GM Service Manual Online
For 1990-2009 cars only

Leak Testing Procedure (On Vehicle)

Tools Required

J 24460-01 Cooling System Tester

Caution: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the pressure cap while the engine is hot and pressure is high will cause the solution to boil instantaneously -- possibly with explosive force -- spewing the solution over the engine, fenders and the person removing the cap.

  1. Ensure that the radiator and the heater hose clamps are properly positioned and secured.
  2. Inspect the connections for any leaks. Repair the connections as required.
  3. Inspect the connections for any leaks. Repair the connections as required.
  4. Remove the radiator fill cap.
  5. Fill the cooling system to the base of the radiator neck.

  6. Object Number: 11658  Size: SH
  7. Connect the cooling system tester J 24460-01 to the radiator neck.
  8. Apply normal system operating pressure. Do not exceed 138 kPa (20 psi).
  9. The system should hold pressure for two minutes.
  10. • If a measurable amount of pressure drops in less than two minutes, check the radiator for leaks.
    • Mark the leaking area and remove the radiator for repair. Refer to Radiator Replacement .

Leak Testing (Off Vehicle)

    Notice: Do not use boil-out tanks that have been used for copper or brass radiators. The flux and caustic cleaners remaining in these tanks will attack the aluminum radiator causing failure. Use a separate tank containing clean water for servicing aluminum and plastic radiators.

  1. Remove the radiator from the vehicle. Refer to Radiator Replacement .
  2. Clean the radiator core so that the damaged area can be seen.
  3. Remove dirt and insects from the radiator fins with a common water hose, without the nozzle. Do not exceed 138 kPa (20 psi) of pressure.
  4. Find the radiator core leaks by adding water to the radiator.

  5. Object Number: 3339  Size: SH
  6. Install test fittings, or rubber test caps, in the inlet and outlet necks. Seal the oil cooler fittings with metal plugs in order to protect the cooler and to keep fluid from coming out.

  7. Object Number: 11658  Size: SH
  8. Attach the J 24460-01 to the radiator.
  9. Gradually apply normal system pressure until 138 kPa (20 psi) is reached. Do not exceed 138 kPa (20 psi).
  10. Check the pressure gauge to see if there is pressure loss.
  11. In order to ensure that there are no small leaks, run water over the suspect area. Look for any bubbles. Using a mild detergent can be helpful.
  12. If a large water tank is available, you can submerge the radiator. You can then check for air bubbles.