Fluid for my transfer case

Discussion in 'OT Driven' started by RobinHood, Oct 24, 2007.

  1. RobinHood

    RobinHood New Member

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    I have a 77 GMC Sierra Classic

    I have a 203 fulltime 4wd transfer case. the front driveshaft is off right now...

    I can hear the chain when I give it any decent amount of gas...

    I'm assuming that means i need new oil.

    New cars use ATF but what should I use for mine?

    Is ATF ok? or too thin? or what?
     
  2. RobinHood

    RobinHood New Member

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    autozone.com says SE ?

    wtf is se?
     
  3. GTLifter

    GTLifter Banned

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    a lot of chain driven t-cases use ATF...

    either find an owners manual or call a stealership
     
  4. RobinHood

    RobinHood New Member

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    ATF is too thin for a 203

    I've been looking and people say either 10w30 or 10w40
     
  5. RobinHood

    RobinHood New Member

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    tech at Chevy said 80w90.
     
  6. RobinHood

    RobinHood New Member

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    put 80w90 in it.

    still getting a chain noise.
     
  7. affende

    affende Resident 4X4 Elitest Prick

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    dam you people need to keep your fucking fingers off the keyboard. 1030, 1040, atf? What The FUCK??

    8090 or 70140 if you do harsh shit (not if you are in cold climate).

    you might be hearing a stretched chain or bad bearings allowing the shafts to slop and putting slack in the chain.

    pull the plug, check the case for shavings, refill with the proper fluid.



    ATF is for the more moders olanetary style transfercases ... yours is chain drive by gear ... you need thick shit.
     
  8. RobinHood

    RobinHood New Member

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    8090 is in there now.

    I think soon, I might get the kit that allows it to be part time, and rebuild it in the process of that.
     
  9. deusexaethera

    deusexaethera OT Supporter

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    Chain noise has nothing to do with the oil. The chain is old and it's worn out so it's longer than it's supposed to be, and the sound you hear is the rollers banging against the sides of the sprocket teeth.

    Granted, this is something I learned from mountain biking, but a chain is a chain, and they all wear out the same way.
     
  10. CastorTroy

    CastorTroy New Member

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    The correct oil for a NP203 is actually 10w-40 motor oil. 90w gear oil is way too thick to properly lubricate the chain, so you need to drain it and refill before it does further damage to it.

    Also make sure you don't have the t-case shifter in the Hi-Loc position without the front shaft installed.
     
  11. RobinHood

    RobinHood New Member

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    Can someone give me actual sources that say its 10w40

    I'm getting real confused.
     
  12. RobinHood

    RobinHood New Member

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  13. deusexaethera

    deusexaethera OT Supporter

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    You gonna replace the chain like you need to, or just pour in some snake oil and hope for the best?

    Get a remanned transfer case if you don't want to deal with having the thing taken apart at the shop. It'll probably be done better by the factory anyway.
     
  14. deusexaethera

    deusexaethera OT Supporter

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    But the transfer case doesn't need the de-acidifiers that motor oil has. Maybe that's the right weight, but wouldn't gear oil still be better?
     
  15. RobinHood

    RobinHood New Member

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    I am going to rebuild it. I am training to be a mechainic so it will be good practice...

    Plus I want to put a conversion kit in to make it part time.
     
  16. CastorTroy

    CastorTroy New Member

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    Google "NP203 oil" and you'll get a hundred. I know off my head because I had an '73 with a NP205 (came with the manual trans) but they used the NP203 behind the automatics, the owners manual listed 10w-40 motor oil for the NP203.
     
  17. RobinHood

    RobinHood New Member

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    Ok. So is putting 80w90 in it a bad thing to do?

    Like the guy said above I think the chain is pretty screwed up...
     
  18. affende

    affende Resident 4X4 Elitest Prick

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    1040 for a gear drive transfer case? :bowrofl:
     
  19. deusexaethera

    deusexaethera OT Supporter

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    It won't hurt it necessarily; the chain doesn't need pressurized oil to keep it lubricated, so oil that's too thick won't inhibit lubrication, but thick oil is more likely to froth up and force its way out through the oil seals.

    That said, oil that's too thin won't produce a lubricating film strong enough to withstand the pressure on the chain rollers, and they'll break through the film and scrape against each other and wear out all over again.

    You should really get a shop manual for the thing, or at the very least ask the dealer what to use. We're just a bunch of hosers around here.
     
  20. GTLifter

    GTLifter Banned

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    203 is chaindriven
     
  21. CastorTroy

    CastorTroy New Member

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    1040 would be pretty dumb for a gear drive huh :bowrofl: Unfortunately we're talking about the NP203, which is a chain drive, full-time t-case. Keywords here are chain drive, and full-time. Most chain drive, part-time cases do fine with some thick gear oil, or even thin ATF, but the NP203 is one of the exceptions to this rule.

    Try using Google as I suggested earlier, you will find 10w-40 motor oil is correct.
     
  22. affende

    affende Resident 4X4 Elitest Prick

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    i apologize ... im fucking retarded .. i was thinking a 205 :o
     
  23. RobinHood

    RobinHood New Member

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    Ok. So 10w40 it is.

    Will be replacing as soon as I have time.
     

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