Radiator Cap Testing

Remove the radiator cap, wet its seal with engine coolant, then install it on a pressure tester.

Courtesy of KIA MOTORS AMERICA, INC.
Apply a pressure of 93.16 - 122.58 kPa (0.95 - 1.25 kg/cm² , 13.51 - 17.78 psi).
Check for a drop in pressure.
If the pressure drops, replace the cap.