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Discussion Starter #1
I have this annoying squeaking coming from the alternator. The sound is always persistent, cold or hot and is at the pace of the engine revs.

Strangely, when I brought it to a mechanic, they put a dollop of rubber grease on the belt and it killed the sound .... for about half an hour. Now its half as loud, but still nonetheless annoying.

Seeing that its unlikely grease on a belt can affect the alternator bearings, and the fact that the previous owner had the alternator bearings changed just 1.5 years and ~22,000 km before, are these bearings another common problem area for the beast?
Or is it possible that the alternator (or one of the pulleys on its belt) is out of alignment?
 

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Sounds like what i had.

Does it sound like crickets? Like a "sss sss sss ssss" noise?
 

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Yeah. But the "pulses" of squeaks are longer than the average cricket. Like 80% of each rotation.
That's exactly what i had on mine.

I tried to use the "Belt Squeak" products and it would help with the noise for about 15 minutes then it would re-appear again.
There were times where i would spray so much on the pulleys out of sheer anger because the noise would drive me insane. F*ck!

At first i thought it was my alternator bearing because the noise always seemed to go away when i sprayed on the alternator pulley.

But i solved it but replacing the rubber belts.

I didn't replace any tensioners or sh*t like that (JUST the belts on their own) and now the noise has been gone for the last three weeks :)
The only thing i can hear now is the VANOS when the hood is up :goldcup:

Here's my original thread.

http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/206931-hissing-noise-during-idle-any-ways-reduce-sound-now.html
 

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Thanks for the help. I can't believe that the belts would easily cause such an annoyance.
Neither could i. I took it to a BMW specialist and he immediately said "it's the belts" and i said "are you sure"? And he said "Positive".
And i was thinking "man if he changes the belts and the noise is still there i'll be very angry" LOL
But he did the belts and that's it. Noise was gone forever.

Give it a shot. Change the belts tomorrow and i'm 95% sure the noise will be solved.
 

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Could it be the bearings in the alternator? If it is, it's an absolute b*tch of a job due to the alternator being quite far down in the engine bay. The front of the car will most likely have to be stripped down if it is the alternator bearings. However Dimi's right, it's worth changing the belts and seeing if that solves the problem.

Have a look at this Wheeler Dealer video? Does it sound anything like this?

http://www.youtube.com/watch?v=kaQhgKwnR4w


I can't think of anything else it could be!
 

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I just solved this same issue. I had a lot of noise from the alternator area. Wanting to be safe I rebuilt the alternator with new bearings and voltage regulator. Same noise. So the only thing left was the belt. Just changed that and the noise is all gone. I suspect that the tight radius around the alternator pulley causes a lot of side load on the belt and it glazes over time...then the sqeak is back. From what I have looked at there is nothing else to do but put on a new belt. At least it is a 5 minute job and only 35 bucks...easy diy.
 

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I just solved this same issue. I had a lot of noise from the alternator area. Wanting to be safe I rebuilt the alternator with new bearings and voltage regulator. Same noise. So the only thing left was the belt. Just changed that and the noise is all gone. I suspect that the tight radius around the alternator pulley causes a lot of side load on the belt and it glazes over time...then the sqeak is back. From what I have looked at there is nothing else to do but put on a new belt. At least it is a 5 minute job and only 35 bucks...easy diy.
F*ck that. Speaking of rebuilding the alternator, I myself was also just about to purchase a brand new alternator from Realoem for $700 to fix the noise. Luckily it turned out to just be the belts.

Yep, like Mach said, it's the belts for sure.
 

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Discussion Starter #12 (Edited)
Have a look at this Wheeler Dealer video? Does it sound anything like this?
Actually, I feel like an idiot. I have been watching that YouTube video a few times already, but it made me believe it was the bearing the moment I heard it, despite the sound being completely different. My alternator squeaks, the one on the show is grinding.

From what I have looked at there is nothing else to do but put on a new belt. At least it is a 5 minute job and only 35 bucks...easy diy.
Seeing that my belt is only a year old, and that the new belts still may start squeaking later down the road.
I will likely replicate what a local BMW owner did when his E90 320d developed a louder noise from its belts: After trip to the service center to change his belts and tensioner only to have the noise return a month later, he decided to experiment and used a candle to coat the belt with wax along with a sprayed layer of silicone grease to silence it.

Make sure you have a diagram of the belt path handy - it'll save a lot of head scratching and swearing!
It's called Google Image and online BMW TIS manuals ;) Thanks for the advice though.

There is a free tool out now available at your parts store. At least here in Canada. It is a little gauge to measure the depth of the Vgroove. It is very surprising how warn out they are when they still look good.
Thanks a lot. Will keep a close eye on them.
 
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