Last weekend I used my four wheel drive on my truck while getting some fire wood. The next morning when I started down the road I noticed that the four wheel drive was was still locked in, but the switch was on two wheel drive. I finally got it to pop out, and thought that maybe it was just frozen from where it was cold out. Yesterday I had to use it again so I locked the hubs in and started up that hill that required its use. I quickley noticed that the front wheels weren't turning, but the transmission was in four low like I had selected.
I finally made it up the hill, but ran into the some problem with the four drive not wanting to pop out. I finally got it to pop out after I shut the truck off and then restarted it. Later on when I got home I test it again to see how things worked. I made sure the hubs where locked and put the truck in neutral. Then I selected four wheel drive and once it did the same thing.
A few months ago I changed out the factory POS and put Warn Hubs on and it seemed to be working fine. Anyone have a clue??

 

jimbeam87 welcome to FTE!

I'm guessing you have ESOF?

if so, it sounds like the shift motor on the transfer case is becoming problematic. Pull it iff and test it. Maybe a cleaning and an some WD-40 will help, but it probably needs replacing.

 

Can you simplify it? What do you mean by pop out. Are the wheel hubs working OK? So there is no vacuum because you blocked it off?

 

Vacuum??
The transfer case locks into four wheel, but the hubs don't seem to be locking in all the way. I can tell its shift into four wheel drive because got it stuck in four wheel low and it wouldn't pop out.

A friend of mine suggested the shift motor thing, but I don't even know where its at.

Was there something else I was suppse to do when I changed them hubs out. I do remember having a ring or something left over, but I remember there being two sets of rings. They might of lock rings, but I cat really remember.

 

The stock automatic hubs use vacuum to shift the hubs into FREE and LOCK. When you installed the manual hubs you should have plugged the vacuum lines that ran to the stock automatic hubs.

The shift motor is located on the transfer case. It does the actual shifting from 2H to 4H to 4L. Most neighborhood auto part stores will have a replacement motor in stock if you need one.

 

The only line I remember seeing is the wire for the ABS sensor, but I'll check again. I had the "Locked or Automatic" type of hubs on there and the were dry as a bone.

 

Yes, the dry hubs were probably why it failed. Most folks don't pay any attention to the hubs until they need them, at which point it is too late. They should be removed, cleaned and given a very light coating of grease every 30k miles or so.

While the vacuum lines should have been plugged, this is not the reason for your truck to have problems shifting into and out of 4H or 4L. The motor on the transfer case has nothing to do with the vacuum at the hubs.

 

The other thing to remember when shifting into and out of 4 LOW is you need to put it in Neutral and step on the brake pretty hard before moving it out of low. There was a thread about this earlier in the week. It's even covered in your manual.

 

I'll give this a try and see whats happens.

Thanks JDM

 

That's probably it. Does your AC work good? What do those rings look like you left out?

 

I haven't tried the AC lately so I can't answer that one. The ring is a retaining ring is remember correctly.

I found the vacum line and stuck a screw in it for the time being to see if that worked. After that I made sure the hubs were locked and turned the drive shaft going to the front in. The axle on the drives side didn't turn, but the one on the passenger side turned. I tried it on the hill behind my house and it would climb it. I took the lock out apart to check things out and it looked fine.
Does the shift motor look like a small starter??

 

Yep small starter. Your AC won't work with any vacuum leaking.

 

I have a 07 F350 diesel, 4wd not working:

#1 have 12 inches of vacuum at the output of the pump AND the solenoid going to the front hubs, is this enough vacuum to fully engage the hubs?

#2 I found that the inside seal on the drivers side is not completely seated,( pump does not shut off) and I can't create any vacuum (manually) directly from the hub like I can the other side.

I plugged that line ( bad side - pump shuts off) , engaged 4wd thinking I would get power to the other side ( good side) , but I did not ,,,,,,I'm thinking either 12 inches of vacuum is not enough or possibly it is, and being that the front axle is not ''POSI TRACTION'' (probably not) the differential can't push power to the good side ???. Any help is greatly appreciated, especially if you know for sure the designed vacuum amount from out of the box condition? Thanks a bunch

 

I have a 07 F350 diesel, 4wd not working:

#1 have 12 inches of vacuum at the output of the pump AND the solenoid going to the front hubs, is this enough vacuum to fully engage the hubs?

#2 I found that the inside seal on the drivers side is not completely seated,( pump does not shut off) and I can't create any vacuum (manually) directly from the hub like I can the other side.

I plugged that line ( bad side - pump shuts off) , engaged 4wd thinking I would get power to the other side ( good side) , but I did not ,,,,,,I'm thinking either 12 inches of vacuum is not enough or possibly it is, and being that the front axle is not ''POSI TRACTION'' (probably not) the differential can't push power to the good side ???. Any help is greatly appreciated, especially if you know for sure the designed vacuum amount from out of the box condition? Thanks a bunch

 

I have an '08 SD with ESOF. Lately, when I am in sand, my truck wants to get easily stuck.... never used to do that. I am usually able to get out, but have had some very close calls lately. It is shifting into 4WD-High and 4WD-Low but it just seems that the truck sinks instead of digging in. Once it does get traction (at 2-3 MPH) I get a severe bumping/hopping from the rear. I have recently been deflating rear tires down to 30lbs, but that doesn't seem to change the problem (I usually keep 60 lbs in) Tires and Rims are stock Ford 20". I am not an off-roader, this happens at the beach in 10"-12" of fine,dry sand in Pismo Beach near the shore, not in the dunes.

Anyone have a similar experience ? Thanks.