I know there are some other threads about rear differential leaks on this board. I had been noticing dark spots on my garage floor for months, but always dry. Convinced myself they were soot from the exhaust per conversion on those prior threads. Yesterday I happened to notice that the spot on the floor was still wet, and it definitely wasn't water. I'm not much of a gear head, but I'm pretty sure this is the differential, and I'm pretty sure it's leaking gear oil.

The round piece with the square inset there at the bottom is actually threaded on the outside. Is there supposed to be a cap on it? If not, what are the threads for?

Is there anything I could/should do to stem the leak and or refill this oil before getting it to the shop? They can't get me in for another week and it's my daily.

 

On further inspection, the seam to the left is the source. There's some kind of pliable caulk like material that I pushed on with a paper towel and squished out a good bit of oil.

 

 

Thank you, Lance. That's some reassuring news. Ok to keep driving while waiting for my appointment? Or should I get a rental car?

 

 

I have a half dozen spots that are all under two inches (because I obviously don't park in the exact same spot every time). I would also tend to think it's not a very fast leak because it was only two days ago when I found the first wet one. They had heretofore always been dried up.

 

Maybe the leak can be fixed by simply tightening up the diff housing bolts? Immediately to the left of the seal in the pic. Although I don't know the torque spec for those bolts and the top ones might be a hassle to get to. Worth a check I reckon, just to see if one or more have come relatively loose.

 

I will give it a go if someone could help me identify the torque specs.

Also considering getting a bottle of Castrol BOT 720 to add to the reservoir since I don't really know how long it has been leaking.

 

Whoever assembled the differential did a sloppy job of sealing the gasket. Don’t mess with it. It is a warranty item. They will probably replace the differential.

 

+1.

 

A couple more photos. There is more than one leak. The gasket as noted previously is definitely leaking, but so is a spot further toward the front of the car. I noticed a wet spot on that crossing support, and while I can't get a great view above it without a lift, it looks like the pinion seal is leaking as well.

 

Are the differential leaks bad workmanship, bad parts or both? Are these why differentials are clunking and then being replaced or are these two unrelated issues?

 

Shop says it's the pinion seal only and not the gasket where the cover attaches. They topped off the gear oil for me and I'll bring it back when they have a loaner available for the seal replacement. I'm still of the opinion that there are two leaks. I guess we will see. At this point, no new differential for me.

 

I had the same issue as you in my ftype R. They replaced the differential under warranty. Known issue

 

It seems like mine has developed a minor leak in the diff now. Saw a small spot on the garage floor, and on closer inspection I found a drop of oil hanging from the oval flat part on the underside of the diff (easilly seen in the pick above).
Will take it to the dealer as soon as they have available time. Out of warranty, so this fix will have to come from my own pocket....

 

So my leak was in front of the diff at the pinion seal. Oil was essentially dispersing up over the top of the diff when the car was in motion, then settling down by gravity along the gasket seal when parked. I thought for sure the gasket was also leaking. They replaced the pinion seal and I've been parking over a clean cardboard box. No more drips.

 

My guess is that my leak is the pinion seal as well. From what I have heard/read, they have made modifications to the original seal due to a "not good enough" design.
The workshop/dealer will be in contact for setting a time appointment as soon as they have received the new seal. They did not have it in stock, but felt reasonable sure the pinion seal is the problem, so no need for them to inspect the car before ordering the seal.

 

My 2016 6S also had that small leak. Jut had it repaired. They said it was a pinion seal failure.

 

It would be interesting to know when this new seal design was introduced into production models

 

Sorry but I do not know. Had my seal replaced with a new one last week. Unfortunately after driving some considerable (and fun) distance over the weekend, there still seems to be a minor leak present.

Car going in tomorrow for further "investigations".

Edit: car is checked for leaks and the diff and pinion seal is 100% sealed and thight. What I thought was still a leak, was most probabely some "leftover oilspill" from the previous leak, that had ended up at places which he (the mechanic) was not able to reach. Some active driving in curvy mountain roads in very warm temperatures made the "leftover oil spill" move from were it was collected.