Hi Guys, looking for some real techie advice on how to proceed with the trans ( gearbox) for my '99 4.0 XK8 with 50k on odo. I understand valve body problems which I have, Ft drum problems I do not have yet. I can see how the drum explosion can be caused by valves in the body sticking as when it acts up the up shift are radical and very hard.
My observations. When the eng/trans is hot. It seems like the valve in the body sticks till additional pressure is applied, then wham. If I baby it and careful getting into 3rd w/light acceleration she is fine.
I had the fluid and filter changed. Technician stated fluid in bad shape, burned, no heavy partials in pan or filter. I know not all fluid flushed. ( power flush which is another topic of benefit verse damage)
Trans acted strong for about a month. Now slowly creeping back to conditions stated above. What would you do. Thank you, Rich

 

The valve body bores may be worn. You can try swapping the main pressure valve for the updated version, but a rebuilt valve body may be required.

http://jagrepair.com/images/AutoRepa...%20ZF5HP24.pdf

 

Take a look here

https://www.jaguarforums.com/forum/x...ng-kit-146100/

 

That kit is interesting, and may be better than the ZF valve, but it's hard to quantify since it hasn't been in use for very long. The best choice is a new or professionally reconditioned valve body, but that takes it out of the DIY realm that so many of us favor.