Hubs not engaging wtf.

[20046.0]

Well today went to grab a flare stack out of some slick mud and got stuck.

I replaced my axle seals about 2 months ago and I have used 4x4 a few times since then.

Now my vents do not reset to defrost when I switch to 4x4.
My transfer case engages and the front driveshaft does spin.

Now where to start? Does it sound like a faulty hub? When everything was removed everything looked to be in good condition.

[E-Man]

Check your vaccum lines in the wheel well where they connect to the hubs to actuate the ESOF. The lines rot and break very easily and will cause the vent deforst issue you mentioned, as well as the hubs not engaging. $7 worth of new vaccum lines from an auto parts store should fix it. I fixed mine last week and wrapped the new lines in conduit loom to try and prevent the lines from rotting again.

[20046.0]

Originally Posted by E-Man

Check your vaccum lines in the wheel well where they connect to the hubs to actuate the ESOF. The lines rot and break very easily and will cause the vent deforst issue you mentioned, as well as the hubs not engaging. $7 worth of new vaccum lines from an auto parts store should fix it. I fixed mine last week and wrapped the new lines in conduit loom to try and prevent the lines from rotting again.

Vac pump runs and turns off. When I disconnect the line to the pump and the resivor the pump turns on again trying to create vaccum. So the pump is alright and the lines from the pump to resvoir seem fine.

Now say if only one of my vac lines to my hub is damaged will it cause no 4x4 all together? Or should one wheel lock? Thanks

[jesilvas]

If they are vacuum controlled hubs, they will not lock if you have a vacuum leak.
If you try to auto lock them and your vents go to defrost, you have a vacuum leak to the hubs.

[20046.0]

Originally Posted by jesilvas

If they are vacuum controlled hubs, they will not lock if you have a vacuum leak.
If you try to auto lock them and your vents go to defrost, you have a vacuum leak to the hubs.

I know this, I had a issue with my vac pump. Replaced it and fixed my problem of no 4x4. This was a year or so ago.

The funny thing is the leak comes and goes? It will defrost then go back to vents. Going to grab a vaccum tester and unplug the left hub and plug the right and test each accordingly?

[jesilvas]

Probably best to isolate each hub, and any line you can think of.

[20046.0]

Originally Posted by jesilvas

Probably best to isolate each hub, and any line you can think of.

Going to try that, found a good trouble shooting guide. I hope it's just the lines, don't feel like tearing into the front axle this month.

[20046.0]

I'm going to remove the vac lines from the hubs. Then just cover my finger over the hole to see if there is any vac strength at all.

How much vac does it require to lock a hub in HG's?

[E-Man]

Here's a good video that helped me. 90% of the time the issue is the vaccum line running through the wheel well to the hubs.

How To: Find and Diagnose ESOF Hub Vacuum Leaks - YouTube

How To: Find and Diagnose ESOF Hub Vacuum Leaks - YouTube

[E-Man]

Originally Posted by 20046.0

Vac pump runs and turns off. When I disconnect the line to the pump and the resivor the pump turns on again trying to create vaccum. So the pump is alright and the lines from the pump to resvoir seem fine.

Now say if only one of my vac lines to my hub is damaged will it cause no 4x4 all together? Or should one wheel lock? Thanks

Exactly what mine was doing. I could also hear the t-case engaging, but the hubs wouldn't lock.