importance of radiator cap

[60-1talon]

why is the radiator cap so important what is it real function besides closing the thermostat housing

 

[oldman]

The cooling system is a closed system, The purpose of the cap is real for refilling.

 

[luv2rallye]

The cooling system must be pressurized to transfer heat from engine to radiator. Pressurized systems also raise the boiling point and lower the freezing point. The cap keeps the system under proper pressure (and relieves pressure when it over boils).

 

[oldman]

The cooling system must be pressurized to transfer heat from engine to radiator. Pressurized systems also raise the boiling point and lower the freezing point. The cap keeps the system under proper pressure (and relieves pressure when it over boils).

I stand corrected. You're right, they do have pressure rating on caps.

 

[Defiant]

http://auto.howstuffworks.com/cooling-system.htm