Does anyone else have a coolant temp gauge that moves all over the place? During the warm weather the needle pretty much points straight up and stays. During the winter it only gets close to that if I'm traveling at 70mph, it's a little below that at 55mph, but in town, it struggles to get above the mark between the bottom of the gauge and straight up. As soon as I speed up again the needle goes up. The heater is so so. I'm assuming it's the thermostat, but when my Oldsmobile's went, the needle hardly came off the bottom no matter what the temp, and I had almost no heat. Any suggestions?

 

Not sure where you're located, but here in Wisconsin - in the winter, my needle is all over the place.

For instance: I have a 30 minute commute to and from work each day. Tonight, on my way home, I stopped by the gas station next to my place (2 blocks from home) to get some gas. Jumped out, fueled up real quick and got back in. In the 5ish minutes the car was off, the needle dropped all the way back to the bottom. Didn't even get back up to 'warm' by the time I got home.

Heater is strong.

Summertime - never an issue.

 

In Missouri (not as cold as Wisconsin) and the temp needle moves to straight up after about 10 to 15 minutes of warm up and stays there. If your heat is so so I would think the thermostat may be sticking and needs to be replaced.

 

Mine only wandered when the t-stat needed replacing. It's been rock solid since then. I'm surprised you haven't gotten the code for "cooling system performance" if it's that bad.

 

I live in west Michigan, and the car has done this for the last couple winters, but never this bad. I have a 30 minute drive to work, and if I'm going 70mph the needles pointed almost straight up. If I'm suddenly driving in town, the needle almost drops like a rock. I've never gotten an error code related to the cooling system, I might take the car to the auto store so they can read the codes.

 

Well, if you don't have any codes and your heat works, I wouldn't worry about it then. Odd that it dips when you're going slower (less air passing over the radiator).

 

I'm going to have to go play around with the heater controls. Normally I set the temp in the car at 68F, so the heater doesn't have to work that hard anyway. Last week I over road the settings and set the heater on high, and noticed that for being set on high the air coming out of the dash wasn't overly hot, just so so. when I did that with my Jetta GLX's climatronic, you could cook anything in the way of the vents.

 

Adding that to the wandering temp gauge, it really sounds like your thermostat is stuck open. I'm just surprised it hasn't tripped the code (I think it's P2181).

 

Apparently my car has a high tolerance for being out of manufactures specs. The codes for the cam follower didn't trigger until more than just the pump and intake cam were damaged, so it doesn't surprise me that it won't trigger for the thermostat either. It's just like me, it doesn't like going to the doctor until things get really bad.

 

Well, went to Auto Zone, and sure enough code P2181 popped up, and it is related to the cooling system. Interestingly, both this code and the code for the bad diverter valve, didn't trigger the check engine light. Must not be important enough. The check engine light does work, as it comes on with the other warning lights when you start the car.