Hey all,

I have been fighting an intermittant ESOF problem for about 5 months now. I recently replaced the LF bearing, have replaced both nipples, both lines, and the solenoid. (The solenoid really didn't need it, but I found one OEM brand new for 20.00. Couldnt resist)

Mitey mite is saying good vacuum at the pump, and the resevior. Both hubs hold ok when the truck is sitting in the shop, as tested from the tee by the resevior.

I pulled the LF locking hub a couple months ago and rebuilt/cleaned it up. It seems like it does not consistantly lock or unlock. The best analogy someone posted on here is that it is like a ballpoint click pen, and it seems like it takes a few times to either lock it or unlock it when sticking my finger in and operating it.

As for the road, it seemed to work properly when the truck was jacked up, locked and unlocked on the fly heading out to the driveway, but has been hit or miss since then.

Is it possible to have to replace that little plastic clicker in it?
Can it be losing vacuum when the wheels are turning?

Thanks for all the help, I know a of y'all go to Warns, but I gotta admit, I do like the ability to just lock in on the snowy roads out my way. Some places drift over, but most stay clean.

Dig

 

Put a set of lock out hub's on it and plug the the vacuum line's and than you now what you have. After some many miles Ford's hub's are junk!!

 

The locking hubs are interchangeable. Swap them from side to side to prove if it is the hub or not.

It is possible that the wheel bearing seal is causing a vac leak while truck is in motion.

From Guzzle's Needle Bearing Lube LINK
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</TD></TR><TR><TD align=middle colSpan=2>Here is a quote about vacuum seal leaks in the ESOF SuperDuty hubs
from Grampy_Jim - The Diesel Stop on the subject of vacuum leaks:

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Grampy_Jim:

"The 'lock' signal to the hubs is weak... about 12 inches Hg. The unlock signal is very weak.... about 6 inches. It doesn't take much of a leak to create problems. Unless there is some kind of concern with the PVH solenoid, the hubs cannot 'self-engage'.

Many owners labour under the notion that the yellow O-ring is the only seal to worry about..... This seal, unless damaged in installation, is rare to fail... Once it is installed, it doesn't move.

The dark coloured O-ring on the locking hub assembly never seems to give concerns, even after removing and reinstalling the hub multiple times.

The usual culprit is the large knuckle seal (the expensive one). What will fool the yellow O-ring crowd is that disturbing the large knuckle seal can allow it to perform well in a recheck of the system - but that wont last long. A worn out seal is a worn out seal....
(EDIT: knuckle seal - Ford part number F81Z-3254-CB; dust seal - Ford part number F81Z-1S175-HCA)

The insidious part of a leaking knuckle seal.... If it allows air to enter the knuckle cavity, it can also allow moisture and dirt to enter the knuckle cavity. This contamination can damage the spindle bearing and destroy the stub axle.

I have seen them so bad that mud has plugged off the vacuum lines.

Those that service their ESOF hubs regularly never have any nasty surprises..... those that drive from one breakdown to the next, hate the system."
--------------------
Ford Master Tech - Diesel Certified.





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Hey Whitetail,

One thing I dont understand, I know a lot of people go to different hubs. But, if I am going to get out and lock em in, why doesn't the Ford ones work, and just use the lock ****? I can override my autos, and have been doing it all winter.

And, I guess that seal would point to a leak while rolling. I figured on going in. Thanks.