Pinion Seal Replacement

[Clayboy]

Looking to learn from the experience of others, so appreciate any assistance. While changing my oil and doing my customary underside inspection while the oil drains, I noticed I was leaking differential fluid from the rear pinion seal. I do have a 2005 FSM, so other than the special tools, I think I can repurpose existing tools, replacement is relatively straightforward... but, this will be my first time for this particular procedure. I do most of my own work, and I do have access to a lift. Thank you!

Clayboy

 

[JR]

Make sure to thoroughly check all your universal joints and carrier bearing if you have one. Sometimes the seals will begin leaking on their own, but its usually from a driveline issue. Could be small enough you dont even notice it (yet). Articulate all u joints to make sure they are free and dont have a rough spot in them. Also make sure if you have a 2 piece drive shaft to scribe match marks in them before you remove them. They are balanced as a set and if you put them back together 180* out they will most likely have a bad vibration from bieng out of balance.

 

[WOT]

I just had to do the front seal... and forgot to mark the nut to the pinion before taking it off. (https://www.turbodieselregister.com/forums/showthread.php?238620-pinion-yoke-seal-need-help-locating) . At any rate, it's straight forward. I don't know if the rear has the companion seal or not, but i ended up having to replace the one on the front.

1) mark driveshaft to pinion
2) mark pinion nut to pinion
3) remove, shaft, remove nut, replace seal(s) if there are two
4) install nut and tighten to same position
5) install driveshaft

I believe there was an article on it not too far back in one of the TDR issues... think it was by Joe Donnelly.

 

[Clayboy]

Thank you! Noted on the scrib marks - I do that and always take a lot of digital pix. Check the u-joints and don't think they are the culprit, but I am considering replacing those as preventative mx and/or in case they are a contributing factor.

 

[PFranzese]

Add a little sealant around the seal body where it presses in the axle housing and also on the splines of the yoke to seal from oil leaks.

My rear axle was re-geared by a dodge dealer, they did a great job with less gear noise than from the factory, but the tech didn't add a little silicon around the seal body where it presses into the housing and after a long while I started to some wetness around the pinion. I didn't change it for over a year since the leak never got worse, I was just tired of seeing the wetness around the pinion on the housing. When I got the pinion off the seal itself was totally dry and you could see the oil weeping out around the metal body. A new seal and dab of silicon and we are dry.

 

[Clayboy]

Thank you! Copy on the wetness, mine also does not seem to be a constant leak so I too am just getting tired of seeing it and having to crawl under my truck to check the fluid level before any long trips.

 

[sag2]

If it is just wet, and not actually leaking (having to add fluid) you are better off leaving it alone until it really starts to leak. If you don't get the pre-load correct on the nut you will be replacing a ring and pinion next. Have it done by someone that will stand behind it (because they also may not do it correctly) or leave it alone.

 

[rbattelle]

110,000 miles and my front pinion seal started leaking. Fluid is very clearly coming from the pinion seal.

The factory manual says to remove the axle shafts, measure the rotating torque on the pinion yoke, and when reinstalling set the bearing preload to match the rotating torque you measured before removal. Is this really necessary?

Also, it has been suggested that a plugged axle vent could cause leakage like this. Is it just wishful thinking to hope maybe that's what's going on? I'm apprehensive about this job for the reasons sag2 points out.

On edit: I just checked the vent tube. I can't blow air in or out of the tube at all, suggesting it's blocked at the axle. But what could possibly have gotten in there and blocked it? The little plastic vent on the end is fully functional.

-Ryan

 

[sag2]

110,000 miles and my front pinion seal started leaking. Fluid is very clearly coming from the pinion seal.

The factory manual says to remove the axle shafts, measure the rotating torque on the pinion yoke, and when reinstalling set the bearing preload to match the rotating torque you measured before removal. Is this really necessary?

Also, it has been suggested that a plugged axle vent could cause leakage like this. Is it just wishful thinking to hope maybe that's what's going on? I'm apprehensive about this job for the reasons sag2 points out.

On edit: I just checked the vent tube. I can't blow air in or out of the tube at all, suggesting it's blocked at the axle. But what could possibly have gotten in there and blocked it? The little plastic vent on the end is fully functional.

-Ryan

Have not seen you post for a while, hope everything is well. Some dirt may have worked it's way into the line and hardened with the oil residue. Pull the hose off the axle and blow through it. Also remember that the differential is sealed so you will not necessarily be able to blow "through" the hose.

 

[rbattelle]

Have not seen you post for a while, hope everything is well. Some dirt may have worked it's way into the line and hardened with the oil residue. Pull the hose off the axle and blow through it. Also remember that the differential is sealed so you will not necessarily be able to blow "through" the hose.

Hey sag, it's been awhile since I posted. I'm good, just consumed with other projects.

I did as you suggested, and am convinced the vent tube is not clogged. I guess that means a pinion seal replacement is in my near future. Ugh.

Do you suggest I invest in the pinion flange holder and seal installer tool they recommend in the service manual? What about removing the axle shafts?

-Ryan

 

[LFalconer]

FWIW I had the front pinion seal replaced at my local Dodge Dealer about 18K ago. It is now seeping a small bit of fluid again. Going to leave it alone for now.

Next step is to put in the free running hub kit for me. Then I will change it one more time [hopefully]

Luke

 

[sag2]

Hey sag, it's been awhile since I posted. I'm good, just consumed with other projects.

I did as you suggested, and am convinced the vent tube is not clogged. I guess that means a pinion seal replacement is in my near future. Ugh.

Do you suggest I invest in the pinion flange holder and seal installer tool they recommend in the service manual? What about removing the axle shafts?

-Ryan

The right way is to remove the shafts and torque the nut to the the proper torque and turning torque. But that is a lot of work and almost no one does it that way. If it were my 12 year old truck I think I would mark the nut and pinion and reinstall the nut to the exact spot it is in now. But as I have always suggested I would not change the seal unless it is actually dripping on the ground. But if you do you will need the yoke holding tool or something equivalent (long large angle iron drilled for two of the bolts) and a big breaker bar. Go slow and check nut location often. Once you go too far you can't just back it off.

 

[BillDriscoll]

Had mine done 2 years ago....listen to whoever said about preload and proper torque. The original shop that did it, didn't put it back together right and when I put it in 4wd the nut backed off after I drove it 1000 miles from home. Took it to a local Dodge shop (out of town of course) and ended up getting a new ring and pinion nut and seals and fluid. The Dodge dealer noted it on the repair bill. The original shop wouldn't pick up anything or admit it was their fault.
Took me a BBB complaint and had the shop call the Dodge dealer and talk to the Dodge mechanic before the original guy ponied up for the 1800dollars repair bill, rental car, hotel rooms etc.
Guess I was lucky the Dodge mechanic owned a truck just like mine!!

 

[brods]

The right way is to remove the shafts and torque the nut to the the proper torque and turning torque. But that is a lot of work and almost no one does it that way. If it were my 12 year old truck I think I would mark the nut and pinion and reinstall the nut to the exact spot it is in now. But as I have always suggested I would not change the seal unless it is actually dripping on the ground. But if you do you will need the yoke holding tool or something equivalent (long large angle iron drilled for two of the bolts) and a big breaker bar. Go slow and check nut location often. Once you go too far you can't just back it off.

Would the correct procedure of pulling the axles and measuring turning torque be the same when switching the pinion flange for yoke style one?

 

[sag2]

Would the correct procedure of pulling the axles and measuring turning torque be the same when switching the pinion flange for yoke style one?

Yes, any time you remove the pinion nut the "correct" procedure is to measure the turning torque when installing the nut (new or used) again.

 

[brods]

Thanks Sag2. It took a lot of time to scrape the white pipe dope like crud off each of the splines of the pinion shaft (with rags packed around the bearing to keep the junk from falling in). Is there a trick for getting that stuff off easily so others don't waste their time with it?

 

[sag2]

A wire brush should work easily.