I'm looking at a 91 350 SDL, which apparently has had no engine work done, including upgrades or modifications. Of course I've read everything on this thread, but I just spoke to a Mercedes mechanic whose theory was that this engine was more susceptible to carbon accumulation when driven in stop and go, and urban speeds. He didn't know about the stronger rods.

Putting that aside, was the 91 already modified by Mercedes, or are number of these still problematic. Wouldn't it be better to look for one whose engine had been modified?

Thanks,

Peter4