Radiator Cap: Description and Operation
COOLING SYSTEM PRESSURE CAPDESCRIPTION
The cooling system pressure cap is located on the coolant outlet connector near the front of the cylinder head. The pressure cap is constructed of stainless steel. Rubber seals provide sealing to the outlet connector and to the coolant recovery system. A calibrated spring located between the cap and the connector seal provides for cooling system pressure release.
CROSS-SECTIONAL VIEW
TOP VIEW
OPERATION
The pressure cap allows the cooling system to operate at higher than atmospheric pressure. The higher pressure raises the coolant boiling point, allowing increased radiator cooling capacity. The pressure cap will release cooling system pressure in a range of 97 - 124 kPa (14 - 18 psi).
A vent valve located in the center of the cap allows a coolant flow to and from the coolant recovery system bottle. This valve is spring loaded in the closed position. However, it must be free to open during system cool-down. If the valve is stuck shut, the radiator hoses will collapse on cool-down.
Clean the vent valve to ensure proper sealing function.
A gasket in the pressure cap seals the top of the filler neck so that vacuum is maintained to draw coolant back into the system from the coolant recovery system bottle.