I recently joined this form for insight into a problem I'm having with my XJ8 (2004, about 100k miles). I've read many posts - this is really a great site!

My problem is that I've been loosing transmission fluid for a while and began to notice minor gear shifting issues (hesitation, lurch, unnatural up and down shifting in the middle gears). It does not occur if I manually shift.

A month ago I decided to add a bottle of fluid. The issues seemed to go away but the leak went on. Now, after about a month of more leaking the issues are beginning to return. I want to fix the leak myself if possible but I'm not sure where it's coming from. I noticed oil collecting on the pan bolts so I figured I need a new pan and gasket. Now I'm not so sure because I noticed oil collecting on one rear transmission mounting bolt, just below the universal joint and on the side of the transmission that has the mechatronic sleeve just above it (see photo).

My question is, does anyone know where this ZF transmission tends to leak? I could just start replacing stuff but I don't want to waist money and time and am afraid that approach could create new problems (I'm not a great mechanic but pretty handy). Any advice is appreciated.

I know where to get more cost effective parts and fluids based on form posts but can't order stuff until I'm more confident about what's wrong. I know there is no leak at the rear seal where the tranny connects to the axel.

 

The most common location for leaks is the socket for plug-in of the telematics link to the ECU. Yours seems pretty bad, it is normally just a little weep of fluid.

The TCM is contained within the gearbox. There is a sealing sleeve around this socket that fails after a while, and has to be replaced. New ZF seals are improved apparently. Normally replacing this seal is done when the fluid and filter is replaced as the box has to be drained. Fluid replacement is a job best left to the experts, because you need access to the diagnostics package to determine fluid temperature. However, for those with the kit, it is possible but you have to be under the car to do it.

 

As above.


https://www.jaguarforums.com/forum/s...ics-faq-30991/

 

Thanks again for the help! The link from bydand to a 2009 post by CCC was a much appreciated and useful source of guidance.

I completed the work last night and all is good so far. I removed 4.5 quarts and pumped in about 7 liters. So, the unit was leaking for some time and was leaking more than I expected.

I think you were correct Frazer, the sleeve was probably the source of the leak. Also, replacing that was the hardest part. Between not having enough room to work and the new sleeve being very hard to insert (very tight, even after lubing seals), I struggled, cursed, and worried that something was wrong with my approach. But got it and I'm back on the road!

 

Another leak source are the transmission cooling lines. They tend to leak at the crimp points between the rubber and metal. Also, check both ends - at the trans and radiator as well.

I have a leak I hope to get to the bottom of this upcoming weekend as I have all the parts ready to go...

 

Ditto on the coolant lines, especially up front. Look at the crimps where the alum transitions to the rubber hose. I know what you mean on getting that sleeve in, I couldn't make it happen for the life of me, then my friend took over and just had the touch! W/e, as long as it's done!