear (Fig. 7A–31). Tighten the mounting bolts.

3.Check the clearance at two other locations (120° from each other) to make sure the clearance is correct.

4.If one or more locations do not have the same clearance, loosen the bolts and adjust the clearance until all three locations have the same clearance.

To set the clearance with a dial indicator:

1.After the oil pump is installed, do not tighten the mounting bolts.

2.Mount a dial indicator on the engine (Fig. 7A–32). Makesure the dial indicator arm is tight against one of the gear teeth. Zero the dial indicator.

3.Adjust the clearance by moving the oil pump backward and forward until the clearance is between 0.005–0.009” (0,127–0,228 mm). Tighten the mounting bolts.

4.Check the clearance at two other locations (120° from each other) to make sure the clearance is correct.

5.If one or more locations do not have the same clearance, loosen the bolts and adjust the clearance until all three locations have the same clearance.

7A–9 PISTONS, RODS AND CRANKSHAFT 7A–9.1 Removing Pistons, Rods and Crankshaft

1.Remove the engine flywheel, oil pan and oil pump.

2.Put a mark on the rods and caps. The caps, rods and pistons must be installed in the cylinder bore they were removed from.

NOTE:The notch on the cap and the notch on the rod must be together.

3.Remove the rod bolts and caps and remove the pistons from the engine (Fig. 7A–33).

4.Remove the adapter and the bearing plate and the snap ring from the end of the crankshaft. Remove the bearing plate, with the bearing, from the engine.

5.Remove the crankshaft from the engine. Be careful to prevent damage to the bearing in the engine block.

6.Check the following items:

(a)Crankshaft: Keyway, journal diameters, out–of–round conditions.

(b)Rods: Condition of the bearing surface.

(c)Pistons: Scratch marks, ring groove, clearance, cracks or damage.

(d)Cylinder Block: Condition of the bearings, cylinder walls.

7A–9.2 Crankshaft Bearing and End Play

The engine uses a ball bearing which is located in the closure plate and on the crankshaft. If is not necessary to separate the crankshaft from the closure plate if the bearing turns easily on the shaft or there is no noise from the bearing.

To replace the bearing, remove the inner retaining ring then press the crankshaft out of the closure plate (Fig. 7A–34). The bearing will stay on the shaft and can be pressed off after the two snap rings are removed (Fig. 7A–35). Clean the bearing in clean solvent and allow to dry. Oil with engine oil and check the condition. Replace as needed.

To check the crankshaft end play, use the following procedure:

1.Start with one white gasket (next to the block) then add one blue gasket (0.005” [0,127 mm]). (Or use the same sequence of gaskets as used during disassembly procedure).

2.Install the closure plate and tighten the four bolts to 30 ft.–lbs. (41 Nm) torque. Hit the end of the shaft with a soft hammer to make sure it is all the way down.

3.Mount the dial indicator (Fig. 7A–36), set the dial to zero and then place a screwdriver between the counterweight and the block. Pry the crankshaft toward the closure plate end and read the dial indicator. If the end play is not between 0.004–0.010” (0,101–0,254 mm) then go to step 4.

4.Remove the closure plate and add or remove gaskets to get the correct end play. Replace the closure plate, tighten the bolts to the correct torque, and repeat the end play check. Install the rear oil seal after the end play is correct.

Use a cylinder hone to hone the correct surface on the cylinder walls(Fig. 7A–34). Check the clearance between the piston and cylinder wall. If it is over maximum, use an oversized piston.

If the new main bearing inserts are installed in the block, push the bearing even with the outside surface of the block. Make sure the oil holes in the bearing are in alignment with the holes in the engine block.

Check the ring gap in the cylinder bore (Fig. 7A–38).

Install the rings on the pistons (Fig. 7A–39).

Install the piston and rod assembly and tighten the rod bolts to 200 in.–lbs. (23 Nm) torque.

PI–01904

Fig. 7A–38 Checking Ring Gap

7A–10 CYLINDER HEAD

Use a new gasket. Put the cylinder head in position and install the bolts. Make sure the washers are used. Tighten the bolts to 35 ft.–lbs. (48 Nm) torque in the correct sequence (Fig. 7A–40).

Bevel Up Bevel Down

Fig. 7A–39 Installing Rings

B–02284

7A–11 INTAKE AND EXHAUST MANIFOLD

Put a heavy flat washer or spacers on the manifold where the bolts are used to fasten the manifold and side panels to the engine block. Install the intake and exhaust and tighten the bolts to 25 ft.–lbs. (34 Nm) torque.

A–02678

7A–12 FLYWHEEL

It is not necessary to remove the engine from the loader to remove the flywheel.

Fig. 7A–40 Torque Sequence

Remove the four (4) bolts and use a puller to removethe flywheel from the engine crankshaft.

Check the flywheel (Fig. 7A–41) for broken fins, cracks or keyway damage. Do not try to replace the ring gear on the flywheel. You must replace the flywheel and ring gear as an assembly.

Fig. 7A–41 Engine Flywheel

B–02981

ParagraphPage NumberNumber

ASSEMBLY OF THE ENGINE 7B–157B–30

CAMSHAFT7B–107B–26

CRANKSHAFT7B–97B–26

CYLINDER BLOCK7B–77B–23

CYLINDER HEAD 7B–67B–19

ENGINE, BLOWER HOUSING & RADIATOR7B–37B–9

ENGINE FLYWHEEL7B–167B–33

ENGINE OVERHAUL7B–47B–17

FUEL SYSTEM 7B–27B–3

MANIFOLD ASSEMBLY7B–127B–27

OIL PUMP & OIL FILTER ASSEMBLY 7B–137B–27

PISTONS & PISTON RINGS 7B–87B–23

ROCKER ARMS & SHAFT 7B–57B–18

TIMING GEAR 7B–117B–27

TROUBLESHOOTING7B–17B–1

WATER PUMP7B–147B–28

DO NOT service the Bobcat loader without instructions or taking the necessary safety precautions. Before working on the loader, see the warnings and instructions at the beginning of this Service Manual. After making the repair or adjustment, always check the function of the loader. Failure to obey warnings may cause injury or death.