[CININ]

I’ve got a 2009 630i, I understand this so the 3 series category, but the N52 (N52N) is more prominant in the 3 series.

Around the alternator, there is an audible whinding/whining sound; it follows revs (increase Revs = increase sound of whinding).

The sound had progressively been getting more and more aggressive and louder.

This video is exactly what I’m hearing, I hope someone can give me a direct explanation or solution.

Video:

[lordnikon]

Sounds like power steering pump failing.

[CININ]

Are you sure about that? Cause my service center said they think it’s the alternator bearing, but they don’t know. The ruled out the power steering pump

[lordnikon]

You can rule out alternator whine by slipping off the serpentine belt and see if the noise it still there.

[CININ]

If I do that wouldn’t the belt just be too loose for it to power anything. Eg: power steering pump, ac compressor. Wouldn’t they all turn off as well? Or would the tensioner compensate for the removal of the alternator pulley and allow for the power steering and ac compressor to continue working? Thanks

[gaze2]

You have to remove the whole belt, otherwise it will be a mess....

[NZE90]

That is the one way clutch in the alternator. Perfectly normal noise.

[CININ]

Yeah, however at the point of my car it’s become audible at idle, extremely loud. Rattles and vibrates. Do you think that the one way clutch can be replaced? Rather than go buy an entirely new alternator? Thanks

Btw this is the sound (on insta):
https://www.instagram.com/reel/C9UfP...BmcWFzbTNpZw==

[NZE90]

Right. I could only hear the noise at high revs in your vid. Yes you can buy the clutch pulley by itself i think.