M.B.DOC,

I have been particularly harsh on Mercedes-Benz about the problem with the connecting rods, likely due to my personal experience and disappointment having to trade in such an otherwise superior vehicle to keep from falling into poverty. I am very curious about what the design changes were to the corrected or later part number rods, and which ones really corrected the problem. It seems to me there could be a number of engineering failures, from the specified base material and heat treatment, to the manufacturing tolerances specified, or even the forging sequence used by different suppliers. That not all fail in a given time period is an indication the error was not a nominal design error, but one that affects the individual rods based on some statistical basis tht is related to the manufacturing processes used. It is still an error, and the fact that it took three redesigns to get it right, if it really is right now, is not a confidence inspiring fact if you have had your engine rebuilt before the last design iteration.

After all that what I really want to know is, are you aware of what makes the new rods different than the three predecessor and original designs? This is what I could not get from the local service manager and drove me to trade the car in. I would still like to know what the changes were, and how they are going to fix the problem, just because I am curious, not because I want to make trouble for MB. They have already been reasonable enough with me on the trade in, which I suppose is a benefit of having bought the car from them to start with, and is not an avenue for others that buy them privately.

If you know the answer I would appreciate "closure" on the subject. Thanks, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)