GM Service Manual Online
For 1990-2009 cars only

Testing Procedure

Tools Required

J 25087-C Oil Pressure Test Kit

  1. Check the engine oil level.
  2. Raise the vehicle. Suitably support the vehicle. Refer to Section 0A.
  3. Remove the oil filter.
  4. Assemble the plunger valve in the large hole of the tester base.
  5. Insert the small hose in the small hole of the tester base.
  6. Connect the gauge to the end of the hose.
  7. Insert the flat side of the rubber plug into the bypass valve. Do not depress the bypass valve.
  8. Install the tester on the filter mounting pad.
  9. Start the engine. Run the engine until the engine reaches operating temperature in order to check the following conditions:
  10. • The overall pressure reading
    • The operation of the sender switch
    • The operation of the lifters
  11. Note the oil pressure reading. The oil pressure should read approximately 414 kPa (60 psi) at 1850 RPM while using 10W30 engine oil.
  12. If the oil pressure reading is adequate, check the oil pressure sending switch.
  13. If the oil pressure reading is low, depress the valve on the tester base in order to isolate the oil pump or the pump's components from the lubricating system.
  14. • If the oil pressure reading is adequate, the previous low reading is due to worn bearings or another condition.
    • If the oil pressure reading is low, the oil pump is faulty.