i wanted to see if anyone had any ideas on what could be causing the coolant in my car to build up pressure and start pouring out into the overflow. It fills up the reservoir and eventually sends it out the little vent hole on top. The engine is a 1978 302 bored 30 over with flat top pistons, edelbrock 4 barrel intake mild cam with 1963 260 heads. engine is in a 1963 ford falcon. everything in and on the engine is new + freshly rebuilt heads, and the block was cleaned before assembly. also car has a large aluminum radiator and fan. if i try to drive the car more than 10 miles i have to pull over and drain the overflow and pour it back into the radiator. it doesn't get hot (which i've never let it get too hot) unless it loses too much coolant. engine has done this since we first assembled it. surely someone else has ran into this. bad head gaskets? coolant "jackets" clogged? thanks if you can help

 

I don't know if this is the answer to the problem, but if there is no spring in the lower radiator hose it will collapse from the suction of the water pump and cause the water pump to suck in air through the shaft seal and thereby creating excessive cooling system pressure.

 

i'll have to check but i'm assuming it does or at least shouldn't collapse. the hoses were new and the correct ones. thanks