Originally Posted by 8bit (Post 2027018)

Have you tried changing the expansion tank cap?

Originally Posted by riverman (Post 2022934)

Having just completed a coolant pump change in my 2010 XKR, the latest revision I found was AJ813909. After a couple hours research looking for the hard (brittle) tube (B in graphic) and the little Y shaped part number (A in graphic) connecting the pump bypass and the throttle body to the heater return, I realized the design had been changed to a simpler and more reliable configuration. The Y part is no longer available, nor is the hard tube. They are replaced by a new design that has a thick rubber tube coming off the large coolant tube (C in graphic) thermostat to upper manifold. As my car is a daily driver who has put about 60k of the 120k miles on my XKR, I try to minimize unecessary downtime. As I do my almost all of my own mechanical work, I would definitely recommend at a minimum changing those parts (for about $100 US) and save yourself the extra hours of labor that will be needed when they deteriorate from the inside out simply due to age. The new design requires replacement of the large coolant tube and the Y part, but eliminates the brittle plastic tube, and you get a new plastic bleeder connection to plug into the coolant pump, which is another common failure point that will cause you to have to go to the new design.


https://cimg5.ibsrv.net/gimg/www.jag...63fc16c7fc.png
OLD DESIGN - 5.0 S/C
https://cimg8.ibsrv.net/gimg/www.jag...16f79a0f35.jpg
NEW DESIGN - 5.0 S/C (you can just see the new grey colored "Y" part at the top of the picture.)