4wd not engaging

[kirakitty]

I have search a bunch of threads, but nothing seemed to answer my issue, (I have many, ask anyone).

96 b4000 4.0L , I have had the problem for a while, and decided to look due the predicted 24-36" of snow coming to long island.

I turn the knob and the 4hi light goes on, I hear the shift motor turn, but no 4WD. I pulled the shift motor off and threw the switch and it move between 2wd 4hi and 4low without a problem, I manually turned the transfer case to 4hi and turned the switch to 4hi and reassembled it. grabbed the front drive shaft and it moved a little then locked in place. Figured I was done. when I drove it, I still only had 1 rear tire spinning. I just replaced front bearings and cleaned out the hubs that were filled with grease. coated everything with a thin film of oil. What am I missing? What throws the shafts out to engage the hubs? is it centrifugal or is there a solenoid somewhere?

worst part of this whole thing is the fact that I'm a friggin mechanical engineer

 

[RonD]

Ford auto hubs engage when front axle is powered, it turns
In 2WD the front axle and drive line should not spin
In 4WD front drive line and axle are powered and turn which engages the auto hubs

To disengage auto hubs you shift in to 2WD and then you back up 20-50ft

That's the way they worked new

If possible shift into 2WD and have someone look under front of vehicle to see if front drive line is moving when vehicle moves.
It shouldn't, if it does then auto hubs are engaged, well at least one of them
If drive line doesn't move shift in to 4WD and check again.
If drive line is turning then transfer case is working as it should, problem is in the auto hubs.
If drive line isn't moving then there is a problem in the transfer case

When I was having an issue with my auto hubs they made a clicking noise, i.e. they were trying to engage but couldn't.
I did the clean out and light oiling like you did and they are still working, been 5 or 6 years.

 

[adsm08]

I would say the issue is likely in the hubs.

 

[kirakitty]

thanks all, Will focus on hubs, also When I shift to 4lo, I get the same thing, but of course the gearing is low so I assume the transfer case is working. only has 34k miles on it.