Just thought I'd post a little fix today I figured out. Here's the situation... 2004 F350 with 4WD stock auto locking hubs. I engaged them when the snow hit bad last week and they were stuck on. Since, the weather has warmed up, and I've tried moving the switch back and forth several times to turn on and off 4wd, but they're still stuck. I also tried manually locking and unlocking them at the wheel by turning the hub. Still locked. So I decided to look for a vacuum leak. But the only vacuum gauge I have is on my little Mighty-Vac tool that I never use. Here's the fix:
I get the mighty vac out and decide the first thing I should check should be if the hub seals are actually working and can hold a vacuum. (1 in a 100 chance right? Those things always go bad) I just hook a hose to the might-vac and then to the nipple on the back of the knuckle, and surprise surprise, the seals are actually holding! I'm shocked! So I think to myself, what if I just imitate the vacuum pump? Can I move the hub lock? So I pump it up to about 15 Lbs of vacuum. Hold it there for 30 seconds or so. Then release the pressure. (As I do, I can hear things moving in the hub lock) After the pressure hits 0, I pump it back up to around 6 lbs of vacuum, hold it for 30 seconds, and then release. And presto! I can turn the axle by rotating the U-Joint with a bar. I Then do the same on my passenger side and it works as well! Just to press my luck I manually rotate the hub lock, test the axle and yes it locks. Then manually unlock it, and it comes free!
So the bad news is I guess I have a bad vacuum line or solenoid. The GREAT news is that those darn expensive hub seals are okay and I didn't have to dissemble anything. I'll go chasing down the vacuum problem when the weather is nicer. For now I'm just stoked that I can turn corners without the wheels chirping.
So, if you have hubs that are locked, and their seals still work, maybe this can help you get them unlocked. Good luck. And thanks to this gentleman's video for demonstrating the vacuum pattern that is used to work these hub locks.
I get the mighty vac out and decide the first thing I should check should be if the hub seals are actually working and can hold a vacuum. (1 in a 100 chance right? Those things always go bad) I just hook a hose to the might-vac and then to the nipple on the back of the knuckle, and surprise surprise, the seals are actually holding! I'm shocked! So I think to myself, what if I just imitate the vacuum pump? Can I move the hub lock? So I pump it up to about 15 Lbs of vacuum. Hold it there for 30 seconds or so. Then release the pressure. (As I do, I can hear things moving in the hub lock) After the pressure hits 0, I pump it back up to around 6 lbs of vacuum, hold it for 30 seconds, and then release. And presto! I can turn the axle by rotating the U-Joint with a bar. I Then do the same on my passenger side and it works as well! Just to press my luck I manually rotate the hub lock, test the axle and yes it locks. Then manually unlock it, and it comes free!
So the bad news is I guess I have a bad vacuum line or solenoid. The GREAT news is that those darn expensive hub seals are okay and I didn't have to dissemble anything. I'll go chasing down the vacuum problem when the weather is nicer. For now I'm just stoked that I can turn corners without the wheels chirping.
So, if you have hubs that are locked, and their seals still work, maybe this can help you get them unlocked. Good luck. And thanks to this gentleman's video for demonstrating the vacuum pattern that is used to work these hub locks.
