[super_kit_car]

you need to do a cooling system pressure test to determine the problem. there is a pump that screws on where your radiator cap was. you pump it up and look for leaks. if it is the head gaskets, you will see fluid come out at the bottom of the heads near the exhaust manifolds. if you find a leak correct the problem. also, are you losing water or is the gauge just jumpish, could be a faulty ground or gauge. if you are not losing water, it's the gauge or ground.