Small Pinion Seal Leak = Replace Differential!

BlaineBug · December 17, 2019

I just sent an email to GM to see if they can send me a build sheet with RPO codes or not. I've read some information stating that they won't provide this anymore unless you order it through their archive, but I'll let you know.

Nonetheless, I posed the picture of my rear differential the other day showing some oily residue near the pinion. Shortly after, I cleaned off the housing with about 3/4 can of brake cleaner. I was surprised to see that it hasn't seeped since. As I said it didn't appear that the oil on my housing was necessarily fresh. I also removed the fill plug on the cover and the oil level was just slightly below the hole, so it's still just about entirely full for certain. Who knows what's up. I'm going in for the recall this Friday but I guess I won't be able to mention it since the housing is dry. If it stays dry I won't be concerned about it in all honesty. I still have about 1,500 miles remaining on the 36,000 mile bumper-to-bumper warranty so there is plenty of time to see if the seepage will return or not.

BlaineBug · December 18, 2019

PS, I received the build sheet from GM. I'm not seeing a supplier code, only GL4 for "Rear axle 3.08 ratio" and G80 for "Fully automatic locking rear differential." I'm guessing this information is missing the RPO codes but this is the best you'll get from the online customer service.

Sconman · December 31, 2019

I have a 2019 silverado with 13,000 miles on it. The rear diff seal has been replaced 3 times, the latest with the new "re-engineered" yoke, but still leaking. Now they are looking at the drive shaft or differential itself. Something is slightly out of round or wobbling enough to make the seal fail within hours of replacement.

Jaden3305 · January 9, 2020

Well I have a 2019 Chevy Silverado High Country and my Rear end had a leak so GM is replacing the rear end. The problem I’m having is the dealership is waiting on parts. My truck has been at the shop for two months and I only had it 6 days.

Colossus · January 9, 2020

That sucks, Jaden. We are seeing parts availability for various issues being a huge issue lately. Some say the strike last year is the big cause of this, but with being on this awesome forum for over 10+ years now it seems to be a major issue every time a new truck/design comes out. I recall similar parts availability issues when the K2s were released in 2014 and similar issues being talked about when the GMT-900s were released in 2007.

Do they have you in a loaner?

BlaineBug · January 9, 2020

Strange thing, it has been a few hundred miles since I showed that picture of my rear end. I cleaned it with a full can of brake cleaner and haven't seen anything since. Is it possible that the seal needed to "wear in" to the brand new pinion upon assembly? From what it looked like, it was not a fresh spray but rather old oily residue. The differential is full of fluid as well. I'm not accustomed to things that only leak "sometimes" but that appears to be the case here. I can also understand an imperfect sealing surface OR seal itself that eventually wear together after some time.

Jaden3305 · January 10, 2020

6 hours ago, Colossus said:

That sucks, Jaden. We are seeing parts availability for various issues being a huge issue lately. Some say the strike last year is the big cause of this, but with being on this awesome forum for over 10+ years now it seems to be a major issue every time a new truck/design comes out. I recall similar parts availability issues when the K2s were released in 2014 and similar issues being talked about when the GMT-900s were released in 2007.

Do they have you in a loaner?

Yes I’m in my second loaner vehicle now. They give me a new one every 30 days.

bobboberton1 · January 12, 2020

I got under my truck to ensure I washed off all the dirt from a snow day and discovered the same issue. A nice splatter all over the underside of my truck from the leaking seal and the scent of rear diff fluid when underneath. If I dab it after it sits I’ll get a nice oil spot as well. Dealer is replacing yoke (and seal) of course part is back ordered. No eta.

e.texerado · January 16, 2020

On 1/12/2020 at 1:54 AM, bobboberton1 said:

I got under my truck to ensure I washed off all the dirt from a snow day and discovered the same issue. A nice splatter all over the underside of my truck from the leaking seal and the scent of rear diff fluid when underneath. If I Dan it after it airs I’ll get a nice oil spot as well. Dealer is replacing yoke (and seal) of course part is back ordered. No eta.

dealer didn't mention yoke for mine, however seal is back ordered. heck of a way to undercoat truck..

eldercat · January 16, 2020

I have been waiting since first of November for a seal. I get one drop of fluid when the truck sits in the garage for a couple of days. Noticed mine around 500 miles, I am at 4900 now.

swathdiver · January 16, 2020

Don't those new trucks have the same AAM 9.5 or 9.76 12-Bolt Salisbury differentials as the K2s?

bobboberton1 · January 16, 2020

1 hour ago, eldercat said:

I have been waiting since first of November for a seal. I get one drop of fluid when the truck sits in the garage for a couple of days. Noticed mine around 500 miles, I am at 4900 now.

What did the dealer quote you for repair? I’ve been told I need a new yoke. Of course the thread started off with another user getting an entire axle! Did it make a hell of a mess under your truck as well? I have a oil mess everywhere.

eldercat · January 17, 2020

21 hours ago, bobboberton1 said:

What did the dealer quote you for repair? I’ve been told I need a new yoke. Of course the thread started off with another user getting an entire axle! Did it make a hell of a mess under your truck as well? I have a oil mess everywhere.

All they told me was a seal. Yes it has slung fluid under the truck. I mentioned this thread to the dealer and how one individual was given a new rear end they said, "I bet that service department got in trouble"!

Zach-91 · February 5, 2020

Found that mine is leaking this week. Taking it in Monday to get a loaner and have it fixed. Assuming they will just do the seal on mine as well. Have splatter on the exhaust, bottom of the bed, and the fuel tank. Could easily be wiped off with some degreaser but am leaving it until it's fixed.

bobboberton1 · February 5, 2020

1 hour ago, Zach-91 said:

Found that mine is leaking this week. Taking it in Monday to get a loaner and have it fixed. Assuming they will just do the seal on mine as well. Have splatter on the exhaust, bottom of the bed, and the fuel tank. Could easily be wiped off with some degreaser but am leaving it until it's fixed.

Sorry to hear. Same exact experience as well. I didn't bother to take a look at the part before it was repaired but seeing your picture now. They replaced the whole yoke assembly to fix the leak on mine. Didn't realize the original was painted / coated as pictured, mine is bare steel and already taking on a rusty patina. Oh well, Interested to see how they tackle your repair. Best of luck!