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auto hub problem

8K views 8 replies 6 participants last post by  02 CCSB 
#1 ·
I got a problem with my auto locking hubs. I've cleaned them and greased. Everyting internally looks ok, no noticable wear or tear on them.

Problem is that they lock and unlock on the bench just fine. But when I put them on the truck and switch from auto to lock, then back to auto they do not unlock (all while turning the wheel hub back and forth). All of this was done with the truck on stands and not running. the only way I could get them to unlock in auto position was to hit the hubs with a soft face hammer. then they unlocked but would lock up again when switched from auto to lock to auto. Its like thy are binding/stuck when on the truck. What confuses me is that when I try them off the truck they lock/unlock fine.

Anyone got any suggestions. I would like to stay with the ford hubs as my aftermarket wheels have closed hub caps with no access to hubs with the wheels on. Winter is coming and I need this fixed. Dont really want to spend the money on new hubs if i dont have to.

Thanks in advance, Robert
 
#2 ·
Spend the money on new hubs.

The ESOF system sends a signal to lock and a different signal to unlock the hubs. If it ain't working right unlocking can be just as undependable as locking. The only good thing about the Ford hubs is that you can manually lock them in.

I've had to tow a trailer home with a hub locked in because I couldn't get it to unlock. Sucky.
 
#3 ·
What do you mean signal? They are vacuum controlled. Is that what you are meaning by that? Sorry I read it as more like a electronic signal.


It works much like a clicker pen does. It give a vacuum for about 10-15 seconds to allow them to engage 4x4 and then a short vacuum pulse a bit less powerful to unlock them. If you pull your hubs out and stick your hand inside while they are in auto or you work the mechanism.

To save me time writing it out I copied this over from another site as it may help you diagnosing your issue.

The hubs work on a pulse not a constant vacuum. The easiest way to describe it is like a clicker ink pen. The vacuum pulse is sent to the hub for about 15 seconds then stops. In that time the hubs should click in and be locked. When you turn the 4wd off it sends a shorter and less powerful vacuum pulse to the hubs and clicks them again to unlock them.

If your hubs don't turn from from auto to locked you will need to take them off and clean and lube them. Pull them off and soak them in trans mission fluid overnight. Clean the excess fluid off them the next day and work them between auto and locked until they move freely. After you reinstall them you will need to turn them back and forth every month or two to keep them working freely. There are also instructions on how to take them completely apart and clean and lube them. Sometimes you need to do this if you have sucked water into them. Below are my instructions on testing your vacuum system to determine where the leak is. Start by checking the vacuum lines at the hubs. They turn "crunchy" very quickly there.

It should take no more than 2 minutes for the vacuum pump to cut off from an empty tank.

ESOF 4WD Troubleshooting

It is easier to troubleshoot the system if you have a “Mityvac” vacuum pump. Turn the ignition switch to run (you don’t have to start the truck) and the air controls to vent and the fan control to low. If the truck’s vacuum pump comes on wait until it stops running before each test (open the hood and you’ll hear it better). First you need to remove both lines (left and right vacuum lines) from the hubs. Plug the passenger’s side line and attach the vacuum pump to the driver’s side line. Switch the dash controller to 4WD high. The vacuum gauge should go to 10 in.-Hg. or higher. (It should hold the vacuum at 10 in.-Hg. or higher for 45 seconds on engage and 15 seconds on disengage.) Repeat the test plugging the drivers side and testing the passengers side. If you have the right amount of steady vacuum the problem is probably in the hubs. If you do not have the right amount of vacuum or it is bleeding off, plug the lines back on the hubs and go to the next step. Second remove the vacuum lines from the PVH (Pulse Vacuum Hublock). This is the solenoid located on the passenger side fender well behind the battery and in front of the vacuum pump. Plug the vacuum tester into the lower hose and wait for the vacuum pump to build back up and shut off. The vacuum gauge should read and hold steady at 10 in.-Hg. or more. If it does, the vacuum reservoir should be fine and not leaking, so go on to the next step. Third, plug the bottom line back to the bottom of the solenoid and hook the vacuum gauge to the top barb of the solenoid (not the vacuum line but to the solenoid itself). Try switching between 2WD and 4WD again. The gauge should read 10 in.-Hg. for 45 seconds on engage and for 15 seconds on disengage. If it doesn’t it is probably the solenoid (PVH) on the fender that needs replacing. This was my problem so this was as far as I have gone. If all these things check out, THEN you need to go to the hubs and check them for leaks with the vacuum tester. Most of the time it’s a fuse, PVH, vacuum line or vacuum pump and not the hubs.
 
#4 ·
If you end up finding it is your hubs then look on ebay for used ones as the will cost you less than half that of new.
 
#7 ·
Didn't think about that.
 
#8 ·
Coming from first hand experience i can tell you if you can spare the investment the dynatrac kit is awesome. Not being able to go offroad without a buddys truck near by because you dont know if your hubs will lock in or unlock whenever they feel like it sucks. I was stranded 30min past the pavements end due to my hubs unlocking when i was spinning out. There was a wet root in front of my tire that stuck out of the ground no more than 6" but halted my 01 F350 w/37's for over an hour untill my buddy could come get me out.(with his 92 sidekick) lol
 
#9 ·
Might also check the stub shaft for excessive movement indicating a bad spindle bearing. If the stub shaft is allowed to drop on the inboard end it will put the hub in a bind causing it to hang. Usually when this happens it is hard to slide the hub into the wheel bearing assembly also due to the misalignment. Good luck.
 
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