Need Some Alternator Smarts

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Sep 14, 2009 | 10:28 PM

Black LS2

Thread Starter

Racer

Joined: May 2009

Posts: 261

Likes: 2

From: Boise Idaho

Need Some Alternator Smarts

I have an 2005 with 20,000 miles. The stock alternator has started a whine at exactly 2,000 RPM (not through the stereo; but audible from the engine compartment)

My 87 L98 went through several of the 15si GM alternators over 20 years because one or both of the bearings were too small. I finally solved this with a Motorcraft rebuilt unit that had the bigger bearing.

On the C6’s:

My guess is the pulley bearing, but are there any known problems with the C6 alternator? (search was negative)

What model is the stock alternator (24si?)?

Thanks!

Sep 14, 2009 | 10:41 PM

mpuzach

Race Director

Joined: Mar 2005

Posts: 16,684

Likes: 1,193

From: La Center WA

Wow, this is eerie. My 2005 with just over 20,000 miles recently began doing exactly the same thing. For me it's actually at 2,050 r.p.m. When I began hearing it a month or so ago I had my servicing dealer troubleshoot the noise and they confirmed it was the alternator. They checked it out and determined that other than the whine, it's functioning normally; they recommended to not replace it unless / until it develops more serious problems. I'm glad of that because they said that the cost to replace it would be around $850 (parts and labor). I was later told by forum buddy cclive that a replacement alternator can be bought from Gene Culley for $350 - $375 and that installation is a 15-minute job. That may be but I looked under my hood and frankly, it doesn't look like something that I'd feel comfortable tackling.

It will be interesting to see what other folks here have experienced with their alternators.

Sep 14, 2009 | 10:48 PM

cclive

Team Owner

Joined: Mar 2008

Posts: 21,502

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From: Southern Utah

I don't think that the alternator in the Vette is from the si series. The voltage is not controlled by an internal regulator like the si series but is controlled by the engine computer, so I think it would be difficult to replace it with something else. I must say that we really have not heard alot of alternator problems on the forum, but then most cars here don't have many miles on them, so its probably not a very good sample. I know that there is a replacement Bosch alternator for the car, they may build the oem one also...I seem to remember that it is not made by Delco-Delphi. Bosch makes a good product..."you know the Germans always make good stuff"...to coin a phrase...

(Thanks for the kind word Mike)

And the 12si in my Trans Am has been doing very nicely for the last 35 years...

Last edited by cclive; Sep 14, 2009 at 10:51 PM.

Sep 14, 2009 | 10:53 PM

RicK T

Team Owner

Joined: Sep 2005

Posts: 20,352

Likes: 568

From: Ventura County, Calif

Can't answer your questions directly. But I saved this recent thread because it is informative and like cclive said, we haven't seen much about alternators here. The thread is about High Output units but you asked for alternator smarts so maybe it will benefit you:

http://forums.corvetteforum.com/c6-c...lternator.html

Sep 14, 2009 | 10:56 PM

gtovett

Racer

Joined: Feb 2006

Posts: 326

Likes: 2

From: Folsom California

The Brand is Layo. I had a problem with mine in my 06 that was produced november of 2005. An auto electric guy told me these alternators are considered throw-away alternators. He said they suck and you can't get parts for them to rebuild them. And that he had no way of even taking it apart. He knows his stuff. The new vettes don't use the same ones. I believe they switched in 2008. GM wants somewhere around $540 list price at a dealer for a new alternator. Im not sure about the reliability and brand of the new ones. Mine began to make noise awhile ago. I pulled off the black cover piece and put spray oil around the bearing and it hasn't made any noise since. Hope this info is helpful.

Sep 14, 2009 | 10:56 PM

cclive

Team Owner

Joined: Mar 2008

Posts: 21,502

Likes: 465

From: Southern Utah

I just thought of something else also....some alternators whine when they are under electrical load...not a mechanical but an electrical whine.....so try turning on some of the biggest electrical loads in the car and then listen and see if it is louder. The rear window defog, heated seats and vent blower are the biggest. Turn all of them on and then listen...

Sep 14, 2009 | 10:58 PM

Black LS2

Thread Starter

Racer

Joined: May 2009

Posts: 261

Likes: 2

From: Boise Idaho

Changing them out is really not bad; easier on an L98 than an oil change, and does not look much different on an LS2 (also thanks to the wonderful serpentine belt tensioner).

On my other post I called the L98 alternator a SI, but its actually a CS alternator; I have rebuilt both.

If I can find out some more info about the C6 alternator (model, bearing issues, etc), there is a regional starter and alternator rebuild shop nearby. I bet they could put a better bearing in for a ton less than buying a whole new alternator. At 20,000 miles these are barely broke in. I will do some checking.

Sep 14, 2009 | 11:01 PM

gtovett

Racer

Joined: Feb 2006

Posts: 326

Likes: 2

From: Folsom California

Quick addition. The alternator isn't hard to remove or install at all. You do have to undo the fuel rail cover to move it up to allow for the alternator to come out, but their is a way to get it out, and putting it back in is easier than taking it out. I took mine out in less than 10 mins and put it back in less than 5. Just make sure the belt doesnt fall down. It makes it easier if you tie it up to the bracket while the alternator is out of the car.