Cadillac Repair: 1986 Cadillac Deville runs hot, cylinder head gasket, radiator cap

Question
My 1986 Cadillac Deville four dr. runs hot in city traffic. I lose the water and coolant when it does this and it steams. I replaced the thermastat, sealed the linking end tank on the radiator, checked the water hose and even took out the thermastat and it still gets hot. It has a 4100 engine.

I would appreciate if you would help me with this problem.

Thank you.  Joe   jomil@gator.net  

Answer
Hi Joe, You didn't mention anything about the cooling fans turning on. A temperature sensor, fan motor or fan module could be bad and further testing will need to be done to isolate the problem. If you start up the engine cold with the radiator cap off and with-in 2 minuits coolant is bubbleing out the radiator then you probbly have a bad cylinder head gasket, cracked head or broken head bolt. You still don't have a cardboard in front of the rad or the rad isn't restricted with dirt, leaves etc is it? A rad cap that can't hold pressure, the wrong consentration antifreeze mix, or timing too far advanced would make the engine run hot. The engine will run the best with the thermostat in so make sure you reinstall the one it is supposed to have which is a 195 degree. Bill