I'm not aware of m54 having an issue with swallow serpentine through FMS but I've experienced it happen with the N55.

If you can examine the rod bearings with the engine in place, and especially if you never heard knock, there's a good chance you didn't cause crank damage.

I just did the initial autopsy on wife's n55 that spun 2-3 rod bearings and it looks like the crank survived. Likely needs to be polished and 50% honed just a bit but that can use thicker bearing shells and be restored.

One bearing was worn down to polished copper, but the crazy one: the bearing shells turned enough to overlap and stuck to the crank and spun inside the big end until about 1.3mm wore off the outside of the bearing shells!

The rubber bits kill the engine when they get into the oil galleys and stop the flow. Odds seem good you can clean and change rod bearings.

Where are you located?


–awr–

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)