Hubs. Again.

[tek9tim]

I know this is a problem of me not being able to use proper search terms or have the patience to sift through a million search results to find what I need, and not a lack of this being talked about before. So bear with me...

My hub(s) aren't grabbing in the auto setting anymore. Still no problem with them in lock, but it's getting to the time of year when I only need 4x4 now and again, and usually only grab it when I actually need it and am almost stuck, so it kinda sucks to switch to 4x4 and still be in 4x2.

So my main question... how long do I have before they stop grabbing in lock? I hear reference to these being vacuum actuated. Are they? If so, is this likely a failure of that system, and what are the typical weak points?

Thanks!

[Jarrod B]

find the vac leak and repair. or just keep em manually locked. or lock em before hand in case you need em.

[dieselcrawler]

I do not know from personal experiance, but my understanding is there is a seal in the knuckle that can cause problems as well... but the vaccum lines going to the hubs from the vac pump are the most common problem from what I've read here... the line from the vac pump dry rotted on my yellow truck, symptom is defrost only... it was cracked close to the vac pump, I cut the line back an inch, stuck it back on the pump, used a small zip tie as a hose clamp, and it's worked fine since last fall...