Originally Posted by jdback19
Isn't it a known issue with these cars that the diffs leak? I checked mine when I read about it and sure as **** there was oil on my diff. Sounds like you have a bogus service manager who needs to check the service bulletins.
I've read a lot of posts about leaking pinion seals in the Mustang's 8.8 rear ... and our 2008 was always showing drops of lube hanging under the differential snout and it was obvious that it was from the pinion seal. I also noticed a slight hiss as pressure released when I was removing the fill plug to check level .... and it always started oozing out which tells me it was over filled.
Mine is out of warranty so I bought a new seal to replace it ..... but before doing so, I tried a change in vents to something more inline with what's under my several other Ford vehicles that don't leak. Stock Mustang rear vent has a rubber disc under slight spring pressure inside the vent's loose cap. It's a small hole in the vent, so it will take more psi to open the check valve than you might think.
I made a vent that attaches a hose that has a loop and is then routed inside the frame so no water ingestion .... but there's no restriction in the new vent. I used a brass fitting with a 3/8" hose barb on one end, turned other end down to tap it to fit the threads in the axle tube (7/16-20 sounds right
). Clamped a short hose to it and a 3/8" copper tube with a tight U-curve in it, and then ran a piece of 3/8" hose from there down into a frame hole.
Not a drop of rear axle lube seen leaking since, the housing is now dry on the outside where there once was always lube hanging on.