No 4x4 with hubs in "auto"

WHY NOT · Jun 27, 2013

So I was pulling the header out in a field today and clicked the truck in 4hi and I get stuck spinning on top about 30 ft into the field. The light came on on the dash to "check 4x4" so I get out, pop off my center caps and lock in the hubs and 4x4 worked fine. So I put the hubs back in auto later today and tired it again thinking maybe they were stuck or something and turning them got them un-stuck and nothing.

So what do I need to look for to fix this so my truck goes into 4x4 w/o me having to get out and lock in the hubs or leaving the hubs locked in?

Big Stroker 6.4 · Jun 27, 2013

Vacumm operated hubs, check the vacumm line?

ford rules · Jun 27, 2013

Probably a cracked vacuum line or bad vacuum switch by the pass side battery, thats for a 06 truck not sure if the newer ones are the same just checked your sig.

WHY NOT · Jun 27, 2013

Do the vacuum lines run directly off the hub its self like on top of the axle to the hub(like a break line)? I don't know where to look for the lines to find the problem really.

ford rules · Jun 27, 2013

Yes the do.

HOOV3R · Jun 27, 2013

Vacuum lines hook into the knuckle and vacuum travels through the knuckle. It is sealed by the knuckle seal, the o-ring on the wheel bearing and the seals in the hub.

WHY NOT · Jun 27, 2013

Ok, thanks for the quick responses. I will check the lines as soon as I get a chance.

sootie · Jun 28, 2013

that happens to all our super dutys and we end up replacing the outer portion of the hub. the aluminum corrodes around the oring seal and it wont hold vacuum. it is a simple snap ring to remove it and wire wheel it but the corrosion comes back almost right away. what i do is disconnect the vacuum line from the back of the hub and hook up a hand pump with gauge and see whether the vacuum holds in the hub. that way you determine if the leak is in the hub or in the truck system. also check to see if the vacuum pump is working (if there is a leak it will run constant and burn itself out) it is located behind the drivers side battery, i hope this helps.

INFRNL · Jun 29, 2013

Sounds like its in the hubs to me. I had/have the same problem. I rebuilt my hubs and tested everything. I thought everything tested ok but they still dont work. I had them work once but I think I still have issues in the hubs.

When I have time, I need to see if I can figure it out. I hate it when things don't work properly, drives me nuts, lol

WHY NOT · Jul 12, 2013

Wound up being a busted vacuum line thanks for the help guys

INFRNL · Jul 13, 2013

Glad you got it figured out. Did you only get air out of the defrost or did you air still function properly?

I just tested my hubs. Pumped them up to 10lbs and they hold air just fine. My air works fine, pump shuts off and does not continue to run, etc.

Wonder if my hubs are messed up and not functioning properly.
Guess I will have to do some troubleshooting tomorrow

Decided to mess with it a little bit. Found that my pass side hub does not always like to hold pressure. Going to have to pull that side apart tomorrow. I think I know what it is. The big knuckle seal I believe its called gave me a hard time. I might have damaged it or didn't get it seated properly.