Oil Pressure Diagnosis and Testing

Oil Pressure Diagnosis and Testing

Special Tools
* EN 47971 - Oil Pressure Gauge Adapter
* J 21867 - Pressure Gauge
For equivalent regional tools, refer to Special Tools (Special Tools).




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
* Foamy oil

6. Remove the oil filter and install the EN 47971 - adapter (1).
7. Install the J 21867 - gauge (2), or equivalent to the EN 47971 - adapter (1).
8. Run the engine and measure the engine oil pressure.
9. Compare the readings to Engine Mechanical Specifications (Service Limits & General Specifications).
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
Refer to Oil Pump Cleaning and Inspection (6.2L) (65. Oil Pump Cleaning and Inspection).
* Oil pump-to-engine block bolts loose
Refer to Oil Pump, Screen and Crankshaft Oil Deflector Installation (6.2L) (87. 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 (83. Engine Block Plug Installation).
* Broken valve lifters
Repair, as necessary.

11. If the oil pressure reading on the J 21867 - gauge , or equivalent, is within specifications, inspect for the following conditions:

* Plugged or incorrect oil filter and/or malfunctioning oil bypass valve
The bypass valve is now internal to the oil filter.
* Malfunctioning oil pressure gauge or sensor
Repair, as necessary.