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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 515 (Hybrid/EV Cooling System) >> Diagnostic Information and Procedures >> Hybrid Cooling System Pressure Cap Testing >> Pressure Cap Testing

Pressure Cap Testing

WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
    WARNING:

    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. Fig 1: Identifying Pressure Cap Testing Tool J 42401
    GM850101Courtesy of GENERAL MOTORS COMPANY
  4. Use the J 24460-01  cooling system pressure tester (1) with J 46143  cooling system adapter (2) in order to test the pressure cap.
  5. Test the pressure cap for the following conditions:
    • Pressure release when the J 24460-01  cooling system pressure tester exceeds the pressure rating of the pressure cap.
    • Maintain the rated pressure for at least 10 seconds.

      Note the rate of pressure loss.

  6. Replace the pressure cap under the following conditions:
    • The pressure cap does not release pressure which exceeds the rated pressure of the cap.
    • The pressure cap does not hold the rated pressure.