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Is my transfer case done for?

Discussion in 'GM Powertrain' started by redneckarmyMP, Sep 12, 2012.

  1. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    The truck:
    1986 K5 Blazer
    350ci with SM465 3spd manual with granny low transmission
    NP208c transfer case

    I was out playing in a field this weekend and threw the driveshaft. I stopped to find out what the awful loud noise was and found the u-joint had apparently freed itself from the straps bolting it to the yoke on the rear differential. Nothing else seemed to be damaged so I threw the driveshaft in the backseat, put the truck in 4hi and drove approximately 200 yards to the house.

    I put on a new u-joint this evening and then re-installed the driveshaft. I unlocked the front hubs, put the transfer case back into 2wd, cranked it up and started to go. Now there is an awful loud metallic clunking sound and a vibration as I begin to accelerate at a low speed. It doesnt matter whether its in 2 or 4wd, forward or reverse. I even removed the driveshaft and took a lap around the yard with no noise. Anybody have any ideas?
  2. the phantom

    the phantom Active Member 2 Years ROTM Winner Gold Member 1000 Posts

    Sounds to me that the rear diff. has something going on that caused your universal to pop. I would pull the rear cover and see if you find excessive metal in the oil or anything else unusual.
  3. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    If it's the rear end, I'm gonna lose it. We put the new one in about a year ago. But it sure wouldnt hurt to look. I've been thinking about what caused the problem to begin with in the back of my mind.
  4. the phantom

    the phantom Active Member 2 Years ROTM Winner Gold Member 1000 Posts

    Thats the easiest check. Seems as though the rear diff would still be turning (making noise) even with the driveshaft out so maybe its in the rear of the tranny. Them big Superswampers your running may have taken their toll on her.:lol:(if its a her)
  5. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    yea the noise was gone after i took the driveshaft back out. I'll still give it a look to help rule some things out
  6. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Is your yoke on the rear drive shaft fixed or a slip style?
    If its a slip style which some SM465's had it could be you drained all the fluid out on the way to the house, if thats the case you might get lucky by refilling it, worth a check, otherwise when the U-joint went it could've damaged the tailshaft bearings, that would mena a T case rebuild.
  7. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    It is the slip style. I'm sure I lost fluid on the way back so I'll check into that as well. I'm really hoping a rebuild isnt in my future. Is it worth the time and money for a rebuild or should I look for another one?
  8. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    If your gonna rebuild it depending on what you find inside it could be inexpensive, if your gonna send it out it will be expensive.
    SM465's are a common T case, I'd probably find one from a wreck and I think you'd be better off $$.
    Keep this one around and try your hand at rebuilding, if you get it back together and working right you can always sell it and recoup some of your money.
  9. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    thats a good idea! that may be just what I do. Any idea on good resources for tearing down and rebuilding it?
  10. aloxdaddy99

    aloxdaddy99 Rockstar 3 Years 1000 Posts

    I would rebuild that 208. I just check ebay and they had a "full rebuild kit" listed for $115. There isn't much to a tcase. So with time and taking a lot of pictures during the tear down it shouldn't be that hard to rebuild. But I would try to add fluid to see if the noise goes away before you start to buy parts for a rebuild. If in fact a rebuild is in order I would look into repalcing the slip yoke with a solid mount so this doesn't happen again.

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