Hi all, I have owned my XKR for about 16 months and have known the diff was leaking shortly after purchase due to the oily mess around the diff mounting. After reading several posts on this excellent forum about the nightmare access to the filler plug, I have put the job off until last weekend.

You won't be surprised to hear it took me half a day to remove the plug! After removing the rear anti roll bar for better access, I ended up making a home made tool comprising a 1/2 inch to 1/4 socket adapter with a large L shaped allen key hammered into it. Although it fitted, the plug was so tight that allen key started to twist. I then got a 1/2 wobbly extension and ground it down round the edges and managed to fit this into the plug. Using a socket ratchet, it still wouldn't budge so I tried a medium size torque wrench. Still no luck so I tried my large torque wrench and on the 3rd attempt, the plug finally moved.

I had already bought a hand pump/sucker from fleabay to remove the old oil and was alarmed to find I could only get out .25 litres, yes only a quarter of a litre was left in the diff. I managed to put in just under 1.5 litres of 75w 140 Castrol synthetic diff oil, refitted the plug and cleaned off the mess. A week later, I have checked under the car and there is large amount of oil leaking from the near side output shaft. Yesterday I disconnected the half shaft and unscrewed the output shaft from the diff. On inspection, there are 2 different sized o-rings and what looks like an oil seal that's part of the shaft bearing to stop oil leakage.

My question is this bearing costs a fortune. Do you think just replacing the o rings will stop the oil leak?

P.S. I have already unblocked the diff breather.

 

I have exactly the same issue with a leak from the diff output shaft so I'm curious if you managed to fix your leak. I can see the two o-rings you mention in the parts diagrams but I don't see a separate oil seal, at least not for my 1998 XK8.

I've already tried fitting a new breather but it's still leaking.

 

If you remove the output shaft and look at the shaft bearing, it looks like it has an oil seal built in. The bearing (part no JLM20337) is a staggering £259!. I wasn't willing to pay this price so I just replaced the o rings.

I also disconnected the prop shaft and replaced the input shaft oil seal that was badly leaking. I topped the oil up but unfortunately have been unable to drive it yet due to sending my wheels off to be refurbished.

Hopefully, fingers crossed, just changing the o rings will stop the leak and once the wheels have been returned next week, I will drive it to work for a few days and check again.

I'll let you know the outcome !

 

Thanks for the info. Fingers crossed.

By the way, does the output shaft just pull out by hand once you remove the circlip or do you need a puller?

 

The shaft and bearing assy will pull out by hand. You might remove the diff breather on the top to see if it is stuck closed and causing the buildup of pressure, causing the leak.

I have posted this info several times about checking/replacing the vent assy.

The very thin 'O'ring on the shaft bearing is the one you will need.

I replaced one about 15 years ago and the car came back 2 weeks later with the same leak.

I found the diff vent blocked and replaced it. The car did NOT leak after that!!!!!!!!!!!
It likely did NOT need the new seal, just an open vent!!!!!!!!!!!!

bob gauff

 

The shaft will pull out once the circlip is removed but mine was very tight. However you will only be able to replace one o ring that goes around the bearing. The aluminium housing needs to come out as well as this also has an o ring around it which could be leaking.

I found it impossible to get to the circlip with the assembly still on the diff so I unscrewed the housing complete with the shaft then removed the circlip on the bench. I don't know what tool fits this so I just used a socket extension bar and tapped it on the ridges to unscrew it. I also marked it all with paint so I knew the right position when screwing it back in.

By the way, the o rings (JLM20451 and JLM20327) are silly money, about £17 each!

See the following link for some excellent instructions and pictures. Just ignore the parts for replacing the bearing.

http://georgiajag.com/Documents/V8Axles.html

 

I did hear some pressure being released when I removed the old breather to check it so I was optimistic a new breather would fix the leak but unfortunately no luck. I did notice even the new breather needed a little back-pressure before it pops open so there would normally be a little pressure in the diff casing - is this normal?