Hi Jaguar lovers,

I am excited to say that I was able to check the fluid level of my 1997 Convertible XK8 differential this weekend.

This problem, which has been well written about in previous forums stems from the "lifetime" differential on the XK8. It's darned near impossible to get to the "fill" plug on the back of the differential.

I was seeing spotting on the floor of my garage from the differential, and didn't know how much fluid leaked out over the past 6 months or so that I didn't see while on the road. I did find that my vent was clogged up, so I bought a new one for around $30 bucks at the dealer and replaced it. You can get to the vent by removing the right rear wheel, and putting a 3/8" open end wrench on the vent and unscrewing it. I tried cleaning mine, but it was pretty sticky even after I cleaned it.....so I bit the bullet and bought new.

Anyway, I read about taking a 1/2 inch ratchet and grinding down to fit the 1/2 square differential fill plug receptical, but didn't have much luck with that.

I found (at Harbor Freight) a three pack of Pittsburgh "square drive socket caps" for around $4 that has a 1/2" drive that morphs into a 3/4" hex nut that is perfect to slip into the 1/2" square slot in the plug of the differential. (Item 67011) (skew 9236367011) This allows you to use a 3/4" open or closed end wrench to twist the plug out. I used a closed end wrench to break the plug loose, and switched to an open end 3/4" wrench to unscrew it the rest of the way out. You have a spring loaded nub on the 1/2" square socket cap much like on a regular ratchet that holds the socket on. I had good luck grinding the spring loaded nub off to help insert the square end into the square plug receptical You don't have a lot of room to push/ pull anything up there so anything to make the square drive slip into the square hole is a help.

I used a stick magnet to put the plug in position and used a screwdriver to push the plug into the square hole in the differential fill plug. It is much easier to access the plug with the car on jack stands with the right rear wheel removed. The plug is on the right rear, lower portion of the differential partially blocked by the differential support frame. When the cap is in position and inserted into the fill plug, you can access it with a 3/4" wrench from above and behind the differential. It's slow going with about a 1/6th of a turn per readjustment of the wrench. A ratchet wrench may be helpful, but it will not be able to be removed after the plug comes out about half way. I started with a box 3/4" wrench and finished with a 3/4" open end wrench.

I was concerned that the differential fluid was low, so I had used the removed vent opening to put some more fluid in. Better to have too much than two little I thought. When the plug came out, there was some fluid that came out with it, so I knew that I had a full differential. Now I know that my fluid level is not low.

Re-inserting the plug is a little more trying, using the stick magnet to put it in position and using a screw driver to hold it there while I used the wrench to turn it untill the threads caught and it started to thread in. It was pretty easy then to tighten the plug back into position, put the tire back on and lower the car back to the ground. Took me about 2 hours to do, and I could probably do it in an hour now that I know how. Good piece of mind knowing my differential fluid level is not low! If you need pictures of the cap and differential plug, e-mail me at and I'll send some pictures.

 

Very good info. Do you have any pictures?

 

Naperaeroal, Thanks for the update! I believe I followed the same path but got the tool from Sears since I didn't want to wait for shipping. (Shown inside of the Diff fill-plug). As you can see, if you grind another 1/8" off the length of the tool it will sit flush in the plug and you will have that much more room to back it out but I managed as is. In addition I removed the sway bar bolt and swung the bar up out of the way. I started out with just some 1/2" non-tool, square stock but my plug was so tight it was twisting when I would push on it with the wrench. This tool did the trick.

In addition I took a shop vac and duct taped some 3/8 hose into the end of the large vacuum hose and sucked out the fluid and replaced with the $90 Jag fluid..ouch! But good peace of mind knowing it is full. I will check it annually now.

 

Useful info thanks guys!

Naperaeroal I've taken your email address out, just in case you get flooded with spam.

 

Here are a few pics of the socket cap plugs I used to access the differential plug on my XK8. About $4 from Harbor Freight Tools.

 

Thanks for that Tool Time Tip!!!
It worked great.
Charlie

 

+1 on thanks for the tool tip. The cheap HF set would be perfect for grinding away guilt-free!


Two other options: Gear Wrench set #9230 looks nice and has a thumbwheel feature. Proto offers these with either metric or SAE sized hex heads (#JHAM4S and JHA4S). While it may not be all that useful for the diff plug job, both GW and Proto have quick release buttons.