First time in the snow this season. I selected 4WD when driving down my block in the snow and it worked great. When i hit the wet pavement on the highway I switched the selector back to 2WD. There was an unusual resistance and when i slowed down (~35 mph) it switched to an awful grinding. I stopped and tried selecting back to 4WD, forward, reverse, back to 2WD and the truck wasn't going to move. The left front wheel was seized in position. I hopped out and manually switched to hubs from Auto to Lock and back to Auto. Problem solved. On way back home, once i got on the snow i thought i'd try it again and troubleshoot some more. This time the same wheel seized and slid on the snow as soon as i selected 4WD. Switched back to 2WD, hopped out and cycled the hub again. Back to 2WD no problem. No 4WD for me until i solve this. Snow's still falling. Anyone have any ideas where to start??? Thanks in advance.

1999 F-250 7.3 PSD (120,000 miles)

 

Anyone?
I did some more troubleshooting today. Took it onto some ice and tried just locking the hubs manually. Same thing. The left front wheel rolls about 1/4 turn and stops. It'll roll back about the same and stops again. Stills rolls nicely in 2WD.
I pulled off the wheel and rotor, and slid out the center of the hub to have a closer look. I can't tell where the problems is, and I admit that I haven't really wrapped my brain around how it works exactly, given that the 4WD can be activated from 2 different places?? Does the transfer case go in and out of 4WD? I can buy a new 'hub assembly' as it seems like the most likely culprit. Seems like a fairly simple job, and no special tools.
I did find some seals that were practically just hanging there. Photos below. Might my problem be bearing related? If i'm not mistaken, the hub assembly comes with the outer sealed bearings. What about that seal on the inside?

I'd love to hear from someone who knows 4x4 hubs before replacing the assembly and finding out that it was something else. Is there a thread about this already? Haven't found it.
Thanks

Here's the seals.





And the hub, so far...

 

Guzzle's hub info might help.

Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page

Stewart

 

The dust seal you are pointing at, is not a problem. Most are just hanging there.

I am not sure about your other problem, but I would jack up both front wheel. Put the transfer case in 2X4 and have someone turn the opposite wheel and the bad one should turn in the opposite direction. If not you will have to go deeper than the wheel hub. Just my .02 Jim

 

sounds like a transfer case problem to me. Drive shaft seized up.

 

Thanks for the info.
I'm going to try that Guzzle procedure when i can. I have a feeling though, that this is about more than lubrication at this point. Wish I'd been servicing it up until now though. Not enough hours in the day.
I jacked up the other side as suggested. Other wheel spins opposite when the Manual hubs are in the LOCK position, as suspected. (Axle turns) Both front wheels spin freely and independently when in the AUTO position. (Axle doesn't turn) There is a fair amount of play in the axle, but it think that's normal??
Of course, the selector inside remains in 2WD.
I'm still confused about the difference between the vacuum selection system and the manual system. Anything i can find in this forum seems to be about the Excursion. From my troubleshooting on the road, BOTH systems cause the one wheel to lock up.
Any other ideas out there? Thanks again,
Dan

 

I serviced the front left hub according to Guzzle. I think my problem is in the differential now. Everything seems to work fine in the hubs as far as I can tell. The drive shaft is not seized, in fact it spins freely when i spin it by hand, whether or not the hubs are manually locked. There is excessive play though on the end that goes into the front differential. How much is normal?? Any?
Has anyone seen this? I'd sure love some help troubleshooting it. Thanks,
Dan

 

Below are a couple threads dealing with the operation of the auto/lock hubs, and the transfer case. Hope this helps for understanding operation.

https://www.ford-trucks.com/forums/1...ly-work-2.html

https://www.ford-trucks.com/forums/8...t-working.html

I'm not sure what the problem is, but in post 16 of the thread below, Robin give a test to follow. May shed some light for others with more understanding of the 4x4, front differential operation, and a bump at least.

https://www.ford-trucks.com/forums/1...g-apart-2.html

Good luck

 

What happens when you put the transfercase in 4x4 with the wheels up and the air. Thats when to check the drive shaft and see if its locked or not.
Chet

 

Thanks for the info guys. Read through those threads and I believe I now understand how the system works, more or less. I did some more pulling and twisting under there and am convinced now that my problem is the Differential. Where the drive shaft enters the diff, there is about 3/4 of an inch of side-to-side play. That can't be right.
Also performed the check from PaysonPSD thread. Result ... with hubs unlocked, I can spin the drive shaft freely without either wheel turning. Same thing if i lock either (or both) hubs. Bottom line - the drive shaft ain't hooked to anything in the diff.

So i need to find out what's in there. There's some nice photos of the front side in another recent thread. Is there a bearing in the back? I might pull the front of the diff off tomorrow to see what i can see - hopefully not a handful of metal. I suspect the worst though. Is there a gasket I'll need IF i put it back together?
Thanks again for all the assistance.
Dan

 

I believe that you will not need a gasket, but will need some RTV sealant.

Clean both surfaces, apply the sealant, install the cover, and let it set up overnight or so .... read the directions on the sealant tube and it will state how long it needs to cure before adding the fluid back into the diff.

HTH

 

You are right about side play there, should not be any.
If the bearing is out, I would think you would have a leak. Could be a loose pinion nut.
I would pull the front shaft and check the pinion nut, and replace the seal.
Pull the cover and look at everything, probably needs oil changes anyway, Just my .02 Jim

 

If you have that much side play you probibly have in and out play also. When you stick it in 4x4 the shaft turns and the pinion actually gets pulled into the ring gear and the diff will lock up! There may be no oil in the diff if it's not leaking. I have seen this many times with our off road jeeps. Depending how long it has been run this way you at least will need a new seal, most likely new bearings and worst case a new ring and pinion! Pull your drive shaft and pull in and out on the pinion and turn at the same time. If it goes in and out you can try tightening the pinion nut little by little and see if you can tighten it and take away the play, don't over tighten.Then go from there. Definatly pull the cover and look inside too.

 

Thanks again for suggestions.
I'd checked the diff oil right away when i was 'Guzzling' the hubs and it was fine, with no leaks - not even out the back where the drive shaft was flopping around.
Pulled the diff cover off, and found metal as suspected. See photos. I flushed it out with some parts cleaner, so that should be all the metal.
All the gears/teeth at the front of the Diff look OK, but you can see where a few teeth are damaged near the back. Tough to get a good photo. Pulling the drive shaft after lunch. No experience with Diffs and Pinion Nuts etc, so learning as I go...
Thanks again!! Probably wouldn't attempt this without this awesome forum.

 

Judging by your pics you are gona need a ring and pinion and full install kit/bearings. Not cheap. Sorry for the bad news.