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1988 burb transfer case question

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Michael Wilson, Oct 21, 2012.

  1. Michael Wilson

    Michael Wilson New Member

    Just got a 1988 burb everything seems very good on it. The only thing I have question about is a sound coming from the transfer case. I didn't notice it because I thought it was the fan running. The way I noticed it was coming form the transfer case is I was going to work on the fan because it would not change speeds. When I got in the floor to look under the dash that is when I noticed the noise was coming from the transfer case. Now this truck has sat for 2-3 years for the most part (it has had 50 miles put on it in 3 years) anyway just wondering what could be causing the noise? It could be low on fluid (that is what I am hoping) also does a 1988 burb use automatic transmission fluid like Dex tron III? about how much would it take to fill it up? Thanks
  2. oldmanstruck

    oldmanstruck Member

    don't have 4x4 so can't help you on that.
    But for your fan issue, if you haven't figure it out, it is probably the resistor.
  3. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    Micheal, I would change the fluid in the transfer case (it may have some water in it). I'm afraid, I am not familiar with the T-case used on your truck, so I can't help with the drain and fill plugs, but a google search should find what you need.
  4. Boonduff

    Boonduff Member 3 Years 100 Posts

    Your 1988 Suburban has a NV/NP241 Transfer case which requires 2 2/7 qrts of Dexron III
  5. Michael Wilson

    Michael Wilson New Member

    OK thanks.I checked the transfer case and it is full. Maybe to full. You pull the top plug and fluid really pours out. I am glad that was not dry.

    Now what would be causing a whirl noise almost like the heater fan running on low. It makes this noise just sitting still with the motor running the sound will get louder as the motor speed goes up. Thanks
  6. Boonduff

    Boonduff Member 3 Years 100 Posts

    The transfer case has no moving parts when the vehicle is idling, so the noise you're hearing isn't coming from it. Moving forward in the drivetrain the only thing spinning when idling (other then the engine and its accessories) will be the torque converter, which can make a whirring sound when they're getting tired. Find a good tranny shop and have them check it out. Also, don't automatically rule out the engine and it's accessories if one of them is making the noise it could be resonating down the tranny tunnel fooling you into thinking the source of the noise is further back in the drivetrain.
  7. Michael Wilson

    Michael Wilson New Member

    I just decided that the noise is coming from the tranny. It was low on fluid when we looked at it we added about 2 quarts to bring it to the low mark. Like I said I thought it was the fan running. The noise will change with the speed of the motor. It seems to drive and shift OK just the noise. It might not be to bad if it is the torque convert.

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