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CONDITION POSSIBLE CAUSES CORRECTION LOW OIL PRESSURE 1. Low oil level 1. Check oil level and fill if 2. Faulty oil pressure sending unit 2. Install new sending unit 3. Clogged oil filter 3. Install new oil filter 4. Worn oil pump 4. Replace worn gears or oil pump 5. Thin or diluted oil 5. Change oil to correct viscosity. 6. Excessive bearing clearance 6. Measure bearings for correct 7. Oil pump relief valve stuck 7. Remove valve to inspect, clean 8. Oil pump suction tube loose, 8. Inspect suction tube and clean or 9. Oil pump cover warped or 9. Install new oil pump OIL LEAKS 1. Misaligned or deteriorated 1. Replace gasket 2. Loose fastener, broken or porous 2. Tighten, repair or replace the part 3. Front or rear crankshaft oil seal 3. Replace seal 4. Leaking oil gallery plug or cup 4. Remove and reseal threaded EXCESSIVE OIL CONSUMPTION 1. PCV System malfunction 1. Refer to group 25, Emission 2. Defective valve stem seal(s) 2. Repair or replace seal(s) 3. Worn or broken piston rings 3. Hone cylinder bores. Install new 4. Scuffed pistons/cylinder walls 4. Hone cylinder bores and replace 5. Carbon in oil control ring groove 5. Remove rings and de-carbon 6. Worn valve guides 6. Inspect/replace valve guides as 7. Piston rings fitted too tightly in 7. Remove rings and check ring end INTAKE MANIFOLD LEAKAGE DIAGNOSIS An intake manifold air leak is characterized by lower than normal manifold vacuum. Also, one or WARNING: USE EXTREME CAUTION WHEN THE 9 - 72 4.0L ENGINE XJ DIAGNOSIS AND TESTING (Continued) |