96 sunfire overheating (help!!!!!)

[natmil]

ok I acquired a 96 sunfire from my father in law for free. the car runs very well for its age but it keeps over heating. I am completely baffled by this. I have replaced the thermostat(x4) heater core, head gasket, water pump, and radiator. I am on a mission to get this thing fixed because all the parts are super cheap so I don't mind replacing them. the sunfire has the 2.2l motor in it. what is driving me crazy is that I have ran the car with no thermostat and it will not over heat at all. went on a 3 hour drive with the thermostat out and it toped out at about 170 degree on the high way after a while. as soon as I put the thermostat back in it goes back to overheating. at first I thought I bought a bad thermostat so I bought another and another until I had 4 brand new ones. I thought they all cant be bad so I boiled them and sure enough they all opened at 180 degrees. so im wondering what I should try next? I cant figure out why the thermostat wont open when its on the car and also there is no heat when the thermostat is in aswell.

 

[melsg5]

You should run the car with the correct thermostat which is probably 195. The car is computerized and is designed to work with that temperature themostat. On your overheating the one thing you do not mention is the electric fan for cooling. It should kick in at around 215 and also if equipped with A/C immediately when the A/C is turned on. Does the cooling fan turn on when you turn on the A/C? With the A/C off does the cooling fan run when the car is overheating? How are you determining the car is overheating, just by the gauge reading or is the coolant boiling over? When you changed the radiator did you also change the cooling system pressure cap?
When you changed the head gasket did you have the head checked for straightness and cracks by a machine shop?

 

[Baldan Dugly]

Melsg5 is correct. You didn't mention the fan. The relay may be bad.