As I said it would be real hard to damage that seal with anything they did. There is a labyrinth of parts around it and none of those would have been removed. They would have pulled the tires off. However the brake disk and the Pbrake drum would have been on. Under it are the shoes and springs like the last pic. The seal is where the arrow is. The third pic is where the seal goes at the outer edge of the tube. However if you look at the 2nd picture you can see the tone wheel that is on the axle. That sits down over the axle tube like a hat.
They wouldn't have touched any of that to remove the suspension parts. Just removed the tires for better access. Then for the air ride they would have shut off the suspension, released the air from the springs and replaced the shocks and added the metal springs. I have done a few myself on various makes with air ride when the parts are made of gold and a conversion is a under 300 to eliminate a host of problems.
I could see it if the leak was a rusted steel brake line as it would be easy to hit those and break a rusted one, but that would be noticed real quick and repaired.
I really cannot think of a way they could damage an axle seal without going into the housing and to do that they would have needed to remove the rear brake caliper, then the rotor, then drain the rear axle and remove the cover to remove the axle clips, then pull the axle out far enough that something could get into it, then put it all back together and refill the axle lube and put the brakes back together.
I could see if the tone ring and brake were all rusted that it might stick if the parking brake was applied. Then if the tone wheel was rusted internally a piece of rust could have broke free and fell just right to cut the seal, but I would think the seal is either worn out or cracked from age. I suppose the rear spring that tensions the lip on the seal could have broke and let it leak but without taking it apart myself to verify what caused the seal to fail, I doubt it was anything the shop did.
I have had more than a few similar situations, as have most shops. You put brakes on the rear of the car, the drivers door latch fails. Or you replace the parts that were causing the engine to run rich and as soon as the converter test runs it sets a code because the rich mix caused the converter to fail.
One thing I would do for the repair on that axle. Replace both seals and go through the parking brake with new parts so it works. Also check the axle bearings for wear, if they are worn it can cause the axle to move around and the seals can fail from the motion. The bearing uses the axle as the inner race and a damaged bearing can chew up the axle pretty quick and cause seal failure very fast.
Images (Click to make bigger)
Monday, February 15th, 2021 AT 12:15 PM