Okay, internet friends, I am embarking on the mission that you all cajoled me into - that is to take on myself any work that my XJS needs. So, that means I need some help. The first item for the Jaguar forum hive collective is the rear differential.

Any ideas where it is leaking from? As far as I can tell, the sides by the driveshaft outlets look dry, I can't really see any clear signs of leakage from the propshaft or end cover parts of the diff, yet there was quite a bit of oil on the diff undertray.
The oil looks particularly evident at the locations where the undertray bolts up to the subframe. I am hoping one of you XJS Gurus can point me in the right direction from these photos, as I don't really know what I'm looking at LOL!

I am about to change out the rear calipers and dampers, so I would like to get this done too at the same time before I dive into the front of the car!

 

It does not look to me as if it is leaking at all. The goo you see is old grease from the fulcrum bearings, and grease that gats pushed round the outside of the nipple when greasing. Otherwise it looks fine.
As far as the diff is concerned (rear brakes a different matter) I would change the diff oil, grease all the grease points (10 on the rear axle) and leave it at that.
Greg

 

I agree with Greg.

Oily "stuff" does collect on that tray, coz when that "special" mechanic removes the fill plug to check the level, some always leaks out, and over time it gathers to what you see now. Add to that, when he decides to "top it up" more dribbles out.

I would be cleaning the diff breather, RH topside of the end plate, whilst you are doing the brakes. They do clog up, and then the seals leak quick time.

 

Thanks guys, that is reassuring! $$$ Although I must say it does seem a little tough to swallow to me as there have been a few drips on my garage floor?

I did look at the diff cover, and it seems as though someone has been in there relatively recently (?) I will post a pic when I get home so that you can have a look. Perhaps it used to leak and was never cleaned up properly?

 

If the diff cover is leaking, then undo the securing bolts, clean up the mating surfaces, new gasket and a touch of gunk and refit. Cost almost nothing, apart from a couple of litres or so of Castrol LSD oil (important to get the right oil in there). eg:
CASTROL AXLE LIMITED SLIP 90 | Castrol Australia | Products | Home
But if the input or output shafts were leaking, that would be more complicated and expensive, but I still do not think they are the source, otherwise the output and input shafts would be wet with oil.
Greg

 

Okay guys, here is a better cover of the diff cover. Please let me know if you see any potential leakage areas. I didn't notice any oil, but I could see this funny hole near the diff cover periphery and didn't know if that was normal? You can see it in the second pic, inside the red circle.

 

Undo the diff filler plug and verify there is oil in there. If there is, I doubt you have a leak worth worrying about. In your position I would either take off the cover and reseal it, or just clean it all up, change the oil, do the things Grant advised to the breather etc, and see what happens.
Greg

 

I'm on it, thanks Greg!

 

Are you sure that it isn't carrying back from the gearbox?

 

I agree.

The other choices are 1) output shaft seals....which are no pleasure cruise to replace and 2) the pinion seal....replacement of which can bring big problems if not done 100% correctly.

I drove a Series III XJ6 for many many years with a slight diff leak. Every 3rd or 4th service interval I'd clean the area (30 seconds with aerosol brake wash) just to make sure the oil didn't migrate to the brakes. And, of course, top off the oil once in awhile---a few ounces here and there over time.

Cheers
DD

 

Maybe, I am new to all this, but the only oil that I can see on the gearbox is redish, and I had attributed that to carrying back from the next project that I have to do - leaking power steering rack (I think LOL) Obviously though, my car does have a few leaks, so I suppose at this point anything is a possibility?

How can I easily tell the diff between the XJS Power steering, Diff, and auto Gearbox oil?

The oil on the diff tray definitely smells a lot like the manual gearbox oil smell that I am familiar with, but I suppose diff oil smells like that too?

 

Sorry, just figured out how to do this (again!)

 

Ah, you've got me there although I think that they are broadly similar.
It might be worth giving everything a good clean, go for a drive and then get underneath again and see what's drooling.
Worst case scenario is that all 3 are leaking but at least you will know where you are then.
Anyway, a bit of oil on the underside keeps the rust at bay!

 

Yep, judging by the location of the red drips on my garage floor and the below pic I would say that the steering rack is definitely leaking, so it's at least that but maybe the transmission too. LOL, plenty to keep me busy over the winter! good job I'm enjoying it!

 

The rack needs a rebuild/replace by the look of it; but it could just be where the pipes bolt into the rack needs attention.

It also looks like the gearbox sump gasket might be leaking, but it could easily just be rack fluid getting thrown back there. I suggest you do the rack first and then see having cleaned up everything if the gearbox sump is really leaking. Almost certainly you have the same stuff (ATF) in both the power steering and the gearbox. Take a look in the PS reservoir and see how much is in there.
Greg

 

Sounds like a plan. I will get on it once I've sorted the rear.

 

Any ideas on how I approach cleaning the breather? It seems to have a spring loaded black plastic cap on it that I can spin around, but I can see no clues as to how to remove it for cleaning.
Or should I clean it in situ, it doesn't really seem to have any gunk or other debris around it from what I can see of the exterior?