Sorry I know nothing about four-wheel-drive. Are these manual hubs? When I turn the switch in the 4 x 4 the drive shaft turns but it doesn't feel like it's in four-wheel-drive. The vacuum lines on the hubs were broken and corroded so I replace those, but still does not feel like it's in four-wheel-drive. Do I need to lock the hubs? Did this truck come with automatic locking hubs?

 

The hubs have 2 positions, auto and lock, in auto position they are actuated by the vac system, in lock its exactly that, locked. They might be stuck and not working off the vac system, try turning them to the lock postiton and try your 4wd, roll forward slowly and turn the steering back and forth, steering should feel tighter than normal if 4x4 is engaged

I would venture a guess that since the vac lines were broken and leaking, that the PO probably didnt use the 4x4 much, good chance the hubs are stuck

 

The hub pictured is in the FREE or AUTO position. You would turn it to the right & let it rest on the dot, That would be LOCKED.

 

Have similar issues. Tried turning the hub manually and seemed to be frozen. Is it time for warn manual hubs?

 

That, or some other brand or you could read how to service the stockers in the Tech Folders at the top of this page.

 

This^^^^^^^

If you have the time, since it doesn't snow in this country anymore... I would try repairing (servicing) the one you have now.

 

I see, so why doesn't the AUTO position work when I flip the 4x4 switch? I put new vacuum hoses on the hubs

 

Once you have have established that vacuum is actually making it to the hub when you flip the switch then the issue can be narrowed down to a leaking or sticky hub.

 

A lot of the time the leak/problem is at the Tee fitting just out side the Vac bottle on the fender. It can be the bottle leaking itself as well.

 

Have you established the hubs are working at all in LOCK

 

The vacuum solenoid on the passenger fender is also know to fail sometimes on these ESOF systems.

 

Awesome info. I'll check it out today and report back with some pics.

 

Have you established the hubs are working at all in LOCK

 

Check the solenoid on the inner passenger fender. That was my issue and I also replaced my hubs. Now the ESOF works as it should.