2003 GMC Envoy 4 cyl Four Wheel Drive Automatic 48000 miles
While I was driving I heard a grinding noise and the truck stopped moving would only drive little. Had it towed to the dealer, and found out that the front differential had no oil. Due to a leak in the pinion seal. Now I had reported a leak 6,000 miles ago (from front end) and grinding noises they wrote it off as a leak from front axle seal and a front hub. Now was this just an over sight on their half?
The axle seal and thefront hub are two different things. The seal--seals in the front differential lubricant. The hub is a sealed unit--totaly seperate from the axle seal. The hub is the unit that your wheel connects to--lug nuts screw to the hub studs.
The pinion seal also seals in the same front differential lubricant that the axle seal does.
Did they fix the axle seal and forget to put in differential lubricant--probably. Will they tell you this--probably not. However you can ask them this--When you found the axle seal to be defective and replaced it did you fill the differential with lubricant? They will say--we sure did. Then ask--Well if you did fill the differential with lubricant, did you see any leaks of the pinion seal? They will studder and beat around the bush. You see the differential fill hole is right next to the pinion seal. The differential holds around 3 quarts of lubricant. It is absolutely impossible for any mechanic to miss a leak of that size.
In order for you to run a differential --to the point of almost seizure--in such short period of time (6000 miles ago) you must completely drain the fluid out. Even if the pinion seal was leaking a lot, there will still be some fluid left in the differential case due to the design and location of the seal.