Rear pinion seal replacement and an OOPS with Vent Hose

[chevymotocross]

While getting the broken rear upper shock mount out of my truck, I wanted to take a peak at other stuff while I was under there. The rear end has slung fluid underneath the bed, pretty messy. Also I need to replace the u-joints.

It appears to be a pinion seal leak but usually don't these drip fluid down to underneath the rear end? This leak, the fluid gathered around the pinion flange nut, not really dripping downwards like I've seen on other cars. Either way, it must be the pinion seal since that's the only seal in that area correct?

The nut and shaft are slotted in 3 positions to line up. I will count the number of threads and mark the flange so I can line it up and get the nut exactly back to where it is. Is this a safe way to do this? I know the torque of the pinion nut is extremely important.

Also, I did an OOPS with the rear-end vent hose. I wanted to make sure it was venting (due to the leak). Well, I know now that it is venting but in the process of carefully taking it off, the vent snapped flush at the axle Anyone run into this and are there any decent fixes? I was thinking epoxy to mate the hose to the axle body (while of course making sure excess doesn't plug the vent).

[raceman6135]

It is very possible that differential lubricant is wicking or following the threads on the pinion forward to the nut, and then working its way past the nut to where you can see it. So to answer your first question, the pinion seal is the only seal in the area, but it's not the only place it can leak.

When the pinion nut is installed during final assembly, many people use a small smear of non-hardening sealer on the nut threads to help prevent this little leak.

You can try epoxy, but I've never been able to get the surfaces clean enough of dirt and lubricant in order for it to stick. What I ended up doing was finding a self-tapping screw that would cut into just the broken off part of the vent. Once it had bit into the broken off vent piece, I used a pair of pliers and/or a pry bar to remove the broken piece from the differential.

As you can see, the self-tapping screw must be large enough in diameter to bite into the broken piece, but not so large that it grips the hole in the differential.

Once the old piece is out, a new vent can be installed.

[chevymotocross]

Thank you for the reply! As for the vent hose, before trying your recommendation, I am going to try some permatex which is designed to mate rubber to metal. The rubber hose which surrounds the broken metal piece, bottoms out to the rear-end housing. I'm hoping I can get it clean enough for it to bond and hopefully I will be set with that!