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Old 07-24-2004, 02:48 PM
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Burnt Alternator Brushes

What is causing my Alternator brushes to burn. After about 2 weeks with new brushes, the alternator stops charging and one of the brushes shows signs of being burnt. This has happened to me twice now. When I initially put in the brushes, things seem to work fine.

I'm running a 1978 318 engine out of an Aspen in a 1973 Dodge PU.


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Old 07-25-2004, 08:03 PM
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Have you checked how much voltage it is putting out?

Try changing your regulator..............
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Old 07-26-2004, 06:09 PM
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[color=yellow]Doc Here

Try checking your commutator (The shaft the brushes ride on) For Burrs and pits, Burnish with a very fine Emery paper to remove any burrs and clean the commutator just until the "Black" goes away.

Clean out the insulator spaces (between the paddles) and be sure you don't have any build up or shorts there, especially near the edges in the direction of rotation of the paddles.

Should Help a little.

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Old 08-15-2004, 11:21 AM
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Thank you for your suggestions. I took the alternator apart and found that the commutator was actually burned through in some areas and there was considerable evidence of arcing occuring. I replaced the alternator. Also, I went ahead and replaced the voltage regulator as well. My thinking here was that the voltage regulator could have gone bad and caused the damage to the alternator or that the alternator problems may have damaged the regulator. Either way I did not want to take a chance for $12+.

The truck seems to run fine at this point. I am no longer experiencing the problems of before.

Thanks again for your assist.

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