Alternator whine

AV8R4AA · #1 01-27-2017, 07:40 PM

I have a 2004 air cooled alternator that has a slight whine.
It's not loud, just an intermittent whine.
Bought a mechanic stethoscope to isolate the noise.
It's the alternator for sure. Twice I have removed the serpentine belt
and spun every bearing pully. The last time I removed every pully and regreased them, they are not the noise. Even the alternator spins dead quiet.
Which is odd, because every alternator that had a marginal bearing, sounded
bad with a spin. Mine is solid and smooth with no noise by hand.

It's not a full time alternator whine, I think it's just one of the 2 bearings.
I hate to have to buy a 300+ new alternator for just one bearing.
Anyone have this issue?
Any new bearing kits to install?

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X53Jay4.8is · #2 01-27-2017, 07:56 PM

Quote:

Originally Posted by AV8R4AA

I have a 2004 air cooled alternator that has a slight whine.
It's not loud, just an intermittent whine.
Bought a mechanic stethoscope to isolate the noise.
It's the alternator for sure. Twice I have removed the serpentine belt
and spun every bearing pully. The last time I removed every pully and regreased them, they are not the noise. Even the alternator spins dead quiet.
Which is odd, because every alternator that had a marginal bearing, sounded
bad with a spin. Mine is solid and smooth with no noise by hand.

It's not a full time alternator whine, I think it's just one of the 2 bearings.
I hate to have to buy a 300+ new alternator for just one bearing.
Anyone have this issue?
Any new bearing kits to install?

one thing about those alternator bearings once they go they can lock the engine and stall the car. My 540i Msport bearing began to fail eventhough it was still charging well and when it went it stalled the car right in the driveway. I was glad it happened there vs. on the road. Changed out the alternator and all was good.

AV8R4AA · #3 01-27-2017, 09:05 PM

Ok.
Cha Ching $$$$$
Hello Autohaus

80stech · #4 01-27-2017, 09:31 PM

I've heard the the valeo alternator has a "floating field" which can get knocked out of alignment and cause excessive whine, especially when charging heavy. That was the first thing I replaced on the X. When I bought it I noticed the alternator whine and I just ordered a new one(assuming it was a bad diode), when I went to install it I realized that the one I was replacing was almost new and then investigated a bit and came up with the story of the field(rotor winding) moving. Supposedly happens often in shipping.

Fifty150hs · #5 01-28-2017, 01:04 AM

Replaced a bad alternator with new rebuilt. Had a whine afterwards. After some electrical problems got a replacement alternator (rebuilt), no whine. Has to do with quality of rebuild maybe?

msammy · #6 01-28-2017, 03:18 AM

Quote:

Originally Posted by AV8R4AA

I have a 2004 air cooled alternator that has a slight whine.
It's not loud, just an intermittent whine.
Bought a mechanic stethoscope to isolate the noise.
It's the alternator for sure. Twice I have removed the serpentine belt
and spun every bearing pully. The last time I removed every pully and regreased them, they are not the noise. Even the alternator spins dead quiet.
Which is odd, because every alternator that had a marginal bearing, sounded
bad with a spin. Mine is solid and smooth with no noise by hand.

It's not a full time alternator whine, I think it's just one of the 2 bearings.
I hate to have to buy a 300+ new alternator for just one bearing.
Anyone have this issue?
Any new bearing kits to install?

You say it's intermittent and I'm having the same problem. I've replaced all belts, tensioners and pulleys to no avail and have a weird whine/groan ONLY when the A/C is on. Without A/C, the sound goes away as the A/C compressor puts load on the system and the noise returns (only when the compressor kicks in). Are you having the same symptoms only with A/C on? If so, you may have helped pinpoint my problem, I thought it was the A/C compressor, but maybe it's the Alternator?

semcoinc · #7 01-28-2017, 11:57 AM

Quote:

Originally Posted by AV8R4AA

I have a 2004 air cooled alternator that has a slight whine.
It's not loud, just an intermittent whine.
Bought a mechanic stethoscope to isolate the noise.
It's the alternator for sure. Twice I have removed the serpentine belt
and spun every bearing pully. The last time I removed every pully and regreased them, they are not the noise. Even the alternator spins dead quiet.
Which is odd, because every alternator that had a marginal bearing, sounded
bad with a spin. Mine is solid and smooth with no noise by hand.

It's not a full time alternator whine, I think it's just one of the 2 bearings.
I hate to have to buy a 300+ new alternator for just one bearing.
Anyone have this issue?
Any new bearing kits to install?

I can tell you this for sure, that my 2003 WATER cooled alternator seized up and via serpentine belt tension, prevented the starter from cranking the car. Unknowingly, I jumped it and with extra cranking power got the engine to turn over and start, then all manner of smoke and belt pieces revealed themselves.

Extracted belt and limped home the 5 miles or so without overheating and sans power steering.

No fun to deal with a seized anything on that serpentine belt

So, if it is truly an alternator issue, I'd deal with it on my terms and not in a parking lot somewhere. I got my rebuilt off ebay and believe I'm past the infant mortality stage.

Mike

squidzilla · #8 01-28-2017, 12:03 PM

You can rebuild your OE one with some of the kits they sell on ebay. A member names oldskewel rebuilt his with one of these kits. The seller for his is some guy in Ireland I think. I bought one for the alt on my n62 545i. Between the kit and the voltage regulator I am into it 65.00 or so. The seller provides videos on how to rebuild your alternator and it really does not look hard.