1994 C280 Fan Clutch

[mbsickness]

Over the past few months I have noticed that my car had been down on power. The power was down only enough where an owner would notice. I did notice that when the power was down I could hear the fan roaring away. That brings me to the first replacement fan clutch. To be fair I got a bit cheap and purchased a new but non-OEM fan clutch from an online parts supplier. There was a choice of Original Mercedes or a aftermarket brand and I selected the aftermarket one as it was half the price of the Mercedes unit. Turns out the fan clutch was locked or coupled constantly and I would sound like a UPS truck driving down the road. Even at RPMs above 5k the fan wouldn't uncouple. Since the fan clutches must be stored vertically I wasn't sure if a replacement would get damaged in shipment so I bit the bullet and purchased one at the dealer. Since I was doing the job again I figured I would snap some pictures in the event someone was looking for information on the older 8mm hex head style fan clutch mount which I believe was used from 94-96. I completed the second fan clutch in about 40 minutes start to finish including clean up. To be fair I had two Mercedes specialty tools. One to hold the pully and the other was a shallow 8mm hex.

First you need to remove the fan shrouding from the radiator. It splits in half and each half will fit between the fan and the radiator. I unbolted the radiator support to get just a bit more wiggle room (you will see why soon). There are two 10mm nuts on either side of the core support. Next is to get a piece of cardboard to cover the radiator, otherwise the radiator fins will take a beating, fit the pulley rod to lock the fan pulley. Here is where I disconnected what I believe is the Camshaft sensor. There is a groove in the fan bearing housing specifically for the locking rod. In my case I placed the locking rod i the right place and turned the fan mounting nut until the pulley rod locked the pulley. Fit the special 3/8 drive shallow 8mm hex to a 3/8 breaker bar and sneak it into position. As you can see there is hardly any extra space. The mounting nut is not reverse threaded so simply break the nut loose. Once out of the car there are three 5mm hex head bolts that hold the fan blades to the fan clutch. Here of course is your standard service manual statement......reverse these steps to replace the fan clutch.

Special 8mm Hex with 3/8 Breaker bar


Pulley lock


Pulley Lock installed, sensor connector unhooked for clearance



Pulley Lock different angle (handle over thermostat housing)


Hex socket on mounting nut....living dangerously with no cardboard


Protected radiator

[RemoLexi]

Fan clutch would not contribute to loss of power ..

Also the fan clutch is supposed to have some resistance to it but it locks up after hot air from the radiator blows into it. Storing it vertically vs. flat should not damage it.

Good DIY though, they are a pain in the ass to replace.

[mbsickness]

The second clutch seems to be working as it should and has the same resistance as my C36. The first replacement clutch was extremely stiff to turn even after a fifty mile drive. As the car has logged some miles I am tempted to send it to the dealer to get a scan with the SDS to see if all is well.

[RemoLexi]

So you are losing power but no CEL?

The dealer would probably send you on your way less $150 labor.

[mbsickness]

Yes, no CEL and the loss is so slight most people would not notice. I would say a similar loss of power when there are two passengers in the car vs driving alone. You are likely right...I'll just leave it as is and just scan the OBDII to make sure there aren't any pending codes.

[RemoLexi]

If I was to take a stab in the dark, your air flow meter is probably failing. Some people insist on cleaning them, but for $3 can of cleaner, you can't seriously expect good results.

Also, when was last fuel filter rep? Air filter and are you running a K&N cartridge?

[mbsickness]

I'll look into the air flow meter as I can't remember if it is the new one I bought a few months back or if I put the new one in my C36 and moved the used C36 meter to this car. The fuel filter is two months old and the air filter is under a year old. I ran a K&N filter a year ago but swapped it out as I was afriad of killing the airflow meter. In anycase I'll clean the air flow meter and report back. Thanks.