I WAS DRIVING HOME THE OTHER DAY WHEN THE TEMP GAUGE WENT IN TO THE RED AND I PRECEDED TO PANIC. I QUICKLY PULLED OVER AND DIDNT NOTICE ANYTHING OUT OF THE ORDINARY. THE RADIATOR SEEMED TO BE WORKING, THE UPPER HOSE WAS HOT, THE LOWER ONE WAS COOL, THE ENGINE SMELLED FINE, THE WATER PUMP WAS CRANKING, ECT. I GOT HOME AND CHANGED OUT THE THERMOSTAT BUT IT STILL WAS RECORDING TOO HOT. I CHANGED IN A NEW NISSEN RADIATOR, A SECOND THERMOSTAT, AND NEW COOLANT. AGAIN, THE GAUGE IS SAYING TOO HOT. I THINK IT MIGHT BE A BAD GAUGE NOW, BUT I DONT KNOW HOW TO CHECK IT, ANY HELP OR IDEAS??
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VOLVO LOVER WITH AN 80 AND AN 82

When that little transformer went south on my '79 242, it would wait until the engine / electrical was warm, and then both the temp and fuel gage would jump 25% up the scale. It puzzled me for a while as you could only notice the correlation when the tank was less than 50% full. The local dealer, helpful as usual, told me I was wasting my money and really should bring it in for a new rad and flush.
Of course it only happened when the heater was on defrost and cooking the dashboard.

Rice, More than likely you have a bad Temperature compensator. The same thing happened to me about 6 months ago. New radiator, pump, hoses, thermostat, even a new sender(just under intake manifold). Most of that stuff I had to do anyway. A few weeks after it started the fuel guage went wacky as well.

On the back of the instrument cluster you'll see a small rectangular (1.5 in x .5 in) brass thing attached by 3 connectors. That is the early style temp compensator. Find a used parts guy to get one. I don't think volvo has them new anymore, and if they do they'll want a fortune for it.

I don't know how to test it besides swapping in a new one. Depending on how flexible you are you might not even have to take out the cluster. Just be careful not to crack the board that it is attached to while disconnecting or installing. Good Luck
Marty

I JUST GOT DONE WITH REPLACEING THE SAME UNIT YOUR SPEAKING OF MARTY... AND THAT WAS IN FACT THE PROBLEM. IT TURNS OUT THAT VOLVO RUNS ON A 12 VOLT SYSTEM, BUT THE INSTURMENT PANELS RUN ON GERMAN 10 VOLT DC SYSTEM. SO IN ORDER TO WORK TOGETHER IN THE CAR, A STABILZER OF SOME SORT NEEDS TO BE IN PLACE. MINE HAD INTERNALLY MELTED AND WAS SHORTING OUT THE YELLOW CONNECTING WIRE THUS MAKING THE GUAGE READ FUNNY. THE WHOLE PROCEDURE TOOK 10 MIN. MAX. I REACHED UNDER THE DASH AND FOUND THE BRASS PIECE, FROM THERE IT WAS JUST A UNPLUG THE OLD AND PLUG IN THE NEW... VOLVO HAD A NEW PIECE FOR $20.00; BUT I THINK YOU CAN FIND ONE A LOT CHEAPER THROUGH A U-PULL-IT JUNK YARD. I AM JUST HAPPY TO HAVE MY BABY RUNNING AND LOOKING GOOD AGAIN...BESIDES THAT MY COOLING SYSTEM IS TOP OFF THE LINE NOW WITH ALL GREAT NEW PARTS. THANKS FOR ALL YOUR HELP..ESPECIALLY YOU MARTY.
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VOLVO LOVER WITH AN 80 AND AN 82

Do you have a newer wiring harness in you car. This same thing happened to me a while back. Turns out all of the insulation for the gauge wire was rotted away and it was shorting to ground and thus the high reading. The wire is difficult to get to on a k-jet car. It is a little easier if you remove the big rubber boot. Then you can get at the gauge sender and its wire right below the 3rd intake runner. Good Luck

Matt

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'82 DL - 152k, '93 945 - 100k

I had this same problem with the insulation on the wire rotting away. I simply slipped some new insulation on the wire...loose fitting sleeve of insulation. I pushed it on as far as it could go and the problem was fixed. I didn't need to take off the rubber intake boot.

-Ted

Make sure the main ground to the engine is hooked up. My 87 did this, and after a waterpump, thermostat ect I finally noticed (my brothers car, he was having the work done) that the ground strap that goes from the firewall to the valvecover wasn't on.

Thats all it took, gauge works fine now.

Doug
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Sacramento VCOA President, (sacvolvo@hotmail.com) Admin @ clubvolvo.com 2001 S60 2.4t w/17' Amalthea & Premium package 82 242t 5spd (Offical Project Car!) w/ With more parts than I can list, 85 244ti~ Parts car