Hey guys, I replaced the rear pinion seal on my 2001 XJ and now I have a rubbing/howling noise when I drive it down the road. I marked the yoke and pinion nut before I removed it, replaced the seal, replaced the yoke according to the marks and tightened the pinion nut until it was lined up again, then snugged it a little more. No more than 150 ft/lbs. Nothing is leaking, changed the fluid with 80-90W. After test driving it, I pulled the rubber plug and the fluid looked foamy. Any thoughts? Did I tighten the pinion nut too much? Thanks in advance.

Foamy fluid is normal, the rest I don't know.

I'm hoping I can just take the yoke and pinion nut back off, re-tighten everything (making sure not to over tighten it) and try it again. I'm just not sure if over doing it the first time has screwed me.

Slop in the bearings causes the seal to fail.

So I'm putting it back together and I'm having a difficult time getting the pinion nut tightened back to it's correct position. I can't quite get it the last 1/4 of a turn. Would this mean that the crush sleeve is okay? I didn't have any rear end noise before I changed the seal, just a leak. What do you think?

Well I put it back together, nut in original position and it still rubs/howls at about 20 MPH.

I ended up replacing the ujoints on the rear driveshaft, pulled the cover back off and found gears in good condition and no metal shavings in the fluid (didn't have any the first time I pulled it either a few days ago) but there is definitely a little in and out movement on the pinion gear. With the wheels off and cover open, I turned the axles as fast as I could and there's definitely a chatter coming from the differential (this is with the driveshaft off as well). I have had the pinion nut off twice now and though I marked it and counted threads, is there a chance I just don't have the nut tight enough? I don't have a beefy impact gun so I am wondering if that's worth trying? I know I don't want it too tight but the alternative seems to be a whole new axle assembly.

If there's play in the pinion then it would seem obvious that it needs to be tighter. I would avoid an impact as it can do damage to the internals. It's very odd that it won't tighten back to it's original position any more. Thread damage would be my first guess. Are you using a long ratchet/breaker or a standard length ratchet?

I'm not a diff. expert, maybe one will come around with better help.