I assume coolant disappeared meaning coolant loss. First thing you should do is flush it and then refill properly with coolant. By properly I mean there should be no air bubbles in the system. Clean up the spark plugs, rad cap, inlet & reservoir. Then use the car for a day. After that you can do your diagnosis.

Things to look for are:
- Color spread around the engine & rad coolant inlet. (hose/radiator leak, thermostat)
- Coolant level in the reservoir. It should be over max when hot, down to max when cold. (hose/radiator leak)
- Coolant shouldn't have faint petrol/exhaust smell in it. (gasket leak)
- Exhaust smoke shouldn't be white when hot. (gasket leak)
- Fan should be running properly. (fan motor, electrical)
- Coolant shouldn't jump out like spring when start the car at cold and rev it. (gasket leak)
- Coolant should be flowing out the inlet/through steadily when car is running. (water pump, electrical)

The cheapest stuff you can replace are:
- radiator cap
- thermostat
- fan motor

This post has been edited by eek-1: Feb 13 2012, 01:49 PM