You don't "have" to, but you'll still be applying vacuum to the hub area. While this in itself won't cause any problem, it will still be putting pressure on the hub seal which can eventually wear out and lead to dirt, water and othre crap getting into your rather expensive unit bearings.
Hey guys, Rather than cap the line and leave it dangling at the wheel, how about capping it at the source. I assume the vaccum line comes off the intake on my 5.4....yes? Does anybody know exactly which or where this line is under the engine compartment. I assume if this line isn't plug correctly, you would have a vaccum leak on the motor, which could cause a rough idle, or perhaps other problems. I would also agree, that any open lines at the wheel should also be capped, to keep dirt & water out of the hub. I plan on changing my auto hubs out for manual hubs too. I haven't had a chance to look at mine, I just got the truck running yesterday. I believe there is a retaining ring; somewhere, that must be removed before you can remove the hub. I just haven't located it yet. Is this ring under the auto/manual ****, or do I have to remove the wheel to locate it. My truck has been up north, so everthing is corroded with surface rust, which makes finding anything difficult. Can anybody direct me to exactgly where I can find this retaining ring? I suspect many of these auto-locking hubs fail to completely disengage. This could lead to bearing / axle failure, plus excessive fuel consumption. My F250 doesn't need any help drinking fuel.
Look at the write up I did, it's in the first post in this thread. It has pics and details of the process. The retaining ring has two tabs that stick out and they'll hit you in the face as soon as you look in the hub area.
And YES, you can cap it at the source. There is a vacuum solenoid, not on the intake. Just trace the lines up and you'll run into it. Some guys pull the lines and cap it there. Either way works.
Bronco70 -- YES...those are the correct MM hubs for your application! I wasn't sure myself...because Summit lists them for the F350-F450 only, but went to the MM website and confirmed. They are for the D50 and D60 in the F250.
I have a 2002 F 350 with the auto manual hubs. I have developed two problems with them. One the vaccum doesn't work anymore. I put a gage on the wheel side of the line, and pumped the heck out of it, and did not get any vaccum. The dealer ship tells me, the hub seal is probably leaking, and they are $60.00 each to buy, and 3 hrs. at a shop rate of $110.00 / hr. to install, parts extra. They say I need Special tools to remove hub nut, and another tool for proper installation of the seal.
So to make my problem even worse, I can't turn the hubs to the lock position either. I did manage to get one side to go, but the other still won't move. The hubs are not serviceable. Plastic inside and aluminum housing. duh.... When I got the one to move you should have seen the road dust that came out around the edges. Ford wants $500.00 each for a new hub. and they have lots in stock at the dealership. ..... tells me they know there's a problem with them.
I would like to go manual warn hubs. But I also liked the auto hubs for winter time. But I am also wondering about the loss of vac. Should I replace the seals and repack the bearings also? The truck has 89000Km on it.