I was in traffic yesterday, and my temp gauge kept going up at idle and back down at acceleration. I pulled into a parking lot to take a look at it, and the car didn't seem to be overeating or nothing, at least that's what I assumed. Today it did the same thing. What could be wrong? I have to drive 30 miles to work tomorrow, and I'm afraid to take the interstate with it. Any thoughts? Thank you.

 

Are your fans coming on? Check/replace the thermostat would be one of the first things i would do if the fans are coming on, also check to make sure you have adequate coolant in your radiator.

 

Yes, the fans coming on fine.

 

When you mean goes up, do you mean goes up a few ticks past the middle, or goes up a lot (as in 3/4 of the way to overheated)?

 

3/4 at most and then goes back down.

 

Since your fans are coming on and you have adequate coolant next step is thermostat.

When you start your engine cold see once temperature level goes beyond normal level on a gauge try to feel rubber house that connects at the top of the radiator if it is still cold it means that thermostat is still closed when it must be opened. Do not drive. If you must drive remove thermostat and drive without it.

 

Have you checked the coolant in both the radiator and the coolant reservoir while the engine is cold?

Make sure the radiator is filled to the bottom of the filler neck, and the reservoir is filled to the upper line.

 

It looks like I'm losing coolant. Reservoir is empty, but i added some the other day.

 

Still could be failed/failing thermostat, start by testing it unless there is an obvious leak.

 

I bled the system this morning and filled the reservoir to maximum. I drove about 60 miles, and the coolant level hasn't changed; the temp gauge hasn't fluctuated either. I don't know if that might have fixed the problem. Therefore, I'll check it again in the next couple of days.

 

When I have my obd app running my coolant on 90°+ days in stop and go traffic will get just over 200°. My intake air gets over 60° above ambient, but while cruising my intake air is between 10°-20° above ambient.

Do yourself a favor. Buy a elm327 and get the Torque app for android. I've cleared and read so many fault codes, and the other options make paying for the elm327 well worth it.

 

The coolant does evaporate over time, so just check the coolant every time you check the oil and other fluids. You may end up adding up to a gallon of coolant between timing belt/water pump changes (or over 7 years or so) because of that.

The coolant is pulled from the reservoir into the radiator, then dumped back into the reservoir. The radiator will thus have some coolant even if there is none in the reservoir, but the evaporation loss will first show up in the reservoir level.

Hopefully you've only got an evaporation loss and no other issues.