I've read, with great interest all of the posts concering overheating. My car has done the overheating thing for the past few years. My mechanic has checked everything over and over again and as best as he can tell, everything is operating as it should. I've noticed that many times, it is suggested that the radiator cap be checked. #1, how do you do this, and #2, how would I tell if it is bad and needs to be replaced? It is the only thing I can think of that has not been replaced on my cooling system.

 

Easiest way to check it: replace it. It's what, $3? If you've had the car for more than 2 years and you haven't replaced it, it's due anyway.

A bad rad cap won't make your car overheat. What it will do however, by failing to maintain the proper pressure in the cooling system, is to allow the coolant to boil. This is often mis-diagnosed as "overheating", because it sure looks alot like overheating when coolant and steam is spewing everywhere, although in fact the temperature of the engine might be completely normal.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

you check the cap and cooling system with a preasure tester, like rb said the cap is so cheap it's as easy to just replace it.