Cooling/Overheating issue

**Matto4785** · 05-08-2012, 12:37 PM

As the weather has warmed up I've noticed that the car(according to the crap stock gauge at least) is running hotter than normal and occasionally climbing to near red. No consistent pattern.

Normally, the needle would be just under the halfway mark. I know the stock gauge is not remotely accurate. Now its normally just slightly over the midway point, and occasionally will climb between the 1/2 and 3/4 mark. Occasionally when I shut down the engine when the needle is in this range, the fans stay on after shutdown. It doesnt do it consistently though. Also the needle moves rather quickly in both directions, but not at a consistent speed. Like it would climb fast, stop, climb again, stop, sit there. I'll get the car up to speed and it will drop slowly, then quickly, sometimes pausing.

Sometimes highway speed will cause it to drop, or turning the heat on high, sometimes not.

The car itself runs fine. No missing, no rough running. No SES lights. Got the check gauges light once after I shut it down and restarted. The temp gauge was pegged, then dropped within a few seconds.

Not sure where to look since I cant trust the gauge.
Both belts are brand new. Water pump was replaced within the past 3 years. Coolant was replaced when the water pump was replaced. Not sure on thermostat. No coolant leaks either. Radiator cap is new within year. Radiator isnt blocked by anything and the chin spoiler is still there as is the radiator ducting. Fans still work from what I can tell. I can hear the secondary fan kick on and notice it on the battery gauge.

Bad thermostat maybe? Air pocket? Or maybe the temp sender is bad?

Any ideas?

**FinZ28** · 05-08-2012, 12:56 PM

I think a scanner that reads real-time data could tell you what the actual temp is. Having said that, I'd look at your coolant level and mixture. Sounds like your thermostat may not be working as it should, though. Be careful letting it get hot-you don't want to pop a head gasket and end up with bigger problems.

**Matto4785** · 05-14-2012, 06:05 PM

Sorry for the delay, got caught up at work. I swapped out the thermostat and drained and flushed the coolant. Temp issue is gone. The old thermostat had some rubber or rtv or something stuck in the middle of it.

Not sure if it was the tstat or coolant, but it seems good now. Gonna pull the tstat again in a month and see if there is anymore rubber or rtv in it. That kinda concerns me.

**2002ssslp** · 05-14-2012, 07:43 PM

That should do it. The thermostat only needs a dry gasket, no rtv.

**FinZ28** · 05-14-2012, 10:26 PM

Originally Posted by Matto4785:2775890

Sorry for the delay, got caught up at work. I swapped out the thermostat and drained and flushed the coolant. Temp issue is gone. The old thermostat had some rubber or rtv or something stuck in the middle of it.

Not sure if it was the tstat or coolant, but it seems good now. Gonna pull the tstat again in a month and see if there is anymore rubber or rtv in it. That kinda concerns me.

Glad you got it fixed.

**pajeff02** · 05-15-2012, 03:23 AM

As a general rule, any time you replace the coolant it is a good idea to change out the thermostat. The parts store cheapies are not the way to go either -- go with a GM or other quality brand replacement. A stuck thermostat that goes unnoticed can turn an engine into a boat anchor fairly quickly.