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SERVICE DIAGNOSIS—LUBRICATION CONDITION POSSIBLE CAUSES CORRECTION OIL LEAKS 1. Gaskets and O-Rings. 1. (a) Misaligned or damaged. (a) Replace as necessary. (b) Loose fasteners, broken or porous metal parts. (b) Tighten fasteners, Repair or replace metal parts. 2. Crankshaft rear seal 2. Replace as necessary. 3. Crankshaft seal flange. 3. Polish or replace crankshaft. 4. Oil pan flange cracked. 4. Replace oil pan. 5. Timing chain cover seal, 5. Replace seal. 6. Scratched or damaged vibration 6. Polish or replace damper. OIL PRESSURE DROP 1. Low oil level. 1. Check and correct oil level. 2. Faulty oil pressure sending unit. 2. Replace sending unit. 3. Low oil pressure. 3. Check pump and bearing 4. Clogged oil filter. 4. Replace oil filter. 5. Worn oil pump. 5. Replace as necessary. 6. Thin or diluted oil. 6. Change oil and filter. 7. Excessive bearing clearance. 7. Replace as necessary. 8. Oil pump relief valve stuck. 8. Clean or replace relief valve. 9. Oil pump suction tube loose or 9. Replace as necessary. OIL PUMPING AT RINGS; SPARK PLUGS FOULING 1. Worn or damaged rings. 1. Hone cylinder bores and replace 2. Carbon in oil ring slots. 2. Replace rings. 3. Incorrect ring size installed. 3. Replace rings. 4. Worn valve guides. 4. Ream guides and replace valves. 5. Leaking intake gasket. 5. Replace intake gaskets. 6. Leaking valve guide seals. 6. Replace valve guide seals. 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 (1) Start the engine. (2) Spray a small stream of water at the suspected leak area. (3) If a change in RPM is observed the area of the suspected leak has been found. (4) Repair as required. CYLINDER COMPRESSION PRESSURE TEST The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunc- Ensure the battery is completely charged and the engine starter motor is in good operating condition. DN 4.7L ENGINE 9 - 11 DIAGNOSIS AND TESTING (Continued) |