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Transfer case

421 Views 2 Replies 2 Participants Last post by  Brianblas
Guys I have a 2004 gmc 2500hd transfer case is an NP1 3 button on dash. I bought the truck a few years back from a dealer. I didnt check the transfer case fluid for about 5k miles or so big mistake. Anyway I changed it and it had about 1qt or less in it. The fluid was grayish silver. And a chunk of metel came out along with other pieces much smaller. I drove another 1k miles did another change fluid came out gray again. I'm thinking metel but the 4x4 works in 4low. Anyone else had this issue.
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If the metal chunk is a thin shiny piece of hardened steel, it's probably the piece that's suppose to prevent "pump rub". If you haven't read about pump rub, you should since it's common and probably inevitable in our magnesium transfer case housings. The hardened steel clip prevents the pump ears from eating a hole in the tail section. But they tend to come loose after awhile.

The pump rub hole presents as a tiny pinhole and the ATF leaks out so slowly it doesn't leave a puddle. That might be why it was a quart low (half of the ATF was gone). It's probably gray because it's never been changed before.

I think GM has a band-aid fix, but 3rd parties have better solutions. Search for "pump rub". You might already have a pinhole, so you probably need a new tail section (they also make aluminum ones, which should hold up better). If the t-case still works ok, and since it didn't go dry, just run with it.
Yeah the case has already been fixed where the hole rubs through. It's a remanufactured transfer case. It was a little bigger than a marble and rough all over. I wish I still had the piece it just didnt seem like it would go to anything didnt really have a form just a chunk of metel.
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