??? about X5 4.6 noise similar to supercharger

Secrets · #1 10-13-2015, 10:55 PM

Hey guys, I'm hearing a funny noise similar to the sound of a supercharger when I'm driving particularly when just taking off. With the vehicle at a stand still and I rev it, I'll hear the noise at or about 4000 rpm. I checked the engine bay but the noise seems more obvious under the vehicle.
Has anyone had this issue before or have an input about this? Comments are greatly appreciated.

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J.Belknap · #2 10-14-2015, 09:17 PM

I hear the same thing too man ¯\_(ツ)_/¯

Probably some driveline stuff.

tmv · #3 10-15-2015, 08:56 AM

Post a video or something. Can't imagine sound with words.

Quote:

Originally Posted by J.Belknap

I hear the same thing too man ¯\_(ツ)_/¯

bcredliner · #4 10-15-2015, 04:51 PM

Does the sound change with RPMS? Are you saying there is no sound until you reach 4000 RPMS? Any other symptoms?

Secrets · #5 10-15-2015, 09:47 PM

Quote:

Originally Posted by bcredliner

Does the sound change with RPMS? Are you saying there is no sound until you reach 4000 RPMS? Any other symptoms?

Yes, the noise starts getting louder and more noticeable at 4k rpm. I try not to rev it too high to be on the safe side.

jcp240z · #6 10-17-2015, 02:24 AM

I had a similar noise from my centrifugal fan

blackbeast · #7 10-17-2015, 02:27 AM

I had a very slight high pitched whine that turned out to be my failing alternator. I noticed it for weeks before ever getting the battery light to come on. It was was so faint that I figured it might be normal, but I don't have it with the new alternator.

Sokm · #8 10-19-2015, 08:13 AM

I currently have a failing alternator. Will be changing it soon. I too have a supercharger whine. However I thought that was normal ? Guess the whine will go after I change the alternator

bcredliner · #9 10-19-2015, 01:04 PM

Quote:

Originally Posted by Sokm

I currently have a failing alternator. Will be changing it soon. I too have a supercharger whine. However I thought that was normal ? Guess the whine will go after I change the alternator

Be sure you verify the whine is the alternator. Troubleshoot, troubleshoot. Don't risk chasing down the whine with new parts.

Sokm · #10 10-19-2015, 01:46 PM

Quote:

Originally Posted by bcredliner

Be sure you verify the whine is the alternator. Troubleshoot, troubleshoot. Don't risk chasing down the whine with new parts.

I was at the dealer this morning and checked the alternator. Instead of a 13.8 steady voltage under load with air conditioning and lights on, it was showing nearly 9.9!

So... Also when revving the car in neutral the revs drop and it almost stalls, then bounces back up along with dimming dashboard and lights outside...

So, first thing..alternator out

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