Ford Power Stroke Nation banner

1 - 20 of 23 Posts

·
Registered
Joined
·
204 Posts
Discussion Starter #1
My fuel mileage was crap and I read a thread about making sure the front hubs were not locked in.....mine were set to manual.

Set them to auto, fuel mileage per gallon went WAY up (yay) but now it will not lock in when set to auto....so how do these things work?

My brain says that if setting them to manual lock, and then flipping the switch to 4x4 on the dash makes it all work, that it has to be the hubs...but I keep reading about this vacuum issue.

If I put it in "auto" and flip the ESOF to 4x4 High, the light comes on. I get no 4x4 and I can turn both front axles by hand.

Anyone shed some light into how this system actually locks in the hubs when set to "Auto"? Can you also shed light on what to check, and where it is located in a case like mine?

Thanks
 

·
Registered
Joined
·
3,600 Posts
When set to auto did you roll forward in 4x4, then check to see if the lock up? FWIW, I broke the auto hubs in my dad's 04 fairly easily. They wouldn't engage under auto, but worked fine when manually locked...
 

·
Registered
Joined
·
204 Posts
Discussion Starter #4
What year truck do you have?
Sorry it is a 2006.

Yes, I rolled forward.

Here is what I just tested; not being sure if an '06 has all the vacuum crap.

1) A/C mode selector puts air to the proper place.
2) Turning ESOF to 4x4 lights up light on dash, and on switch
3) Turning ESOF to 4x4 low lights up light on dash, and on switch, and the truck is for sure in low range
4) In both 2 & 3 above, the front axles free spin by hand, the front drive shaft is locked and when I try and tun it, the axles move too.

This again leads me to the hubs. Are these serviceable?

Let me add, there is what looks to be a vacuum line going to each knuckle...I have no vacuum going there and if I use my vacuum pump, I cannot apply vacuum to either side. Again, I have no idea if these are actually vacuum lines or vents.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #5
Ok, the Auto Hub Lock Vacuum Control Solenoid is working just fine.

What I now know is 2 fold.

1) Somewhere in the Auto Hub Lock Vacuum Tubes is a leak as I have zero applied vacuum (using pump).

2) If I apply vacuum at the hub end, I also get no applied vacuum; on either hub.

While I can say that #1 is wrong, and when it is not 34 degrees and raining, I will trace it more, I have no idea if #2 is normal, or what would even be serviceable there.

I would love to have access to another truck right now to see what it does for #2.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #6
I pulled both hubs off this AM and damn if I can see anything wrong. It is very clean in there and all the parts move freely. In fact, one would swear that, from the inside, these things look new.

I am still trying to find how the vacuum pulls on these from the knuckle as I did not see any hole on the inside.

I am going to a buddies house tonight to use his compressor, with low pressure, to blow into the tubes to see if I can find a leak.

Will post more later (when I know more)
 

·
Registered
Joined
·
204 Posts
Discussion Starter #7
Ok, here is where I now stand.

I have vacuum all the way to each knuckle, and all the electronics work as they should.

The issue is with however the vacuum is applied at the knuckle to the hub.

Like I had found in earlier testing, if I pull the hose off, at the knuckle, and apply vacuum, I cannot draw even 1" of vacuum.

All I need to piece together now is how the vacuum is sealed inside the knuckle/hub and in absence of said vacuum, what is the failed part......

Any takers?
 

·
Registered
Joined
·
3,600 Posts
I wish I would help you more but I really have no clue how auto hubs workLOL Hopefully someone who knows will chime in and give you some valuable info.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #9
I did find a nice how-to for the OBS trucks, I am sure that this stupid system is in effect today...there are a few possibilities on what it could be, I just need to decide if I want to tear it all down and find out which one it is.

1) Yellow seal (cheap)
2) Knuckle seal (not so cheap)
3) Hub itself (not so cheap)

Or I could always say screw it and toss on a set of aftermarket manual hubs and just know that I have to get out and set them to lock before hitting the ESOF switch......

One thing is for sure, I have learned a whole lot about this system over the past 24 hours, and can honestly say it is a horrible design.....why they had to way complicate something so simple is beyond me.
 

·
Registered
Joined
·
3,600 Posts
I did find a nice how-to for the OBS trucks, I am sure that this stupid system is in effect today...there are a few possibilities on what it could be, I just need to decide if I want to tear it all down and find out which one it is.

1) Yellow seal (cheap)
2) Knuckle seal (not so cheap)
3) Hub itself (not so cheap)

Or I could always say screw it and toss on a set of aftermarket manual hubs and just know that I have to get out and set them to lock before hitting the ESOF switch......

One thing is for sure, I have learned a whole lot about this system over the past 24 hours, and can honestly say it is a horrible design.....why they had to way complicate something so simple is beyond me.
Well if your auto hubs basically are manual hubs now, just use them as such instead of buying manual hubs.
 

·
Registered
Joined
·
204 Posts
Discussion Starter #12
I have a buddy who is going to let me try his hubs...if they work, then at least I know....but there is no way in the world i am paying Ford $233 each for hubs.

I have a sneaky feeling that someone swapped hubs on me before I purchased it. I find it unlikely that a 2006 with only 25K miles on it, had any sort of failure in the system....it is way too soon, even for a Ford :poke:
 

·
Registered
Joined
·
3,600 Posts
I have a buddy who is going to let me try his hubs...if they work, then at least I know....but there is no way in the world i am paying Ford $233 each for hubs.

I have a sneaky feeling that someone swapped hubs on me before I purchased it. I find it unlikely that a 2006 with only 25K miles on it, had any sort of failure in the system....it is way too soon, even for a Ford :poke:
You would be surprised what the previous owner may have done. I couldn't believe how easily I broke the hubs in the 04. I was in reverse in 4x4 low, taped the gas and SNAP, lost 4wd...
 

·
Registered
Joined
·
204 Posts
Discussion Starter #14
I hear ya, I cannot believe this system is so complex and so fragile....and how much Ford charges for parts.

I have only had my truck for 2 months, and I love it to death, but man is Ford proud of its parts or what?
 

·
Registered
Joined
·
987 Posts
It's only got 25k miles? Is that something that might still be covered under warranty? I've never owned a Powerstroke under warranty so I don't know what the 100k warranty even involves.
 

·
Registered
Joined
·
486 Posts
It could also be one of your seals. Just went through a ball joint job on my rig and the yellow seal you talked about above will make what you described happen. In auto the hubs lock with vacuum. In manual they rely on just your 4x4 kicking in since your hubs are already locked. A small leak will make it not lock in auto. Could be a pinched or rolled o-ring. So far powerstrokeshop.com has been fairly priced for me for parts. I believe our setups are the same. Mine is an 02. Check these write ups out...


Welcome to guzzle's Ford PSD Web Pages


Just my .02 cents!!! Good luck!!!
 

·
Registered
Joined
·
204 Posts
Discussion Starter #18
^

Yea, I am going to try my buddies hubs to rule them in or out...after that, until I need other work in there, it can live as is....not like I use 4wd every day.
 

·
Registered
Joined
·
886 Posts
There are two seals that can (and usually do) cause this problem. One is an o-ring on the hub itself and the other is installed in the knuckle behind the wheel bearing. I have changed a few to fix the exact problem that you have. Usually if the lock out goes bad it doesn`t work in the manual setting either.
 

·
Registered
Joined
·
987 Posts
derail

This is why I'm looking for a non ESOF 4WD!

/derail

Good luck with the temporary swap, hopefully it's the cheapest of the three 'could be wrong' options!
 
1 - 20 of 23 Posts
Top