Cant answer your question, but you should try isolating the noise when your deaf out of 1 ear....my truck has a noise on startup and i havent a clue as to where it's comming from (cant triangulate sounds)....very frusterating....good luck, hope you get it resolved.

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2011 X35d - Platinum Grey/Black/Bamboo
Premium, Convenience, Technology, Rear Climate, ipod/sat - 1st Time BMW Owner

2006 Dodge 2500 Diesel (7500lbs and 13.4 Sec Qtr Mile)
2010 KTM 530 & 300