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| Message: | >[I] Jim if the failures still continue into 2002 productions what would you theorize is the reason? It would seem after that many months plus production changes that it could no longer be assumed as a manufacturing screwup. Are we looking at a poor design problem inherent in the S54 engine? [/I] < Sorry for the late rely. Over the mountains in the high desert for some empty road driving. As of now, we simply don't have enough information. About the only clear details are spun bearings in the lower end and numerous comments regarding the appearance of the crank looking like one or more bearing had experience prolonged heat due to insufficient lubrication. I think we can also be somewhat certain that BMW doesn't yet fully understand, or at the very least has not found a solution, for the lower end failure problem. It will take a couple more months of data to really be certain of this, but it doesn't look promising. Idle speculation: My guess is that the oil system is working fine, but the running clearances were too tight in some cases for the oil to transfer around the crank effectively. This is particularly likely for the 10/01-12/01 engines. It is curious that the #3 bearing is mentioned frequently, as there is really no reason it should suffer out of proportion to the others. The crank ‘should’ be adequately supported. As is the case with all inline 6’s, it enjoys the advantage of having more main bearings than a V configuration engine with the same number of cylinders would. As a matter of fact, most inline sixes have more mains than most V8 engines. Crank whip seems most unlikely. Will has been posting all along that the 91mm stroke @ 8000Rpm is beyond what is prudent in a production engine. We have seen nothing to disprove this as of yet. Not often you see an undersquare high Rpm engine. Most designers prefer to go as oversquare as practical to slow the piston speed and reduce lower end loading. BMW clearly had package size to consider, and proceeded with the undersquare design. Things hard to accept: Based simply on common industry practice, it is very hard to accept that the lower end failures on the S54 are due to improper manufacturing or assembly. Most of the parts are made using in-process gauging, and are subsequently checked at the completion of each process. The same goes for not checking running clearances during assembly. Bear in mind that a simple cold crank power (power draw on starter motor) will reveal an overly tight lower end after assembly. On one hand it is inconceivable that BMW would not perform most or all of these tests, and yet we have these failures before us. This last item may offer a clue as to what cause the evaluation of the failed engines to go more slowly than it might. If I have a difficult time imagining that BMW could allow engines with gross flaws into the field, imagine how difficult it is for BMW’s M division to imagine this, then factor in that they are German. As for evidence of this disbelief, we have the company’s initial reaction where they dumped the returned DME modules and attempted to place the blame on abusive owners. At the end of the day however they are in possession of what we guess are well over 200 failed engines from North America alone. Assuming that is roughly 1/3 of the total, they would have in excess of 600 failed motors to evaluate at this point. My conclusion is that if that is not a sufficient basis to determine the underlying cause and resolve it, we may be facing a situation where the cause is indeed endemic to the design. That would be a very sticky problem indeed for both BMW and owners. This is one reason why BMW’s silence creates a bad situation. The people that comment that BMW’s approach to addressing this is a logical one from a business standpoint miss the point that in the absence of any information from BMW, there is no evidence of corrective action or resolution. oc | ||||
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