noisy transfer case

[Johns02ranger4x4]

Haven't run the truck in 4x4 for some time and when I engage it,it sounds like sand paper on metal, a loud continuous rasping sound. 4x4 is engaging and the rasping sound diminishes when turning a corner. When the 4x4 is diengaged still get the rasping sound until I turn a corner then it quiets down. This is an electronically controlled 4x4. Any ideas as to the cause of this issue would be greatly appreciated.

 

[Curious Hound]

Does it matter which direction you turn? The fact that turning a corner changes the sound, makes it seem like a problem in the front end somewhere - Hubs, bearings, brakes, axle shaft u-joints. Still happening after 4x4 disengaged? I definitely would NOT go to the transfer case right away, probably not even the differential, though checking diff oil level wouldn't be a bad idea.

Put the front end up on jack stands and rotate the wheels by hand - steering wheel straight, turned left, turned right. That will help you get a better idea of where the problem is.

 

[Curious Hound]

Thought of a couple other things. Dust shield rubbing on brake caliper is something I have had to troubleshoot.

Also, what axle is it? If Dana 35 (or28) TTB, check to see if rodents built a nest and packed trash inside the axle beams so that it would rub on the axle drive shaft. Stranger things have happened.

 

[85_Ranger4x4]

Chain might be loose inside the t-case too.

My aunt/uncle had one come loose and it made noise before it bound up and locked up the drivetrain. Luckily for them they couldn't back out of a parking spot. Maybe it can't happen but it would be interesting to lock it up going down the interstate...

Turning would change the speed of the front driveshaft vs the rear driveshaft if it is a 2002 with the live front end which might change how things are moving inside the tcase even when it is disengaged.