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2000 Silverado Transfer case issues

Discussion in 'GM Powertrain' started by DRafalske, Jan 2, 2009.

  1. DRafalske

    DRafalske New Member

    Hi guys. My brother has a 2000 SIlverado 2500, its the non-HD 2500 with a 6.0l gas engine. The transfer case is an NP246 with autotrac. He noticed a bad clicking/popping soundin 4wheel drive the other day, which I mistakenly thought was a bad CV joint. The noise is very much like a bad u-joint/CV joint. After that didn't fix it, I took a look at the transfer case and found it completely dry. I filled it up with fresh ATF (I know the Autotrac takes a special fluid, but its gotta be better than none at all) but the noise persisted and is definitely coming from the case. So I think running it dry damaged the clutches and maybe more. Actually, I suspect this is a victim of pump-rub although I can't find the hole. The case had blown all the fluid out back out by the next day.
    There isn't a whole lot of money to throw at this, so we've decided to source a used transfer case and be done with it. Just need the truck to last one more year before it's put out to pasture. The main question I'm asking is are all NP246 Autotrac cases created equal? I found one for cheap but its out of a 2000 1500. I'm not sure if my brother's truck has a 4L60 or 4L80 trans, but I can find out.
    Thanks for y'all's help!

    Dave
     
  2. Heineken

    Heineken Rockstar

    Definitely sounds like pump rub. Even the non H/D's where victims of the "rub." had the same problem last year. Mine ended up getting the whole T/C rebuilt. Anyway, to answer your question, yes, it should work. However, the t/c you buy, might not be in good shape. I will tell you this; the t/c that I just rebuilt and every other one I've rebuilt, are filled with 3 qts of Mobil 1 FULL synthetic. I know most hold 2 qts to the top of the fill plug. I fill it from the top where the electric switch is at. Also, ATF disipates too quick compared to motor oil. The t/c generates a crap load of heat, that's why I run oil and 1 quart extra. I have read A LOT of info on this and that seems o be he concensus. I hope this helps and good luck
     
  3. DRafalske

    DRafalske New Member

    We went ahead and got that case from the 2000 1500. It worked, but I wound up have to tear down both cases and swap the inputs. The 1500 had a 4L60, and my bro's truck had the 4L80 so the inputs were different. The case is working perfectly. Looked like it had been either replaced or rebuilt sometime. For sure didn't look like it had 125k miles on it.
    Also, this was not a pump rub issue. The clip was intact and there were no holes. We're going to rebuid the old one and sell it to offset the cost of the new one.
    D
     

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