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My 1982 240D seems to run cool. I know that is usually not a problem. The gauge never goes up to the line above 40. Is this normal? I have replaced the thermostat twice, just to make sure the first on was not defective. Got the current one from a Benz dealer, so it is the proper 80C one. I do not mind it running cool for obvious reasons, I just want to make sure it is getting up to proper temps. Trying to get it "winterized" since this is my main transportation and I live in Minnesota. Was thinking this might be a cause of poor fuel economy. I get 27mpg right on the dot every tank.
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You may well be getting a false reading from your gauge and your operating temperature is normal. I say this because German silver in their electrical contacts is prone to tarnishing which builds a higher resistance in electrical circuits. Higher than normal resistance in your gauge circuit results in lower readings at the gauge.
If you can lay your hands on an infrared gun you can measure the engine temperature, near the sensor (between #2 & 3 glow plugs) and compare it. Not withstanding that, I always suggest that you pull the connector off and plug it back a couple times and tha will burnish the silver for a couple years. Warm up your engine and shut it off (easier to work) With the key on, take a reading. Then do the connector excercise and check the reading again. I bet it has gone up!
Aoften forgottenfact is that there is another, tho less likely to tarnish, connection for this era of turbo diesels. Where the wiring harness passes through the glow plug relay, there is a push on plug on the back of the relay. It takes just a minute to unmount the relay and excercise this plug. The final point to check would be the push on multiwire plug on the back of the gauge panel, but this more work and a much better environment for connectors. Still, many have found that the ground in this plug has caused errant readings in the gauge package.
Thanks for the replies. I have had the instrument cluster out a few times. I had to fix the lights and speedo. I have a new sending unit now and will try that. It seems to be getting warm enough while driving, but the gauge had me thrown off a bit. The gauge moves, but just barely off the bottom. I will try all suggestions, as I want to be sure before the 20 below weather sets in.
That gauge should be close to 80 degrees C within 3 to 4 blocks of driving. The false reading post above is a wealth of correct info. follow it to the letter.
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1981 300CD. had a 72 280SEL 4.5, had a 66 250S
Hello,
I have a Benz 190 (Silver-padded 1991 Model).
I reside in Nigeria.
The Benz recently over-heated, the temp got to 110*C from the usual 40-60*C.
The Technician replaced the water pump, but now it stays at 80*C instead of the previous 40-60*C range.
Tech-guy says I need to change the top-cylinder gasket because he suspects that if it is the one that came with the Engine, it might have gotten thin and may cause d over-heating problem.
1. Will replacing the top-cylinder gasket have any effect on the temperature control?
2. From my observation, when the engine is shut off, the magnetic fan (on the water-pump) runs for a few seconds before stopping, is it normal?
3. An air-conditioning unit has been installed on the car (but it has been bad due to faulty compressor unit; and it didnt come with a factory-fitted a/c). What specification of Compressor (magnetic) can I use that will not have much pull on the engine when operated.
Operating temp for an 82 240D?
