Grinding Noises???

[mazda4x4]

I have a 2000 Mazda B3000 4X4. Once in a while when I engage my 4x4 from a complete stop and then start going my 4x4 doesn't engage and just makes a grinding noise. When I put it back in two wheel drive and then back in to 4x4 it just engages fine. It just happens once in a while at a complete stop and then start going. I am wondering if this is something to be worried about or if this just happens? Also kind of dumm question if the rear wheels are spinning when you are stuck are you supposed to be able to put it in 4 wheel drive when the rear wheels are spinning?

 

[ca1rangers]

4x4 high should be enguaged when moving. I beleive with low it should be at a stop in park or neutral. Thats what my Ford is like Pretty sure mazda will be the same way. The grinding may be because you are at a stop. Do not flip it in 4x4 with wheels spinning. If you are stuck wait till wheel stop and go into low and work your way out.