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HELP: some clunking sound

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Jun 4, 2003.

  1. zach78k5

    zach78k5 1/2 ton status

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    when I drive, the truck is fine but when I let off of the gas the rear end area seems to make a clunk noise and feel. I was told that the transmition was recently rebuilt and the noise was probably the drive shaft. does this assesment sound correct or is it more likely the rear end or tranny.
     
  2. zach78k5

    zach78k5 1/2 ton status

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  3. imiceman44

    imiceman44 1 ton status

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    It could be a number of things.
    Ring and pinion back lash, or pinion bearing, it also could be the Rear U joint or the yoke it self.
    If you don't know how to check them let me know.
    It's actually quite easy.
    /forums/images/graemlins/thumb.gif
     
  4. rcpilot

    rcpilot 1/2 ton status

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    Are you running lift blocks in the rear?? If so get used to it...answer, replace rear springs with lift springs and throw the blocks in the junk pile.
     
  5. zach78k5

    zach78k5 1/2 ton status

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    how should I check the u joints or the pinion. I was told when I bought it that it was the driveline or u joints, so I hope that is it. thanks for your help.
     
  6. Lazydog

    Lazydog 1/2 ton status

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    I had a clunking that turned out to be a broken Exhaust hanger. When I hit bumps it would clunk as the pipe flexed and made contact with the body, or rear suspension.
     
  7. JDBlazer454

    JDBlazer454 1/2 ton status

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    I had a similar clunk that ended up being a loose chain in my 203 transfer case. The feeling was enhanced by the lift blocks in the rear. I also had another that clunked that ended up being a worn pinion bearing and bad yoke.
     
  8. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    how should I check the u joints or the pinion. I was told when I bought it that it was the driveline or u joints, so I hope that is it. thanks for your help.

    [/ QUOTE ]

    Well to check the driveline, unhook one side so there is not tension on it and try and wiggle the yokes and see if there is play in them, excessive play will be obvious or it will not clunk like what you describe.
    Second, with the driveline removed or unhooked on one side, try to wiggle the pinion yoke up and down to check for the pinion bearing, and then try rotating it back and forth to check the back lash.
    Any movement that you can see is too much.
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  9. Blue85

    Blue85 Troll Premium Member

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    I think it's the driveshaft splines. If you have a 203 with a slip-style output yoke, then take off the driveshaft, put some thick grease in the splines and see if that helps. If you have a 205 or 203 with a fixed output yoke, then lube the slip splines in the driveshaft. Also check for wear or binding in the shaft.
     

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