Could be the coolant temperature sensor or a bad thermostat-or an AC idle up solenoid not coming on to compensate the load of the compressor.
Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.
Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.
If the block and pressure test passes check the following: Thermostat, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.
Hope this helps-Good Luck
Friday, May 18th, 2007 AT 5:56 PM