Radiator Cap Pressure Testing
WARNING: This page is about a different car, the 1988 Pontiac 6000, 1988 Oldsmobile Cutlass Cruiser, 1988 Oldsmobile Cutlass Ciera, 1988 Chevrolet Celebrity, and 1988 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Visually inspect radiator cap, then dip cap in water and connect to tester. Pump tester to bring pressure to upper limit of cap specifications. If cap fails to hold pressure within specifications, replace cap.
Wet cap gasket before testing.