1999 Silverado rear axles are LEAKING. Any idea why?

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My 1999 Silverado 2WD rear passenger side axle was leaking last month so I had my local shop replace both of the axle gaskets on both sides since they were already doing the work, replaced the fluid with new Pennzoil 75/90 and new diff cover gasket.

For the last week they have both been leaking terribly all over my rims, I wasn't sure where the oil was coming from and today I pulled the wheels and brakes off and sure enough the axle gaskets are leaking. I purchased the gaskets at Star auto, any idea why they would be leaking...could it be bad axle bearings?
 
Big issue. I would take it to the shop and immediately request the manager. Take some pics. Something tells me you've got a fight on your hands but hopefully I am wrong!
 
Did you supply the parts or did the shop? If you supplied the parts you can fight all you want with the shop, any warranty claim will be with the store you bought them from. You may pay more using the parts a shop uses, but if there is a failure the warranty covers everything.
 
This rear axle design is notorious for wearing away the axles themselves where the outer bearing supports the axle. On a '97 2WD I worked on a while back with the same symptoms as you, we had to replace axles, bearings and seals.
 
UPDATE - I was present when the shop installed the axle gaskets and visually observed the install occur. The gaskets were provided by the mechanic which is good news. When they installed the fresh oil into the diff fill hole, the mechanic accidentally overfilled and it spilled onto the shop floor. He wiped it up and reinstalled the fill plug. When the axles were exposed they appeared to be in good condition. Not sure the issue however I will be taking the truck into the shop tomorrow so they can look into the issue for me, should be an interesting discussion. Will keep all updated.
 
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UPDATE -Shop pulled the wheels off and realized that my new axle gaskets have failed, which I already knew. They pulled the axles out, removed the faulty gaskets and replaced them with new ones. Made a new gasket with red RTV and added fresh Pennzoil 75/90. Shop Manager insisted that this happens from time to time and proactively said he would fix the issue. Asked if he recommended any other gaskets such as OEM and he wasn't to concerned about the idea. Worse case scenario if they fail again, I'm back at his shop again. Happy for now. Will keep this thread updated if anything changes.
 
I have been running into this a lot with GM parts. A lot of sub par China [censored], you really need to buy either actual GM parts or from a known good manufacture.
 
As a data point, the axle gaskets were delivered by Star Auto parts. If you are in the market for this type of part, I'd recommend not purchasing them from this retailer. Just my two cents.
 
The diff oil leak did not contaminate them, we were able to salvage the new pads, which was good.

UPDATE: Today I came home from a 5 day vacation to Las Vegas and arrived to my driveway having diff fluid leaked on the ground around my rear passenger tire. Shaking my head...called the mechanic to inform him and he was virtually scratching his head. He asked for me to bring it back to the shop on Wednesday for another inspection. He is however confident that there is something else happening and believes the axle gaskets are not the issue since he has replaced them two times. I'll keep this thread updated with the outcome tomorrow.
 
Quote:
He is however confident that there is something else happening and believes the axle gaskets [seals] are not the issue since he has replaced them two times.


Originally Posted By: beechcraftted
This rear axle design is notorious for wearing away the axles themselves where the outer bearing supports the axle. On a '97 2WD I worked on a while back with the same symptoms as you, we had to replace axles, bearings and seals.
 
Originally Posted By: MolaKule
Quote:
He is however confident that there is something else happening and believes the axle gaskets [seals] are not the issue since he has replaced them two times.


Originally Posted By: beechcraftted
This rear axle design is notorious for wearing away the axles themselves where the outer bearing supports the axle. On a '97 2WD I worked on a while back with the same symptoms as you, we had to replace axles, bearings and seals.




X2.

The two most likely scenarios in my opinion...

- Bearings and possibly axles are shot and destroying the seals from the get go
- Axle vent is severely blocked
 
Another UPDATE: The axle gaskets/seals used the first two rounds were made by Centric. The mechanic pulled the axle apart today and after taking the better part of the morning to inspect the rear end he wants to try one more set of axle seals, however this round he installed National seals. He thinks there may be an issue with the Centric product. IF the Nationals don't do the job then I will take the advice from @beechcraftted and replace the entire axle/bearings etc. Any idea what this complete should cost? The truck only has 82K miles and runs perfectly and looks great, so I want to get another 4-5 years out of the truck. Can anyone tell me where the vent is located?
 
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