Suzuki AN400 Service Manual page 334

9-6 SERVICING INFORMATION
Complaint
Noisy engine.
Engine runs poorly
in high speed range.
Symptom and possible causes
Excessive valve chatter
1. Too large valve clearance.
2. Weakened or broken valve springs.
3. Worn rocker arm or cam surface.
4. Worn and burnt camshaft journal.
Noise seems to come from piston
1. Worn down piston or cylinder.
2. Combustion chamber fouled with carbon.
3. Worn piston pins or piston pin bore.
4. Worn piston rings or ring grooves.
Noise seems to come from timing chain
1. Stretched chain.
2. Worn sprocket.
3. Tension adjuster not working.
Noise seems to come from crankshaft
1. Rattling bearings due to wear.
2. Worn and burnt journal bearings.
3. Too large thrust clearance.
Noise seems to come from transmission
1. Worn or rubbing gears.
2. Worn splines.
3. Worn bearings.
Noise seems to come from water pump
1. Too much play on water pump shaft bearing.
2. Worn or damaged impeller shaft.
3. Worn or damaged mechanical seal.
4. Contact between water pump case and impeller.
Defective engine internal/electrical parts
1. Weakened valve springs.
2. Worn camshaft.
3. Valve timing out of adjustment.
4. Incorrect spark plug gap.
5. Ignition not advanced sufficiently due to poorly
working timing advance circuit.
6. Defective ignition coil.
7. Defective crankshaft position sensor.
8. Defective ECM.
9. Clogged air cleaner element.
10. Clogged fuel hose, resulting in inadequate fuel
supply to injector.
11. Defective fuel pump.
12. Defective throttle position sensor.
Remedy
Adjust.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace.
Replace.
Replace.
Replace.
Repair or replace.
Replace.
Replace.
Replace bearing.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Adjust.
Adjust.
Replace ECM.
Replace.
Replace.
Replace.
Clean.
Clean and prime.
Replace.
Replace.