I replaced the alternator on the '99 SLE that I bought a couple of weeks ago because it was making an odd noise and it appeared to be original. The noise sounded to me like bearing noise. I just bought a new alternator (not rebuilt) from Kragen O'Reilly with a lifetime warranty and installed it. To my surprise, it also makes noise, probably the same noise.

Is it common for alternators on the '99 make noise? I can't imagine that they do, but 2 out of the 2 that I have do, and one is brand new.

I replaced my original alternator that was making a bearing squeak with a lifetime warranty remanufactured one that had a very loud whine for a couple hundred of miles before quieting down. I didn't have time to run to the nearby junkyard and pay almost-new prices for a 100k mile used one. Voltage is fine, the battery is charged fine, there's no noise through the radio with the car running, so it's going to stay for the time being.

It's not common, and sounds like you have a bad alternator. From what I've heard, new/remanufactured alternators for our cars are hit or miss for quality control. If it makes you feel better, the warranty replacement I got was bad right out of the box, and didn't work in the store.

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2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

Especially new, since it's all Made In China crap. At least Re-man's are OE cases, stators and rings, generally with new voltage regulators and bearings.

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Bye Bye:

RIP sandrock

The new one is Ultima Select, made in Mexico. Maybe it'll quiet down after a few miles...
The only physical differernce I noticed so far is that the plastic cap for the battery cable doesn't fit correctly because the 2 internal screws on either side of it protrude a little outside of the case.

Those 2 screws are flush with the outside of the case (as they should be) on the original alternator.

This greatly depends.... If it sounded a bit like a whistle that would come and go, Yes thats 100% normal of the alternator to do that... If it was groaning or chirping then no...lol

if your old alternator was replaced due to bearing wear, and the new alternator already has the same sound, it could be your tensioner assembly. the assembly on my Lesabre seized and was putting way too much tension on the alternator and power steering pulleys. i went through three replaced alternators before i replaced the tensioner. no bearing problems since...

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call me Steve...

HAI, full 2.5" exhaust, resonator delete, Pioneer Audio, F17 transaxle, Toyo Versado LX 215/70/15's

Thanks for the suggestion, but the noise is definitely coming from the alternator. I haven't driven the car since the day I installed the new alternator. I'll keep an 'ear' on it when I begin driving this car.