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Thread: np241...what the(*(*&))(*$$##

  1. #1
    Join Date
    Sep 2006
    Posts
    58

    Default np241...what the(*(*&))(*$$##

    New SM FW, Clutch and rebuilt the NV4500, read about that mess here:

    http://www.thedieselpageforums.com/t...ad.php?t=34301

    30mi after tranny rebuild and SM/clutch install the TC started popping into neutral.

    I pulled the NP241 apart and this is what I found:

    broken spring retainer

    worn range shifting fork-worn through the plastic retainers and into the aluminum and had just started hitting the planetary.
    Planetary looks great, like new.

    a retainer/snap ring was out of it's groove on the outer side of the output.

    What do you suppose was the cause? did the snap ring move and allow movement of the shafts to the point of the fork wear and broken retainer? Did the FW/Tranny work have any affect on this? If this was just a coincidence that it happened now, I wish it would have happened 40 miles ago as I was getting ready to do the clutch and found the other mess!!
    Attached Images Attached Images
    Last edited by 94bluehd; 05-03-2009 at 20:45. Reason: add pics, add text
    1994 6.5 HO vin "F" X-cab, long box 4x4
    Phazer set installed, 97+ cooling mods with 9-blade fan.Turbomaster, gauges, OPS mods with selenoid and lift pump indicator light 4" turbo back open exhaust, remote dual oil by-pass, Amsoil 15w-40, remote PMD #9, battery mods, 98+ airbox, 3.42s w/ NV 4500 converted to South Bend SM system with damper installed, 147K.


  2. #2
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    Hard to say for sure

    There is a very good likelyhood that it was the luck of the draW though.

    There should be no real connection between doing the clutch/FW and the T case failing.

    Just clean it up good and replace the bad pieces and it should be fine.

    Best

    Robyn
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
    Join Date
    Mar 2000
    Location
    South Central Pennsylvania, USA
    Posts
    2,697

    Default

    Unless you severely manhandled the t-case to the point that the spring clip popped loose from the abuse, I'd agree with Robyn that it was coincidence. I would also say that looks like more than 30 miles of damage, though, and likely had been going on for awhile before you got around to the R&R on the clutch.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  4. #4
    Join Date
    Sep 2006
    Posts
    58

    Default

    Thanks for the replies, parts are in the mail. Should have it together this weekend. I am going to be very articulate when i put it back together.
    1994 6.5 HO vin "F" X-cab, long box 4x4
    Phazer set installed, 97+ cooling mods with 9-blade fan.Turbomaster, gauges, OPS mods with selenoid and lift pump indicator light 4" turbo back open exhaust, remote dual oil by-pass, Amsoil 15w-40, remote PMD #9, battery mods, 98+ airbox, 3.42s w/ NV 4500 converted to South Bend SM system with damper installed, 147K.


  5. #5
    Join Date
    Mar 2009
    Location
    Oklahoma
    Posts
    81

    Default

    My family has a truck just like yours (Blue, 94, 1ton, srw, 6.5, NV4500, 4x4) not that that matters much, but it did have the same problem with the tcase at around 320k miles, that coulda had something to do with it . We put new forks, and other parts can't quite remember, in it after it sat for around a year, works just fine again.

  6. #6
    Join Date
    Aug 2003
    Location
    Winnipeg, Manitoba Canada
    Posts
    186

    Default

    Happens occasionally, some talk of it on the off road forums. Some have replaced the snap ring with "Gilly's T-case saver", do a google search...

    It's a two piece collar that you cinch on the shaft with allen screws and replaces or eliminates the snap ring, supposed to be a better fix.
    1994 K1500 Silverado ext cab short box
    stock L56 6.5 TD, F intake, 4L80E, 3.73 gears
    10149599 block, D-Tech PMD on 5288 pump
    Goodyear Wrangler silent armour 265 75 R16 E Pro Grade
    Bushwacker fender flares
    410,000 km

  7. #7
    Join Date
    Sep 2006
    Posts
    58

    Default

    I put in a TC saver the last time I rebuilt it. The snap ring was interior of that, on the other side of of the output bearing.
    1994 6.5 HO vin "F" X-cab, long box 4x4
    Phazer set installed, 97+ cooling mods with 9-blade fan.Turbomaster, gauges, OPS mods with selenoid and lift pump indicator light 4" turbo back open exhaust, remote dual oil by-pass, Amsoil 15w-40, remote PMD #9, battery mods, 98+ airbox, 3.42s w/ NV 4500 converted to South Bend SM system with damper installed, 147K.


  8. #8
    Join Date
    Aug 2003
    Location
    Winnipeg, Manitoba Canada
    Posts
    186

    Default

    Quote Originally Posted by 94bluehd View Post
    I put in a TC saver the last time I rebuilt it. The snap ring was interior of that, on the other side of of the output bearing.
    So is it that the T-case saver acts as sort of a back up, in the event the snap ring was to fail?
    1994 K1500 Silverado ext cab short box
    stock L56 6.5 TD, F intake, 4L80E, 3.73 gears
    10149599 block, D-Tech PMD on 5288 pump
    Goodyear Wrangler silent armour 265 75 R16 E Pro Grade
    Bushwacker fender flares
    410,000 km

  9. #9
    Join Date
    Sep 2006
    Posts
    58

    Default

    No the TC saver replaced the rear snap ring. My problem was a snap ring inside the case. I think it was inside the rear housing on the inner side of the output bearing??? At any rate, it allowed the shaft(s) to move and destroyed the range fork and then the synchro springs.
    1994 6.5 HO vin "F" X-cab, long box 4x4
    Phazer set installed, 97+ cooling mods with 9-blade fan.Turbomaster, gauges, OPS mods with selenoid and lift pump indicator light 4" turbo back open exhaust, remote dual oil by-pass, Amsoil 15w-40, remote PMD #9, battery mods, 98+ airbox, 3.42s w/ NV 4500 converted to South Bend SM system with damper installed, 147K.


  10. #10
    Join Date
    Sep 2006
    Posts
    58

    Default

    If it weren't for bad luck, I would have no luck at all....

    Got it all back together and drove it around town. Pulled the truck back into the shop to fix a loose exhaust and saw the TC leaking along the midline (must have had a space in the gasket material??).

    I pulled the TC out again and when I pulled it apart, there were needle bearings floating around?????after only 4 mi!!!!!!!!!!!!

    One of the needles got into the oil pump and ruined it but that was it. Turns out the pilot bearing for the mainshaft was either defective and/or I messed it up? Got it all back together tonight with a new pilot and oil pump. Wish me luck everyone, I need it.
    1994 6.5 HO vin "F" X-cab, long box 4x4
    Phazer set installed, 97+ cooling mods with 9-blade fan.Turbomaster, gauges, OPS mods with selenoid and lift pump indicator light 4" turbo back open exhaust, remote dual oil by-pass, Amsoil 15w-40, remote PMD #9, battery mods, 98+ airbox, 3.42s w/ NV 4500 converted to South Bend SM system with damper installed, 147K.


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