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loud hum noise

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K5Psycho, Jan 12, 2003.

  1. K5Psycho

    K5Psycho Registered Member

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    ok this is what i got, when i drive my 87 k5 and i reach range of speeds of 45-55 a loud hum starts close to the back of the truck. i have changed the u-joints for the rear drive shafts, i opened the rear end to see if the axle was empty of oil and replaced oil. so if anyone has any idea what this could be please let me know thanks
     
  2. reddog64

    reddog64 1/2 ton status

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    What kind of tires you got??? has it always done this?
     
  3. K5Psycho

    K5Psycho Registered Member

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    i have 33' x12.50 A/Ts when i let go of the gas the hums goes away and i hear the tires hum
    yes it has done this since i got it
     
  4. pilgrim

    pilgrim 1/2 ton status

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    i to replaced my rear shaft and joints and still i have a hummimg vibe outback /forums/images/graemlins/angryfire.gif.. i'am thinking its got to be the bearings in the 14ff.. it only does it under load and noticeable above 1800 in 4th..(sm465)

    i took the rear cover off and all looks well but bearings are very finnicky.. so maybe you could start there.. good luck /forums/images/graemlins/grin.gif
     
  5. evilandangry

    evilandangry 1/2 ton status

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    Are you running stock 10 bolts? It could be the preload on the r&p on maybe the spiders.
     
  6. K5Psycho

    K5Psycho Registered Member

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    yes stock 10bolt with 373 gears and posi trac
     
  7. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    i vote bad bearings on the pinion...Mine does the same thing and the gears are really starting to wear a groove into one another.....if you have a hum it only gets worse trust me! FIx it or swap out axles...Mine is to the point of scary right now... /forums/images/graemlins/crazy.gif
     
  8. K5Psycho

    K5Psycho Registered Member

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    OK I AM GOING TO TRY TO CHANGE THAT THIS WEEKEND ANYONE ELSE KNOW ANYTHING PELASE POST
     
  9. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    Ring and pinion. Try replacing the bearing first jus because its cheaper. While your in there check the wear pattrern on the gears. If the edges are sharp you have a problem. If not you don't have to worry to much about it if the bearings dont quiet things down. If the the noise continues check the "Purple" post for a type of fluid that might help.
     
  10. Muley

    Muley 1/2 ton status

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    My vote is the carrier bearings. That is my problem.

    BowTie, mine is not to the point of being scary just yet, but bad enough that I am not driving it the 150 miles to get my 14 bolt this weekend.
     

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