Well when i bought this car they told me the head might be blown. The water pump was shot and it had overheated. It would start but had excesive amout of white smoke out the muffler so i draind the fluids I got new water pump in it and we used water glass in it to fix the crack. The white smoke has stoped i mean there is nothing comeing out the back. It runs nice to hits highr rpms nice and everything(Drives like a fresh bat straight out of hell hehehe) But when i drive it it will start heating up so ill turn it around to get it home befor it overheats but it will heat up alot but as im still driveing it home will start going down and go back to normal. What do you think it could be im about to go pick up a new thermostat but im still kinda clueless of whats going on. I would think if the head was still crackd it would heat up and stay there and blow something not start cooling it self down. If you know or got any ideas what this could be i thank you lol.