Just experienced a disaster with my E320 and thought I would share the story with everyone. Hopefully, it might help someone avoid a costly repair. My E320 has 149,000 miles, most of which are highway miles. It's well maintained--has the engine wiring harness update, the new design head gasket, and the belt tensioner has been replaced a couple of times.

So what happened on my trip?? Well, the bearing that supports the fan pulley and fan clutch literally fell apart at highway speed. The shocking thing was it made very little noise--in fact I didn't know anything was wrong until I slowed down to exit the highway and then heard a god awful clattering. When I popped the hood, there were strange flecks of what looked like metal fragments all over the top of the engine. I started the engine and could see the fan blade was wobbling and hitting some other parts. The pulley was in place, but I could see it was badly damaged and wobbling. The belt survived but was severely frayed.

Called AAA and they towed it 80 miles to Fairfax, Va. to an independent Mercedes repair facility that I formerly used when I lived up that way. Luckily they were open on Saturday. Turned out the metal flecks were pieces of the bearing that were thrown out by the fan blade. The whole assembly was shot--bearing bracket; fan pulley; fan clutch; fan blade; and belt. Strangely, the belt tensioner was fine. Of course, the parts had to come from the dealer and they were closed for the weekend. Two days later, it was back together and purring nicely. The bill was $748.--the parts alone were $481. Add in the hotel bills, and well, you get the idea--quite a Thanksgiving trip.

The repair facility said they had done two similar jobs on E320's this year. Both times the assembly came off completely and damaged the radiator (add another $350 or so). My advice to everyone who owns an E320 with over 120,000 miles--get this bearing replaced before it gets you. I just wish I had known this part was a failure point.