Oil Pressure Diagnosis and Testing

Oil Pressure Diagnosis and Testing

Special Tools

* EN-47971 Oil Pressure Gauge Adapter

* J 21867 Pressure Gauge





1. With the vehicle on a level surface, run the vehicle for a few minutes. Allow adequate drain down time, 2-3 minutes, and measure the oil level.

2. If required, add the recommended grade engine oil and fill the crankcase until the oil level measures full on the oil level indicator.

3. Run the engine briefly, 10-15 seconds, and verify low or no oil pressure on the vehicle gauge or light.

4. Listen for a noisy valve train or a knocking noise.

5. Inspect for the following conditions:

* Oil diluted by water or glycol antifreeze

Refer to Coolant in Engine Oil Coolant in Engine Oil.

* Foamy oil, which may be caused by a cut or damaged oil pump screen O-ring seal

6. Remove the oil filter and install the EN-47971 (1).

7. Install the J 21867 (2), or equivalent to the EN-47971 (1).

8. Run the engine and measure the engine oil pressure.

9. Compare the readings to Engine Mechanical Specifications (RPO L96 VIN G) Service Limits & General Specifications (RPO L96 VIN G)Engine Mechanical Specifications (RPO LMF VIN 4) Service Limits & General Specifications (RPO LMF VIN 4)Engine Mechanical Specifications (RPO L20 VIN A) Service Limits & General Specifications (RPO L20 VIN A).

10. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the following conditions:

* Oil pump worn or dirty

* Oil pump-to-engine block bolts loose

Refer to Oil Pump, Screen and Crankshaft Oil Deflector Installation 69. Oil Pump, Screen and Crankshaft Oil Deflector Installation.

* Oil pump screen loose, plugged, or damaged

* Oil pump screen O-ring seal missing or damaged

* Malfunctioning oil pump pressure relief valve

* Excessive bearing clearance

* Cracked, porous, or restricted oil galleries

* Oil gallery plugs missing or incorrectly installed

Refer to Engine Block Plug Installation 64. Engine Block Plug Installation.

* Improper operation of the active fuel management oil pressure relief valve

Refer to Oil Pressure Relief Valve Diagnosis and Testing Oil Pressure Relief Valve Diagnosis and Testing.