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voltage prob

Discussion in 'Chevy Trucks' started by TRUP, Feb 3, 2003.

  1. TRUP

    TRUP Member
    Messages: 38

    Drop in voltage.

    On Sunday my voltmeter in my 82 K20 indicated a drop in power from the normal 14 volt to 9-12 volt range. It has remained that way ever since. I'm not doing anything different with the truck than before the drop in the voltage, and the alternator belt is just three weeks old. Is it time for a new alternator? Can anybody recond a replacement? THANX!
  2. wxmn6

    wxmn6 PlowSite.com Addict
    Messages: 1,037

    Since you said that the belt was replaced, it probably got a bit loose and is slipping. Check to make sure that the belt is tight.
  3. Mike 97 SS

    Mike 97 SS Banned
    from U.S.A.
    Messages: 1,106

    Are the belts squealing at all? A squealing belt is a sure sign that it may be loose. Its possible the new belt stretched slightly and is now slipping but I doubt it, you would hear squealing. Assuming you hear no noise, with motor off grab ahold of the alternator belt and see how much it moves around up and down. If it seems normal and tight, I would get the charging system checked at a local repair shop and see what they come up with. Im gonna say you are going to need a new/rebuilt alternator. Mike
  4. Dan S.

    Dan S. Member
    Messages: 31

    If your belt checks out ok, one quick way to check your charging system is with a multi-meter, check the voltage at the battery posts with the engine off and then with engine running at a fast idle, if your alt. is working you should see an increase in voltage. Have Fun
  5. raceman6135

    raceman6135 Member
    Messages: 61

    I agree with Dan: check the actual battery voltage with another gauge. I recently had to replace my Autometer volt meter because it was registering 10 volts while the engine was running, but a multimeter on the battery showed 15.3 volts when the engine was running!

    Replaced the gauge, voltage "mysteriously" went back up!

    By the way, that's the first time I've ever had an Autometer gauge mess up on me, and I've been using their stuff for almost 20 years.

  6. cj3859

    cj3859 Member
    Messages: 44

    dont know if this is true but it worked for me,i had same thing happen on my 86,drove me abit wacked, come to find out on a emissions check my idle was way to low,550 to be exact,so i bumped it up to the required 750 and bingo alt drop was cured,dont know if this will help ya out.
  7. wyldman

    wyldman Member
    Messages: 3,265

    Also check the little plug in the side of the alt for corrosion.If it's dirty,or the wires are broken, it won't charge.
  8. TRUP

    TRUP Member
    Messages: 38

    Before startup, the multimeter showed a charge of 12.3 volts. At idle, the voltage dropped to 11.92. Looks like it's time to replace the alternator.
  9. porkhead1

    porkhead1 Member
    Messages: 70


    Just a suggestion, if you're going to replace your alternator....look around for a shop that rebuilds/repairs alters. & explain to them that you're using your truck for plowing & you'd like an alter. that puts out a lot of amps at low speed/idle.

    Just my $.02.......
  10. fordman

    fordman Senior Member
    Messages: 327

    First I would check all the wires running to and from the alternator, if they're all fine it's probably the alternator. You could do a bench test on the alternator to find out for sure. If you do have to replace the alternator make sure you get a high output one.
  11. TRUP

    TRUP Member
    Messages: 38

    I replaced the alternator & everything is okay, including a nagging oil pressure flucuation. I know how oil pumps work on gasoline motors, but I haven't clue when it comes to diesels.
    Thanks to everybody for the suggestions.:)
  12. porkhead1

    porkhead1 Member
    Messages: 70


    Try "Diesel Page.com" for information on your 6.2.......:)
  13. TRUP

    TRUP Member
    Messages: 38

    WOW! Just what I've been looking for. THANX!!!:cool: