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Cap, Radiator: Inspection
- Hold cap at eye level, right side up. The vent valve at bottom of cap should open. If rubber gasket has swollen and prevents vent valve from opening, replace cap.
- Hold cap at eye level, upside down. If any light can be seen between vent valve and rubber gasket, replace cap. Do not use a replacement cap that has a spring to hold vent shut.
A replacement cap must be the type designed for a coolant reserve/overflow system with a completely sealed diaphragm spring and a rubber gasket. This gasket is used to seal to radiator filler neck top surface. Use of proper cap will allow coolant return to radiator.