Hubs don't work
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Tuned
Joined: Apr 2003
Posts: 282
Likes: 0
From: Va Beach Va
Hubs don't work
I have an 03 SD 6.0. My hubs don't work in the auto mode. I can lock them in and they work fine but don't work with the switch. I pulled one line off the vacuum pump on the passenger's side inner fender and hear vacuum. Any ideas on what the problem is? I think it is both hubs so I was guessing vacuum problem.
Postmaster
Joined: Jan 2005
Posts: 2,753
Likes: 3
From: Phenix City, AL
It may not be both hubs. If one is toast and not locking, you will get no power to the other wheel. That's the problem with an open differential.
Get a vacuum gauge, and check the pulse when you activate the 4WD. You should get a 20 second pulse when you turn it on, then a 5 second pulse when you disengage.
If you are getting a good pulse, pull the hubs and soak them in ATF for a few hours. Clean them up good, including the splines. Apply a LIGHT (say again, LIGHT) coat of grease to the splines and re-install.
If this doesn't work, the hub seal may be toast and it's time to replace.
Get a vacuum gauge, and check the pulse when you activate the 4WD. You should get a 20 second pulse when you turn it on, then a 5 second pulse when you disengage.
If you are getting a good pulse, pull the hubs and soak them in ATF for a few hours. Clean them up good, including the splines. Apply a LIGHT (say again, LIGHT) coat of grease to the splines and re-install.
If this doesn't work, the hub seal may be toast and it's time to replace.
Posting Guru
Joined: Nov 2003
Posts: 1,071
Likes: 1
From: Concord, New Hampshire
if you really want to check them, get out a vacum pump with a guage. 20" for like 20 seconds should lock them, 7" for about 10 to 15sec. should unlock them. the hub, (line on the knuckle. with hub installed) needs to hold 20" for 5min. with no more than a .5" drop. chack both sides independently of course. and then you can put a guage on one side, with the other side connected and see if the truck is applying vac. like i mentioned above.
if the nuckle dosen hold, it could be the locking hub o-ring, the yellow hub o-ring, or the gray seal that seals the nuckle and axle shaft.
good luck
if the nuckle dosen hold, it could be the locking hub o-ring, the yellow hub o-ring, or the gray seal that seals the nuckle and axle shaft.
good luck
