Diff noise and 4wd problems

[Bobbykemp39]

G'day guys just bought a second hand navara D21 and there are a few problems with it and would love some help diagnosing them. First problem, 4wd won't engage, I lock the hubs, put the gear in 4L put the car in gear and let the clutch out and the car doesn't move, not sure if there is a dash light to signal if its engaged, but nothing comes up on the dash anyways. Second problem is the diff makes a knocking sound when I change gear and the rev's are high, and continually knocks when I'm doing 100km, I'm not really a car person so I have no idea, I'm just getting into now but would love as much help as I can possibly get, so if anyone can help me out I would bd forever grateful.
Cheers guys
-bobby

 

[dilmah]

Id pull the back cover off your diff and check the pinion bearings to see if they are catcus. This will also tell you if the ring and pinion gears are excessively worn. This will be evident if you find metal chips in the diff oil or in the bottom of the diff.

 

[Bobbykemp39]

Thanks mate ill pull the cover off and have a look