Radiator Cap


A pressure tester can be used to test the cap's pressure valve.

A pressure tester is used to test the pressure cap.
  • First, visually inspect the sealing surfaces and the vacuum valve.
  • Moisten the sealing surface with water to help it seal during testing.
  • Install the radiator cap on the adapter. Attach the pressure tester to the other end of the adapter.
  • Pump the handle until the gauge reaches its highest point. The needle should reach a high point and remain constant. The pressure rating of the cap is stamped or printed on the top of the radiator cap. This is the point where the pressure cap should relieve pressure.
  • Before removing the cap, release pressure from the system by pushing the tester hose sideways at the cap.