Overheating

First fill coolant then pressure check for a head gasket leak you can also by a chemical tester at auto parts. Also, when engine is warm, stop engine, disconnect radiator fan and check radiator for cold spots if any the radiator is bad.

Do the cooling fans come on before it overheats? If they are not operating it could cause the engine to overheat. Usually this shows up as an overheating issue while stopped in traffic or moving slow and the temperature appears normal while at speeds over forty five mph or so.

If the fans are operating and the overheating is still occurring it could be a failing head gasket. To test that you put a pressure test unit on it while cold. Start the engine and watch the pressure. It should stay close to zero until the engine actually warms up. If you see the pressure start to jump up as soon as you start the engine you are seeing a bad head gasket. To verify that you can put a combustion gas detection kit on the radiator and watch the fluid to see if it turns color (blue to yellow). If it does you have confirmed the problem. Both of those tools can usually be rented/borrowed from an Autozone, Advance, O'Reilly type store. In most of them you actually "buy" the tool and when you return it in the same condition you get the money back.