71 350 running hot coolant backup up problem

[Gregski]

Originally Posted by dozerbill72

Do you know the condition of the radiator?

good question, it came out of a 1969 donor GMC truck, from a guy that I bought the 12 bolt rear end, is it the original one I doubt it, it is a metal one though, very OE like copper/brass material not the plastic aluminum type

I flushed the heck out of it forwards and backwards and it does not appear to be clogged and the cooling fins seems decent and straight

I pressure tested it before putting it in, it was installed to get me by until I can get a brand new one, well the place that sold me a radiator for my '74 said they don't make one like it for this '71 so I am still getting by with this one

did some 15 PSI pressure tests of the system last night and the only tiny leak I can see is from the thermostat housing gasket area so I will work on that today