Bad Hubs??

[DEESLVRGN]

So last weekend, my vacuum pump started running constantly, sometimes while riding along I can hear some god awful noise from the "driver side wheel area".

I have the manual lock hubs and the "circular"swith to go from 2WD 4HI and 4LOW, is that ESOF or do I have to get out and manually lock to put into 4WD?

Second, can I fix just the vacuum leak or have to change the whole $400 hub assembly?

Thanks!!

[DEESLVRGN]

[NYC F-350]

If the pump is running, there is something screwy somewhere. The pump should only run when the switch is moved to a 4 wheel drive position.
Yes, that is the ESOF system on your truck. (Electronic Shift On the Fly)
When you flip the switch, the vac pump should come on and the selector on the hub should move to the "lock" position. I don't think it is a constant vac, but pulsed..IIRC

The knuckle is sealed (2 seals, one on the axle, the other is on the bearing). Theres a rubber vac line on a nipple on the inside of the knuckle.

[DEESLVRGN]

there is no way that little pump is moving those manual hubs..... i need pliers to move it manually

[NYC F-350]

You should remove them. Three torx 27 bolts hold them in. Once those are removed, tap around the outside of the hub with your fist until they pop out a little. You can use a thin reg screwdriver to gently coax them out.
Clean them up, look for metal shavings and needle bearings inside the hub on the truck. If you see that, you need new hubs (I did this this past weekend and found all kinds of scary things). If you get nothing but grease out, thank the Powerstroke gods for smiling upon you and grease the heck out of the hubs before re-installing them. I packed it much like a wheel bearing back in the "old" days.

[DEESLVRGN]

I'll check it out this weekend, thanks

[dxusmc]

the hubs are pulse. There's a plastic disc near your hub that the vaccuum pump sends a pulse of air to rotate. If you have this then you have the hubs that are "auto-lock" instead of "lock-free". It doesn't actually turn the manual lockers, just the disc behind the hub that actuates the gears inside. If you're having a problem with the pump running, chances are its just the pump, not your hub. I'd say disconnect it for a short time and drive to see if you're getting "resistance" from that side. You don't actually need to have the pump hooked up for your 4wd to work, you'll just have to climb out of your truck with some vice grips to get it to lock. But if you're looking to replace the pump, junkyards around me sell them from 50-75 so its not horrible.

[DEESLVRGN]

I can hear the drivers side when riding around, like a really fast pulse then i can feel it kind of hit the spot, but im not in 4WD???

[NYC F-350]

Sounds as though you might be having a u-joint problem (the one on the axle).
Does feel like it grabs?
Sometimes pulls to one side, then if you fight it, it may pull a little in the other direction?
When you are going straight down the road, it can almost fell like the front of the truck "floats from side to side."

Any of that sound familiar?
Also, have you had any work done to the front end recently?

[DEESLVRGN]

Im not getting any pulling, the truck had new tie rod ends in January and an alignment. The mechanic said everything else looked pretty good underneath (doesn't mean they can't go bad) the shop is reputable for our bigger trucks because the other shops can't put em a lift hence they get all the local areas work.

The part that I feel doesnt seem like something heavy duty, more so something smaller finding its place and this all happened the same day, vacuum constantly running, and the npise from the hub and A/C only from the defrost.

When riding and I hear the noise start, if I hit a bump and stops, shortly thereafter it starts again till it finds its place but I need to be on smooth ground for a bit.