This last week we've been pounded with rain that would make even Seattle & London feel great to be in their rainy locations and so I decided to actually test out & use my 4wd for the first time since owning the truck on an actual paved surface instead of a off road situation. Anyway I got sick of sliding sideways trying to get going in 2wd through the rain so I stuck it in 4 wheel High so I could actually move through an intersection with ease and have normal reaction times and 4 wheel drive did indeed solve that problem, but after a mile or two the there is a loud humming noise that gets louder the longer the truck is in 4 wheel drive and it just didn't seem normal to me so I imediately stuck it back in 2 wheel drive out of fear 4wd may blow something apart in the transfer case.

2wd drive works amazing no complaints or funny noises, just 4wd seems to get a weird noise that gets louder the longer its used and doesn't ever start out with a loud noise. I've tried it 3 times and each time it makes no noise until a mile or two down the road.

Maybe need some new gear lube for it? I just got the truck so the status of that is unknown from the previous owner who was a female and had the truck since it was new in 97.

 

Change out the lube -- they're filled with ATF. If that doesn't do it you might be in need of a new chain. While you're under there anyway, you ought to throw a transfer case saver at it.