check the thermostat. if it stays shut, thats your problem. also, run idle and do as he said and check and see if fans are coming on. haha, you have what i have, an air cooled engine. except when i drive it stays cold. kinda like a motorcycle. but that's because i took the thermo. out and put a metal ring in it's place. but def. check the fans and see if, when it overheats, it boils over or atleast trys to boil over at the radiator cap.