Heres the deal.... I floor it in my car and the temp gauge skyrockets to 240+ then it sticks there I have to shut it down and let it cool.

The hose isn't hot neither is the radiator. There's plenty of fluid in the system. If i turn the cap hot water moves into the radiator, you can feel the difference. There's nothing the coolant to look like a blown head gasket and i had a buddy follow me there is no white smoke.

 

Stuck open t stat?

 

+1. Check the tstat.

 

Is this on a mod motor?

 

If you run it without the cap, or the cap loose, can you tell when the t stat opens, and can you see the water pump moving coolant? Any chance water pump is turning wrong direction.... happens more than you'd think on the sbf's.

 

Its a 93 5L. I will check to see if the tstat opens in the car and also water pump direction. Will report results!

 

It was getting flow but not much. Took out the tstat and put it in a pot to bring to a boil. It only opened just a hair even with the water at full boil. Got another swapped in there and the problem is gone.

 

You get a gold star for fixing it !

 

Great find !

 

I think with it opening just a bit it could keep the engine cool enough with normal driving but once I got the temp up with WOT it couldn't keep up and would never bring it down.