Strange problem that is hard to describe with my bx.

[Tooljunkie]

Its loading up the driveline, imagine an 80 degree day on asphalt. Good and grippy, in 4wd while turning you are winding up the driveline with all that good traction. There is no way to release it unles wheels slip or asphalt tears or something breaks. Torque load needs somewhere to go. Thats why posi-trac in cars have clutches to let excess torque release-aka limited slip. Otherwise stuff would break.

Likely the noise is different between idle and higher rpm's. Lower rpms may make more noise.

 

[Grouse Feathers]

There is no one answer, you have to use judgement. The tractor is built to take some binding in 4wd. If you need to use 4wd to fill the loader from a gravel pile, turn drive 30 yards on dirt or loose gravel and dump the loader, leave it in 4wd. If you need to haul the gravel 200 yards across a paved driveway with two turns, take it out of 4wd. I often feel it binding on the lawn, the only damage it's doing is to the lawn so again its a judgement call.

 

[trapperdrew]

That's good to know.
I would much rather rip up the lawn then to break my bx.