[chucksue]

I have a 35 ford with a 37 flathead. New water pumps new core new thermostats. When the motor is cold thermostat is closed. Motor warms up thermostat open. I plugged the overflow tube and drilled and threaded a fitting in the radiator cap. Put a balloon on the fitting and started the motor. The balloon didn’t inflate so there isn’t any compression leak in the head gasket. Yesterday I went to a Route 66 cruise and when I stopped the car at different places the radiator would overflow out the tube. When I got home the antifreeze was down 2 gallons? Any ideas.