Overheating issue

My fiancee has a 2001 Eclipse Spyder GS that seems to overheat at times, usually when in traffic or parked after a long drive. The temp guage rises quickly and then falls after she drives again. She said she can hear the fans turning on, but never popped the hood to confirm. The car has been to the dealership 4 times for this problem: they replaced the thermostat twice and purged any air out of the radiator, but the problem still persists. Any other ideas on what to check? Her commute is stop and go traffic for an hour+ and we really can't afford to replace an engine right now. Thanks!

There's not much to the cooling system really.  There's the coolant, thermostat, fans, the lines, temp sensor, fan switch, and radiator cap.  Two have been taken care of and one is probably good (still good to check the fans though), so that leaves the rest.  A bad seal on the rad cap can also cause overheating because it will allow air in and pressure out.  Pressure is the key here.


...and welcome to MF.

Thanks for the quick reply. Maybe I'll start small and get a new radiator cap to see if that has any effect. Can these be bought at the bigger auto places like Autozone or Advance Auto? Or is there a good online source for these? Thanks again!

Your problem may just be a bad sensor.  I had the same problem on a '95 grand prix that would run hot whenever I stopped but when I resumed driving, it would drop the temp back down to normal.  If your water is boiling in the resivor then you are over heating, if not, more than likely a bad sensor.

That is true.  A bad sensor can and will give high or low readings in any car.  Try that first, their not expensive at all and are fairly common things to go bad.

This could be 1 in a million things.
 
Shal we start eliminating them?
 
however unlikely.. here they are. Radiator cap, sensor, thermostat, fans, coolant levels, coolant leak.

Don't forget to check your moo cow...  ummm, I mean, hoses

Thanks guys. I'll start with the radiator cap and sensor to see if that helps. Do these cars have 1 or 2 fans? Is it possible that one of the fans (if applicable) isn't working? Maybe a bad relay switch?

I had this EXACT problem with my GT... turned out there was a 'blockage' of unknown origins in one of the lines. (This is according to Mitsu. after I had service done and that problem started occuring.) Got a system flush done (pro bono, by Mitsu.) and never had it happen again.

OK...the overheating problem is still happening and the fiancee and I took the car to another dealership. They seem to think that the AC condensor may be the culprit. Would a bad condensor cause overheating? Thanks!

Does the AC condenser affect the temp even if you dont have it turned on?  My car has the same temp issues wether the a/c is on or not.  Let me know if you ever did figure out what caused the temp issue.  I already replaced my radiator cap and flushed the radiator.  Now, I'm going to get the thermostat replaced.  I guess the coolant temp sensor will be after that if the new thermos doesn't fix it.  Did you ever replace that sensor?