Recently my 96 C280 has started running a bit warm (100° - 110°) when sitting in traffic or at a drive through, etc.... I have read that this may be due to the fan clutch. How do you test the fan clutch to determine if it needs replacement, and is this somehting that I can do myself? Thanks.

When it gets to that temp, you should be able to hear the fan clutch pulling air through the radiator when the engine is revved up. Additionally, if you open the hood, and rev the engine up you should be able to feel the airflow from the mechanical cooling fan (keep your fingers clear).

Also, your car may be closer to overheating than your coolant temp gauge actually indicates. For an explanantion on how the gauge works on engines where it is controlled by the motornic control unit, see my thread http://www.peachparts.com/shopforum/showthread.php?t=127687&highlight=thought+mercedes+real+coolant+temp+gauge

Also, check the fuse for the aux cooling fans and make sure they are working properly. On that engine, they are steplessly variable speed and they should start to come on at 95C and speed up if the engine gets hotter.

__________________
Ali Al-Chalabi

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

Thanks for the information. Now, another question. If I monitor the coolant temperature via my scantool, is that the actual temperature of the coolant, or is this a "dummy" signal much as is sent to the gage?

I too have a 96 C280 that has been overheating. It stays at 87C and rises to 100C during idling times.
I have changed the water pump, thermostat, some kind of electronic magnetic valve next to the firewall on the passenger side, a new fan clutch and it still sits at the same temp range.
Before the new water pump it set below 80C and never rose above that.
I had a 1987 190E 2.6 and it set below 80C and never moved much, except down.
My question is, what should the temp be set for, why did the new water pump change the temp range and what else could be down to return it to the proper range?
Steve Dale
Lubbock, Tx.

same prob, after new water pump, my temp sits higher also...

From what I understand, your car is operating properly now. I have a 94 C280, and it operates much as yours does. 87 most of the time, but above 100 when stuck in traffic. I've even seen it as high as 110 when stuck in traffic on a hot day in the summer. The thermostat is set to begin opening at 87 and will be fully open at just over 100 degrees. If you don't like the car running that hot (and I don't like it, believe me) then you can look up a user here by the name of JimF. He has developed a resistor that you plug into the coolant temp sensor that tricks your aux. cooling fans into coming on at a lower temperature (I think they are set to come on at 100 by the factory). He offers three different temperature setting with the resistor, so you can find one you feel comfortable with. I installed one last summer and it works very well, although the fans run more than I'd like. I'd have probably bought one higher temperature setting if I knew better. The car doesn't hit 100 any more, and I'm much happier for it. I did decide to take it out in the winter, to let the car run a bit warmer.

Thanks for the info. If you have the e-mail for jimf I would appreciate it.
I don't like the car running that hot. Worries me with regards to gaskets, head, oil, etc.
Thanks again.