The main bearings are the cause of the noise. Yes, the thrust bearing is replaced. No, we don't measure fore/aft crank play prior to dis-assembly. We replace the rod bearings as well, but only because we're already there, so why not?

The customers didn't have to do anything other than bring the car in and complain about the noise! Obviously something is wrong, right?

When we had the first few complaints MB didn't have a fix yet, but was aware of the problem. We recorded the DUNK-DUNK-DUNK noise on a few different cars and sent the sound files to MB Technical Assistance. We asked our clients to be patient, and within a few weeks MB Service Engineering had the solution (Yeah, I'd like to tell you that we figured it out at the dealership but I'd be lying if I did. We knew it was a bottom-end issue, but if we took a crack at it without MB support we would've just replaced the bearings with the same size and the noise would still be there).

Once we had the answer it was simply a matter of contacting the owners of the problem cars (yes, we keep track of stuff like that) and scheduling appointments to make the repairs.

Once the engine(s) were torn-down we simply recorded the casting numbers on the block and crank, ordered the appropriate bearing shells, and re-assembled everything. Problem fixed. It's not like building an engine from scratch. No micrometers, plasti-gage, etc. required. No specs to look up. No clearances to measure. The casting numbers have all the information needed to do the job right.

My shop hasn't done this job in quite a while. I figure that most of the problem engines have been fixed already. Maybe your dealer has a short memory? If you're dealer can't/won't acknowledge the problem, the first step is to call MBUSA Customer Assistance. Let us know how it goes.