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      10-11-2012, 08:30 PM   #1
Private First Class

Drives: 2009 BMW 135i M-Sport 6MT
Join Date: Jun 2012
Location: Los Angeles, CA

iTrader: (0)

Weird humming/"mooing" sound from exhaust side of engine? Got a video.

I've noticed this noise on and off since I bought the car a couple months ago, but today I could hear it sitting in traffic so I decided to shoot a video of it today after it seemed to become more noticeable.

It's an odd humming noise that sometimes will cycle on and off every ~8 seconds at idle, other times it's continuous. After about 38 seconds in the video it starts fluctuating. Any ideas? It definitely doesn't sound normal.

Thanks in advance!
2009 BMW 135i - Alpine White/Coral Red - M-Sport+Premium + 6-Speed Manual