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Alternator Going Bad?

Discussion in 'General Discussion' started by MrSony, Jan 9, 2017.

  1. Bar50

    Bar50 Royal Smart Person

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    Should be an internal regulator Delcotron 10si alternator that was born on his Regal?
     
  2. L67ss

    L67ss Royal Smart Person

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    I honestly can't remember. I know some years were internal and some were external. Been so long since I messed with carb motors I'm fuzzy on that
     
  3. airboatgreg

    airboatgreg Greasemonkey

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    Bar50 you are right on. Probably regulator but of age that diode trio will need to be replaced along with brushes and bearings. Alternator shop is a great option.
     
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  4. airboatgreg

    airboatgreg Greasemonkey

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    Also possible rectifier.
     
  5. Texas82GP

    Texas82GP Comic Book Super Hero
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    My dad had a small fleet of big block powered Chevy/GMC C60/C65/C70 trucks ranging in year model from 73 to 77. We used to crack those alternators open on the side of the road and replace the regulator. We used a wrench and allen wrench to get the pulley off and partially straightened paper clips to hold the brushes in place while putting it back together. When we pulled them off, they were too hot to work on (from the all iron BBC) and were often still warm when they went back on.
     
  6. olds307 and 403

    olds307 and 403 Royal Smart Person

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    Isn't a 1985 a 12 SI alternator? I upgraded to the CS130 100 amp alternator, it is the replacement for the 1988 Cutlass Supreme Classic. I have found the 10 SI chrome alternators don't last. One reason GM went to the 12 SI case was the superior venting and a better fan for higher output alternators. I am betting you just need a new regulator and you may as well throw in new brushes as well.
     
  7. pontiacgp

    pontiacgp Rocket Powered Basset Hound

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    from my experience with alternators is a diode is burnt the alternator still charges but at a reduced rate, if you have a warning light the light will be on low with a diode burnt, if the rectifier and diodes are gone you'll get alternating current to the battery, if the voltage regulate is gone the voltage spikes, if the alternator stops charging I'd put my money on the brushes....

    or the one thing overlooked is the alternator getting excited?
     
    #17 pontiacgp, Jan 10, 2017
    Last edited: Jan 10, 2017
  8. MrSony

    MrSony Royal Smart Person

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    I don't know what model or style it is, I just know it came on my 3.8 when I got the car, it's a 70Amp which matches the RPO code on the trunk lid, and it died at 89,730 miles. Here's some pictures and a fun video.

     

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  9. olds307 and 403

    olds307 and 403 Royal Smart Person

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    That is a 10 SI alternator. If you are fine with 70 amps, the regulator and brushes are cheap as dirt, open it up see what is up with it. They usually make a bit of noise turning them.
     
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  10. MrSony

    MrSony Royal Smart Person

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    A little addendum to this thread, I pilfered my dad's old Sentry Gold Alternator he had on his grand prix back in the late 1990s. Works good. No squeaking. Also replaced my 160 t-stat with a 195. Car runs MONEY now. And the heat kind of works. I think the vacuum ball controls the flapper doors or whatever that direct heat to defrost or normal vents because I get barely any heat from the defrost vents and no where else. It's warm, but it's like someone mouth breathing on you. No force behind it. That'll get sorted soon. So, to recap: Squeaking Alternator = Bad. Get a new one or try and rebuild it. Thread Over.
     
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