i need some opinions. its snowing in georgia, the roads are all iced up and i've been driving in 4wd the last 2 days. late yesterday the tcase began to make an occasional thumping sound. i don't have a tcase saver. i have not taken anything apart yet. its too cold and wet.

with posilok engaged and in 2wd (and front drive shaft turning), i get a steady clicking/grinding noise that sounds like the chain rubbing on something.

with posilok not engaged and in 2wd (and front drive shaft not turning), i have no noise.

in 4wd, i get a thumping when starting off or coasting down. its quiet if it hold a very steady throttle.

i've got no way to work on the truck tonight and no spare snap ring. so here's the questions -

1. does the chain turn when in 2wd ?

2. as long as its not making any noise in 2wd - is it safe to drive in 2wd to work and back for a couple of days without doing any damage? its a 5 mile drive. or do i need to park it?

 

mine does same thing , sometimes it does it sometimes it dont , if t does i take it out of 4wd and let it ride in 2wd

 

The chain might spin but without any force/torque until 4wd is engaged. I'd have a look at the dbl cardan joint on front driveshaft if I were you. Remove shaft to check it.

 

well, i think i found the problem and i'm an idiot.

i put it up on jacks and checked all rotations, all feel/sound fine. all u-joints ok, except the double carden cup has a lot of minor cracking. it can wait.

i cranked it and ran it in gear, 2, 4, low, high. no noise, no malfunction.

operated the posilok several times and got some varying results. its not wanting to act exactly right and i think that was the problem. its gotten hard to engage/disengage, so i think it had poor engagement and was slipping under torque or flex or something and i've probably burred up the collar. i've got it engaged fully and just did a several mile road test in all different gears. no more thumping in 4wd and no more grind in 2wd.