brief history:

notice whining. wait a year before I do anything about it. NO other problems (charging, overvoltage, nothing).

one year later, start diagnosing. take belt off, and whine is gone.

then, i recall that the whine started about the same time that I changed AIR pump. So, changed it again. no effect.

decided it must be the alternator bearings. unplugging the alternator connector and running the engine, the noise was still there. put on a brand new (non rebuilt, non reman) napa alternator. whine is still there.

changed power steering pump. no change.

changed the drive belt to a spare. still whining.

tried unplugging alternator connector again on the new napa alternator.. no whine this time, it's gone.

so, i'm thinking my brand new alternator must be defective. It does seem to get quite warm. I should note that i'm using an optima red-top, it's about a year old.

thoughout all of this though, there are NO other symptoms. regulated voltage is perfect it about 14.4 (idle all the way through the RPM range); alternator does just fine under load (headlights, stock dual radiator fans, vent fan, etc.)

ideas? thoughts?

 

It will get warm, but if it's really quickly, then you could have a wiring problem somewhere. Grab a multimeter & measure the resistance from the alternator case to the battery negative. It should be pretty low (say...less than 50 ohms, but should be really close to 5 or so). Do the same for the remaining terminals on the alternator to the positive terminal. If I remember correctly, one of the terminals will not show continuity unless the key is in RUN. If any of the resistance measurements are irregularly high, find out why & fix it.

I'd guess that the ground strap may not be working too well (i.e.: old/corroded). You could even take a piece of heavier gauge wire and temporarily run it from the battery - to the engine block to see if that helps.

 

yeah, it gets warm quickly. I've checked the grounds and alt-bat cables in the past, but checked them all again, all measure no voltage loss/drop, all the ground straps are in good shape too (thank goodness things don't corrode in california).

I noticed that the alternator is buzzing/whining with power applied to it (key in "run" position) but with the engine NOT running.

i guess i'll take it off, take it back, and swap it for alt #3.

 

Mine does that as well, but it's pretty faint. You have to pop the hood and lean in toward the engine to hear it.

 

another new alternator, same problem.

gets hot quickly, whines too.

this one puts out 14.7V instead of 14.4 like the previous new one.

this one however, keeps whining even if the connector on the back (not the battery cable, but the connector that turns the alternator on) is unplugged. ???

I did note that the battery voltage with everything disconnected and off was only 12.05v which sounds fully discharged. I don't know why - the alternator is charging its heart out. i'm putting an overnight 10A charger on it to see what it does. the charge current stabilized at 11A on the charger, so the battery is definately taking current like a normal discharged battery (yet I never have starting problems).

sigh....this is so frustrating. if, after charging the battery the problem still remains (or the battery simply never stops charging), i'm going to swap it for another new one.

Everything passes all the tests yet the problem remains.

 

I don't think your whine is coming from the alternator. Try checking the pulley on the belt tensioner. Take the belt off, spin it by hand, and listen. If it makes noise, either replace the bearing in it, or get a new pulley with the bearing preinstalled ($15 or less). Those little pullies spin about 3x engine rpm, and the bearings just don't last. I replace mine every 40K-50K miles (that's as long as they'll go for me without getting noisy).

 

I guess I forgot to mention, but that pulley has been replaced as well with a new bearing.

It's definately the alternator. With the 2nd alternator, you could unplug it and the whine was gone completely. Further, I finally used a mechanics stethoscope thing, and when you touch the alternator case (especially the center), the shrill is so loud in the headset that if it was much louder, it would be painful. Everything else is dead silent - PS pump, water pump, AC compressor, AIR pump, and the tensioner.

 

well, i solved the problem.

short version: NEW belt, NEW tensioner pulley, NEW tensioner. noise GONE.

I don't really understand why (I had already tried a different belt and had replaced the tensioner pulley bearing with a new one), but..at this point, i'm not going to argue.

 

was it a higher pitch whine? Something like almost a squeal?

I had a problem like that with my tahoe. I had replaced my alternator bearings previously, so I thought that coudln't be it. I replaced the tensioner pulley/bearing, and the idler pulley/bearing. Still had a whine that was almost a squeal. I went to ask my mechanic. He came out, sprayed brake cleaner on the belt, while the engine was running, and the noise went away. Then he told me to go get a new belt. So I did, and the noise was gone.

bottom line...my belt was bad and the whine I thought I was hearing was actually the belt squealing.

 

I wouldn't say so, no. definately not the sound that you might hear on an old V-belt car with a loose alternator belt or something like that.

i tried two belts, though; and neither had any different sound at all.

the new belt is a goodyear gatorback, which had a different belt V design than the other two.

 

man, i feel bad about all the money u spent replacing things...cars can be a b*tch sometime

 

My car is making the exact same noise! when the key is in the on position. I to have run all kinds of voltage and load tests. I have been driving myself NUTZ trying to get rid of the alternator whine. Tomorrow i am going to go get a gator belt tensioner and pulley.