Cooling System

Last summer I was driving my 1990 LeSabre LC and the temp gage suddenly went up. I didn't worry too much about it because when i slammed the dash it went back to normal. The seemingly simple problem is now starting to get to me. I replaced the thermostat and put a new radiator cap on it but it has over heated a couple of times since: once while doing 20mph on a dirt road, once while flying (85+) on my way to work, and once while cruising at 55. I took it to the mechanic and he drove it around and it never heated up for him. He took some readings and said that they were all normal. Does anyone have any idea where my problem may be hiding?

Thanks,
Hot n' bothered...
Greig8

The readings were as follows:
Cooling fan 1 on at 220F
Cooling fan 2 on at 238F
Flow ON
Average Engine Temp. 224 (???)

While I was driving the the other day I took a short vid of the guage. The needle had crept up and was sitting in the red and then it suddenly dropps back down to the regular temperature. I showed the mechanic and he said it could be the Temperature Sender/switch. He is replacing it tomorrow and I pray that this is finally gone.

Greig8

Your coolent could be mixed wrong, with either too much coolent or too much water. It is possible (but highly unlikely) that your new thermostat is sticking or not opening all the time as it should. Maybe your oil pressure or level is low causing your engine to work too hard and overheat.

If your car overheated three times then how could your problem be a temperature sender which if faulty would send a hot signal when in fact your car was NOT hot (but it WAS hot three times)?

After your mechanic changes the temp sensor, be sure that he bleeds the system also.