Radiator Cap Testing

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

Fig 1: Performing Radiator Cap Test
Courtesy of HYUNDAI MOTOR AMERICA
Apply a pressure of 93.16 ~ 122.58kpa (0.95 ~ 1.25kg/cm² , 13.51 ~ 17.78psi).
Check for a drop in pressure.
If the pressure drops, replace the cap.