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NP421 is making a whining noise!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90BlazerK5, Feb 18, 2002.

  1. 90BlazerK5

    90BlazerK5 Registered Member

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    Heres the problem guys... After putting the blazer in four wheel drive, I noticed that the transfer case would start making a whining sound.. really high pitched, like a bearing going bad. So, yesterday, I changed out the fluid- replaced it with Dexron, as recomended by Chevy for my year, and the noise is still there, except now it makes it in 2wd occasionally too, around 15-20 mph. The old fluid came out black (I have no idea on if or when the previous owner ever changed it), but it didn't smell burnt. What could be causing this whining noise, and what can I do to fix it?

    Where did all these damned dirty apes come from!?!
     
  2. ftn96

    ftn96 1/2 ton status

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    Take it out and replace all the bearings and seals. The kit is about $75 dollars from Standardtransmission.com

    The T-case is simple to rebuilt. Way simpler than you would think. I can fax or E-mail you a copy of the parts break down. This will help you when your putting it back together to make sure you have everything in the right order. But it only goes back together one way. Let me know if you need the parts sheet.
    Also, if you wanna go ahead and replace the chain while your in there, I think it is also $75 from the same place.

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     
  3. DPI

    DPI 1/2 ton status

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    Hey Brandon, I would like a copy of the parts break down if you can swing it.
    BTW, my 241 whines in 4 lo.

    <a target="_blank" href=http://coloradok5.com/gallery/albuo71>My K5 Stuff</a>
     
  4. ftn96

    ftn96 1/2 ton status

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    Ok, by popular demand, here you go.

    <a target="_blank" href=http://www.mccords.s5.com/241expl.gif>241 Diagram with part titles</a>

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    hey ftn, would you please e-mail me the break down on the 241 trans case. I don't need it yet but it is always something good to have. e-mail to scotts4x4@aol.com
    thanks
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    hey ftn, guess i should have looked at the last thread. got it now, thanks
     
  7. ftn96

    ftn96 1/2 ton status

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    [​IMG]MAO!!!!!

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     
  8. ftn96

    ftn96 1/2 ton status

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    One tip I can give you guys when your putting it back together. IT will save you some dis-assembly and re-assembly.
    While you are looking down over the t-case while it is propped up, the front output shaft is resting down in the t-case. When your are sliding the speedo gear down the shaft and are trying to install the retainer snap ring, you will notice that it doesn't line up with the detent. YOU WILL HAVE TO GRAB THE SHAFT AND PULL IT UP OUT OF THE CASE TILL THE SNAP RING WILL BE ABLE TO GO IN THE GROOVE. This is where the buddy's extra hand would come in handy, or the wifes if you have a pair of gloves where she ownt get her nails dirty!!! [​IMG]

    But you could just lay it down on its side. But I didn't think of that till the next day when my hang over went away. [​IMG]

    But even on its side, just remember that you'll have to pull it out a little.

    Happy slushing!!![​IMG]

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     
  9. DPI

    DPI 1/2 ton status

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    Thanks! You the man!

    <a target="_blank" href=http://coloradok5.com/gallery/albuo71>My K5 Stuff</a>
     
  10. 90BlazerK5

    90BlazerK5 Registered Member

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    Allright! Tahnks guys! Just ordered the kit from Standard Transmission... good deal too! They beat everybody local here by at least fifty bucks.. three day shipping too! Guess I know what I'm doing Saturday... it'll be so nice not to have to drive it with a whine [​IMG]

    Where did all these damned dirty apes come from!?!
     
  11. ftn96

    ftn96 1/2 ton status

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    Welcome. Glad I can give something back to the site. Let me know if you need any help or info.

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     

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