Of course, just as I fix my oil leaks on the engine, I think I have a leak in the rear end? DOH!
There is a drop or two of oil directly under the area behind Right Hand side inboard brake, where it joins up to differential.
Is this the differential axle seal? I assume differential rebuild is necessary? I’m hoping to do a drain/refill of differential and hope for the best right now.
It’s probably a diff output shaft seal. Differential rebuild is not necessary, but if you really wanted to fix it, you’d have to pull the dif and pull the output shafts, which are just held in with flange and bolts.
Then you either rebuild the assemblies yourself, or send them off in exchange for freshly rebuilt ones, I believe Coventry used to do it. I don’t know who does it now.
There’s an old thread of mine on here somewhere I asked @Dick_Maury a bunch of questions about output shaft assemblies, as always, his answers are worth reading.
I rebuilt mine myself, setting up float, installing new seals, all that, but I had dad looking over my shoulder, he has done it a few times. It’s not hard, just tedious, like everything else. You need a couple of specialty tools, in particular a giant socket to takeoff the big nut that holds everything together.
Then, of course, you have the IRS laying on the floor in front of you, so I deep down that rabbit hole do you want to go for new bearings seals yada yada.
You might even be able to do output shafts in situ, but you’re still taking everything else apart to get enough room to work, so I just pull the IRS.
If it were mine, and it were just a couple of drips, I’d ignore it until I was ready to bite off the IRS refurbish. And I definitely wouldn’t tear into the differential itself unless it had a problem. Don’t rebuild the differential just for the sake of rebuilding it.
My .02
Bob
Actually, the side axles can be removed in the car without dropping the rear suspension. Remove the shocks, trailing arm, halfshaft, caliper and rotor. Make note of the shims for alignment so they can go back in the same place. Axle is held onto the diff with 5 bolts. On the 1989, they should be self locking bolts and not wire tied in place. If you drop the rear, you still have to remove the caliper, rotor and halfshaft so not any time saved. This way, you do not have to mess with the exhaust or driveshaft.
Thanks, although from what I’ve read here, removing inward brake calipers/rotors without dropping irs is such a pita that most think its easier dropping the irs?
I do want to eventually go down that rabbit hole, so i may see if i can nurse it a couple years. I have the dana without drain hole, so have been pumping out as much as i can in the past. I am going to try removing diff plate a bit so i can get as much old oil out? May even tip car side to side to help. Also, ive been using synthetic. Should i switch back to dino oil?
If you have the Dana, everything is different. The output bearing assembly is held on by 3 bolts, not 5. The output bearing and seal assembly is completely different than the Salisbury. Parts are hard to get.
I’d clean things and see where the leak is from. It may just be the oring between the output bearing assembly and the case, rather than the outout shaft seal. That’s easy to change once the caliper and disc are off.
This thread on another forum will probably be everything you ever need to know about the Dana.Dana demystified
Thanks. Will do, thanks for the info. Not in the mood to climb under jackstands for a few weeks, so may move my drip pan to the back of the garage until summer. 
It’s so typical for these cars though. I literally solved all oil leaks for the engine. And now this. I swear Jaguars have to leak oil to exist.
I read somewhere in archives that non synthetic is recommended, so may try that.
And if i ever dropped my irs, I’d probably switch to a Salisbury diff setup, and go 3.54:1 (one day I’d like to put in a 5 speed manual trans). And i dig the inboard brakes.
Changing the fluid won’t stop a leak. Synthetic is fine, and most no cotain limited slip additive, so you don’t have to add anything.
If you go for a 5 speed, 3.07 is still way too long. I put a 3.54 in mine, and 5th provides a nice cruising RPM, basically the same as the late cars with the 4L80 4 speed automatic in 4th. The late cars also used the 3.54.
So many consider, and do, swap the automatic out for a 4 or 5 speed manual, personally, I’m not racing anyone, so I prefer the 3-speed automatic.
If I want to drive fast, just pedal-to-the-metal and the XJS provides that “go fast” thrill. Makes the other cars on the highway look like pylons in slalom test drive.
Besides, I’ve had bad knees for 20+years, so I stopped driving manual transmissions back then.
Greg,
Having done that, I would consider doing it in situ only and only if (and that’s still a big if) I had a lift.
Otherwise be prepared for a week in hell on your back at the floor of your garage… and undoing those calliper bolts is much easier said than done.
Definitely drop the cage, undoing the exhaust and propshaft is a small price to pay, and considering the amount of work involved do it all and properly.
Not something you want to be doing twice.
Mind you, my car failed inspection because one brake disc was covered in oil.
If you want to buy time maybe put some leak-stop product that softens the seals?
I did that on my transmission, it did stop a small leak, and two years later is still ok.
Thanks for the responses, in a couple weeks I’ll be taking off the tie plate and have a good inspection. Maybe I’ll get lucky and my fill plug is leaking!!! I can dream…
Will also allow me to unbolt the diff cover just enough for a proper drain.
With the Dana diff, the caliper bolts are much easier as they bolt to the diff housing instead of the caliper housing. They are accessed through a hole in the brake rotor so you can use a socket and an impact wrench. If your brake rotors are wet, check the calipers for leaks. The Dana diff uses two o-rings to seal into the diff housing instead of 1 like the Salisbury diffs. The bearing is a sealed bearing with seals on each end. I have seen them go bad but have yet to see one leak. If it were to leak, it would probably be a bit of grease as it would take both seals to fail before the diff fluid could get to the outside.
Thanks for all the valuable info. I don’t have time to inspect this weekend, but I’ve noticed the leak has stopped.
Where is the vent on the Dana? Because this may be a coincidence or the cause - a few days ago I jacked up the left side of the car a bit high using the jack point behind left front wheel. Both left tires were off ground. After that, there was suddenly a few drops of diff oil on right side from right side of tie plate. Over the last couple days, it’s just been a drop. As of yesterday, no drops at all.
I know the fill plug is on right side. Perhaps it is not in tight enough? I remember i had issues getting it to stop leaking when i changed oil last year. Eventually it stopped. I put nothing on threads.
The vent is somewhat above the fill hole. Rear gaskets are prone to leak but this will not get on the discs. There is a vent on the inside so the splashing fluid will not leak out throught the vent. Check your brake fluid level. When a rear caliper leaks, it can bring dirt down with it and appear as oil.
Thanks, I am certain it’s diff oil. It was thick, and had that distinctive smell.
Isn’t it great when things fix themselves?
But then what would we do with ourselves?