over the past two weeks my car has over heated about 4 times the temp will go up too 250F then drop like a rock too about 180F. after that i took the thermostat out(which is only 6 weeks old) and it didnt over heat anymore. now i got what looks like a slightly blow head gasket i say this because there is radiator fluid on the back of my intake and white smoke coming from under my hood. My question is can a faulty radiator cap cause it too over heat or is it just a bad thremostat?

[This message has been edited by Agent Smith (edited February 27, 2005).]

bad T-stat..

I've run several "brand new" thermostats in the past that were junk right out of the box. The best one's that worked perfectly in my cars were the Robertshaw Extra Performance ones and others that are similar. The difference is that these never cut the flow of water completely off when they're closed. Plus when they open, they open WITH the flow of the water instead of AGAINST the flow like conventional ones. Since a heater is no longer a concern for me, I run a water restrictor instead that works great for keeping mine cool.

<font face="Arial,Verdana" size="2">Originally posted by 1981coupe400ci:
bad T-stat.. </font>

Yup sounds like the t-stat is sticking. I would replace it with a fail safe one