Diff oil change

[paulXK8]

Finally getting round to changing the diff oil in my 2005 XK8 convertible (59000 miles). I know it's meant to be filled for life so no drain plug but it can be pumped out through the filler plug. The problem is where is the filler plug? I expected it to be about 3/4 of the way up the rear of the unit but I can't see any plug there. The only thing I can see is a vertical hex plug at the top of the finned alloy rear casing which has a loose metal cap which can be turned. I suspect this is the breather. Is this also the only access for filling? If so how is the oil level checked? The correct amount is 1.8 litres but pumping out is unlikely to completely empty the unit. Any advice gratefully received.

[Astromorg]

'Fraid you'll have to look more closely, because it's where you think it is! - 3/4 way up the rear cover.

Accessibility seems to vary slightly from car to car, but it's always awkward. I have a dedicated piece of steel, 1/2 x 1/2 x 1 inch that can be manoeuvred into the square recess in the level plug and then turned with a 15 mm ratchet spanner. I also take the precaution of attaching a length of string to that piece of square steel to rescue it from the depths of the A frame when you drop it or it falls out (It will happen!)

Some have made access easier by cutting a hole in the floor of the boot that can then be covered by plate or grommet after use, but there does seem to be some doubt as to whether it can be done in a later car. Here's a couple of links about that with photos.

http://www.jagrepair.com/JaguarDifferan ... Change.htm

https://www.jaguarforums.com/forum/xk8- ... fferential

Specified oil is Shell Spirax Super TS90, but availability seems difficult. Castrol Syntrax 75W 140 is a good alternative.

Later Edit: 75W 90 might be a closer match than 75W 140

[paulXK8]

Thanks for the info. Problem with the hole cutting technique on my 2005 vehicle is that to get it high enough in the boot to clear the stabiliser bar you would remove one of the the fixings for the battery connection box. The set up is a bit different from the one in the pics. I suppose the box position could be altered to accommodate. For the short square bar technique the anti-roll bar would need to come off. Getting the plug back in looks even worse than getting it out.
No fluid dripping from the diff but there must be a seep as there is oily dirt below it, so I need to get into it sometime soon.

[mike020150]

Don't give up! It can be done with a knuckle-scraping combination of 1/2" drive adaptors etc. Some of these tasks should be meted out as punishments to cavalier designers/engineers! Mike.

[paulXK8]

Gone for the hole in the boot technique - works on my 2005 XK8 convertible if you get the hole in the right place - top of 50mm hole right up where the vertical of the boot goes horizontal and the right edge of the hole just to the left of the stud which holds the power connector box (pity I got it slightly wrong first time .......). Only thing is you have to go through the bracket plate behind also. However this wide bracket plate looks like it horizontally stiffens non-structural things behind the rear wheels by connecting the boot to the rest of the floor pan through two light diagonal struts, so a hole is not going to affect it. Once you have the hole a wobble extension set up goes straight onto the filler plug. Large extension needed to get enough torque to loosen it. After this 1.7L of blackish fluid sucked out and refill done with a funnel and tube. Not quite finished yet as had a little fluid spill so need some more. Will fill hole with sealed plastic plug. Drilling holes in your car is perhaps not for everyone but my mind is at rest regarding the diff.

[doug424]

Hello everybody.

Over the years I too have considered how the change the fluid in the differential, and after lying under the car pondering how to do it came to the conclusion that with the diff in place it was impossible.

Luckily, fate intervened and the fuel pump failed, replacement being another impossible job as the fuel pipe unions to the tank are only being accessible with the differential removed. With such fortuitous luck now coming my way, this was the opportunity to carry out two impossible jobs.

I’ll not go into how I did it as I think it has been covered very well elsewhere. Since I had the rear of the car in pieces, I did at the same time wax all those places it is not normal to access, replace all the bushes on the rear suspension, had all the parts that came off shot blasted and Hammerite coated and replaced the fuel filter.

Not using the Jaguar very much it did not matter that it took me weeks to do and having a large heated garage I could work regardless of weather and light.

I consider both jobs total swines to do and all the access problems could have been designed out. Two first class examples of bean counter engineering.

I have attached a few photos which may help.

Good luck everbody.
Doug Barrass.
Ashford, Kent.

[Andy P]

Well done on doing all that work Doug.
Other people might not be able to see the results but at least you know it's all good under there.
Take care.
Enjoy your Jaguar's.
Andy