2003 Track Package, all stock.
99,000 kilometers

My water temp gauge seems to have started fluctuating a lot while driving... It's completely random, low speed, high speed, low rpm, high rpm, doesn't matter...

But the gauge has started to go higher than the usual 1/3 of the way up. It seems like having my AC on makes it more likely to creep, and it will go to about halfway, sometimes just over halfway... If I turn my AC off the water temp gauge usually comes back down...

It will also creep up without the AC on sometimes... Fans seem to be working just fine, and I jacked up the front of the car and took of the heater bleeder screw and the rad cap and ran the car for about 5 minutes... Zero air bubbles came out.

Any ideas what I should check first?
Why would AC put more load on an engine to make it hotter?

Got a 3000km road trip coming up and need to get this sorted out... Thanks.

 

Sounds like you could go for a good radiator flush. Get some new fluid in and clean out the system and it would be a lot more efficient at maintaining temperature. The fact that the temperature doesn't *keep* climbing tells me that your thermostat is working, your cooling system is just not as efficient as it should be. Something else you can check is the seal on the cap of the radiator - if there's not a good seal then it won't hold pressure making your car run hotter.

 

Drove some more testing things out...

It's weird because this was happening last week, but last night I was cruisin around with no issues at all.

Just now, I was at a red light and the temp gauge started to creep up to almost 80%... I can hear the fans on. Light turns green and I get up to about 60km/h and within 5 seconds temp gauge goes back down to normal temp...

Get onto the highway (going about 100km/h) and the gauge is sitting at about 50% so I tried a couple things... If I put the car into neutral (still going 100km/h) and coast, the gauge goes up to about 80% withing 10 seconds... Put it back in gear and within 10 seconds it goes back down to about 50%... I tried this numerous times just to make sure it wasn't a coincidence.

Any ideas??

 

Ahhh, it's your thermostat sticking. Sit at a red light, let the temp go up a bit. Once it's over 50% then rev the engine and hold it to about 2k RPM. If the temp on the engine starts to go down after a minute or so then it's your thermostat. I had the exact issue on my honda.

 

I had the same issue recently however my drivers side fan quit working hence overheating while sitting still. Replaced thermostat previously at about 85k miles.

 

Anyone else have any input?


Is there no way to troubleshoot and eliminate possibilities without changing things?