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Old 04-10-2011, 09:24 PM   #11
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Join Date: Mar 2010
Location: Toronto
Posts: 73
My Ride: 2002 325xi
Alternator noise at 1000 rpm

Can a failing voltage regulator cause excessively loud noise only at a certain rpm, let say 1000rpm? I have been hearing this alternator noise/whine at 1000rpm all the time. I replaced the alternator with a refurbished once last year and the noise is still there. Some mechanics said it's normal sound when the alternator recharges. Why do I only hear it at 1000rpm? The pitch is quite high and I find it really annoying. I have looked into the possibility of vacuum leak and concluded that that's not the reason. Any insight would be appreciated.
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