Rear diff pinion seal leak

[Kach]

So, last night while running some wire to install a Modulite, I noticed some dampness at the rear pinion seal on the rear end. It's definitely gear oil, but not even enough to drip after the truck has sat there for several hours. I had my ring and pinion replaced about 9 months ago. This was at midnight so I haven't pulled the plug to check the level yet.

1) does this seal get replaced when the ring and pinion get replaced? Excuse my lack of knowledge there, but seems like it would have to.

2) Assuming the diff oil level is good, do you think it is OK to drive through the weekend?


Our plans were to take our travel trailer up skiing for the weekend. I really don't want to disappoint our kids...

 

[lpennock]

Seal has to be replaced with pinion replacement. No way to replace outer bearing without removal.

Personally if there is no fluid loss, dripping or signs of oil slinging I would run for this trip. Heck if it is only sweating a bit I would run it until get has a actual drip.

 

[tommyturbo]

Kach. I had the same problem that eventually started to show drops on the driveway and
keeping a watch on the Mag-Hytec sight glass.
After getting a quote from the dealer for around $450.00, I decided to try replacing the seal
myself. The UTUBE videos seemed a little mickey mouse and the manual showed removing the
axles and using sensitive torque drag readings and I decided all that was way beyond my skills.
Around the same time, the cracked DPF was being replaced at a muffler shop that referred the
pinion seal work to a performance driveline shop nearby. They quoted $85.00 labor and do it
while I wait. ( 45 minutes). I supplied the Mopar seal. I asked them if they do the factory
procedure and they said that they do a lot of AA-14's with Duramax's. They said that they know
how to set up the torque specs by "feel". So far, o.k. If you search around the TDR you will find
the best "opinion" about pinions. Maybe it was BOB4X4 that mentioned that if the leak wasn't
that bad to just leave it alone. Sounds good. It was that after a year or so, the wind and evaporation
wasn't keeping the oil from dripping on the driveway.
Tommyturbo

 

[Kach]

Thanks everyone, after further research I'm less worried about it. Diff was full. Modulite install was a success, so time to load up and hit the slopes!

 

[sag2]

Unless it is dripping on the ground leave it alone. As far as the shop doing it by "feel", I would let them do it on anyones truck but mine. They might get lucky, and many do, but the right way to avoid pinion failure is the factory way.

 

[tommyturbo]

sag2. I agree. It sounds risky but I will definitely post if anything happens.
tommyturbo

 

[lpennock]

The seal can be replaced without all the steps called out in the manual. Mark pinion nut location and count the number of threads showing so you can get nut back in same location.

 

[tommyturbo]

Kach. You are probably on your way to enjoy a good trip with your family by now with confidence.
Your post has brought out opinions about pinions from master mechanic forum members.
In the future, you will have to tackle the seal replacement. For me, I wasn't comfortable having the dealer
do it after they botched a simple transmission and diff cover swap. So I chose a recommended driveline
shop. I know the factory procedure should be the way to go but I didn't know where to take it. Time will tell.
I have great respect for skilled mechanics and it seems unfair to see them categorized in the Skilled Trades in the
want ads when actually the experience and skills are up there with the so called Professionals careers. Automotive
wrenching is a grueling knuckle busting physical ordeal requiring patience and finesse. After 40+ years making a living
as a machinist, not a mechanic (same horse, different saddle) I am still all thumbs with automotive.
I hope when its time for the seal replacement, that you can be pointed in the right direction.
tommyturbo

 

[Kach]

Thanks all for the replies - home safe after a fun and exhausting long ski weekend! Beautiful sunny days and the truck got us there and back safe (as she always does, thanks in large part to all I've learned here at TDR).

I think my plan is to keep an eye on it and give the shop that did the rear-end a chance to check it out. I hadn't been under the back of the truck in a while - do oh think it's a bit fishy to be looking at a seal replacement again about 9 mos. and maybe 10k miles after the diff replacement? Wondering if it was not installed correctly...?

 

[PWong]

it's a bit fishy to be looking at a seal replacement again about 9 mos. and maybe 10k miles after the diff replacement? Wondering if it was not installed correctly...?

In December 2014 I had a big truck shop did two front axle seals and front pinion seal.
After pickup found noise from front differential. Took it back right the way and they fixed the noise.

I checked the temp of the front and rear diff housing near the front bearing after driving around. There was a 30 degrees difference. The front was above 150F while the rear was below 120F.
Guess what happened next?
Noise came back on October 2017, 50000 miles later. The front pinion bearing was gone!!! Couldn't trust any shop.


I bought a new rotating torque wrench/dial gauge. Replaced all four bearings, set the backlash and pre-load with the help of a friend.

 

[PWong]

The yoke could be bad if it leaks after new seal replacement.

 

[Joseph Donnelly]

TDR #67, p. 80

 

[cerberusiam]

The yoke could be bad if it leaks after new seal replacement.

Or they did not get enough thread sealant on the splines.

 

[Bob4x4]

Or they did not get enough thread sealant on the splines.

That is one step some forget on the AAM