The Stovebolt Site Forums The Shop Area Engine Shop One problem and then another

Hello:

How grateful I am that there is a forum as this to bring my problems to and come across some truly insightful people like yourselves that have the answers! First it was the carburetor that won't keep it's prime now it's the engine overheating. Chevy 216, newly rebuilt, new water pump, hoses, and thermostat, etc. Has a Harrison heater which is hooked up. Started the engine the other day and ran it for about 5 minutes, it boiled over and spit out most of it's coolant. Thought the thermostat was in backwards so I turned it around and reassembled. Refilled coolant system and started and ran it for two minutes and it started to boil over again but I shut it down before it got to bad. Seems like little or no coolant is getting through the engine, as if it's full of air or could there be air in the lines to the Harrison heater? Any thoughts on this? My stupid question is this, the thermostat, does the spring end of it point up or down when installed, there is no flow direction on it? Thanks I appreciate it. Any further insight on my previous fuel and carburetor question is also appreciated.


Dave

Just think, the end that has to heat up and move the piston is what goes on the engine side. So the longest end would go toward the engine, the side with the spring.

It is possible to have a new but bad thermostat.

Another way to make sure there is no air bubbles is to remove the temp gauge probe/sending unit.

take the thermostat and put in a pan of water on the stove and heat the water till it opens. just to see if it does open. the spring goes down towards the block. also i like to fill the block through the thermostst housing that way you know it is not air bound.

Guys:

Thanks, I appreciate it, could the heater be holding air in it? And the temp probe is a great idea.

Dave

You can test the thermostat in a pot of water above the rated temperature of the thermostat. Put it in and see if it opens. You can run the truck without it to see what happens. It is designed to stay closed until the rated temperature is reached and then open. This gets your engine up to temperature as fast as it can. There is a wax filled capsule that melts at temp and expands to open the valve. It wouldn't hurt to try it without it to see what happens. You could have a hose collapsing on the suction side of the water pump. A fuel mixture that is way to lean will burn to hot. You can bypass the heater with a hose for the time being. Could be a stopped up radiator. I have seen the fan on backwards but that would show up when you were driving at the speed to cancel the air blowing through the radiator with the fan blowing through. Test the thermostat and go from there.
EDIT: Boy you guys are fast by the time I finished typing you had already said it all.

Have you drilled a small hole in the thermostat to allow air to escape when filling with coolant?

The same thing happened to me when I replaced the water pump and thermostat. Finally I would let the truck cool down, let some coolent out, refill with water, ran the truck until it started to over heat again. I did this three times and finally it stopped and I haven't had a problem since. I'm not sure why this happened but I'm thinking air.

Iron Clad

I typically leave the T stat out while filling the radatior. This will push the air to the top and as you watch the water leval rise put the t-stat in just b4 water reaches threads on the housing.

Bad t-stat possable
newly rebuilt? did the head gasket get put on backwards and block a water port?
Leaking head gasket?
bad pump/ loose /damaged impeller-it happens not often though
somebody already mentioned collasped hose and/or plugged radaitor
if it overheats again check for cold spots on rad

Good Luck and let us know what you find
Brad
most likely Air in system take stat out and let set a while to see if leval goes down