Radiator Cap: Inspection

Check that the radiator cap does not have deformation, cracks or damage.
Attach the radiator cap tester to radiator cap.

Fig 1: Checking Radiator Cap Using 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.
Standard:

73.6 - 103.0 kPa (0.75 - 1.05 kgf/cm ² , 11 - 15 psi)

Service limit:

63.6 kPa (0.65 kgf/cm ² , 9 psi)

CAUTION: Be sure to remove foreign matter and rust from the cap in advance. Otherwise, results of pressure test will be incorrect.