I just fixed my 4 wheel drive and i don't think it has worked sense i bought it, 2 years, so don't know if its supposed to make a turning noise, like gears turning not sure if its normal.

 

For the love of god check the fluid! There is 2 plugs on the back of the t case take out the top one with a 1 3/16ths wrench or sockit. The (trans fuid) in the T case should be level with the plug. Other wise. Could be a lot of other things. Drive shaft, t case baring, anything in the front axle. Check the fluid there too 3/8ths square ratchet drive in the only plug on the diff cover of the axle. Fluid should be level with plug.

Smell or taste fluid to see if its burnt!

 

so there should be no noise? even when reving up, and turning doesn't sound bad just rater be safe then sorry