compression test, stethascope, ect. did your car overheat really bad, or just for a second? if it went for a while, it could be a bad bearing, warped block (doubtful) head, headgasket, it could be almost anything, but get a stethascope on it (you can buy one at an auto parts store) and listen to each cylinder, then do a compression test, if one is off by more than 15-20 psi, it is pretty much screwed.