I have a general question about coolant temperatures in different cars. I've noticed that on some cars, the temperature is pretty much steady at a constant point on the gauge no matter what the operating conditions are. On other cars, I notice the temperature can vary significantly depending on whether it's city driving or highway driving, or even on the ambient outside temperature.

What is the reason for this? Is it a design difference? Is it a gauge difference?

Some of the cars that I've owned (or still own) caused me to ponder this:

1995 E420 - temp fluctuates
1989 Corvette - temp fluctuates
1995 BMW 525ia - temp steady
1989 Mazda MPV 4wd - temp steady


Thanks,

Warren

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2011 C300

Gone but not forgotten:

1995 E420
1990 500SL

The reason that the temp is steady on other cars is because the needle is programmed to not let you read the actual temperature. The needle is basically a dummy light, it stays in the dead center until the car is on the verge of overheating, at which point the needle will move rapidly to the red zone. This is done to solve the problem of owners needlessly worrying about how their car is running a few degrees hotter. The car can run a few degrees hotter in this setup and the owner will have no clue because the needle will not budge. In fact, some Japanese cars have their gauges programmed to sit at the same exact location even with temperature variations of 20C or more!

I'll take the real Mercedes gauge anyday. Now only if we still had the oil pressure gauge.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Ali, this is very true, my father in law has a 2002 Peugeot 406 Estate. Nice car, the gauge in that never moves at all, for the very reason you stated, where as the MB gauge's give an accurate readout.

What was you saying about the oil pressure one, do you not have it in your car?

Nope, no oil pressure gauge, unfortunately. Don't know of the exact year it was done away with in the US, but I do know that the C class did not have one when it debuted in 94 in the US, so it was sometime around then.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Thats really strange, im sure that all Mercs her in the Uk have the standard dash layout, Temp, Tank, Oil and Econ gauge on the left, speedo in the middle and revcounter and clock on the right.

Looks like they mucy have changed it for the US market....strange, its quite a useful thing to have