G424 Service Manual Adjustment and Troubleshooting177
Oil Pressure Problems
Symptom Cause
1. Low oil pressure. A. Low oil level in crankcase.
B. Defective oil-pressure gauge and/or sender.
C. Oil broken down, contains water, wrong viscosity, engine running too hot
or too cold, excessive idling with cold water (condensation).
D. Relief valve stuck open, pickup tube restricted, worn parts in oil pump,
air leak on suction side of oil pump or pickup tube.
E. Oil passage plugs leaking, cracked or porous cylinder block.
F. Excessive bearing clearance.
2. High oil pressure. A. Wrong viscosity, oil full of sludge or tar.
B. Defective oil pressure gauge and/or sender.
C. Clogged or restricted oil passage.
D. Oil pump relief valve stuck closed.
IMPORTANT: Oil pressure slightly higher than normal does not always indicate a problem.
Tolerance stack-up In the engine, oil viscosity or weather conditions could cause high oil pres-sure.
3. Excessive oil consumption. A. Oil leaks.
B. Oil diluted or of the wrong viscosity.
C. Oil level too high.
D. Drain holes in cylinder head plugged causing flooding of valve guides.
E. Defective valve seals.
F. Intake manifold gasket leaking, worn valve stem or valve guides.
G. Defective oil cooler (if so equipped).
H. Glazed, scuffed, worn, stuck, improperly installed; ring grooves worn;
improper break-in; wrong end gap.
I. Piston out-of-round, scored, tapered, glazed; excessive piston-to-cylinder
clearance; cracked piston.
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