94 popping in 4wd

As soon as I engage 4wd I can feel and hear the truck popping . Just checked tue front carrier - looked fine , cad looked brand new and the fork works as it should , I just put new u joints in the axle shafts as they were sloppy but it still pops.

The previous owner is my friend and he said it had started doing this a little while before he sold it to me. It was intermittent at first but now it’s constant. He said when he first started hearing it he opened the tcase and it checked out , put a new chain in anyways.

This is while idling in a straight line on loose gravel , sand.

The pinion to ring gear has almost zero play checked by hand but the little spider gears had some wiggle . All the teeth looked good, pinion bearing isn’t sloppy .

I’m thinking it’s the tcase and he missed something when he opened it up.

Rear axle was rebuilt within the last 800 miles and has a Yukon grizzly locker

Try dropping one drive shaft at a time ? Maybe an easy way to eliminate an axle as the problem. Then again may hide the problem by not loading it up right?

Any chance it has the wrong gear ratios front to back?

T-case is likely but I have had the output/input connection between the trans/case be worn out and cause a “pop” noise. That was on a nv4500 truck that had been beat worse than Tina Turner though.

I’ve realized I’m of no help here and I’ve just wasted ink posting this

He said it didn’t use to do it and then started one day but was intermittent. I have all 4 wheel off the ground , ran it in 4hi and can’t get it to pop. His buddy put the Yukon grizzly locker in. I’m wondering if the lash wasn’t close enough to perfect. It does make locker noise while turning but this is a nasty pop that happens in a straight line a couple times within 20 feet

Hook it to some immovable object, put it in 4wd, and see if the front wheels spin or it just continuously pops.
If it just pops, I would open the transfer case and check the plastic pads on the front wheel drive shift fork, and the parts that it operates.

Friend of mine fought a popping in fwd in a 95 for a long time. Put two different transfer cases in a still the same thing. Finally found out the shifter was out of adjustment and not completely locking in. Just a thought to look at.

I’d double check that chain be replaced.

Could also need sprockets as well. I know mine did.

You are probably loosing the mode range shift fork pads. The fork that shifts high range to low range. When those plastic pads go it will cause the T-case to pop in and out of gear.