1986 v6 3.8 L. I am having trouble with what started as a coolant leak. Took it to a mechanic and he 'changed the thermostat' and one section of rubber tubing. I am wondering if he put the thermostat in upside down. mine is a mount on top of intake that faces up (not the side mount). Should the long end point up or down? if that is right, what would cause the car to go from no temp registered to pegging out in seconds and then having the overflow boil antifreeze everywhere? I started to go after the head gasket and am wondering if I am overthinking it and is is something minor. when I released the stopcock on the radiator, nothing came out...so what if the radiator was blocked? any help? thanks in advance.