Yeah, mine goes back and forth like maybe 15 degrees. Maybe you just lost a shear pin or something like that somewhere in the line?

 

The transfer case/PTU is blown as I mentioned before.

 

I would not expect a shear pin in the driveline. So I think the gears have eaten through. Since the PTU does engage (ie when the propeller shaft is rotated the wheels turn) I think the damage is in the transfer case. The electrical checks seem to show the PTU is fine. Will replace the transfer case & post results... may take a few days.

 

They're a ***** on those, take your time and good luck.

 

We were trying to narrow everything down first since it's a major job wptski. I never heard of that particular failure mode for the driveline otherwise I would have suggested that Bill do exactly what he did to test it. I'm surprised it made absolutely no noticeable noise at any time when it basically grenaded itself.

 

Gearing can wear slowly without making much noise till nothing meshes or it can go boom from sudden stress applied.

I'm a retired industrial mechanic from the auto industry(Ford) and I've seen it all!

 

Fair enough, it just didn't seem like it was a major rush so I wanted to keep him from open heart surgery if it was avoidable.

 

Yes, consider the case where a non-full time 4WD is left engaged on dry, hard surface roads. The windup that occurs usually destroys the gears by gradually eating into them until they don't have enough left to engage any more. I'm trying to figure out where I could have initiated that process. I think that the proximity of the exhaust system is part of that by slowly boiling away the lube.

 

They just aren't a very strong design, a quarter million miles is pretty good out of it. I would say if you think your fluid boiled then maybe you have a cat getting hotter than normal.

 

The case would have to get over 400F to boil heavy gear lube. There once was a guy((wwest(Willard West)) in this forum that always said that the transfer case was the weak link in the Ford design.