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  1. #1

    Default Does this sound like a bad fan clutch?

    Hello everyone! I have a noise I need some help identifying. Took the video below so you could hear it. This is from my 1999 Suburban K2500 7.4L. My first guess is a bad fan clutch, but I am not sure as this is my first time dealing with that. Anything else it could be? The noise comes at startup for a minute or two then typically goes away only to reappear every so often while I am driving.

  2. #2


    You have a bad pully bearing, ps pump, alternator, or waterpump. I would pull the belt off and spin the pullys by hand listening and feeling for a crunchy or squeak.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

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  4. #3


    OK, I pulled the belt and spun everything. Everything seemed to spin pretty freely, the only noise I could hear was from the alternator. Here is a video of the alternator turning:

  5. #4


    Something to try if you cannot identify the issue using Pikey's suggestion. While it's running, take a 2-3 foot long piece of hose or some other type of tube apparatus. Hold one end to your ear, and move the other end around to each pulley. Sometimes this will help specify where the sound is originating.

  6. Thanks bettingsumo thanked for this post
  7. #5


    So I took the belt off and spun everything, but could not really replicate the sound. The only place I could hear any sort of noise was coming from the alternator. There is a video below, please tell me what you think.

    I am just curious, if it was the alternator bearings would I hear the sound all the time? The fact that the noise is intermittent confuses me, because it seems like it should come from something that cycles on and off... No? Or is it possible that the alternator bearings are just starting to wear funny and only make the noise when they happen to fall in a certain position....

    estrom: sounds like an good technique to isolate the sound. Not sure how I can (safely) reach some of those pulleys while it is running, but worth exploring. At the very least I should be able to listen in on the alternator.

  8. #6


    If you haven't put thw belt back on, I'd check the water pump. Grab the fan at the center and try to see if you have any movement on the shaft side-to-side
    "American by birth, Southern by the grace of GOD"

  9. #7


    The noise could be intermittent because as the different accessories demand draw, the belt tension changes. Try turning the AC on and off to see if the noise comes and goes. When the AC clutch engages, it will put a different tension on the belt.
    I like all dogs I meet, and some people too.

  10. #8


    Sounds like the alternator shaft bearing has gone south. Mine has done this as well. Is there a way to replace it without buying a new alternator

  11. #9


    Quote Originally Posted by BurbanMan View Post
    Sounds like the alternator shaft bearing has gone south. Mine has done this as well. Is there a way to replace it without buying a new alternator
    I looked into just replacing the bearing and while it is an option the time and effort doesn't seem to make sense as the brushes and all will probably fail sometime in the not too distant future anyways. I think just replacing the whole alternator is the way I am going to go.

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