im hearing a strong grinding noise from the left front of my truck what is it on 2003 Chevrolet Avalanche 1500

im hearing a sound like gears grinding together in the front of truck on drivers side, and i can hear that something is loose, i looked but didnt see anything wrong. but it sounds like clinging, like the wheel is loose ,and the grinding isnt constant if i stop it will stop but sometimes upon take off it starts grinding again. like some thing is loose or broken or trying to engage while driving. also having problems with 4 wheel drive .it says service four wheel drive in the instrument cluster could that be part of the problem or the whole problem?

2 answers 2 comments
To many possibilities, needs to be seen to tell, get a mechanic to check it out.
seek diag and est from a frt end shop. could be hub bearing,shocks,tie rod ends or several other issues