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JX
DIAGNOSIS AND TESTING (Continued)
ENGINE DIAGNOSIS—MECHANICAL
CONDITION
NOISY VALVES
CONNECTING ROD NOISE
MAIN BEARING NOISE
OIL PRESSURE DROP
OIL LEAKS
OIL CONSUMPTION OR SPARK
PLUGS OIL FOULED
POSSIBLE CAUSES
1. High or low oil level in crankcase.
2. Thin or diluted oil.
3. Low oil pressure.
4. Dirt in tappets/lash adjsuters.
5. Worn rocker arms.
6. Worn tappets/lash adjusters.
7. Worn valve guides.
8. Excessive runout of valve seats.
9. Missing adjuster pivot.
1. Insufficient oil supply.
2. Low oil pressure.
3. Thin or diluted oil.
4. Excessive bearing clearance.
5. Connecting rod journal out-of-round.
6. Misaligned connecting rods.
1. Insufficient oil supply.
2. Low oil pressure.
3. Thin or diluted oil.
4. Excessive bearing clearance.
5. Excessive end play.
6. Crankshaft journal out-of-round, worn.
7. Loose flywheel or torque converter.
1. Low oil level.
2. Faulty oil pressure sending unit.
3. Low oil pressure.
4. Clogged oil filter.
5. Worn parts in oil pump.
6. Thin or diluted oil.
7. Excessive bearing clearance.
8. Oil pump relief valve stuck.
9. Oil pump suction tube loose, bent cracked, or
blocked.
10. Oil pump cover warped or cracked.
1. Misaligned or deteriorated gaskets.
2. Loose fastener, broken or porous metal part.
3. Misaligned or deteriorated cup or threaded plug.
1. PCV system malfunction.
2. Worn, scuffed or broken rings.
3. Carbon in oil ring slot.
4. Rings fitted too tightly in grooves.
5. Worn valve guides.
6. Valve stem unseated or defective.
ENGINE
CORRECTION
1. Checkfor correct oil level (refer to Group 0,
Lubrication and Maintenance).
2. Change oil (refer to Group 0, Lubrication
and Maintenance.
3. Check engine oil level.
4. Replace rocker arm/hydraulic lash adjuster
assembly.
5. Inspect oil supply to rocker arms.
6. Install new rocker arm/hydraulic lash
adjuster assembly.
7. Ream and install new valves with oversize
stems.
8. Grind valve seats and valves.
9. Replace rocker arm/hydraulic lash adjuster
assembly.
1. Check engine oil level (refer to Group 0,
Lubrication and Maintenance.
2. Check engine oil level. Inspect oil pump
relief valve and spring.
3. Change oil to correct viscosity.
4. Measure bearings for correct clearance.
Repair as necessary.
5. Replace crankshaft or grind journals.
6. Replace bent connecting rods.
1. Check engine oil level (refer to Group 0,
Lubrication and Maintenance).
2. Check engine oil level. Inspect oil pump
relief valve.
3. Change oil to correct viscosity.
4. Measure bearings for correct clearance.
Repair as necessary.
5. Check thrust bearing for wear on flanges.
6. Grind journals or replace crankshaft.
7. Tighten to correct torque.
1. Check engine oil level.
2. Install new sending unit.
3. Check sending unit and check main
bearing oil clearance.
4. Install new oil filter.
5. Replace worn parts or pump.
6. Change oil to correct viscosity.
7. Measure bearings for correct clearance.
8. Remove valve and inpsect, clean
and install.
9. Remove oil pan and install new tube, or
clean if necessary.
10. Install new oil pump.
1. Replace the gasket.
2. Tighten, repair or replace the part.
3. Replace.
1. Check system. Clean and repair, as
necessary (refer to Group 25, Emissions
Control System).
2. Hone cylinder bores. Install new rings.
3. Install new rings.
4. Remove the rings. Check grooves. If
groove is not proper width, replace piston.
5. Ream guides and replace valves with
oversize valves and seals.
6. Repair or replace seal.
9 - 11
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