Getting some odd readings on my temp gauge.

On the drive to work, early in the AM, ambient temp about 70 deg. F, the gauge reads at about the 9:00 position, which has been the "normal" position since I've had the car. It's about a 20-25 minute drive, and the gauge reaches its "normal" position within 5 min or less.

In contrast, on the drive home from work, ambient temps about 90 deg. F, the gauge reads quite a bit higher, almost 3/4 of the way up the gauge, and stays there. In the past the ambient temperature did not make much difference at all on the temp gauge reading, even driving for longer stretches, or in stop and go traffic, etcetera.

Any ideas on what could be causing this new behavior? Thanks in advance...

Yeah, I have a temp guage that'll read 3/4 when I turn on my lights (I pretty sure that there is some type of short behind the guages...the fuel guage goes whacky, too). ANY other time (no matter the temp...it'll be below the half-way mark.......

It sounds like your car has been behaving for a long time. It might just be the thermostat because if its been in there a long time its probably bad. I usually change mine about every 3 years or so. The thermostat regulates the temp. You didn't mention if the afternoon drive was with the

a/c on but that will raise the temp a bit. My mothers 90 ran hot only when

the was A/C on. The car ended up getting a radiator. The radiator clogs very slowly. It might be OK after the thermostat and a flush

since you have the older radiator. Good idea to make sure there isn't any leaves and crap clogging the fins in the radiator, also.

Dave 82 242ti

BTW, you mentioned that I have "the older radiator". Am I to assume, then, that there's a newer one that will fit in my '81? And if so, is it any better in design than the one I've got? Thanks in advance...

Your car originally has an all metal radiator, these are tougher, they

take vibration better and radiator shops can work with them. The newer

radiator came out in 83-84 and they are better because they are aluminum

with plastic tanks. They radiate heat better when they are all aluminum.

However, the plastic tanks are not as durable as an all metal design and the have the nerve to charge more for them. Most folks buy the all metal replacement for half the price of the aluminum.

Dave 82 242ti

> It sounds like your car has been behaving for a long time.

Yup, the Beast's running better than ever...I'm actually getting better mpg than it's spec'd for, plenty 'o' power too.

>It might just be the thermostat because if its been in there a long time its probably bad.

That would have been my first thought as well, except that I just replaced it a couple of months ago, before summer really started heating up. (you may remember me asking about a coolant leak that I ended up with during that process - it turned out that I had not "wrapped" the thermostat's rubber gasket around the little ridge, the gasket was kinda squashed down into the hole and was letting some juice go by.)

>You didn't mention if the afternoon drive was with the a/c on but that will raise the temp a bit.

Ah, if only I HAD A/C, I'd be a happy man, and I'd expect it to heat up a bit...but unfortunately the compressor's seized, and I'm running with no A/C for now.

I've checked to make sure the radiator's not blocked by debris, but I haven't flushed it (suppose I should have done that when I did the t-stat, huh?) so I'll try that at the next opportunity. The coolant is really clean & clear, not cloudy or rusty at all, so I didn't think about flushing it. Thanks for the tip!

My temp guage is starting to be wierd too. While driving it'll sit at the 1/3 position and then it'll travel up to the 2/3 position sometimes. If I give the dash a whack, it will go to the 1/2 way mark, so I can pretty safely say that there's something wrong with the wirin or the guage, and that my problem is not engine related. Give your dash a whack and see if your guage moves or not. I had originally thought something was wrong with the thermostat or the temp sender till I hit the dash and noticed it show the correct reading.

I believe the original problem in this thread involves the thermostat, plugged radiator or poor air circulation. Your problem however sounds just like the one I had in my '86 245. As far as I know we have the same temperature compensation board in the instrument cluster. If so, you might try what I did. I removed the cluster, opened it up and removed the temperature compensator board. I resoldered the board just like we do with relays, carefully scraped the board connecting pins to clean them, cleaned the two connections to the temp guage, and reassembled/replaced the cluster. My temp guage is now reading normally. It's not really a hard job to do. Make a note or drawing of where the different wires connect to the back of the instrument cluster.

Thanks Jim! Dave says my '81 doesn't have a temperature compensation board, (apparently your '86 was the first year they started using those)but if a flush doesn't solve my problem, I'll take a look. After reading the many Don Foster soldering posts on the board, I've invested in an iron & a spool of solder, so I'm prepared for many inexpensive repairs to come!

Andrew -

If percussive maintenance (whack) solved the problem, even temporarily, you likely have a loose/cracked temperature compensation board. They can be removed, cleaned, re-soldered, and even by-passed. That last is my preference b/c I like a more accurate reading of what's going on in there.

Good Luck,

Bob

:>)