I have a 2003 F250 SD with ESOF 4x4. my left hub has seized up and can only be turned with a wrench, but it felt like my ESOF was still working. I had to put my truck in for service and I asked them to see if they could clean and lube the hubs so that I could manually lock and unlock the left hub without using tools.

I got a call saying they did the hub maintenance, but the left hub was still unable to be turned and that they recommended the WARNs. I told them that I was under the impression that the WARNs would turn my truck from ESOF to a manual since they dont work with the factory vacuum pump. The shop assured me that these trucks dont shift into 4x4 unless the hubs are locked anyway so nothing would change. I mentioned the vacuum pump and ESOF again and they said they would put it on the lift switch it to ESOF and see what happened.

They called me back and said they stuck the truck on the lift switched it into 4x4 and nothing happened. Now, I live in the country where everyone has a 4x4 and most of them are trucks, the majority 3/4 ton or better. This is a good shop and the owner is a good friend of mine so I know he isnt trying to pull anything over on me. On the other hand I know that ESOF works if the hubs are not locked, or at least its supposed too. I also know that as of last week when I had the hubs unlocked and switched turned the **** to 4x4 I felt the truck go into 4x4.

He says he went back and looked over his Ford documentation because I had him second guessing his mechanics and he verified that the ESOF wont work unless the hubs are locked, which is why the WARNs wouldnt change anything.

Well now Im very confused, second guessing him and myself. He runs a pretty good shop and he has several ASE master techs on staff, so I know they know their stuff, but something just seems all wrong here.

Can someone please help me straighten this out?

 

Hubs are to be turned to the Auto position and then the ESOF works. Can he see the word auto on the hubs?

Could it be that your truck was already converted to manual only?

 

When you hit the switch then the vacuum pump engages the hubs, if they are working correctly.

 

My truck was not converted to manual, that I know.

DT, what should they see happen if they have the truck on a lift and use the ESOF while the hubs are in auto if all is working properly?

 

They might hear them turn and hear the transfer case engage. How about your defrost? does it come on when you flip the switch.

If it comes on then there is a leak somewhere.

 

Nope defrost doesnt come on when I flip the switch as far as I can tell...but it hasnt gotten above 30 here all winter, so Im not sure I would notice if it did since the heat is always on anyway.

I just called him back and I think I figured out what he was saying. He says that up on the lift with the truck in gear ESOF does nothing with the hubs in auto, but if he locks the hubs it works fine. So basically what it sounds like is somewhere there is an issue and my truck through mechanical problems has become a manual 4x4. However, he said he doesnt see a problem with the vacuum lines.

He also said the hubs are not serviceable, so I either have to go WARN or have new ford hubs installed if I want to be able to turn them by hand without the assistance of a wrench.

We are real short on cash right now and if I can put off buying replacement hubs for a while, I would like to do that. I know that 4x4 is working now in manual, but is it possible that my front left hub could become further damaged and not even work in manual, or is that unlikely to happen?

 

Your mechanic is not very ESOF savvy. There are 2 positions: auto and lock. when in auto, a vacuum pulse will lock or unlock the hub. When in lock, the hub is manually locked. The Warn's (or any manual hub for that matter) does not have the "auto" position. It has "unlocked" or "open" or something like that. When in lock the hub is manually locked. When in "unlocked" the hub is unlocked. The Warn's do not have the vacuum system to lock and unlock the hub. You have to buy the OEM hub for ESOF if you want it to work. EVERY OTHER HUB IS MANUAL. To reiterate, if you do not use the Ford OEM ESOF hub, you will have to get out and lock your hubs. Plus if you don't plug the lines going to your hubs, your ventilation will shift to defrost every time you go in or out of 4wd.

To clarify, your mechanic is mistaken, you do not have to have the hub locked for the 4wd to work. In "auto" your hub is normally unlocked and gets locked/unlocked from a vacuum pulse sent when you turn your 4x4 switch. If you want your ESOF to work then you MUST get OEM ESOF hubs from Ford ($$$).

 

There are a few potential problems that may be preventing your hubs from auto-locking, many of which are not expensive to fix.

To auto-lock the hub, the PVH (Pulse Vacuum Hublock) solenoid provides full vacuum to the hub for about 30-40 seconds. To unlock the hub, the PVH solenoid provides a lower vacuum pulse to the hub.

Things that can go wrong to check are....

1) Do you have vacuum at the input of the PVH solenoid. If you do not, find out why. This is unlikely, because if you don't have vacuum here, you probably also do not have vacuum to run your heater controls.

2) Do you have vacuum at the output of the PVH for 30-40 seconds after switching to 4x4. You can test this by disconnecting the output hose from the PVH and attaching a vacuum gauge. If you do not, the PVH solenoid is bad.

3) Is there a vacuum leak in the lines to the hubs, or the hubs themselves. Or are the vacuum lines plugged, preventing the vacuum from getting to the hubs. You can test this with a vacuum pump and gauge. Apply vacuum to the line going to the hubs at the PVH. If it holds, you don't have a leak. Test for vacuum at the hubs while applying vacuum to the line at the PVH. If you're getting vacuum through the lines to the hub, there aren't any plugs. If vacuum isn't holding, work your way down the lines to find where the vacuum leak is. It could be in any of the lines or the hub itself. If the hub itself isn't holding vacuum, there are 3 rubber o-rings in the hub that need replaced.

If you are getting vacuum to all the right places and there are no leaks, etc. Then the vacuum lock mechanism in the hub is damaged or stuck. Unfortunately, that part of the hub is not servicable. If this is the case you have the choce of replacing the hubs with auto-hubs from Ford, or Warn manual hubs. Many people opt for the manual hubs, you just have to get out to lock them. Many people lock them and leave them locked during conditions where they expect they may need 4WD and there is no problem with doing this.

Also, I'm assuming your transfer case is shifting properly. If your 4x4 indicator light is not coming on on the dash, then the computer will not even attempt to lock the hubs and you have a whole other set of potential problems that need to be attended to first.

 

I realized I never really answered this question. As long as you can manually lock or unlock the hubs, you can continue to use them as manual hubs. This is really not a problem, just lock them before you use 4x4 and unlock them when you don't need 4x4. However, if the hub already requires a wrench to lock/unlock, it's unlikely that it's going to get any better and may very well freeze up totally eventually, or the plastic "****" is eventually going to break. You could try soaking around the edge of the **** with penetrating oil to see if it will eventually loosen up. It certainly wouldn't hurt to try.

 

Thanks for all the help. I have tried using oil, silicone spray and neither helped at all. I would really like to get the ford replacement hubs, but they are very pricey. I have tried driving with my hubs locked without 4x4 engaged and my MPG suffers quite a bit. I was hoping to get the warns and leave them locked as a solution to loss of ESOF, but with the decrease in MPG, it doesnt seem realistic.

I may have to take it to Ford if they are the only ones that can reliably diagnose the ESOF. I know the 4x4 will engage with hubs locked and my mechanic says he doesnt see a vacuum leak.

 

then the front hubs will lock, the xfer case will engage and the front wheels will start spinning.

 

Check out this link on how to clean & lube up your ESOF hubs yourself...



ESOF_Lube



You'll want to spend some time reading through and DEFINITELY bookmark the homepage for that link - here it is for you:



Guzzle's_homepage



Guzzle also sells the o-rings needed for many repairs for a VERY fair price and has STELLAR service as well - you'll find a link to it on his pages as well

 

No need to go to ford,read BRIAN42's post.

Everything is working correctly on your truck.(except the vacuum hubs)

You stated that 4wd worked when you switched the ESOF,and had the hubs "locked".Exactly how they are supposed to work!

Now,if you select "auto" on the hubs and do not have 4x4,most likely a hub problem,(kinda confirmed by your original post).

Only 2 options if you want ESOF to work in auto(unlocking / locking hubs),you must buy the ford hubs.

If you can live with getting out of your truck to "lock in and unlock"your hubs,then the warn hub is an excellent option.

Hope this helps.

 

Way to go Navy! I couldn't have said this any better.

The hubs are pretty straight forward. If the hubs aren't locking when AUTO is selected, then either the hub seal needs serviced or you have a vacuum leak on the hub side. They aren't complex at all to service/replace the big yellow seal. Les

 

Your front wheels have to be moving for the ESOF hubs to actually lock in. The vacuum might be telling it to lock but there has to be a little movement for the hubs to slide into the "locked" position.

I doubt the mechanic tried that.