So I have possibly a few issues & I realize I haven't diagnosed everything yet. I have a 1999 F350, and when I purchased the truck 2 years ago I never attempted the 4 wheel drive (I live on Florida.....it's flat.....but ok that's my fault for not testing it). So anyways I slowly started to lose the AC from blowing out any climate control setting besides defrost. After realizing my hub vacuum lines were completely shot I replaced them with some new lines & hose clamps, still nothing. I bypassed the resevoir & the climate control works so I have yet to install the new resevoir but once I do hopefully that fixes the issue.
Now onto the next issue.....my front hubs writing is worn away so I don't know what it's set on but I cannot for the life of me rotate the hubs to the other position. So let's just assume those are shot & need replaced (right?). Next, i was contemplating replacing them with manual warn locks, but it would be nice to use the cabin switch on the fly, so if I replace them with the OEM hubs, is there anything else in that system I should be looking at? Apparently there is this 'pulse hub locking solenoid' that I took out to investigate my climate control situation which has a sponge type filter that fell apart on me & I made a make-shift filter & replaced but obviously haven't attempted yet because of my resevior. Another thing I noticed was when I'm under the truck looking on the back side of the 'knuckle' there is a 'dust cap' that is kind of flopping around.....what would that indicate? Does the hub vacuum line thread into the knuckle & pull a vacuum thru the knuckle into the hubs? I'm just curious if I replace the front hubs with new OEM hubs, am I just wasting time & money because I have another issue where it's going to fail again soon there after....?
Just trying to understand tho system & how much work or how far do I have to go to get this things back to operating condition.
Thanks everyone & sorry for the lengthy questions.

 

go to Guzzles website & look up esof hub service/repair

 

Your ESOF hubs need a bit of maintenance, and if used occasionally will continue working fine. Leave them be too long and they stop working. In addition to the rotted out vac lines there are o rings inside that will stop sealing when their lube goes away. It is very possible your hubs will be fine once removed and rebuilt. Here's Guzzle's page to service the hubs. Many including myself switch to manual hubs simply to have a bullet proof system. Down side is you have to stop and get out, natch. If I used mine more often I'd definitely stick with the ESOF.

That loose dust cap flopping on the back of the knuckle is common and not really an issue. Mine are doing that. The actual seal is further in. IIRC there is an updated steel part that replaces the plastic one, and it stays put.

 

I personally went with manual warn hubs. I don't mind having to get out to lock them in knowing I have the peace of mind of a decent hub. I don't like the factory hubs at all, to me they are too cheap and plastic,.....keep in mind if your in a situation that you really need 4wd and one of your hubs lets go you are now stuck in 2wd. I've personally seen this happen before and seen people spend the night in freezing weather in the middle of nowhere because our trucks are worthless in 2wd when you are in a 4wd only situation.

Just my opinion though. A lot of people like the ease of the auto hubs and will probably never be in that spot, (or at least somewhere they can be towed).

 

Turning your hubs counter clockwise is AUTO position. Not being able to turn your hubs manually indicates they need servicing. Follow the link posted above.

 

Here's a couple of posts that I used when working through my (more than one) ESOF issue...

Post #19 --> https://www.ford-trucks.com/forums/6...-number-2.html

Post #6 --> https://www.ford-trucks.com/forums/8...cume-leak.html

Good luck. I gave up after the 3rd failure and 2nd vacuum pump and capped the hubs off at the solenoid.