Mysterious 4WD Noise

Last fall I used 4WD for the first time in a few months and immediately noticed a high pitched noise that only occurred when decelerating (i.e., foot was off the gas). Imagine a jet spooling down, that’s the best way I can describe it. I replaced the TC with a new Jasper unit. There was definitely an issue with the old TC. When I turned the output shaft it felt as though sand were in the bearings.


Now, with the new TC in, I hear a howl noise in 4WD that increases in volume and pitch as I speed up. It happens regardless of whether my foot is on the petal. It’s possible that this new noise existed before with the old TC and that I just didn’t hear it over the old noise I mentioned above.


Can you guys help me isolate the issue? Some other relevant facts...
1) I don’t know if this would affect anything but I do have a small TC drop installed.
2) Absolutely no noise in 2WD.
3) I've noticed that sometimes it takes 10-15 seconds for 4WD to disengage. I don't know if this is normal or not.

That link is helpful, but wouldn't any of the noises it describes in the front axle also happen when in 2WD since it's still spinning?

Noise might be just the planetary gear noise. My NP242 makes a whirring noise in 4WD...high range, and is more noticeable in low range. Has since day one.

jls095 said:

That link is helpful, but wouldn't any of the noises it describes in the front axle also happen when in 2WD since it's still spinning?

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No. Without 4WD engaged the front axle is not "under load", it is just hanging out, chillin'.

Flyfisher said:

Noise might be just the planetary gear noise. My NP242 makes a whirring noise in 4WD...high range, and is more noticeable in low range. Has since day one.

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I remember that my 4WD was never silent and that there was some noise. It's just that this time it's louder than I remember it.