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Noisy NP208 (my transfer case "whines")

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by arveetek, Mar 10, 2002.

  1. arveetek

    arveetek 1/2 ton status

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    Noisy NP208 (my transfer case \"whines\")

    I just bought my K-10 about a month ago, and I've noticed that the T/Case really gets a high-pitched whine sort of noise at about 60 mph. At least I think it's the T/Case. The transmission growls a bit, but I don't think that's where the noise is coming from. It's really annoying. I checked the fluid in the T/Case, and it was a little over a quart low. I topped it off, but it didn't help any.

    Is this a sign of trouble ahead? Is it normal? Anything I can do about it? I used Dexron-III in the T/Case....is there something better that would help?

    Thanks guys.

    Later

    Casey
     
  2. Twiz

    Twiz 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Could be the NP208, If they run low on fluid, they tend to self distruct. I'm pretty sure they only hold a couple of Qts of fluid.

    Any change when you get on/off the throttle?
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: Noisy NP208 (my transfer case \"whines\")

    Just so you know, my 208 has always whined a little bit, mainly during light throttle and when I'm decelerating. The whine is very subtle, though.
     
  4. arveetek

    arveetek 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Yes, the whine changes with throttle application. It whines most when applying hard throttle at or around 60 mph. It also whines when letting off the throttle at that speed. There's no noise when coasting.

    The whine is present at other speeds as well, it's just worse at 60 mph.
     
  5. Twiz

    Twiz 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Do you think it might be rear gears? It might be the 208, but aren't they diirect-drive? (still could be a bearing thing, I'm just guessing, you know TTT)

    Rear gears will usualy make noise in one direction, but not the other. Not sure about the T-case.
     
  6. 79Beast

    79Beast 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    I personally run a 205, but I'd rather have your 208. Running low on fluid could easily have excessively worn the chain or a bearing or two causing loud whining. Running thicker oil or even sythetic is a last try fix. I have always heard that 208's are nearly indestructable When Kept Lubricated. You may have to pull it and go through it.
     
  7. arveetek

    arveetek 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    I'm pretty sure it's not the rear gears.....my C-20 has a little gear whine, and the K-10 has a different whine, and it's much closer to the driver. The 31" aggressive tires whine on the road as well, but this particular whine is a different noise altogether.

    I also notice that the noise is much quieter when the truck is cold, and all the fluids are thick.

    What can I replace the Dexron-III with that will work all right?

    Thanks for the help guys.

    Casey
     
  8. arveetek

    arveetek 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Any other thoughts?

    Any fluid recommendations?
     
  9. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Does the whine change in different gears? R...D? Does it change when you put it in 4wd? I can't say I have ever heard a 208 type case whine very much... most times a bearing seems to go like in mine right now and then it won't hold fluid and growls quite a bit. You could try doing some exploritory surgery... pull the drive shaft... pull the back tailshaft housing and check the bearing and a peek. Maybe even pull that back case half and look inside. There is a magnet inside these cases that tends to hold alot of crude kinda by the drain hole. You could also visually inspect the chain and some of the gears. It is kinda time consuming but good to kill an afternoon if you seriously think the tcase is your problem.
     
  10. arveetek

    arveetek 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    Thanks for the idea.

    The noise is present under acceleration, and deceleration, so that eliminates the rear gears, I suspect.

    I don't really notice the noise changes any in 4WD, but I'm not driving that fast when I am in 4WD. The tranny itself growls though, especially when in 4WD.

    Could it be the 465 that's making the whine noise? I know it's getting worn out, cause you can hear it growl while sitting in neutral and idling. Push the clutch in and the noise goes away. At low rpms, it really growls, but I don't hear that when driving down the road. Just the whine.

    I'm really not for sure. I just assumed the T/case, because this is the first truck I've owned that made this kind of noise, and this is the first truck I've owned that had a transfer case. Poor reasoning, I know, but I gotta start somewhere! /forums/images/icons/smile.gif
     
  11. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: Noisy NP208 (my transfer case \"whines\")

    I would find it much more likely to be the tranny making a noise like that, but that is IMO. Seen that quite a bit in manual trannys... but hard to say over the net. Might inquire about getting a trained ear like a gearhead buddy or maybe a local small towm mechanic would be able to listen while you drive... or better yet block the frt wheels and lift the rear wheels up and try getting the noise by listening under it.This is way safer if you do it on a hoist and easier, but can be done if you are careful at home with a buddy
     

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