IMO is the flavor of this discussion since no documents have been referenced, linked, copied, even exist.

The RPM argument doesn't make any sense to me, since the '90/'91 OM603.970 was already at a reduced max. RPM vs the 3.0L OM603.96, one of the reasons it only made 134hp vs the 148hp 3l engines. The later OM603.971 RPM was raised back up to within 100rpm of the 3.0 though, which increased its HP again. This along with advanced timing by 1* didn't have any more problems. The head was changed again, as was the head gasket, after the introduction of the .971 though. Does this support one poster's hydrolocking theory? I'd be interested in whether the head bolts were also changed in this case.

I still see this as only opinions and theory, with no conclusive answer, no test data, nothing at all. Anyone who calls this one is getting sand in his ears. Whether it was hydrolockiing from leaking gaskets, irregular combustioin from cetane, lugging from US market low-speed operation, sulfur reduction from regular to LSD to ULSD, weak rods, a rush to market, sunspots, we'll never know unless some real data emerges.

My experience with Mercedes-Benz Engineering was that nothing would begin production until the proper FEA was complete in critical areas, and FMEAs complete & analyzed, and any critical failures rectified. This experience goes through the introduction of the 60x series so I don't buy the rush to market theory, ... at all. I saw examples of the opposite, where an introduction was delayed pending engineering changes.

I do enjoy the theories and discussion however.

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Gone to the dark side

- Jeff

Yes, the documents exist. I have some old microfische from a now closed factory dealer. Covering engines OM603.96/97 turbo. Dated 11/92 document numbers 07 102 2034 03, 07 102 2035 03, 07 102 2036 03 and 07 102 2071 03. Here's the problem- my local library got rid of the fische readers and the only other way to copy them, in my entire county, is a local company that charges $3.00 per page. 180 pages per sheet x four sheets = not happening without the $. Here's the rub! The factory never issued a formal recall. They DID do all the contact of purchasers and corrections that made it look like a recall. They played their cards close and did not have to release lots of information the way the would have under a recall.

The same information might be found in the W126 FSM CDs, I don't know, I don't have one. What remains as cold hard fact are the factory changed the head gaskets and RPM settings in .970s (3/90-6/91) and that was all they changed as of 11/92. These changes are shown in the microfische. They were in effect before the .971 (7/91-5/93) and .972 (9/91-7/93) had stopped production. The rod bending stopped after these changes. The fuel (according to ASTM and DIN) contradicts the idea that US fuel was causing the damage. At the time they were built, German diesel was 38 min. cetane and American fuel was 40 min. cetane.

The rush to market was actually a point of pride with the factory. This is detailed in the documentary "Fascination: The History of the Mercedes Benz Brand" (c) 2007 Producer- Wolf Nagel. Historical consultant DaimlerChrysler Archive- Dr. Harry Niemann. {paraphrased from narration} "With the introduction of the six cylinder diesel family OM603, Mercedes Benz made a quantum leap in emission reduction while simultaneously making gains in power and torque up to 15% more than the venerable five cylinder family. This was even done in a period of just less than two years before its January 1985 debut." I bought this two disc doc. set at the factory museum in Stuttgart in PAL format. When I find a way to work around the PAL and copyright protection, I will post it.

I am honestly not trying to be king of the playground but if I have any information and people are looking for it, I do NOT believe in withholding it.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!