Alternator Whine?

[Jelly]

Has anyone heard of such a problem?

I know of no other way to describe it other than saying that a whining sound appears to be coming from the alternator...no, not the pulley, but the alternator itself.

It's starting to get annoying!

 

[sbc350gearhead]

My alternator starting whining about a week before it went out.

 

[labman]

Sounds like the lubed for life bearing is dry. Remove the belt and try spinning the pulley by hand. Any noise, roughness, or total lack of resistance means the bearing is dry. A little oil in it might extend its life. Better yet a new bearing. Otherwise, it is another alternator. More expensive, but the quickest, easiest, and less likely to give future problems.

 

[MolaKule]

If you have one of those needle-type grease injectors with the Zerk fitting, use Redline CV-2 and try to inject some grease into the bearings.

 

[Chumley]

follow labmans advice, then if nothing else is
wrong:

If you live in a major metro area, pull the alt.,
take it apart. Take it to a bearing supply store
which you can find in your local yellow pages
under "bearings." Hand it to the nice man behind
the counter and in a few minutes he'll come back
with two new bearings and say something like,
"That'll be eight dollars!" Have a machine shop
press them on and you'll be back in business.
Check the brush length and replace those also if
they are worn. (minus the cleaning and paint
job, that's more that's more than most alternator
rebuild shops do for a lot more money)

You don't mention your application but most
auto parts stores will sell you a replacement
brush/voltage regulator assembly to fit most
Bosch, Motorola, etc. alternators for around $15
to $20.

Chumley

 

[goldfinger]

Mine was doing that about 2 years ago and I went ahead and had it replaced before it went out completely. At the time I had no idea where the noise was even coming from until the mechanic told me.

I noticed today it's starting to make the whining noise again.

Does yours make the noise at all RPM ranges? Mine doesn't at idle, only about 1,200 - 1,800RPM. Maybe the engine noise drowns it out at higher RPMs?

 

[Jelly]

You been driving my truck around or something??

You've pretty much described my situation..

At idle, no noise.

If you rev it up at a stop, you hear it.
You also hear it until you get up to about 60.
You also don't hear it at high r.p.m.'s.

 

[Brett Miller]

Spray a little lube on the bearing in the tensioner pulley and you may be surprised how quiet things get.

 

[Cutehumor]

my g/f car last year alternator bearings went bad, I just went ahead and replaced it with one of those duralast lifetime warranty alternators. what kind of grease are you guys using? I might put some grease on the bearings so I don't have to worry about this in the future.

 

[labman]

It is difficult to get grease into a sealed bearing without messing up the seals. It is easy to get too much in that ends up elsewhere causing problems. I think this is another case where leaving well enough alone may be best.

 

[9c1]

Most current alternators are not field rebuildable any longer. Many use a crushable sleeve to apply pressure to the bearing, and special fixtures are needed to remove and replace the bearings. There are a few, especially older units, that still can be field rebuilt, but it varies by model and even size of alternator.
We no longer teach students how to rebuild alternators and starters because so few are field rebuildable, and most shops don't want their techs spending time on bench work. They also want a third party to warrantee the part. The rebuilders pay their employees far less than automotive technicians make. I’m sure there is an Economics 101 lesson in here someplace, but I’ll leave that to folks with that specialty.
Terry

 

[shortyb]

Alternator whining? Tell it to shut up and just charge the battery

.

Seriously, try to oil the bearings or rebuild if possible. If not, new alternator time. As 9c1 says, so many are one-shot these days but if your inclined to provide alittle maintenance for a better unit, try and find one that is rebuildable. They are generally better built than the disposable ones anyway.

 

[Sumerduckman]

A lot of times, a high pitched whine is caused by one or more of the large internal diodes ' giving it up'. It caused an imbalance in the circuit and they will oscillate/whine. It is new alternator time.

 

[Sumerduckman]

Needed to add. It is easy enough to determine if it is diodes, or bearings. Disconnect the wiring from the alternator. Then start the motor. If it is bearings, it will still make the noise. If it is diodes it will not.

 

[radiometer]

I recently had the alternator replaced in my Mitsubishi Pickup after over 200k miles of use. After a while I began hearing an objectional noise at the front of the engine. To isolate this noise I removed both drive belts and started up the engine. No noise. I then replaced the first belt and started up again. The noise is now present. I then knew the sound had to be coming from along the track of that belt. I spun the alternator pulley by hand. BINGO. There it is. I returned to the shop that supplied it and they replaced it. Driving just fine now.

[ December 07, 2003, 05:24 PM: Message edited by: rugerman1 ]