I bought my truck used about a year ago. Since then I have replaced the inner hub seal on the left rear three times (Twice on my own and once by Les Schwab tire), and now it is leaking again. What can this be caused from? I've changed the fluid in the axle there are no metal filings the rear end seams to be in tact, and is working fine.

Is there something that I'm missing?

The Truck is a 2000 F350SD 7.3L Single Rear Wheel 4x4.

 

Same thing happened to my brother's truck, same side. Have to ask - Do you go muddin' alot? What happened to his was - he works on pipelines (welder) and gets into a plenty of all kinds of mud, mostly gritty, sandy stuff. The inner seal somehow let a little grit in and it got trapped. Wore out the spindle just enough to let the grease bleed by. Couldn't tell by looking, but it had a ring wore right where the seal goes.
Also, how hard (easy) was the seal going in? Could the hub be worn/egged?

 

Dimes to donuts your problem is a plugged differential vent.

There is a vent line that runs out of the diff to maintain atmospheric pressure. If the line is plugged, the increased temp and movement causes a buildup of pressure within the diff. This pressure will cause your seals to blow in short order.

I had the same thing happen to me on my '89, and did the exact same thing as you did until my uncle, and old farmer, pointed it out to me. I cleaned out the vent and my problem was solved.

Waxy

 

Either situation is very possible. The person that owned the truck before me was in the mud allot.

How do I know this?

When I bought the truck there was at least 4 inches of mud caked thoughout the under carrage. I spent 2 hours with a pressure washer under my father-in laws car lift. I'll check for both the wear on the hub/axle and the vent tube. Although the new seals always seam to go on prety tight.

I'm hoping it's the vent tube.


Thanks Guys!

 

One more thing: Since the seal has gone out 3 times it is getting very spendy replacing the synthetic axle lube that Ford calls for.

Any suggestion on where to find it cheaper? Besides (FORD)

 

First thing I would do is what WAXY suggested. Clean off all the mud from the vent tube and locate the cap. Make sure its not crammed full of mud, then sort of twist it until its free. Of course there could be crud trapped down deep and you'll have to remove the tube and blow it out. In that case just break loose that factory crimp with a pair of pliers, remove the tube, blow it out and reinstall it with a stainless steel hose clamp.

If the tube's not stopped up, then you'll have to check the inside dimension of your hub, make sure its not galled (worn rough) or egg-shaped. You could use (borrow) a set of calipers that measure inside and outside dimensions. If the hub's good then check the spindle. Just run the calipers along the journal where the seal rides and see if the size varies....BTW...check the outside dimension of your seal against the inside dimension of your hub.

Rear end fluid - I always go to one of the parts stores and get mobile 1 ATF, then get a bottle of that additive for the limited slip - if thats what you have. Works great for me. You might have to get that additive at FORD if you live in a small town like I do.
Hope this helps - let us know

 

I think you meant Mobil 1 gear oil...ATF is way too thin for a 10.5" ring and pinion.
-T

 

What happened to the synthetic oil Ford calls for? Do you guys just disreguard that all together? I'd hate to put something in that wouldn't do the job.

 

Use synthetic. It's not THAT much more money.
(don't use ATF in your differential, not the greatest of ideas...sure would keep your diff clean, though! haha)
-T

 

I changed my rear seal 3 times too. I have 1990 F250HD 260Kmiles. I lightly sanded the axle housing where the seal goes and put red high temp silicone on it (thin). There was some wear and I didn't want build it back up with metal or change the whole thing out. It's been running fine for 4 years. Mine leaked most when parked with that tire lower than the other side. I always joked sooner or later it'd fix itself. Nothing leaks forever if you don't add fluid. I did keep mine full though. I use 85-140, no factory limited slip though, but no problems.

 

After you check all the above, vent tube, spindle and hub, look at the surface on the spindle where the seal rides. If its worn get a new wear sleeve. They sell em at NAPA. Also check to make sure the seal is being installed correctly. It has an "oil side" marked on the seal. Also use a quality seal. Lastly make sure your bearings are good and that they get torqued back up properly when the hub is reinstalled. Check the hub to make sure it runs straight.

 

Man! I need to stop posting advice if I can't get my stuff straight! Mobil 1 Gear Lube! is what i meant! Sorry Buckaroo! And the Ford stuff is great too, but I can't get that around here except at the Ford place.

 

Thanks Everyone! For all the advise.

I plan on getting to it this weekend. Also figured while I'm at it I will install a Mag-Hytec differential cover. I just ordered it today from dirrect form Mag-Hytec as well as the oil they give a $25 discount if you get the oil with the cover at the same time. Oil was only $25 can't beat that.

I'll let you know how the fix/install goes this weekend.

Thanks Again.

 

Found a fairly deep gouge with a rough edge on the axle shaft where the seal rides. It was to late to go to napa and get a new wear sleeve. So I did what Tim Ervin said to do I lightly sanded the gouge and rough edge down put a thin coat of High-Temp ATV on and re-installed a new seal. We'll see how long that lasts. Now I know what easy-sleeve to get it starts leaking again.

While I was at it I insalled a new Mag-Hytec diff cover and it was a piece of cake. I didn't spill a drop of oil when I filled it beacause of the easy fill hole/dip stick. It will keep things cool and it Looks cool to.

Thanks for all the Help.