GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 24460-01 Cooling System and Cap Pressure Tester

Caution: With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.

Notice: Do not use pressure greater than 138 kPa (20 psi) to test the radiator. Damage to the radiator will result if a higher pressure is used.


    Object Number: 1375  Size: SH
  1. Remove the surge tank cap, only after the system has cooled. Refer to Cooling System .
  2. Install the surge tank cap on J 24460-01 .
  3. Slowly pump the J 24460-01 to obtain the minimum holding pressure. Do not exceed 138 kPa (20 psi).
  4. If the cap fails to hold 103 kPa (15 psi), install a new cap. Before installing the cap, wet the new cap with coolant.

  5. Object Number: 1377  Size: SH
  6. Install the J 24460-01 on the surge tank and do the following test:.
  7. 5.1.  Pump the cooling system to 103 kPa (15 psi). Do not exceed 138 kPa (20 psi).
    5.2. Check the surge tank for leaks.
    5.3. Watch for a drop in pressure on the J 24460-01 .

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.


    Object Number: 3339  Size: SH
  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. Find the radiator core leaks by adding water to the radiator.
  4. 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.
  5. 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.

  6. Object Number: 11658  Size: SH
  7. Attach the J 24460-01 to the radiator.
  8. Gradually apply normal system pressure until 138 kPa (20 psi) is reached. Do not exceed 138 kPa (20 psi).
  9. Check the J 24460-01 to see if there is pressure loss.
  10. 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.
  11. If a large water tank is available, you can submerge the radiator. You can then check for air bubbles.