New Alternator Making Whistling/Whining Noise

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Jesse_Wenting

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Need some help understanding why my new alternator is making a whining noise. I replaced the belt, tensioner and idler before the alternator and there's no irregular moment in the alternator pulley, however there is a slight whine when hand turning and the pulley does not free spin for more than about a second. Voltages are 12.43 off and 14.49 at idle, but the battery I'm using has been below 10v at one point
 

df2x4

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Is it an ACDelco Professional by chance?

I put one of those (a 105A version) on my Suburban a few months back and it did the same thing for a little while. After a week or two it went away completely, though.
 

98 Nitro

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My 24 month warranty on an AC Delco alternator crapped out in month 25, so I put a Powermaster 115 amp one in a few months ago-no whine and US made with 36month warranty.
 

Jesse_Wenting

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Mine has been whining for years, LOL.
I want my pig to sound mint bro lmao

My 24 month warranty on an AC Delco alternator crapped out in month 25, so I put a Powermaster 115 amp one in a few months ago-no whine and US made with 36month warranty.
Honestly if I can't figure it out, I'll replace it with a Mechman 250 Elite and keep the ACDelco as a spare since it's.. literally.. NEW
 

Wheeler

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Two weeks ago I installed a new 105 AC Delco Alternator. It has been perfect. One I took off had a bearing making a whine, but this one great. A new one should not make ANY noise.
 
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