Jeep Cherokee 1999 Electronic Service Manual page 1031

9 - 14 ENGINE
DI AGN OSI S AN D T EST I N G (Cont inue d)
CONDITION
LOW OIL PRESSURE
OIL LEAKS
EXCESSIVE OIL
CONSUMPTION OR SPARK
PLUGS OIL FOULED
POSSIBLE CAUSES
4. Excessive main bearing clearance
5. Excessive end play
6. Crankshaft main journal out of
round or worn
7. Loose flywheel or torque converter
1. Low oil level
2. Faulty oil pressure sending unit
3. Clogged oil filter
4. Worn oil pump
5. Thin or diluted oil
6. Excessive bearing clearance
7. Oil pump relief valve stuck
8. Oil pump suction tube loose,
broken, bent or clogged
9. Oil pump cover warped or cracked
1. Misaligned or deteriorated gaskets
2. Loose fastener, broken or porous
metal part
3. Front or rear crankshaft oil seal
leaking
4. Leaking oil gallery plug or cup plug
1. PCV System malfunction
2. Defective valve stem seal(s)
3. Worn or broken piston rings
4. Scuffed pistons/cylinder walls
5. Carbon in oil control ring groove
6. Worn valve guides
7. Piston rings fitted too tightly in
grooves
CORRECTION
4. Measure bearings for correct
clearance. Repair as necessary
5. Check crankshaft thrust bearing for
excessive wear on flanges
6. Grind journals or replace crankshaft
7. Inspect crankshaft, flexplate/
flywheel and bolts for damage.
Tighten to correct torque
1. Check oil level and fill if necessary
2. Install new sending unit
3. Install new oil filter
4. Replace worn gears or oil pump
assy
5. Change oil to correct viscosity.
Refer to this group for correct
procedure/engine oil specifications
6. Measure bearings for correct
clearance
7. Remove valve to inspect, clean and
reinstall
8. Inspect suction tube and clean or
replace if necessary
9. Install new oil pump
1. Replace gasket
2. Tighten, repair or replace the part
3. Replace seal
4. Remove and reseal threaded plug.
Replace cup style plug
1. Refer to group 25, Emission
Control System for correct operation
2. Repair or replace seal(s)
3. Hone cylinder bores. Install new
rings
4. Hone cylinder bores and replace
pistons as required
5. Remove rings and de-carbon piston
6. Inspect/replace valve guides as
necessary
7. Remove rings and check ring end
gap and side clearance. Replace if
necessary
X J