Other threads mention that the seals are known to leak causing the Vanos to lose its ability to index correctly. I heard the telltale rattle and experienced the rough engine as the intake valves were advancing incorrectly. This was the failure mode on the right bank. The dealer suggested he replace both sides, and while the front of the engine was apart the chains, chain guides, valve cover gaskets, and a coolant leak was also repaired.

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2013 X5 3.5i M Sport
2004 M3 cabriolet SMG