Larry,
The archives seem full of examples of this problem on M103's and even at relatively low mileage. It's also mentioned in Stu Ritter's new book as a common M103 problem and in other places.

What's disturbing is that this car has probably never had coolant temps above 105C and never had tap water in the coolant. It's not the money that gripes me because just the tags and taxes on a new E-Class would more than pay for it where I live. It's the idea of somebody taking the engine apart and the inconvenience of finding a reliable shop and getting it fixed.

I suppose the bright side of it is that I didn't have a BMW V8 that had to have a short block installed because of cylinder etching or a Lexus V6 having to be stripped because of the gelling problem.

My brother-in-law has got it figured out. I told him that he was spending a fortune having to replace his Cadillacs every few years because they didn't last. He said he'd thought about getting a Lexus or Mercedes but then he wouldn't have an excuse to buy a new car every four years.