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Noise from NP208

Discussion in 'The Garage' started by tcmcucv, Jun 18, 2004.

  1. tcmcucv

    tcmcucv Newbie

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    Hi, I have a 1985 cucv blazer with the NP208. The truck drives quietly for about the first 10min of driving. After that a grinding/rattling noise seems to come from the transfer case. I replaced all the universals and just rebuilt the rearend. The noise gets louder in reverse and especially at highway speeds. I am thinking it could be the chain. If anyone has any idea what this is please post. I have a whole new bearing set and chain but would only replace the chain for now due to time constraints if that was most likely the problem. Thank you.
     
  2. bigyellowjimmy

    bigyellowjimmy 1/2 ton status

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    Welcome!

    I'd make sure that's where the noise is coming from for sure, put the rear up on jackstands, block the front wheels firmly and have an assistant run the truck in gear while you are underneath to determine exactly where the noise is coming from. Im sure you've already checked the fluid /forums/images/graemlins/thumb.gif


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  3. tcmcucv

    tcmcucv Newbie

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    Thank you, I've been meaning to join for awhile and plan on getting the more inclusive membership latr today. We took it up earlier, the fluid has always been topped off or checked at every oil change. It only makes the sound when cold in the reverse gear. The fluid has to warm up/it has to run for awhile going forward before it makes the sound in any other gear. You can distinctly hear it coming from the transfer case when in the air. This is driving me nuts.
     
  4. bigyellowjimmy

    bigyellowjimmy 1/2 ton status

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    [ QUOTE ]
    It only makes the sound when cold in the reverse gear. The fluid has to warm up/it has to run for awhile going forward before it makes the sound in any other gear. You can distinctly hear it coming from the transfer case when in the air.

    [/ QUOTE ]

    You are using ATF fluid right?

    Any play in the rear output shaft?


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  5. HarryH3

    HarryH3 1 ton status Author

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    The chain only drives the front output shaft and isn't moving when in 2WD with the front hubs unlocked. /forums/images/graemlins/frown.gif
     
  6. tcmcucv

    tcmcucv Newbie

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    I've always used atf. This is the weirdest thing, im just going to go through it this week. It makes the noise very loudly when in excess of 60 mph. it changes when you put it in 4 wd but never fully goes away. The rear output shaft has no play in it. I'll find out when i take it apart. Thanks for the help.
     

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