Hey optimusprime,

The information you're looking for is 1991 300CE with the 3.0L-24v M104 engine. 104 200 13 28 part number is used on the later 3.2L M104 motors which is what I thought I accidentally installed since I was working on a 95 E320 during the same week doing the same repair job. I had correctly installed part number 104 200 05 28 after confirming the Febi stamped number 11949 when I took the fan pulley off to examine it.

Right now I'm attributing the failure to a bad aftermarket part. Even though it is Febi it's still not an OE dealer part. The bearing hub is either pressed too far onto the shaft or it is too small so the pulley sits too close to the engine.