Possible Causes in overheating :
1. Engine coolant level may be very low.
The Fix: Refill coolant to proper level.
2. Engine's drive belts may be broken or slipping.
The Fix: Tighten or replace belts.
3. The electric cooling fan may not be coming on.
The Fix: Repair or replace cooling fan. Repair wiring. Replace cooling fan temp sensor.
4. The ignition timing may be set wrong.
The Fix: Adjust ignition timing.
5. There may be a vacuum leak.
The Fix: Check and replace vacuum lines as required.
6. The engine may have mechanical problems.
The Fix: Check compression to determine engine condition.
7. The engine's thermostat may be stuck closed.
The Fix: Replace thermostat.
8. There may be a leak in the cooling system.
The Fix: Repair leak and refill coolant. Cylinder head gasket(s) may be bad.
The Fix: Replace cylinder head gasket(s).