Questions about my transfer case, 98 suburban

Discussion in 'Maintenance & Upkeep' started by zuper8, Sep 29, 2010.

  1. zuper8

    zuper8 Rockstar

    I want to change the transfer case fluid on my 98 K1500 Suburban, it has 185K and the fluid has only been changed once according to receipts.

    I have done a LOT of searching trying to figure out if my transfer case takes Autotrac II or Dex III. I cannot get a consistent answer, even at the dealership. I do have two quarts of Autotrac II. So, does anyone here know for sure if my truck takes it? Secondly, if it doesn't, would it be okay to run it in my transfer case anyway?

    And my dumb question is.... where the heck is the drain plug on this thing? I can easily find the fill plug, looks like it just takes a 3/8 ratchet.... but can't find the drain plug??? I have looked at photos and write-ups for Chevy transfer cases but none of them seem to feature my exact transfer case. so yeah where is the silly drain plug at :oops:
  2. vms4evr

    vms4evr Rockstar 100 Posts

    Here ya go Rachael.

    Right out of the GM shop manual. You'll need to get under there and find the part # on the transfer case and who makes it. From there...

    If you have:
    NVG 246 Transfer Case
    Use Auto-Trak II Fluid GM P/N 12378508
    2.0 quarts

    If you have:
    NVG 241 Transfer Case or NVG 243 Transfer Case
    Use Dexron III Fluid GM P/N 12346143
    2.2 quarts

    If you have:
    Borg-Warner 4401 Transfer Case or Borg-Warner 4470 Transfer Case
    Use Dexron III Fluid GM P/N 12346143
    1.6 quarts


    For New Venture Gear Transfer Cases, an identification tag is attached to the rear case half. The tag provides the transfer case model number, the low range reduction ratio, and the assembly part number.

    For the Borg-Warner Transfer Cases, an identification tag is attached to an extension housing bolt. The tag provides the transfer case model number, the serial number, a build date, and a low range reduction ratio.
  3. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Proper identification is the key to knowing what fluid you need, just like vms4evr described.

    The only thing I would add is that my NV246 fill plug required a 5/16" square (which just isn't for sale). So I bought a cheap 3/8" extension from Harbor Freight and ground it down to 5/16". Just want you can get the fill plug off before removing the drain plug so you'll know you can refill it.
  4. zuper8

    zuper8 Rockstar

    Thank you thank you both for the very helpful information!!

    I crawled under there, and found a round metal tag that said "246 GM" at the top... so looks like I got the right fluid...

    And thanks for the heads up on the 5/16 fill/ drain plugs MrShorty, the bottom one is intact but the top looks like the last person in there really biffed it and I just hope I can get it out... I don't have a grinder so I will ask my mechanic buddies if they can help me out.

    One final thing, there was also a yellow service tag on the unit that said "Use Dex III ATF"?? wth lol. oh well, I'm throwing that blue stuff in there anyways, GM can't even seem to make up their minds.
  5. vms4evr

    vms4evr Rockstar 100 Posts

    Couple of things.

    Don't ever remove a drain plug before you make sure you can remove the fill plug. I don't care what you are working on. You need to always know you can fill it back up. ;-)

    From what I have read. Autotrac fluid is an ATF III with a friction modifier added. That additive stops chatter in some of the parts in some transmissions. So in other words. Adding it to your tranny that needs Dexron III means you just put more expensive Dexron III in there. Should be no big deal. You might want to post later as to whether it caused you any headaches.

    MrShorty. Thanks. I didn't realize that 5/16" issue. My transfer case requires a 15mm socket for drain and fill. So no problem. That kind of stuff sounds so typical of the engineers though. I have a handful of Kent Moore tools just because of GM designs. The standard tool will not work. Not using the custom tool means taking half the car apart to get around it... Pita... Kent Moore makes all those special tools you see in the shop manuals that list a Jxxxx tool, etc. You can find a lot of them on the bay for cheap.
  6. zuper8

    zuper8 Rockstar

    Yes, I actually did make sure I could remove the fill plug first!! Learned that lesson last month when I did the rear diff fluid.

    Of course, now I can't get the drain plug loose so I gotta wait til my boyfriend gets home to see if he can do it :p

    And for whatever reason, my transfer case definitely takes a 1/4 inch drive, it fits perfectly.... maybe it's one of those things where the builders just used whatever was lying around haha. course with that tiny ratchet, it's no wonder i'm having trouble breaking the bottom one loose.

    EDIT: got it loose, the fluid that came out was bright red. looked very clean though for being in there 80K. going to try and get some updated aluminum drain plugs that have a hex on them.
    Last edited: Sep 30, 2010

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