Help, cannot stop rear pinion seal leak

[TJ Jonny]

Hello all, new to the TJ community but no stranger to wrenching and vehicle forums.

I inherited my father's 2004 TJ SE 2.4, only has 52K, on it a couple months ago.

I cannot stop the rear pinion seal from leaking and about to replace my third seal in as many days. First one was a duralast seal from AutoZone and it leaked worse than the original seal. I installed a Mopar seal I picked up from the dealer yesterday and this one is leaking worse than the previous two.

I carefully marked and replaced the yoke and nut, torqued it to spec, etc.. I cleaned up the yoke with brake clean and made sure there was not a groove worn into from the original seal. All looks well. Before I pick up another seal tomorrow, I would really appreciate any advice if any of you have ran into this in the past!

Jon

 

[Rob5589]

Welcome aboard. So, there could be a few things going on.

Improper install, the seal is somehow getting tweaked when you are installing it.

The yoke surface could be bad. Use fine emory cloth to clean up the surface and wipe with brake cleaner.

Most seals have a spring to put some tension on the seal to yoke contact. The spring can pop out during install. You can pack the inside of the seal with grease to avoid this.

There can also be some bad vibration causing the seal to go bad. The driveline or bad pinion bearings can cause this. I would assume you would notice while driving and/or while installing the seal but maybe not.

 

[Mike_H]

In addition, Wrap some saran wrap around the splines and grease the seal surface before install. That will help prevent nicking the seal upon installation.

 

[ac_]

Can you tell where it is leaking? Is it leaking between the seal and the housing or is it leaking between the yoke and the seal? If it is leaking between the housing and the seal, You can put a small amount of silicone around the outside of the seal, but let it sit for a while before use for the silicone to dry completely, and if it is leaking between the seal, and the yoke make sure you pre-lube the seal with some grease before you install, and I would also put some on the yoke too. Also check where the seal hits the yoke and make sure there is no scratches in the yoke. Or sometimes where the yoke is the seal can create a ring. If that is the case you, have a couple of options one see if you can push the new seal in further or not quite as far so it seals in a different place. Sometimes they sell a yoke saver that is an aluminum cover that you can press on the yoke to give a new sealing surface or replace the yoke altogether.

It is hard to diagnose without looking, but I hope I gave you something to look for to give you clues to solve this issue.

My guess would be a bad sealing surface on the yoke.

 

[Jerry Bransford]

Try find an SKF CR (Chicago Rawhide) seal. They're more rugged and less likely leak.

 

[TJ Jonny]

Thank you for all the quick replies! After failing to fix the leak twice, I wanted another opinion so I really appreciate the input. I was sure to carefully install the seal as I have done in the past without an issue. I used 300 grit sand paper and brake clean to clean up the yoke, it didn't look new, but it sure didn't look banged up either.

The OEM seal came greased up and ready to install. The leak I am seeing with the OEM seal now is grease (black), but it is a little runny and smells like gear oil. I am pretty sure it is not pure grease working its way out.

it looks likes its leaking between the seal and yoke. I think I'm just going to replace the yoke and try to nip this in the *ss....What are your thoughts on reusing the pinion seal with +/-8 miles on it? I won't be removing the seal, just replacing the yoke.Worth trying to save the $22 at the dealer?

 

[Rob5589]

Personally, I would replace the seal if you are swapping out the yoke. Something else to check, make sure the vent hose is clear of crud/obstructions/kinks.

 

[TJ Jonny]

Thanks Rob, the hose is free and clear...I blew it out to make sure it wasn't the culprit causing the seal to go bad and even used a pipe cleaner to clean from nipple into the diff. I just spoke with local dealer and they recommended just swapping the yoke and not to worry about the seal since it was installed just two days ago and has very little use. ( I trust these guy as much as one can trust a reputable dealer, been going here for years) I think I'll go that route, at least attempt to save the seal and the brand new fluid that is in there.

 

[billiebob]

Not sure if it can be installed backwards on a TJ but that is an issue with many other seals.

 

[billiebob]

And then comes a time to cut yer losses and just take it to the dealer..... should come with a at least a week of warranty.

 

[TJ Jonny]

Not sure if it can be installed backwards on a TJ but that is an issue with many other seals.

The Mopar seal has a flange and it cannot be installed backwards, the Duralast seal did not have it.

 

[TJ Jonny]

Guys, here are some pictures of the leak with the OEM Mopar replacement. At first I though it was just the grease that came on the seal oozing out, but when I did the classic smell test, it smells like gear oil and it is much thinner than typical grease. I'm going to wipe it clean after work, go for a quick drive and see if it is back after a mile or two drive.

I ordered a new yoke, nut and seal this morning and will pick them up on my way home this evening and will replace them if after my short drive, it is clearly still leaking.

Sent from my iPhone using Tapatalk

 

[Rob5589]

Looks like a combo of grease and oil. Looks like some metallic in the fluid, too. Have you changed the oil recently?

You sure have some rust on that thing. A new yoke is probably a good idea. Snap a shot of the old yoke after you pull it.

 

[TJ Jonny]

Yeah, that's what I figured as well, grease and oil. The metallic look is deceptive due to the flash taking the picture. The gear oil is less than a week old, maybe 100 miles on it max.

New England rust belt jeep for 13 years, fortunately the frame is in much better shape that the driveline. Very little rust otherwise


Sent from my iPhone using Tapatalk

 

[Jerry Bransford]

Some difficult to cure pinion seal leaks are caused by a worn pinion yoke, where it spins against the seal.

 

[TJ Jonny]

Some difficult to cure pinion seal leaks are caused by a worn pinion shaft, where it spins against the seal.

I hope replacing the yoke will fix this issue. It only has 52K miles on, I don't want to rebuild the rear end....

 

[TJ Jonny]

Just to be sure, what is the torque spec for the pinion nut? It's possible I did not torque it down tight enough I suppose.

EDIT: Found it...I tightened it correctly
Pinion Bearing Nut: 160-200 ft-lbs

 

[Rob5589]

Tightening down the pinion nut can be tricky on worn bearings. Definitely make sure there is no in and out play. Even if you are at 200 ft/lbs but still have some play, tighten it more. There should be none.

 

[TJ Jonny]

There was zero movement as far as I could tell

 

[RaymondT]

Just to be sure, what is the torque spec for the pinion nut? It's possible I did not torque it down tight enough I suppose.

EDIT: Found it...I tightened it correctly
Pinion Bearing Nut: 160-200 ft-lbs

Some of those pictures give us the impression that the seal is riding on rust. Did you dress the yoke surface? I always keep a 1" roll of 320gr to polish surfaces where the seal rides.

160ft lbs is a starting point. It won't even start to compress the crush sleeve. Both the Jeep shop manual and Spicer's Dana 35 manual call for torque upward of 260 to 300ft lbs in small increments while monitoring rotational torque. Too loose to over-tight & destroying the bearings is about 1/6th of a turn.