My non-turbo started overheating last week. The temperature gauge is usually in the middle, but is now 80% of the way up (but just below red). There are no noises and no symptoms. I changed coolant and thermostat. My water pump is not leaking. I even installed an electric fan which did absolutely nothing. Where's the gremlin?

If it indeed is overheating, I would have tried feeling with my hand over the radiator to check if it is uniformly warm. If it has cool areas, it is partially clogged and needs to be replaced(/rodded).

Erling.
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My 240 Page

Is your car an early year 240? Say, Pre 1986 or so? Does the engine feel hot and uncomfortably heated? If the engine itself is okay and you dont think the car is warm, the coolant level is normal, and the thermostat is good...I would seriously check the converter on the back of the insturment panel. If you take the insturment cluster out and look directly behind the fuel / heat gauge you will notice a silver / copper box about 1" X 1/2" or so. These do go bad and need to be replaced. Its a simple un-plug and plug-in process. You could even get a replacement from the junkyard for cheap to see if it is the problem.

This has happened to a couple of my Volvo's in the past. I was getting really hot readings but everything was normal. With a laser thermometer, my car was within perfect temp. Once I replaced the converter on the instrument cluster everything was normal...even the gas gauges read more acurate. I am not saying this is your problem but it has happened many times in the past to me and others and it could be a start for you.

Best of Luck
Ryan Rice
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VOLVO LOVER WITH AN 80 AND AN 82

That's a great idea! Thanks!
By the way, I'd like to install an electronic/digital temperature gauge. Any recommendations?

I am not 100% sure on a digital temperature gauge for you. I know VDO makes a couple models and as far as buying one, I dont have a clue where to send you. I know Dakota Digital makes every type of gauge your brain can think of...but they can be a little pricey.

Actually come to think of it, here in Portland I noticed some good quality/low priced gauges and gauge clusters at discount import parts. They have a website www.discountimportparts.com and they could possibly order what you need. give it a shot.

Ryan Rice
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VOLVO LOVER WITH AN 80 AND AN 82

Early models had a voltage regulator on the back of the instrument cluster. It produced a fixed voltage of about 7 Volts for the temp and fuel gauges. This made their readings independent of battery voltage fluctuations. It might also be the temp sensor.

If you want a permanent digital gauge I think VDO makes a few. Check egauges.com. If you just want it temporarily for testing the resistance of the sensor can be monitored with a digital Ohmmeter.