Something freaked me out today while driving to work. I was stopped at a light and I noticed that the gauge indicated that the coolant temperature was slowly creeping up. After the light I continued to drive for a little bit and gauge almost went into the red zone.

Just as I was about to pull over it quickly dropped back down to just under the middle, where it usually sits. I kept my eye on it for a bit and was a little jittery. It never went that high again but it waver around the middle.

Anybody experience something like this? I'm almost due for a oil change at 90k miles.

 

Check coolant level, maybe there was a bubble in the system. I ran into this several times with my bmw, I just needed to bleed the system better. This is, of course, a best case scenario. Good luck.

 

Yes, there could be air in the system. It could be caused by a bad water pump (very common on 2IS models, look for pink coolant running down the front of the short block) or somehow air trapped in the lines. To remove air try this :

*Park on an incline (front higher than rear)
*Remove radiator cap
*Plop down a catch pan/canister/etc
*Start the car
*Every few minutes flip the HVAC setting from cold to hot to cycle the coolant through the heater core
*You should top off coolant to the top of the radiator any time the level dips (typically does this when the fan kicks in)
*When you think you've watched enough of the bubble escape from the open radiator, cap it.
*Drive it.

GL!

 

could be a lose or dirty temperature sensor connector.

 

I'm fairly sure its just low on coolant now. I just remembered that my heat recently sort of stopped working normally after I replaced my AC compressor. I'm having my mechanic look at it tomorrow.

 

This happened to me recently. I got into an accident a while ago and I removed the radiator and that drained out about a quart of coolant. I didn't refill it since the coolant was at max on the overflow tank. I was driving home from school and I usually never look at my gauge but I noticed it was one tick mark from the "H". I pull over for a few minutes and it randomly went back to the middle. My heater wasn't working either unless I was going past 3K RPM. I opened the radiator cap and noticed nothing inside so I poured a quart of coolant in and my heater worked and never went beyond the center of the gauge again.

 

lameeeee. Just found out my radiator is leaking and i had almost no coolant in the car. Dealer told me they pressure tested the coolant system.