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Thread: Belt Squeal

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  1. #1

    Question Belt Squeal

    Hi, this is my first post. I have a 2004 Chevy Silverado Z71 with the 5.3 engine. One belt application to the best of my knowledge. I had a slight belt squeal when the vehicle was first started and would usually go away sometime after the truck warmed up. Its cold in Ohio right now. I tried to spray some belt dressing on the belt and this really made the belt squeal or whatever is wrong. Now it doesn't go away after warmed up and does increase with engine RPM's. I just applied spray last night so it might wear off and quiet down some over time. What could be wrong to make the squeal worse after the belt dressing? The belt was replaced about a year ago. I did spray the belt dressing on both sides of the belt. One other thing is that the belt noise did go away right after I applied the belt dressing but didn't take very long for it to start squealing.

  2. #2
    Jr. Mechanic
    Join Date
    Dec 2008
    Gettysburg, Pa.

    Default belt squeal

    Belts can squeal from slipping but also from being too sticky much like the sound of cellophane tape when pulled off the roll fast. Usually as the belt wears it sits deeper in the grooves and the outer edges begin to rub on the strait up and down outer edges of the air conditioner pulley. If you have to put anything on the belt such as dressing you only hide the problem. Belt dressing is fine for V-belts but is never needed for serpentine belts do to the great amount of surface area for traction offered by serpentine belts. I hot glued a piece of emory cloth to a stick and ran it on the edge of the belt til the squealing stopped.

  3. #3


    Thanks for the tip. When you say the edge, do you mean the sides of the belt (both sides?) or the top opposite the groved side or a edge formed by these 2 surfaces? I assume you tried this with the truck running.

  4. #4

    Join Date
    Aug 2008
    East of Branson, Missouri
    Blog Entries


    Also, though unlikely with such a newer vehicle, it could be one of the pulleys or component that's in need of attention.

    Had a squeal that got worse and worse. Turned out to be the ac compressor that was giving out and causing problems.

    "The Sarge"
    1999 Chevy Suburban LT- K2500
    7.4 454 Vortec, 4WD
    305/70/16 on Eagle Alloy

  5. #5


    sounds like a typical bearing squeal coming from one of your pulleys....spray with a lubricant and figure out which one it is

  6. #6

    Post Belt Squeal

    I know this my sound stupid, but if your truck has a/c it has a seperate belt located below serpentine belt. Ive had people who didnt know there are two belts with a/c models

  7. #7
    Legend tlperry68's Avatar
    Join Date
    Oct 2008
    Huntington Beach, CA


    I'm going to try to pull out celophane from the container really fast to hear the squeal.
    Bar soap also helps get rid the squeal from belts. If rubbed on the underside of the belt it coats it and you don't hear it much. Do not do this with the engine running.
    Trevor - Huntington Beach, CA
    2007 GMC 2500 4X4

  8. #8
    Jr. Mechanic
    Join Date
    Dec 2008
    Gettysburg, Pa.

    Default belt squeal

    Never ever put soap on your belts. Soap will dry out the "wetting" agents in rubber and you need these to keep dry rot from happening. I doubt you can duplicate the sound with cellophane tape as the tape and belt are two totally different materials however the concept of adhesion or cohesion is the same.
    You said the squeal went away right when you sprayed it then came back soon after. If it were a bearing I think it would have been much longer til the squeal came back . I did mean the sides of the belt. The top and bottom (smooth and ribbed) surfaces are "drive" surfaces and should never be nothing but clean and dry.

  9. #9
    Jr. Mechanic catbert's Avatar
    Join Date
    Sep 2008
    Tobacco Road, NC


    My 4.3 made the same noise when cold. I changed the belt - no change. I'm taking in to have the dealer check out the tensioner, and probably replace it under warranty. That part seems to be a weak point, and has been since the mid nineties.

  10. #10

    Default check idler pulley

    I had a 97 Blazer that made that noise and it turned out the idler or tension pulley had bad bearings.

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