it runs great. its all good until the temp gets to just over half way mark.then the coolant comes back from the motor into the overflow tank, and gushes out. when i shut the car off it goes back into the motor.

i just put a new waterpump in it, tried 2 thermostats and i checked and the radiator isnt clogged. i noticed theres a sensor on the thermostat housing whats that do? and what else could be wrong?

it also did this before i just put new head gaskets in, which is why i had to fix that i guess.