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Really need some help here, my 2001 F250 has 4 wheel drive. The locking hubs have been frozen to where I cannot move the switch on the hub(been like this for 10 years) does this mean that my 4 wheel drive is not working. The switch on the dash works and the light on the cluster shows it in 4 wheel drive. I know this is a stupid question but I never really needed to put it in 4 wheel drive but I now live in Oregon and need it....
 

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Is the hub frozen in the AUTO or LOCK position ?

You should see a small indentation or dimple on the outside of the ring above one of the triangular arrows

In the photo, reference the upper blue hand drawn arrow and you will see the small "dimple".
 

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climb under the truck and see if you can spin the front driveshaft by hand with the transfer case in 2WD. If it spins then at least 1 of the hubs is not locking. If you cannot turn it then chances are the hubs are locked and your 4WD will work when the transfer case is shifted into 4WD. However, with the hubs locked all the time you are turning all of the front axle components all of the time, even in 2WD.
 

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The vacuum operated automatic hubs are notorious for being very hard or impossible to turn. If your hubs are in the AUTO position, they will still work fine (as long as all the vacuum seals are good). If they are in the LOCK position, they will be locked all the time.


To see if they are working, do this:
1. With the transfer case in 2WD (dash switch in 2WD), see if you can turn the front driveshaft by hand. If it spins freely, the hubs are unlocked.
2. Start the engine and shift to 4WD. Try to spin the front driveshaft by hand again. If you can't turn the driveshaft, both hubs are locked and are working properly. If you can turn the driveshaft by hand, one or both hubs are unlocked. If this is the case, it could be a leak in the vacuum system or a bad hub.


The LOCK position just allows you to manually lock the hubs in the event that you need 4WD and the vacuum control is not working. Turning the dial is not normally required.
 

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The vacuum operated automatic hubs are notorious for being very hard or impossible to turn. If your hubs are in the AUTO position, they will still work fine (as long as all the vacuum seals are good). If they are in the LOCK position, they will be locked all the time.


To see if they are working, do this:
1. With the transfer case in 2WD (dash switch in 2WD), see if you can turn the front driveshaft by hand. If it spins freely, the hubs are unlocked.
2. Start the engine and shift to 4WD. Try to spin the front driveshaft by hand again. If you can't turn the driveshaft, both hubs are locked and are working properly. If you can turn the driveshaft by hand, one or both hubs are unlocked. If this is the case, it could be a leak in the vacuum system or a bad hub.


The LOCK position just allows you to manually lock the hubs in the event that you need 4WD and the vacuum control is not working. Turning the dial is not normally required.
This is what I was getting at but just a step at a time :winking:

Great write-up.
 

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After further thought, I messed up that description a bit. For step 2, I got things backwards in my head thinking about my truck and manual hubs. If you do what I described, the driveshaft should not turn by hand in 4WD since it will be locked to the transmission and rear driveshaft via the transfer case.


If you shift to 4WD, the only way you will be able to see if the hubs are locked would be to jack the tire off the ground and try to rotate it by hand. If you turn the tire and the axle shaft going through the steering knuckle turns with it, your hub has properly locked. If the tire spins freely and the axleshaft does not turn, the hub is unlocked.
 
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