def sounds like a head gasket or a head. Probably nothing wrong with the block because I think it's made of cast. It usually is worth getting a new head, but sometimes it can get expensive if you can't do the work yourself. The easiest way to tell if it's def the head or the head gasket is to look at the oil, if there's water in it, it's one of the two. probably the overheating is because your losing water in motor, and when the water gets low, you overheat.
