Radiator Cap Pressure Test

Use an adapter to attack the cap to tester.

Fig 1: Testing Radiator Cap
Courtesy of KIA MOTORS AMERICA, INC.
Increase the pressure until the gauge indicator stops moving.
- Main valve opening pressure: 14-18 psi (86-125 kPa).
- Main valve closing pressure: 12 psi (83 kPa)
Check that the pressure level is maintained at or above the limit.
Replace that radiator cap if the reading does not remain at or above the limit.
NOTE: Be sure that the cap is clean before testing, since rust or other foreign material on the cap seal will cause an improper reading.