Quote:
Originally Posted by popdog
Can others confirm that this is correct/normal? New E90 M3 owner here. I've been wondering what this noise is since I purchased the car. It sounds like gears rotating and happens 3-4 times on startup for about 5 seconds each. Like others have mentioned, it happens most of the time, but not always.
Here is a video of what I'm referring to. Turn volume up. Noise begins at 0:02.
P.S. Apologies for resurrecting an old thread. This was the only one I could find regarding this specific noise. |
Sounds like brake vacuum pump operating. If you hear it very often then your brake vacuum sensor may be on its way out. It's a common issue especially if you have recently done a brake fluid change and accidentally spilled brake fluid on the sensor. Luckily it's a cheap $20 fix. You can buy the sensor separately from the vacuum hose.