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Does Alternator Make any Noise when dying?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Boss, Sep 18, 2001.

  1. Boss

    Boss 1/2 ton status Author

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    Ok, about two weeks ago my truck started making some strange noises under the hood. It's like a growling sound and is very constant. Keeps growling and growling.
    I checked and everytime this happens my alternator vibrates as the noise gets louder and stops as the noise stops and then vibrates again and so on.
    I first thought it was the PS pump, but it's not the typical noise a PS pump makes when it's dying...those make a high screech type sounds...hard to explain.
    But my steering was normal as usual. Then I swapped the AGR box for another AGR box they just sent me and now my steering is almost like Manual steering, but runs cooler. Then I discovered a leak in the new AGR box [​IMG] (for those who know my AGR problems...it never ends).
    Anyhow, I'm hoping it's not the pump and thinking it might be the alternator. I'm getting ready to put on a 200amp alternator I have soon, but not till a couple of weeks probably.
    Question is, does the alternator make any kind of noise when going bad? Oh, yes, my battery is still getting charged like normal.
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  2. POWERMAD

    POWERMAD 1/2 ton status

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    hey Boss it sounds like the bearings are going out.
    Are the pullies all in line? That is one cause of bearing failure.
    Another being the belt to tight. But they do go bad on occacion.

    <font color=green> Too bad ignorance isn't painful </font color=green>
     
  3. rampage

    rampage 1/2 ton status

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    The alternator will make sort of a growling noise when the bearings wear out but that should be a constant noise. If it is coming and going then I would think that it is the clutch in the fan. But then again, it is hard to tell just from a description of the sound, it is much easier to diagnose where sounds are coming from when actually listening to it. [​IMG]
     
  4. Burbinator

    Burbinator 1/2 ton status

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    Is the alternator getting hot at all, beyond normal (like "burn the heck out of you" hot)? Could be a bearing in the alternator, if it's hot, or possibly a water pump. The 'ol garden-hose-in-the-ear trick would isolate it better. Usually, when alternators go, the diodes, windings, regulator, etc. die a silent death. If it's a bearing, the increased heat will eventually burn it out.

    - Alan

    '82 K10 Suburban Silverado (AKA U.S.S. Nimitz)
     
  5. Boss

    Boss 1/2 ton status Author

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    Yes, the pullies are in line.
    Yes, the alternator does get pretty hot. When I checked it, I just cranked it the first thing in the morning and it got warm pretty quick. I then drove around and checked again and it was pretty darn hot, but so was everything else in under the hood [​IMG].
    The sound it makes goes in and out, but quick and constant. I know it's hard to diagnose (sp?) when you're not actually there and listening. I just didn't know alternators made noise when they went. My old alternator in my old truck just died, no warning signs or nothing. That in turn killed my battery too. Since yall are telling me that they do make noise, then I'm guessing it is the alternator, since it doesn vibrate when the noise happens. I'm just glad it aint the PS pump. I've changed that 3 times already and don't want to do it again for a longggg time!! Thanks again fellas
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  6. Burbinator

    Burbinator 1/2 ton status

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    Sounds like the alternator is the likely culprit. Good luck!

    - Alan

    '82 K10 Suburban Silverado (AKA U.S.S. Nimitz)
     
  7. POWERMAD

    POWERMAD 1/2 ton status

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    More than likely what is happening is the when the alternator comes under a load it puts a strain on the bearings.
    If you run it awile longer it will prolly start to do it all the time.
    That is untill it locks up then the belt will start squeling like a stuck pig.

    <font color=green> Too bad ignorance isn't painful </font color=green>
     
  8. HuskerBlazer

    HuskerBlazer 1/2 ton status

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    IMHO, alternators are pretty variable when they go out. Had one in an old car that gave no warnings and then last week mine went out in the Blazer. Just froze up the bearings. When the serpentine belt went around it rattled everything because it couldn't turn the alt. Scared the sh!t outta me because it sounded like the worst knocking engine I'd ever heard. Thought my engine took dump.



    K-5...Soccer moms inquire within.
     
  9. Boss

    Boss 1/2 ton status Author

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    Thank you all!! [​IMG]
    I'll swap out my alternator soon then. don't want that think locking up on me!![​IMG]. Thanks again.

    Pic of my truck Before N' After
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  10. beater74

    beater74 1/2 ton status

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    i'd replace that thing ASAP that can be very DANGEROUS. my budy was curzen home from work and his engine compartment cought on fire from a bad alt. bering, he knew it was going bad ,he just thought he could make it a few more days.if you can't put your 200 amp on now i'd pick up a cheap'o one from autozone for now.
     
  11. Boss

    Boss 1/2 ton status Author

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    whoa, you're scarying me with that. I was going to put it off till this weekend!! It's been 2 weeks already!!
    Boss

    Pic of my truck Before N' After
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  12. HarryH3

    HarryH3 1 ton status Author

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    Before you replace anything, make sure that the brace from the back of the alternator to the intake manifold is tight (or even there). I once had an alternator fail on a long trip and had to replace it with one that didn't have the rear section of the housing clocked correctly for the application. This meant that the bolt hole didn't line up with that little bracket. So I left the bracket off. The alternator would sometimes vibrate and make a sound almost like an a/c compressor running. Once I had time to clock the housing correctly and put the bracket back on, the vibration was gone. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
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  13. Thumper

    Thumper 1/2 ton status

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    Is it a serpentine belt or the old v type? If its the old type, just pop the alternator belt off and start the truck to see if the noise is still there. Same goes for the PS pump. Nothing will be hurt by running it for a minute without the belt on.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  14. DieselDan

    DieselDan 1/2 ton status

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    I had my altenator on a 86 Vetter start making growling noise, you'ld have sworn it was the bearing(s). Voltatge also dropped some. Pulled it immediately and took it to the local altenator/starter shop, turns out the diode(s) were burnt out. The guy there said it was pretty common failure on late style CS altenators.

    Real trucks don't have spark plugs!
     
  15. Boss

    Boss 1/2 ton status Author

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    Thump,
    It's the serpentine style.

    Harry,
    Yeah, I checked and bracket back there was tight on the manifold and on the back of the alternator.

    You know what though, to my amazement, the noise stopped last night. Right when I was checking everything. The alternator is "burn your hand hot" though, after a 5 min. drive.
    This morning, I didn't hear anything either. (I haven't changed it out yet due to lack of time) (have to customize some things to throw on this 200amp alternator that's why). Anyhow, is that a good sign the noise stopped? Thanks again fellas.
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     

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