Oil Pressure Diagnosis and Testing

Special Tools

• EN-21867  Pressure Gauge
• EN-21867-850  Active Fuel Management Oil Pressure Adapter

For equivalent regional tools, refer to 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

     Refer to Coolant in Engine Oil .

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

6. Courtesy of GENERAL MOTORS COMPANY

   Remove the oil pressure sensor (1) and seal (2).

7. Courtesy of GENERAL MOTORS COMPANY

   Install the EN-21867-850  active fuel management oil pressure adapter (2) and EN-21867  pressure gauge (1), or equivalent.

8. Run the engine until the engine reaches normal operating temperature and measure the engine oil pressure.
9. Compare the readings to Engine Mechanical Specifications .
10. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the following conditions:
    • Valve lifter oil manifold filter plugged or damaged. Refer to Valve Lifter Oil Manifold Cleaning and Inspection .
    • Check if the engine oil cooler or oil cooler lines are plugged or damaged.
    • Oil pump worn or dirty. Refer to Oil Pump Cleaning and Inspection .
    • Oil pump-to-engine block bolts loose. Refer to Oil Pump Installation .
    • Oil pump screen loose, plugged, or damaged.
    • Oil pump screen O-ring seal missing or damaged.
    • Excessive debris in the oil pan and/or oil filter (possibly indicating internal engine damage).
    • Malfunctioning oil pump pressure relief valve. Refer to DTC P06DA-P06DD .
    • Excessive bearing clearance and/or bearing damage. Refer to Crankshaft and Bearing Cleaning and Inspection , and Camshaft and Bearings Cleaning and Inspection .
    • Cracked, porous, or restricted oil galleries.
    • Oil gallery plugs missing or incorrectly installed. Refer to Engine Block Plug Installation .