2005 F250

When vacuum is applied to the hubs, they lock in. When vacuum is UN-applied to the hubs, the passenger side will not disengage completely. I Understand that no vacuum is required to UNLOCK the hubs and that its spring driven only. I have to get out and work the u joint behind the wheel and flip the manual hub **** from auto to lock before it comes free,

The manual hub was taken apart and the grease is clean. I cleaned it a little and regreased but could not disassemble. But I need some help understanding how the system works if I have any chance of fixing it.

If you manually engage and unlock the hubs at the wheel, I dont seem to be able to duplicate the issue.

What does the vacuum do in the hub that is different from manually turning the hubs?

This may not help, but I'll throw it out there.

Something I've always heard about Ford hubs is that you may need to drive in reverse for about 10-15 ft to get the hub to disengage.

I only have an F150, but I have had to do this before to get the hub to disengage.

Maybe it would translate to the 250 hubs.

Had same problem on my work truck, ended up just replacing the hub with warn manual locking hubs. Not ideal but solved the problem.

The hubs manually turn freely. That's the issue. Replacing those would solve nothing I don't think.

When I took them out, they function smoothly. Once reinstalled, they seemed t engage and disengage axle fine. But for some reason when the vacuum engages the axles, that side doesn't disengage.

God forbid you have to get out of your truck to lock the hubs

Meh...its more a matter of something not working as designed. The desire to get out or not is really of zero consequence. I REALLY hope Ford has addressed this 'system' in the 2017 super duty. :/


I think the issue is totally related to just the hublock itself. Its not disengaging when the 'low vacuum' is applied when going from 4h to 2h. But It works fine manually. I thought that once automatically disengaged, the spring in the hublock was in charge.

Its that hub. Its 'sticky' for some reason. Ive greased the piss out of it though. Maybe Ill take apart and clean hub and shaft splines with a brass brush and re-lube. It just hangs on disconnect. SOmetimes it disconnects, sometimes it doesnt.

When the hubs are OUT of the truck, they turn and click and unclick just fine, its something to do with what happens once it clicks over the splined shaft....its sticking there.

Spring getting pinched?

I switched my Nissan from auto hubs to warn manuals to avoid issues like that.

Bump.

ESOF not working. When I place a vaccuum directly to the pass. knuckle, it will not hold. Replaced wheel hub assembly and axle shaft seal. Still not holding. Any ideas?

Also trying to figure out how exactly the vaccuum engages the hub. I don't get it.

4wd works by manually turning the hubs, just no ESOF.

2000 F-250. Headed to Colorado next week.

You plugged your MityVac directly into that hub and completely isolated it?

If so, there are only a couple of seals in the hub, including an O-ring that often leaks.

If you can't get it to work, then you can simply lock your hubs AND flip the switch on the dash for 4wd.

I pulled the vacuum line off the drivers side knuckle, plug my vacuum pump in, and it holds vacuum

When I do the same to the pass side, it does not hold vacuum.

I have also ensured that the vacuum fitting on the knuckle is cleaned out

A/C goes from vent to defrost when its trying to engage, then eventually back to vent.

Did you redo the HUB seals?

This is what I am talking about:
http://www.guzzle7pt3.com/nblube.php

If you verified the driver wheel is ok, and the pass wheel leaks, the seals on the hub may be shot and the seals need to be replaced.

A vacuum loss of 1 lb over 1 minute is acceptable.

Backing up 10-15 feet also helps this process.

Guzzle also has a great writeup for ESOF Hub Maintenance here.

Also..here...for posterity. If you keep the truck long, you will need this again.

http://www.powerstroke.org/forum/attachments/general-6-0l-discussion/242394d1392304892-what-did-you-do-your-6-0-today-4wd.pdf