The Stovebolt Site Forums The Shop Area Engine Shop Ideas about overheating engine

I have a rebuilt 283 in a 1957 Chevy pickup. It has a new short water pump with a Edelbrock intake. I'm using my original radiator (formerly a 261), I installed a fan shroud. The thermostat has been replaced. It overheats, but it appears as if the thermostat is not opening, since the fluid in the radiator never seems to heat up. Also, I get no heat out of the heater, which makes me think there is no circulation. The timing seems to be roughly correct. I'm wondering if I'm getting cavitation in the water pump. I have tried running without the radiator cap initially to remove air pockets. Any thoughts about what I could try next would be appreciated.

Take out the thermostat. See if that makes a differance.

Dan Bentler

Have you tried running the engine without the thermostat installed to see if it circulates ? With the radiator cap off you can look in the radiator and see if there is any ciculation in the radiator. And when you test the flow with the thermostat out, and it circulates. Then you may have accidently put the thermostat in wrong or it could be bad or you may have gotten the wrong thermostat.

How long does it run before it gets hot?

Sounds like an air pocket behind the thermostat. Drill a small hole in the thermostat flange to release the trapped air. Also, park it on the steepest incline, nose up, to help burp the air out of the system,
Scott

Seems like everybody was on track. I took out the thermostat and drilled a small relief hole as Scott suggested. It worked great. The engine had been sitting for about 3 years (which I neglected to mention), so maybe that contributed to the air pocket issue. In any case it works great now, I thank all of you for your responses. This was really getting on my nerves (and the antifreeze was getting on the floor). Thanks again, much appreciated.
Don