Tools Required

WARNING: This page is about a different car, the 2002 Saturn LW300 and 2002 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.

J43421 Cooling System Pressure Test Adapter

NOTE: If vehicle has experienced cooling system boil over, the pressure cap must be replaced.

Remove the pressure cap from the coolant surge tank.
Make sure that all parts of the pressure cap, tester, and adapter are clean.
Wet the rubber gasket of the pressure cap with water and install onto the Cooling System Pressure Test Adapter J43421.

Fig 1: Attaching Pressure Cap To Pressure Test Adaptor
Courtesy of GENERAL MOTORS CORP.
Hold the tester with the test cap adapter J43421 hanging straight down.
CAUTION: WEAR SAFETY GOGGLES.

CAUTION: NEVER PUMP THE PRESSURE CAP ABOVE 152 KPA (22 PSI).
Pump the tester, watch the pressure gauge, and read the maximum pressure before the relief valve opens. Stop pumping. The pressure cap is rated at 138 kPa (20 psi).
Cap opening pressure: 138-145 kPa (20-21 psi)

Vacuum relief setting: 10 kPa (1.5 psi) below atmospheric pressure

Fig 2: Testing Pressure Cap
Courtesy of GENERAL MOTORS CORP.
Watch needle for 30 seconds to see if it falls. The needle should not fall below 68.1 kPa (10 psi).