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Alternator belt coming loose??

Discussion in 'The Garage' started by hidesertwheelin, Dec 13, 2006.

  1. hidesertwheelin

    hidesertwheelin 1/2 ton status

    Nov 13, 2004
    Likes Received:
    Hesperia, CA
    My alternator belt on my 82 Jimmy keeps coming loose. So loose that it won't charge the batteries. I use a screwdriver to move the alt to tighten the belt, then tighten the bolts. I'll start the truck and it starts to charge the batteries. After 5 Min. I turn off the motor and the alternator has slid towards the block, loosening the belt again. All the bolts are tight and I have to loosen them to re-adjust the alternator. Anyone ever have this problem :confused: Any ideas to fix it?
  2. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

    Apr 5, 2003
    Likes Received:
    Pueblo, CO
    My beater 78 Malibu had that problem. I got used to having a 9/16 wrench and long screwdriver in the glovebox. I traced my problem to the upper bolt on the alternator that goes to the upper bracket. The threads were pulling from out of the alternator. You could torque it down as much as you can and it would still loosen up. Plus all that pulling on the belt caused it to stretch over time adding to the problem. I was able to tap the hole for the next larger size up bolt, but I had to open up the groove on the bracket to make room for it. It proved to only be a temporary fix though. Might have been able to put a heli-coil in it, but just got another alternator. (chucking a belt due to the ever loosening alt in a bad section of Dearborn, MI had a lot to do with the decision too)
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

    Jul 22, 2001
    Likes Received:
    Mesa , Arizona USA
    You can use a longer belt and a locking nut behind it . Have a friend or spouse hold the tension , and you use two wrenches to tighten it .

    Simple fix .
  4. diesel4me

    diesel4me 1 ton status Premium Member

    Jul 24, 2003
    Likes Received:
    another way...

    I've had alternators strip out the threads too--I use a nut behind the stripped alternator hole,and a longer bolt if needed, rather than try re-tapping it for a bigger bolt--as mentioned already,the bigger bolt wont "slide" in the slot in the bracket!:doah: --using a square nut is best,then it'll wedge itself between the alternator and bracket,and you wont need two wrenches to hold it and tighten it up..

    As for it slipping back and loosening the belt,I think you could simply add another bolt and washers to the slot in the bracket, and tighten it up--that should prevent it from "creeping" back towards the motor and loosening the belt up...;)

    I drove my friends truck 50 miles once to pick up some parts--when I got there it refused to turn over--when I opened the hood to get it jump started,I realized why the battery ran down..all he had for an "adjustment" on his alternator was a beat up block of WOOD he'd hammered in there between the motor and alternator in a rush ,when the bolt in his alternator snapped off 6 months prior!:eek1: ..the belt was so loose I couldn't believe it stayed on!..I ended up using a ratchet tie down strap to pull the alternator tight,and had to use rope to tie the parts down in the bed!..last time I ever borrowed HIS truck!..:doah: :mad:
  5. BadBob

    BadBob 1/2 ton status

    Aug 14, 2005
    Likes Received:
    Lyndon, KS
    If the threads aren't pulling out, maybe it's just sliding. You might go looking for a "bite" washer, whatever those things are actually called.

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