Hi had the same problem and it wasn't none of those things that you guy are talking about it was on the bottom of me x5 I'll send a picture one of the bolts that hold the rubber mount in the back was lose not a lot but i saw that the washer was lose so i tried to adjust it but i couldn't so i remover it (22mm) and sprayed it with. Wd40 and then i was able to put it back and tighten it all the why, i never had the noise again. Thank god a also you need some thread lock (blue) they told me that i was possible that the thread lock gave due to the cold temp. And the vibration loosened it.
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