Radiator Cap: Inspection

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

Stop the engine.
The engine coolant is pressurized when it is hot. Wait until engine coolant cools down before proceeding the work.
If the engine coolant is spilt over the engine, exhaust pipe or the under cover, completely wipe it off to avoid emission of smoke or causing a fire.

Remove the radiator cap.
Check that there is no deformation, cracks or other damages.

Check the opening pressure of the radiator cap.

Attach radiator cap tester.

Courtesy of SUBARU OF AMERICA, INC.

Increase pressure until the radiator cap tester gauge needle stops. Radiator cap is functioning properly if it holds the service limit pressure for 5 - 6 seconds. Replace the radiator cap if its valve opens at less than the service limit.
CAUTION:
Be sure to remove foreign matter and rust from the cap in advance.

Otherwise, results of pressure test will be incorrect.

Specification:

93 - 123 kPa (0.95 - 1.25 kg/cm² , 14 - 18 psi)

Service limit:

83 kPa (0.85 kg/cm² , 12 psi)