I have a 2003 civic with 120k+. When I left work today it got really warm. (It didn't over heat, but it's usually about 50% and today it was 75-80%) I checked the oil and antifreeze and it was fine. I started driving again and it started heating up again. I turned the heat on to cool it off and it was blowing cold air. After just a few minutes it started blowing warm air and the temp went back down. After that it was fine for the rest of the way home. (about 10 minutes) When I got home I got the mail and sat in the driveway for a minute and it heated up again while I was sitting there.

Any idea what the heck is going on with my car?

Thermostat. Not a hard fix. $15 part and you can probably do it yourself.

You turned the heat on to cool it off?

I Wear Pants;627490 wrote:You turned the heat on to cool it off?

Yes, that can help a car cool down when it's over heating, or so I've been told.

hilliardfan;627404 wrote:Thermostat. Not a hard fix. $15 part and you can probably do it yourself.

That would be my guess as well.

I Wear Pants;627490 wrote:You turned the heat on to cool it off?

that is the first and most obvious thing to do to prevent overheating

keep an eye on the coolant. also check to see if the color of the exhaust is more cloudy than normal. hopefully it isn't something like a gasket.

Thanks for your suggestions guys. I'll try the thermostat and see what happens next.

If its not thermostat its water pump

I'm not sure if they did a good job, but the timing belt and water pump were just changed about 10k miles ago.

you'd notice it in 10k miles. Sounds like a thermostat to me.