Radiator Pressure Cap-Inspection

Fig 1: Cooling System Pressure Cap

Courtesy of CHRYSLER LLC

1 - OVERFLOW NIPPLE

2 - MAIN SPRING

3 - GASKET RETAINER

4 - STAINLESS-STEEL SWIVEL TOP

5 - RUBBER SEALS

6 - VENT VALVE

7 - COOLANT PRESSURE CONTAINER

8 - FILLER NECK

Hold the cap in your hand, right side up . The vent valve at the bottom of the cap should be normally closed. The vent valve should open with a slight pull with your finger nail. Replace the pressure cap for any of the following:

Rubber gasket has swollen, preventing the valve from opening, replace the cap.
Any light can be seen between the vent valve and the rubber gasket. Use only a replacement cap specified for your vehicle. A wrong cap can result in overheating of engine damage. .
Gasket on the bottom of the cap shows noticeable thinning.
Cap has been through more then one engine overheat.