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Old 05-10-2017, 05:45 PM   #1
Duck 37
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Unhappy Alternator noise

I have a whinning noise coming from my alterntor,if I take the power off of it the noise stops.The real issue is this is a new unit and I've tried two others. New belt and no sign of water pump problem. At idle its low, but ay higher RPM's you can hear it in the cab Any thought would be appreciated.
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Old 05-11-2017, 08:28 AM   #2
biketopia
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Re: Alternator noise

You picking up feedback through your speakers?
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Old 05-11-2017, 09:30 AM   #3
Duck 37
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Smile Re: Alternator noise

The truck is bare bones at this time,no speakers.Thanks for the reply
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Old 05-11-2017, 10:08 AM   #4
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Re: Alternator noise

How is the voltage output?
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Old 05-11-2017, 01:58 PM   #5
GASoline71
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Re: Alternator noise

Just pretend it is blower whine...

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Old 05-11-2017, 09:29 PM   #6
Duck 37
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Talking Re: Alternator noise

14 volts across the terminals. I thought it was more like a gear drive.
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Old 05-11-2017, 10:30 PM   #7
Wrenchbender Ret
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Re: Alternator noise

A shorted diode will make it whine like a bad bearing, but you say you have tried other alts. This is a tough one.
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Old 05-12-2017, 01:01 AM   #8
'68OrangeSunshine
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Re: Alternator noise

I've got the same gripe on the last 2 alternators on the L6 292 in my '68 C/10. I replaced it with one ''lifetime guarantee'' alternator [external regulator type] from O'Reilly's.
New one on and same whine, same red GENERATOR light in the dash. If I rev up the RPMs, and let it settle down, the whine and red light go out, until the next light. I may have to shim one of the pulleys in the front. It's possible the belt's misaligned.
I'm thinking of getting a 12SI alternator. Getting a good vintage alternator out of O'Reilly's was like pulling teeth. Never had that problem when they were Checker Auto.
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Old 05-12-2017, 09:19 AM   #9
Duck 37
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Smile Re: Alternator noise

The fellow who rebuilt this alternator is a personel freind and has been in the business for 20 yrs. He's scratching his head. He's making a house call to my place today. Has to be something in the truck,it started after I bought it with the old unit.THANKs for all the replies.
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