Let us go through the checklist and see if we missed out anything.
1. Coolant in radiator is good.
2. Reserve tank requires topping up. This indicates a leak in the cooling system. A pressure test would be required to find out where the leak is coming from.
3. Head gasket replaced. Was overheating the reason for replacing the gasket? Did you reface the head? Was the condition of the engine block surface checked for eveness?
4. Radiator fan running but only at 3/4 gauge reading. This would indicated the fan is running too late. Disconnect the fan switch wire and use a jumper across the wire connector terminals to run the fan full time. Test if overheating occurs. If fan is turning on too late, the fan switch is the most likely culprit.
5. When reserve tank was full and steaming, was the fans running? After engine cooled down, was the reserve tank coolant absorbed back into radiator?
6. Radiator cap and thermostat replaced.
7. Cruising speed no problem with overheating.
This eliminates a fault with the thermostat.
Occurs only when climbing hills. This could mean partially clogged radiator or weak water pump.
Occurs when at idling. This could mean the fan is not working or there is air in cooling system.
Monday, September 7th, 2009 AT 8:20 AM