9" axle pinion seal

[hoss103]

Since I have the bed off my truck, I decided it'd be a great time to try to repair the oil leak on the front of the rear end. It had been leaking out around the pinion shaft, getting to the U-joint, and being slung into a real nice line on the underside of the bed, framerails, shocks, etc.

I replace the pinion seal, get it all put back together, and a day later there's a small puddle under the yoke where it's been leaking around the pinion shaft again.

Crap! I assume I've just done a crappy job of getting the new pinion seal in, so I tear it back apart and have a look. It turns out the seal is holding fine, but the oil is actually leaking out around the splines between the pinion shaft and yoke. This time I even try putting a small layer of gasket maker on the splines before I put it back together, but to no avail- there's another small puddle a day later.

What's the deal? To me, it seems like a silly design to rely on the splines to create an oil-tight seal. Are my splines so worn that they no longer seal against each other? Is there something I'm missing here?

[ima71 trucks are older]

when you replaced the seal did you use a new crush sleave or did you put in a solid spacer? Torque the nut and test the pinion preload?

SOMETIMES marking the nut and reusing a old crush sleave will get them to seal, but usually not.

[hoss103]

when you replaced the seal did you use a new crush sleave or did you put in a solid spacer? Torque the nut and test the pinion preload?

SOMETIMES marking the nut and reusing a old crush sleave will get them to seal, but usually not.

No, I didn't use a new crush sleeve- I'll head over to my NAPA this afternoon and see if they have one. I was a dummy and thought I could get away with using the old one. I didn't realize it had so much to do with making a good seal.

So do you happen to know the preload and final torque values? I knew I shoulda just come here first instead of trying to wing it on my own!

[ima71 trucks are older]

with old bearings it should take 8inch/lbs to spin the pinion. you should try it repetedly as you tighten the pinion nut to 175 ft/lbs

[hoss103]

Thanks a bunch, I'll try that with a new sleeve. I've learned a lot working on this old truck, but I've got a long way to go!

[FORDification]

Yep, a crush sleeve is something that should never be reused. In fact, when setting up the correct pinion/ring gear clearance, the crush sleeve comes into play, and if you get the pinion gear too deep into the ring gear, you have to replace the crush sleeve and start over.

[averagef250]

I reuse the crush sleeves for just a seal replacement without issue. I don't really see a problem with it. You're taking it apart and putting it back together exactly as it was.

If it's not exactly as it was, then you have a different problem.

Sealing a splined yoke to the shaft it's on is usually done under the washer that's between the nut and yoke. Sealer on the splines isn't going to work. If everything's clean, a bead of RTV that fills all the space under that washer should seal perfectly.

[hoss103]

Thanks for all the replies, guys!

Sealing a splined yoke to the shaft it's on is usually done under the washer that's between the nut and yoke. Sealer on the splines isn't going to work. If everything's clean, a bead of RTV that fills all the space under that washer should seal perfectly.

Should there be a washer there on the 9"? Mine doesn't have one, and I doubt this has been taken apart before I got to it (but it's certainly possible). So to seal this, I should put a bead of gasket maker/sealer under the washer (or pinion nut, since I have no washer) before cranking it back down, right?