Contour Enthusiasts Group Archives Forums General Troubleshooting erratic temperature gauge

I changed my coolant October of last year at 54k miles, from regular stuff to the orange long-life stuff. I flushed it out pretty good in the process. Drove it all Michigan winter with no problems except the temp gauge was always on the low side compared to before, between "N" and "O." of "NORMAL."

Now the weather is warming up and the temp gauge seems to be changing from day to day. It has 61k miles now. Sometimes it barely makes it pass the normal range, other times it goes up to the "R." More often than not it still goes up to bewteen N and O. It doesn't seem to change much during the drive except for couple times when it did move to as far as the "A" then back. That was in heavy city traffic but it worried me. I would like to know what may cause this and if it's a problem. The water pump is still original, but I don't think it's the problem because it hasn't overheated and most of the time it's very cool. A sticky (but not stuck) thermostat perhaps? I do plan to change it to the metal impeller kind when I fix this erratic gauge problem.

I've installed (very recently) a new pump, new t'stat & new cooling fans. When I'm tooling along, the needle hangs around the N-O range. In traffic, on a warm day, A/C off, it may get to the R-M range where the cooling fans cut in at low speed then it drops back quickly and the fans shut off. On a really hot day (>90 F), in traffic, A/C on, it sometimes makes it to the M-A range and the cooling fans go from low to high speed, it then drops back fairly rapidly to the O-R area.

If the A/C is on, the cooling fans will run at low speed all the time, which tends to keep the temp at O-R or lower except when in very hot stop & go city traffic when it's like stated above.

It all has to do with at what temp the t'stat opens, whether the fans are already running at low speed and at what temp the PCM decides to bump the fan speed up to high. Sounds to me like yours is working OK.

My car is almost the same exact way. I worry sometimes, but it always ends up cooling down.

mine was exactly the same way, right before my wp went. Since I changed the water pump, the needle never moves past r. And that is if I'm driving it really hard. Usually it stays right on the o. I would very seriously consider changing the waterpump RIGHT NOW!! Even if you were not experiencing symtoms yet, it should be done. The plastic impellar wp's usually only last about 50,000 miles before going. Since you're past that... Such an easy thing to do, so cheap, and could save you so much in the long run. also, if the temp goes up and then all the sudden drops back down (much quicker than the fans could cool it down) then this is def. your wp. I'm not trying to definatly diagnose, or scare anyone, just trying to help.

Brad10071977 & MassContour:

If you look at the strategy the PCM uses to turn the cooling fans on, that kind of fluctuation of the temp gauge is normal when driving in stop and go traffic, on a hot day, while doing a lot of idling. If you're out in the open, on a hot day (90+ deg F), tooling along at over 35-40 MPH, I'd say that temps higher than the "R" on the gauge MIGHT be cause for concern. If it's over 100 deg F outside, you just might expect to see readings close to mid scale while cruising along.

This all assumes you have a stock 'stat and normal PCM programming. Guy's like Demon with 160 deg 'stats and tweeked PCMs will prolly read lower on the gauge. If the car's sitting still and the fans aren't running, there ain't a hell of a lot of cooling going on.

As I said before, if your cooling system's healthy, the A/C's on and the low speed fan circuit is functioning properly, you'll prolly see lower temps and less fluctuation because the fans are running on at least low all the time.

"I'd say that temps higher than the "R" on the gauge MIGHT be cause for concern."
Right. He said it went up into the A, a couple of times. Could be nothing, but the water pump needs to be changed anyways...