Auto hubs wont engage

[smokenstroke]

Had my truck for about a month now. So tday i needed 4x4 to get up a lil slope that was pretty muddy. So i put the truck in nuetral and then put in 4x4 high. The selonoid (?) not sure on spelling, engaged i know for sure. And the light came on the screen. So started up the hill and felt the truck spinning. Looked out and only the rear tires were spinning. So had to get out and lock the hubs with pliers (?) (dont know why they are hard to turn) Then made it up the hill fine with all four wheels going. So what is the problem with my auto 4x4? Is the vacum, hose leak, seal leak, etc. And how would i test to see what it is?

Thanks ahead for the input!

Thanks
JD Roper

[HOUTX01X]

probably a vacuum leak. did your heat/air start blowing out of the defrost vents up on the dash?

[smokenstroke]

I didnt notice, would it do that when i just flip the switch on the dash? If it does that mean a vacum leak/seal for sure?

[NCHornet]

Yep vacuum leak it is, most common place is the back of the front hubs where the vacuum lins slips over the nipple, the line will split and boom, no more vacuum, trim off the damaged area and replace. The other common area is pass footwell, there is a vacuum line that can kicked loose. As for your hubs being hard to turn, spray all around the center section with wd/40 or other lube, then spray the center cross poiece that you grab to turn, you will notice it is pourous and will absorb the lubricant. Spray it and let it sit for 10-15 min, spray it again and wait, do this 3-4 times then try and operate the hub. Mine were so hard I had to use channel locks, now I can spin them with 2 fingers. Apply lube here everytime you change your oil.

NCH

[cak899]

I have the same kind of thing happen to my 6.0, but mine will lock in with a clunk that sounds awful after a couple tire rotations. If i lock them there is no slip at all... is that noise normal. Sorry for posing in a 7.3 forum but just read this and thought someone may have the answer.

[smokenstroke]

OK, thanks Kevin, gonna look into it tomorrow!

[ipz2222]

Start by pulling the hose off at the hub. put a vacumn guage on the hose, turn the key on and turn selector to 4wd. ck vac guage . If no vac, youre problem is upstream. I you have vac, remove nipple. It is probably stopped upwith rust. Replace both sides with brass fittings. To everyone else that's not haveing problems, replace those fittings with brass.

[choupique108]

Mine done this and i have changed the motor on the pass. fender, the hoses from the frame to the hubs, Lockout hubs(i got 5 brand new ones for $50).

NC hornet is that hose in the passanger footwell hard to find or is it out in the open? Im gonna have to check that out.

[smokenstroke]

You got auto locking hubs for $50?

[RJSteele]

Does anyone have any idea if these Auto/Locking Hubs are rebuildable new seals etc? Seems like a waste to have to throw them away? Thanks