Last August I had the pinion seal replaced in my rear diff. I pulled the 3rd member myself and took it into Rearend Specialties. That seal was maybe a year and a half old. Now, 7 months later, I'm leaking again. I don't have time to pull the 3rd member so I'm dropping the rig off to them tomorrow to check it out.

Any thoughts as to how/why a seal is blowing again? What should I/they look for when digging in there. I wouldn't expect the seal to trash this often!

Diff vent plugged?

Vent should be OK, I've got an extended breather under the hood. I think I'll change the filter on it and try to check the line out complete. Thanks for the tip....

Did they install a Speedi Sleeve?? If the yolk is grooved, the seal won't last long.

</font><blockquote><font size="1" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">quote:</font><hr /><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Originally posted by Don West:
<strong>Vent should be OK, I've got an extended breather under the hood. I think I'll change the filter on it and try to check the line out complete. Thanks for the tip....</strong></font><hr /></blockquote><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">I had the same problem with my vent line. If you have any dips in the vent line as it runs forward, oil vapor can condense and pool in the line. Cold gear oil is thick enough to partially plug the vent line and let a bit of pressure build up, enough to force oil past the weakest seal. I had 2 axle seals and one pinion seal leak before the shop that changed mine (no longer in business) suggested I check the vent line.

Sure enough, when I tried to blow through the vent line, it took a pretty good puff of air to blow it free. I rerouted my rear line to run back and up inside the taillight housing where the filter is now. Since the vent line slopes downhill to the axle, any oil that condenses will run back into the axle.

I had no problems when I first installed the vent line (in the summer) but in the winter, it started leaking. Cold weather makes the gear oil thicker and in the exposed vent line, it doesn't warm up as you drive.

Shouldn't have to pull the third to do the seal - if you are careful. Especially easy if you used a solid sleeve instead of a crush sleeve when the gears were set up. Assuming there are no grooves in the yoke where the seal rides, very lightly hone the yoke on the sealing surface with emery cloth. Else, go with a new (or newish equivalent) yoke.

That seal is VERY easy to replace and a cheap part. Do it yourself, takes about 30 min. at the most. And you don't have to pull the third to do it. I wouldn't be overly concerned with it failing, its common, especially if you go offroad.

Red Rock-
You say this is easy? Mine has been bad (seems to have stopped leaking??) for about 6 months. It started leaking after a 1000 mile 1 day trip, after I got home. Can you please decribe the process of changing this seal out? I know I read a very informative post about this a while back, but I can't seem to locate it. Maybe it was 4crawler who described it in several (about 8)easy steps, I think it was on the ORC. It had very detailed directions on how to properly stake the nut and such, with all the torque values, etc. Remember, The more details the better!! (I.E. torque values, etc.)
Thank you! Maybe now I can change this damn seal!
Jason

Hmmm, well. thanks for all the advice. I still don't have any time to deal with it myself right now (I just moved and am still trying to get things together). I'll take it by the shop tomorrow and get it done with this time. If it happens again I'll read up on doing it myself.

Disconnet the drive shaft at the rear only, leave it connected to your t-case and just move it to the side.

Take the nut off (companion flange) You will notice the nut has been staked, just bend that stake out so you can turn the nut...you will know what I am taking about when you see the nut.

Remove the seal, a screw driver and hammer work great...don't worry about destroying the seal, its already bad and your replacing it anyway. Just don't dig the screw driver into the housing, just the seal.

Replace the seal. It will fit tight, use a small block of wood to tap it back in flush.

Replace the nut and re-stake it...you can re-use the same nut you took off or replace it, its up to you.

Replace your drive shaft....and your done.

Oh and there is no need to drain your diff to do this either. A little gear oil will come out when you pull the seal, just have a rag for the drips.

The first time you do this may take a little longer than 30 min. Maybe 35 minutes..