GM Service Manual Online
For 1990-2009 cars only

Oil Pressure Test


    Object Number: 262507  Size: SH
  1. Remove the oil pressure switch from the engine block (1).

  2. Object Number: 262510  Size: SH
  3. Install a pressure gage (1) instead of the oil-pressure switch.
  4. Start the engine, and run the engine at idle until normal operating temperature is reached.
  5. With the engine speed at 4000 RPM, measure the oil pressure.
  6. Normal Oil Pressure
    323-421 kPa (47-61 psi) at 4000 RPM

  7. If the oil pressure is below specification, refer to the following table.
  8. Stop the engine.
  9. Remove the pressure gage.
  10. Install the oil pressure switch.
  11. Tighten
    Tighten the oil pressure switch to 14 N·m (11 lb ft).

  12. Run the engine, and inspect for oil leaks from the oil pressure switch.

Oil Pressure Diagnosis

Problem

Action

The oil level is low.

Fill the oil to the FULL mark on the oil level indicator.

The idle speed is slow.

Adjust the idle speed.

The oil pressure switch is incorrect or malfunctioning.

Replace the oil pressure switch.

The oil pressure indicator is incorrect or malfunctioning.

Replace the oil pressure indicator.

The oil viscosity is improper.

Fill the oil tank. Use oil of the proper viscosity for the expected temperature.

The oil is diluted with one of the following materials:

    • Moisture
    • An unburned fuel mixture

Fill with new oil.

The oil pump is worn or dirty.

Replace or clean the oil pump as necessary.

The oil filter is plugged.

Replace the oil filter.

The oil pick-up screen is loose or plugged.

Adjust or replace the screen as necessary.

The oil pick-up tube has a hole.

Replace the tube.

The bearing clearance is excessive.

Replace the bearings as necessary.

The oil galleries display one of the following conditions:

    • Cracked
    • Porous
    • Restricted

Repair or replace the block as necessary.

The gallery plugs are missing or incorrectly installed.

Install the plugs, or repair the plugs as necessary.

The oil pump pressure regulator valve is malfunctioning.

Replace the valve.

The camshaft is worn or poorly machined.

Replace the camshaft.

The valve guides are worn.

Replace the guides.