Yes I read through those and could not find a resolution. The sound I hear is a perfect rythm of 3 scratch sounds (dry bearing sound) twice every second or so.

Almost sounds like a bad water pump bearing.

The engine otherwise has the typical mercedes sewing machine whine.

I would have to "take it to bits" to find that source of noise.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)