Diesel Forum - TheDieselStop.com - Reply to Topic
1999-2007 General Questions General questions related to 1999-2007 Super Duty trucks. If it doesn't fit the other categories, post it here. Gas engine discussion that pertains to all models is allowed. Specific gas engine questions should use the Gas Engines forum.

Thread: Why would both ESOF hubs stop engaging at the same time? Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the Diesel Forum - TheDieselStop.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
12-30-2013 11:26 PM
jdrake This is great! thank you all for the troubleshooting instructions (and in layman's terms too) and for merging my double post. Now, to get to work!
12-30-2013 12:25 AM
Originally Posted by jdrake View Post
I apologize if this is a repeat. I thought I posted it 2 days ago but don't see it anywhere (I'm new here).
Merged your two posts, as they both had replies.

Welcome to TheDieselStop. Looks like the guys are giving you some good advice.

12-29-2013 11:44 PM
YT90SC Think of the hublocks as click type ball point pens. Push them on with a vacuum pulse, push them off with another. The solenoid provides 15 inches of vacuum to apply and 7 inches to unapply. Any leak will stop operation of both hublocks as they are tied together. Lines, vacuum hub seal failure due to bad ball joints, wheel bearing failure, solenoid failure, hublock failure of their vacuum diaphragm, torn hublock or wheel bearing o rings, vacuum pump failure.... the list goes on. Buy a handheld vacuum pump with guage. disconnect the lines at the solenoid. Check for adequate source vacuum once the pump turns off- over 15 inches Hg. If that is fine, put the source vacuum back on the solenoid and the pump gage on the outlet of the solenoid. Check for 15 inches to apply and release in 4x4 and 7 to apply and release in 2wd. The 4x4 module can hold one on or off till a timer has elapsed, IIRC 2 minutes. If you got good readings there, you have a leak somewhere in the hublocks/bearings/lines. Remove each line at the spindle. block with a golf tee or something of the like. apply hand pump vacuum to check the integrity of the lines. Check each hub with the hand pump. Should hold 15 inches Hg with no leaks. Do this with the wheels off the ground and spin them hublocks engaged and disengaged. You will find your fault eventually.
12-29-2013 09:50 PM
Why would both ESOF hubs stop engaging at the same time?

I apologize if this is a repeat. I thought I posted it 2 days ago but don't see it anywhere (I'm new here).

My ESOF has been working fine until recently but went to use it this week and the hubs don't lock. I can manually lock them, and did, and was able to use the 4wd many times this week as my road is flooded. Seems like if it was a vacuum line leak it would only affect one side? Might it be the solenoid? How do I check? Please use few acronyms as possible as this is my first diesel (2000 F250 7.3 200K). Also, I like the auto hubs and am not a serious off-roader so want to keep them. Better fuel mileage and less wear/tear on drive train. Thanks
12-27-2013 08:42 PM
hillco The vacuum-operated thing probably failed, or your luck just ran out on the hubs in general. I think I put two of the vacuum switch things on my '99 in only about 135,000 miles. Best advice, forget the hubs are automatic and use them like manual hubs. If your heater goes nuts, pull the line to the switch thing and put a pen cap in it to block it.
12-27-2013 07:09 PM
Why would both ESOF hubs stop engaging at the same time?

Up until recently my ESOF hubs have been working fine (2000 F250 7.3 218K miles), though I don't often have occasion to use the 4wd in Ohio. Now recently they won't engage automatically. Manual engagement is fine. It would seem to me that if it was a vacuum line to the hub only one side would fail (the one with the bad line)? So maybe its the solenoid that failed? But the heater controls work fine. What should I be looking for and how do I diagnose.
Before I get too many comments, I know that most people like to put manual hubs on and toss the OEM hubs. If I were a serious off-raoder that would make sense. But I'm not. I like the convenience of having 4wd on demand without having to turn all the axles/bearings/gears 99.5% of my driving hours. Should save fuel as well as wear and tear. Bottom line, I want to keep the ESOF hubs even if I have to rebuild or replace them. Heck, they've gone 218K on the first set. If I get 200K out of another set that should do me.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

For the best viewing experience please update your browser to Google Chrome