When I was shopping for a w211 wagon I tried to avoid the m272 like the plague because of these very issues. And from what I saw the early m112 and m113 powered w211s now sell for more than the later m272/273. The cat is out of the bag and people know to avoid these cars. MB fixed the balance shaft issue half way through the 07 model year but all m272s before that are suspect.

Beyond the balance shaft issue the 272/273 are too complicated for their own good. The intake manifold is just one example.

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CENSORED due to not family friendly words