Within the past six months, the temperature guage on my wife’s 1996 SC2 (70,000 miles on it, by the way) started showing that the car was over heating. We flushed the radiator, replaced the thermostat, replaced the temperature sending unit, replaced the radiator (the old one was fairly gummed up), and replaced the water pump. The radiator cap is just fine. The temperature guage is still showing that the car is overheating… the thing is, the fan is coming on like it should, and I have driven it a while with the temperature guage in the red without the car blowing up (it was an experiment). What is going on with this car? Why does it insist that it is still overheating?
You could have a blown head gasket.
You did all that work and cheeped out on the radiator cap???
Anyway I doubt if it is the cap. How is the radiator fan(s) doing?
Sorry to say it but it sounds like a head gasket to me.