nother question- alternator whine/whir

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Noticed it yesterday after we replaced the Intake Air hose. At first we thought it was the AC compressor, but it does it with a higher electrical load. When revving, it whines/ whirrs. The higher the engine RPM, the higher pitched the noise. Could this be a sign of a dying/failing alternator?
 
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Most likely a failing bearing. If that's the case, the alternator is going bad. How old? How many miles on it?
 
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You could try a touch of WD-40 lubricant, and I do mean just a touch, and see if that quiets it down until it can be replaced. No doubt that it will have to be replaced. They are typically cheap and an easy job at that on most cars. If it is for that Cavalier then I imagine it would be cheap, around a $100 I'm sure. You're lucky, the altenator on my F150 is around $500.
 

Nick R

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13 years old, almost 126,000 miles. Its not a bearing sqeal. I don't know how to describe it. At first I thought that the new intake hose reverberated, and it was "whistling" or something. Its strange. Also, if it matters, I got a 100w power inverter. To test the electrical system as best I can (the inverter wont work with less than 13v for reference). I turned on the headlights, plugged my laptop and cell phone into the inverter, turned the A/C on high, plugged two portable DVD players into the other 12V outlets.... turned the radio on. With all this on idling, the power inverter turns off due to low voltage. If I tap the gas, it works for about 30 seconds, and then turns off again. I would imagine at idle it can't supply the amperage needed, but I may be wrong.
 
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Well the reason I suggested the bearings/brushes is because on my old Altima before I sold it, the alternator was making a whining noise, almost like the sound of a supercharger. I had it rebuilt with new brushes and the noise went away and it worked fine.. but I could be wrong, I'm only going by past experience on one particular application maybe some lubricant to quiet it down is all that's needed. Before I had mine rebuilt, I tried some spray and it didn't do anything.
 
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Its probably on its way out at that age. I would remove the belt, and spin the pulley by hand, if it doesn't feel or sound smooth, the bearings or brushes are going....
 
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May very well be the alternator. I have had several Delco/Delphi alts. whine when they start to fail. I would say the whining is more likely related to one of the six diodes failing rather than a bearing problem.
 
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My Delco 10SI (yeah, ancient) did this when I had a bad battery. The thing started fine, but drew way too many amps trying to charge the battery. Check your voltage with the car off. You should be able to run your inverter with just the battery with some minimal load.
 
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So did you put on an aftermarket air intake? It is probably wind whistling over the throttle blade or through the idle air control hole. Take the intake off entirely, I bet the whistle is even higher/louder. It takes more air to rev or to make the power it takes to turn the alternator to power the headlights etc, so the whistle gets louder. Just throwing it out there as a possibility.
 

Nick R

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No aftermarket air intake. It didn't do it before. The sound is coming from the alternator, if I listen next to it, that is where it is coming from. Turning off all excess electrical load makes the sound disappear almost completely.
 
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 Originally Posted By: rudolphna
No aftermarket air intake. It didn't do it before. The sound is coming from the alternator, if I listen next to it, that is where it is coming from. Turning off all excess electrical load makes the sound disappear almost completely.
I believe autozone or advanced auto parts will do free altenator testing right in the parking lot.
 

Nick R

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We tested the alternator here, it was putting out 14.5V most of the time, dropping down to 7-8V every 7 seconds or so, for about 1 second then back again to 14.5.
 
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