Ah Ha! Radiator pressure tester makes a discovery. 2 leaks (not in the radiator). One is (I think) where the thermostat assembly connects to the head. Pretty good leak there fluid poors down the block right underneath that connection. Probably will need a new gasket there. The other is somewhere underneath the throttle body. Slow drip from that one. Must be a hose connection somewhere underneath there that needs to be tightened.


Judging from the amount of fluid loss from a COLD motor test. The cooling system could never come up to pressure when hot and was keeping it from being able to cool causing the boil.

Thank You Autozone