I've posted this on another forum, but wanted expertise from this one too.

I have a question that I've wondered about regarding radiators.

I've always been under the impression that you can pressurize both liquids and gasses,
but liquids do not expand whereas gasses will.

Soooo, what causes the expansion in our cooling systems?
Is is there always some air trapped in the system somewhere or does the heat generated
near the hot spots in the heads cause percolation?

So then the question follows; where is the recovered fluid in the overflow tank going to in the
cooling system??

I hope someone's explanation doesn't make me feel like a dolt....LOL

Joe