Oldsmobile/Buick Repair: GMC 4x4 problems, gmc 4x4, cv joints

Question
2000 GMC sierra PU, 4x4 engages but binds up when turning. Thought cv joints but did the circle test and no clicking? Makes noise in 2 wheel, kind of a humming that is new , engages into 4 wheel as it should but does not want to turn low speed, if you power up you can get thru the turn but it fights the turn. Seems like its binding up. Had it up on a rack and the mechanic could see nothing obvious and told me to drive it until something was more obvious which I do not want to do. What do we check ?

Answer
Hello Charlie,
On smooth dry pavement, you will feel some binding in a sharp turn.
You are not supposed to use four wheel drive on smooth dry pavement.
There is no differential in the transfer case, and on turns, the front wheels rotate at a different speed than the rear, and that will act as a bind.
So use the four wheel drive off road, or on slippery roads, and the binding should be minimal, or even unnoticable, but that is because the poorer traction allows the slip to take place without you noticing it is happening.

I really don't think anything is wrong with your truck.

After using 4X4, and disengaging it, try backing up a little to release any built up torque on the system, possibly due to different wear amounts of the front to rear tires, and see if the humm also quits as things relax to their normal two wheel drive condition.

Van