I have an 04 f350 d 4x4 with the esof. Pass side hub is leaking air, not holding vacuum when the 4wd switch is put in 4wd. I know this because I tested it with a vacuum pump. My hubs have a auto and lock setting. When I turn the hubs to lock is that manually putting the hubs in 4wd ? I tried that and it didn't feel like the truck was in 4wd. And the 4wd switch in the dash was switched to 4wd

 

Yes - if you’ve manually locked the hubs and have engaged the 4wd in the cab, then you should have 4wd. That’s why you have the option to manually lock them, in case the vacuum system dies.

 

common pproblem on 4H, 4L selector is the selector **** itself.

it develops cracks on the plastic that results in the **** just spinning.

so make sure the indicator light changes correctly as you select. if not, check the plastic ****.

 

Until I can find out why I’m not getting vacuum to my hubs I’ve left my auto-locking hubs in lock.

I’ve been told it doesn’t really hurt anything.

When I turn the switch on the dash is when it actually goes into 4wd.

 

 

Stop on a dirt road. Floor it. If your rears spin and it takes a few to get moving, you're not in 4H. If you immediately launch forward, you're in 4H.

 

With truck NOT running, Lock the hub, then try to turn the shaft, by hand

this will tell you if it’s engaging or not

 

 

 

The **** is fine. it turns the switch. Turns to 4h 4l and off. I can here the motor turning on/off

 

I tried that on snow. Didn't feel like it was in 4wd at all. That's the reason of my original post.

 

Put it in 4wd and see if you can turn the front driveshaft by hand. If you can't, jack the front wheels/wheel up and try again, if you still can't it's likely the lock out hub is broken.

If the front driveshaft turns with wheels jacked up it is the transfer case.

 

You don't even have to jack it up. Put it in 2wd and lock both hubs then try to turn the front driveshaft by hand it should be locked if not then one of your hubs isn't engaging. Then if both hubs are working unlock the hubs and shift into 4x4 and try to turn the front drive shaft if it turns then the transfer case isn't engaging.