I would check the cylinder compressions and see if maybe you have a leaky head gasket.
Have you, or anybody else put stop leak in this radiator system?
I know alot of people have switched back from the red radiator fluid to the green, did you do that on this car?
Reason for my questions, leaky head gasket, self explanitory. Stop leak can clog the the small orifices in the head gasket which will cause cylinder head temp to climb. If the radiator fluid type was changed, and not properrly flushed, some of the old red fluid may congeal and clog some ports or the radiator itself.
Does the temp gulp when it first starts up? I mean like when you first start the engine, and the temp passes the 190 range and gets up to like 210, then gulps back down to 190. Then slowly creeps back up till ur running too warm? This is an indication that you have air in your system from a possible head leak.
Good luck and let us know what you find.
Thursday, July 13th, 2006 AT 5:00 PM