GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • J 24460-01 Cooling System Pressure Tester
    • J 42401 Radiator Cap/Surge Tank Test Adapter

    Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

  1. Remove the pressure cap.
  2. Wash the pressure cap sealing surface with water.

  3. Object Number: 850101  Size: SH

    Important: Lubricate J-42401 and pressure cap O-rings with coolant and press cap to seat O-ring on J-42401 before turning to engage threads.

  4. Use the J 24460-01  (1) with J 42401  (2) in order to test the pressure cap.
  5. Test the pressure cap to verify the following conditions are met:
  6. • Main pressure release occurs between 2 psi below and 5 psi above the rated cap pressure.
    • The hold pressure reads greater than 3 psi below the rated cap pressure 60 seconds after initial pressure release.
  7. Replace the pressure cap if the conditions in step 4 are not met.