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High pitched whistling noise


Addicted2bass
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Hopefully someone in here has had this problem. This is on my 96 GP 3.1. Ill start from the beginning.

 

Ever since I bought the car in april it has randomly made a loud and extremely high pitched whistling noise from the serp belt/pulley side of the engine at idle. For awhile it would only do it every once in awhile and there was no rhyme or reason to it. But the last few months it started happening more and more.

 

I finally got fed up and took the serp belt off and spun each pulley. Sure enough when i spun the one on the alt it made a squeaky noise. I was told the brushes were probably bad on the alt so i replaced it. all was good for about a week and half. Then earlier this week it started again.

 

The noise only happens at idle as soon as i get on the throttle it goes away. The serp belt is in pretty good shape, but i have no idea how old it is. A couple people have told me it could be a vacum leak, or i may have just got a bad alt. Any help is much appreciated.

 

 

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The whistling could also be confused with a loud alternator "whining". Pull the alt and take it to a store to be tested for free before it craps the bed and leaves you stranded.

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Alternator bearings are shot.

 

Umm no. Bearings do not make a nigh pitched noise when they go bad. They make a grinding noise, which you cant hear unless you put your ear about 4" away from the alt. I know, my alternator has been like this for years. If it was alternator whine, you would hear it throughout the RPM range. Since his goes away once the throttle is pressed, I dont believe its an alternator.

 

You can check the PS pump, as that can whine, but really, Id look at the tensioner pulley. That usually makes a hell of a noise when it goes bad.

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O really.. I guess when I got mine TESTED at AutoZone and it passed all the tests except the fact that it was whistling in the machine was a fluke.

 

Jay can you tell me what would make a whistling sound that is on an alternator when it is spinning? Im curious to know why I am wrong.

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The reason that the bearings themselves dont whine or make a whistling noise is because they are metal ball bearings. They are sealed. When they start to go, they grind against the track that they are in. ( if youve never seen this, take off the seals on the bearing and youll know what I mean ) Next time you have your car running, pop the hood, and put your head close to your alternator, youll hear it grinding.

 

Theres 3 things that can cause an alternator to make its whine or whistling noise:

The regulator

The diode

Increased circuit impedance

 

Now to further explain this, whine caused by the regulator can be distinguished from the alternator in that regulator induced noise intensity changes in intensity and pitch with current load at a constant engine speed. Thus turning on the lights won't increase alternator whine but will increase regulator induced alternator whine.

 

If a diode fails the amount of ripple voltage increases. Alternator whine can be a symptom of a bad alternator diode.

 

Alternator whine can be caused by poor electrical connections, especially at the battery.

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The reason that the bearings themselves dont whine or make a whistling noise is because they are metal ball bearings. They are sealed. When they start to go, they grind against the track that they are in. ( if youve never seen this, take off the seals on the bearing and youll know what I mean ) Next time you have your car running, pop the hood, and put your head close to your alternator, youll hear it grinding.

 

Theres 3 things that can cause an alternator to make its whine or whistling noise:

The regulator

The diode

Increased circuit impedance

 

Now to further explain this, whine caused by the regulator can be distinguished from the alternator in that regulator induced noise intensity changes in intensity and pitch with current load at a constant engine speed. Thus turning on the lights won't increase alternator whine but will increase regulator induced alternator whine.

 

If a diode fails the amount of ripple voltage increases. Alternator whine can be a symptom of a bad alternator diode.

 

Alternator whine can be caused by poor electrical connections, especially at the battery.

 

Yeah I see what your saying. But if the diode failed wouldn't it test bad? See my alternator tested good.. there was just a whining coming from the insde.

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Theres 3 sets of diodes. They all dont have to fail at the same time. If one pair fails, then you wont notice it until an extreme damand of current is needed from the alternator, but still can last a very long time with just the two pairs. But yet you would hear this whining noise from the alternator.

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You can check the PS pump, as that can whine, but really, Id look at the tensioner pulley. That usually makes a hell of a noise when it goes bad.

 

werd to the PS pump, but it does sound more like the tensioner pulley. the PS pump is more of a rattling/whining sound

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Ive heard tensioner pulley from a few people. Its not original but i dont know how old it is. The car is a 96 and has 120k on it, the alt that was on there was not original either for that matter. When i spun the pulley on the alt it would make a squeaking noise, but only on one spot. I assumed that this noise would be constant when the pulley was spinning and that was the culprit.

 

19Cutlass94 you mentioned that their could be a bad connection at the battery? I hope its something that simple. As soon as i have some daylight to work with (ive been workin 11 hour days lately) im going to check my battery connections.

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All alts are going to make a whine. Listen to a 4.3 Blazer/S-10 for a good listen to. Kinda like how a flash makes that same noise (the flash on a camera)

 

You COULD ask for another alt, but meh - I'd ignore it.

 

And a rule of thumb - a good ball/taper/etc... bearing sings, a bad one growls.

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Alternator bearings are shot.

 

x2. This exact sound came from my car this summer, i knew it was the Alt but told all my "ricer" friends that it was a s/c, they believed me for a second then i started laughing.

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I took the car to my mechanic the other day. The whole they had the car all day, started it a couple differant times and it didnt make the noise once. The next day after it didnt make they noise and now it has been doing it everytime since then. Its gettin pretty loud. I can hear it from my house when i remote start it in the morning. And i can hear it when im inside the car sitting at idle if i have the radio turned down. Needless to say ive been getting alot of weird looks at stoplights and in parking lots lol.

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Its coming from that general area of the engine, put its impossible to pinpoint. The noise kind of surrounds you so its hard to tell the exact spot its coming from. Its been doing it on and off this weekend, if its making the noise tomorrow im going back to my mechanic.

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If you cant pinpoint it, I highly doubt its the alt then. If it was, you would be able to tell without a doubt. I would start looking at other things like the PS pump, tensioner assembly etc etc.

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