I believe 1996-1997 M104 engines require a wrench to counter-hold the fan clutch during removal. This is different from the bent 1/4" steel tool that was improvised for earlier models. A prior thread, http://www.peachparts.com/shopforum/showthread.php?t=51248, identifies the wrench as a flat 64mm wrench and goes on to incorrectly identify a source for the tool (the incorrect reference is to the earlier version of the tool). The W124 CD identifies the tool as counter holder 120 589 02 01 00. Does anyone know of an alternate source for this tool or an alternate procedure to counter-hold the viscous fan?

In a road emergency on a 1994 104 motor I secured it with a Sears belt wrench - which worked fine.

I found a good source for the tool at http://www.zdmak.com.

Thank you for the timely responses.

After reading the above, I also successfully used a strap wrench from Sears. Before it would work I cleaned the pulley surface with brake clean and wiped it dry (to enhance the bite of the strap). Also, I ground down (shortened) a "L" shaped metric Allen key to make the rotation to fit into the hole at the center of the pulley. It was a tight fit and to enhance clearance I removed the four painted bolts at the top of the radiator so the radiator could rotate forward a little bit. When all was in place I placed a pipe over the long end of the "L" shaped Allen key and got sufficient torque to break the bolt free.

The radiator fins are sharp and some blood was sacrificed to appease the gods. Thanks to all.