Engine - Low Oil Pressure Diagnostic Procedures

Group
ENGINE MECHANICAL

Number
92-20-002-2

Date
JULY, 1992


Model
EXCEL, SCOUPE



Subject
LOW OIL PRESSURE - DIAGNOSTIC PROCEDURE



The low oil pressure light on the instrument cluster will come on when the engine oil pressure drops to about 3-6 psi. Normal oil pressure, at idle when the engine is warm should be about 11 psi.

Low oil pressure can be caused by several items including:

^ Low engine oil level
^ Contaminated oil
^ Clogged oil filter
^ Faulty oil pressure switch
^ Thin or diluted engine oil
^ Oil relief valve stuck open
^ Worn oil pump gears or cover
^ Excessive bearing clearance


When diagnosing a car with the low oil pressure light on, perform the following steps:

1. Check the engine oil level. Fill as needed.
2. Remove the oil pressure switch and install a gauge to verify that the oil pressure is actually low and not just a malfunctioning switch or gauge.
3. Drain the engine oil and remove the oil filter. Inspect the drained oil for signs of dilution or contamination.
4. Replace oil filter and engine oil to manufacturers specification.
5. Retest oil pressure.

NOTE:
If there are signs of contamination (Heavy, Thick, Discolored, Foul Smelling), do the following:

^ Install new oil filter
^ Install new engine oil to manufacture's specification (Substitute 1 Quart of ATF for 1 Quart of engine oil)
^ Start car, and let it idle for 10 minutes
^ Drain oil, and install a new oil filter
^ Refill the engine oil to manufacturers specification
^ Start car and let it idle for 5 minutes, then check oil pressure

If condition still exists after performing these steps, follow the remaining steps:

6. Remove front case and inspect oil pump and relief valve per shop manual instructions.
7. If everything checks out at this point, the engine will have to be opened up to inspect the bearing clearances on the crankshaft and counter balance shafts.






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