whistling alternator.
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Instructor
Joined: Mar 2011
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whistling alternator.
i think my alternator got pretty loud. or is it just when the engine and everything is still cold? how bad is this?
i had my hood open and in garage so it 'whistled' alot louder becouse of that. Is it maybe just the pulley at alternator?
i had my hood open and in garage so it 'whistled' alot louder becouse of that. Is it maybe just the pulley at alternator?
Tech Contributor
Joined: May 2008
Posts: 2,843
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From: Howell Michigan
St. Jude Donor '09-'10-'11
For what it’s worth, there are 36 polls and if the engine is idling at 625 rpm and the alternator rotates at about 3 to 1 with stock pulley, the resulting frequency is, 36*625*3/60 = ~1125Hz, the whine noise you hear.
If you unplug the plug on the alternator the noise should go away. If not, it could be the bearings.
Last edited by Eric D; Dec 22, 2011 at 07:16 AM. Reason: Updated after seeing Zap City's Post about bearing.
Melting Slicks
Joined: May 2006
Posts: 3,201
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From: beach
St. Jude Donor '13
I just replaced mine for the same issue after going completely through the belts and pulleys. It quieted right down. BTW, the car has 24K miles. It was driving me crazy. Bad bearings seemed to be the culprit and it was getting worse.
Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
Good point, it could very well be a bad bearing. By unplugging the alternator if bearings the noise will not change. If the noise quits when unplugged this is normal 36th order whine.
Thread Starter
Instructor
Joined: Mar 2011
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The windings in the alternator produce noise while under load, like right after you start the car. The noise level will reduce as the battery charges. The noise pitch will change with engine speed. This is normal.
For what it’s worth, there are 36 polls and if the engine is idling at 625 rpm and the alternator rotates at about 3 to 1 with stock pulley, the resulting frequency is, 36*625*3/60 = ~1125Hz, the whine noise you hear.
If you unplug the plug on the alternator the noise should go away. If not, it could be the bearings.
For what it’s worth, there are 36 polls and if the engine is idling at 625 rpm and the alternator rotates at about 3 to 1 with stock pulley, the resulting frequency is, 36*625*3/60 = ~1125Hz, the whine noise you hear.
If you unplug the plug on the alternator the noise should go away. If not, it could be the bearings.
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
