350 Chevy Cooling Question

[raritan]

Decided that the 350 needed a thermostat. The housing is a standard thermostat housing with a tube out of each side which goes to exh manifold. Started the engine.... Temp goes up to thermostat rating, water and steam exit exhaust, temp goes down, water stops going out of exhaust, temp goes up, steam and water come out of exhaust. Is this normal on an open system. The temp variation is at least 49 deg F.

[Moody Blu']

is the thermostat in backwards?
it sounds like the water is so cold that it hits the thermostat and closes up.

I dont know though. I'm guessing :D

[RickR]

Do not run your engine that way :eek:
You'll burn up the exhaust hose.
The hoses might be routed incorrectly.

[Murphy]

Raritan,

Go to this site: http://216.37.204.201/mercruiser_oem/Mercruiser.asp?Type=11&SubType=111

Go through the listing and find your engine so you can look at the microfiche for the cooling system setup. Your thermostat housing sounds like mine. If they're the same, the proper assembly and gaskets are important. When you remove the thermostat you should see a brass collar down inside the housing. If it's missing, that could be your problem. Also, when you reassemble the housing don't use any gasket compound. You need a a grounding style gasket (with grommets) for the gauge to work right. You can order everything you need from the website. Good luck.

Murph