Re: Overheating

Posted by Tim Cole On 2012/5/31 19:11:00

Dear wedrivethemall:

I assume you can blow through the heater hose going to the cylinder head. Sometimes those valves are clogged or soldered shut to prevent leaks.

The check what OD said about the oil cooler housing is an easy test. Take off the radiator hoses and fill the system with a hose via the motor outlet. If it backs up easily you have a flow problem. If you want to use a block off plate the water jacket needs to be modified from the backside to allow flow.

I once dealt with a case as follows: The temperature gauge would read 160-180 and it would spout water out the radiator. My inclination was cracked block so I called around for a place with a five gas emissions analyzer to test for CO in the radiator vapors. I got absolutely nowhere because nobody understood what I was talking about. "You want to test whaaaat?"

So I bought some CO test strips from McMaster-Carr, put them under plastic cup sealed to the top of the radiator, sealed the overflow tube with a cork, and ran the motor.
When the test came back negative I fixed a hole in the filler neck, made a new seal for the radiator cap, lowered the overflow tube (it was even with the very top of the filler neck), and let the coolant seek it's own level.

Sometimes these old motors have have problems when the coolant level is too high. I dealt with a Caddy 12 that did the same thing for years. If you filled the coolant too high it would spout out the radiator cap until it got to a certain level. The temperature gauge never got very high. It could have been cavitating, but it didn't use water and so the owner jut drove it that way.