1998 Silverado, Z71, 8.5 ring gear, I had the rear differential rebuilt 1.5 yrs ago, by a transmission shop. This rear end never leaked prior to the rebuild. The transmission shop has replaced the seal three times since the rebuild. These seals begin leaking within 400/500 miles of replacement. Upon removal of the replaced seals there was no physical damage to the rubber seal, nor the pinion shaft itself show any grooves worn into it, making me believe they were installing a seal for a 9.5 ring gear in which the internal diameter of the seal is 2mm larger. This past visit, 3 weeks ago, I presented the replacement seal which was for a 8.5 ring gear. They hopefully installed it, but, it began leaking again, after a couple of long road trips. The rear differential was rebuilt at 278,000 mi. with no leaks, now currently has 311,000 miles three seal replacements and leaking. Any ideas?

Signed, " Tired of placing drip pan under rear of truck."

 

Sounds like it's building up pressure. Make sure the housing vent is working properly. Do not over fill the diff housing. My money says it's a blocked housing vent.

Regards,
Junk

 

96JunkThatMoves:

Thanks for the information/help: Checked it today, end cap was loose to the touch, removed hose from differential housing, blew air through line and out the end cap , probed the vent tube on housing, no restriction nor resistance.

Duckhawk

 

what seal are they using aftermarket or OEM? was the pinion gear replaced also?

 

After market, O' Reilly, next door, watched manager walk there for purchase. Not sure about the pinion gear being replaced there was no reference of it being replaced. I will ask today!

Thanks, Dave