hard rattling noise when drivin 4WD

[angliadeluxe]

hello there!

I have a BJ73 from 1987,
lately, when i want to drive H4+H2, or H4+L4, i hear this very hard rattling noise at high speed in every gear!

when i deblock the H4-switch, the noise is gone.

i opened the PTO-cover and inspected the 4 gears, but didn't find any damage!

drained the oil and there were only a very few metalparticles (not one square inch), stuck on the magnetic drainplug.

i also checked the front camshaft... nothing rattles or clicks!
any ideas?

greetings!

 

[PhrogsPhorever]

Drop the fluid in the front differential also and see what comes out.

Check your front drive shaft and u-joints for any play or loose bolts.

Remove your front drive shaft, lock the hubs, then drive around in 2WD and see if the noise still happens, that can help eliminate the front axle.

Check the front pinion and transfer case output flanges for any play or a loosening stake nut.

Good places to start