4X4 Truck makes roaring noise in the front end?

This problem was noticed on Chevrolet Silverado 1500 Z71.But this same problem is noticed on many 4 wheel drive trucks.
In this problem,the truck makes roaring noise from front end,also not in the 4x4 mode.

In this case first the basic possibilities needs to be checked.
That are brake rotors,wheel calipers,brakes etc etc.
Also check if you notice any kind of leak from the differential on any side OR there is any slack in the CVC joints.

I suggest checking the wheel bearings. Lift the front end and grab the tire at the top and the bottom. Push and pull on the top and bottom of the time and see if you can feel any movement other than the flex of the tire. Also try turning the tire. You may year the noise if the bearing is bad enough. If you find something, replace the wheel bearing assembly.
Also check if you have any clicking noise in 4WD or 2WD while driving left to right.

Properly hear,do you notice noise coming from tires,wheel bearing or from transfer case.
Check the condition of fluid in transfer case.
Is the fluid leaking around the seal from drivers side or passenger side or it is low.

Take the front drive shaft out,and drive the car and see what difference you notice.
Take the shaft from the transfer case to the front diff, not the cv axles.
NOTE : You cannot run with them out as they hold the bearings together.Take the front drive shaft out and properly inspect.

If it still roars, is it the differential bearings?
But If it goes away it is in the diff, and you will feel it as you turn the front, if not then the transfer case is the problem.

This details will help you.Thanks.

-------------

See below latest solved car problems :--------

No power due to weak turbo?

http://schematicsdiagram.blogspot.com/2011/12/no-power-due-to-weak-turbo.html

Before purchasing Second hand car?

http://schematicsdiagram.blogspot.com/2011/12/before-purchasing-second-hand-car.html

Testing mass air flow sensor?

http://schematicsdiagram.blogspot.com/2011/12/testing-mass-air-flow-sensor.html

Where is MAF sensor located on 2000 Ford Expedition?

http://schematicsdiagram.blogspot.com/2011/12/where-is-maf-sensor-located-on-2000.html

Car won't start without hitting the gas pedal?

http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-without-hitting-gas.html

Ford Keyless Remote Fob Reprogramming?

http://schematicsdiagram.blogspot.com/2011/12/ford-keyless-remote-fob-reprogramming.html

1995 Oldsmobile Eighty Eight has bad O2 Sensor?

http://schematicsdiagram.blogspot.com/2011/12/1995-oldsmobile-eighty-eight-has-bad-o2.html

Dual Exhaust on 1996 Chevrolet camaro z28?

http://schematicsdiagram.blogspot.com/2011/12/dual-exhaust-on-1996-chevrolet-camaro.html