F250 4x4 engagement issue

[Sticks&Strings]

So last night I went to leave my property and it was wet. I backed up and when I started to go forward my tires slipped. I put it in 4h not wanting to leave big ruts, nothing. Reverse, forward, nothing. 4L same deal. I got out and manually locked the hubs and it worked and I got unstuck. What is the issue/repair.

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[BURTONboy]

Its a vacuum issue and ive got it happening right now as well. I have not taken the time to try and figure out what the fix is yet though.


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[Lsube0555]

It is a vacuum issue, it could be as simple as the line going to the hub came undone or the valve under the hood or it could be the seal in the hub that is not holding and leaking causing it not to engage. Just a pain to have to get out and lock in but that’s what I do when I get to where I’m going then unlock once back on the road.

[RWB]

Yep vacuum hose leak. Mine will switch to defrost when I engage the 4wd. Its been like this for years I just manually engage the hubs.

[Wfalls]

Yes I just had mine fixed this week . Vacuum leak

[Old Bald Guy]

Yep vacuum hose leak. Mine will switch to defrost when I engage the 4wd. Its been like this for years I just manually engage the hubs.

Same exact thing with my 03. If I’m gonna be in mud a while I lock them manually. If I just have to go through a certain muddy spot I can get by with just kicking it in 4wd and make it through before the vacuum drops enough for the hubs to unlock.

[kmitchl]

Yep. Vacuum leak.

[79F250]

Like others have said you either have a vacuum leak or this seal is bad. (Left picture)
Special tool shown to install seal (right picture) there’s also a chance if your hub bearing is bad that could cause it to loose vacuum not as likely but possible

[Rubberdown]

Didn’t see what year but check next to the vacuum pump under the hood. There one line that goes to the defroster and one that goes to the turbo and one that goes to the hubs. Mine was broken the other day there and it was an easy fix. Here’s to hoping.

[toledo]

Ford is slacking. Seems like a lot of money to be having to get out and lock hubs.

[68rustbucket]

My ‘03 did that. Opened the hood and found a squirrel nest the size of a basketball, built around the vacuum pump. The rodent had chewed the lines.

[Low Fence]

Ford is slacking. Seems like a lot of money to be having to get out and lock hubs.

They are lacking so bad they have the best 4wd system made in a full size truck. Mine just started the last time I tried it. I’ll gladly get out vs snap another GM front end in half