GM Service Manual Online
For 1990-2009 cars only

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.

Use the outlined instructions in Pressure Cap Description in order to remove the cap:

  1. Remove the cap.
  2. Wet the radiator cap gasket with water.
  3. Wash off any sediment from the sealing surface.
  4. Install the cap to J 24460-01 .
  5. Use the plunger handle of J 24460-01 in order to increase the pressure as specified on the cap.
  6. Note the rate of decrease in the pressure.
  7. The specified reading of the pressure should remain within the corresponding pressure scale for more than 10 seconds.
  8. Replace the radiator cap if it does not maintain the pressure for more than 10 seconds.