Happy New Year All, I just bought my first Jaguar 2 months(2006 Xk8 with 20k miles) ago from a private seller in florida. I drove the car all the way home to my home in PA. experienced a smooth ride and very good fuel economy. No issues but also no hills. On my way to register the car, I have to ascend a long uphill that has a very minor grade to it. Near the top, I heard the car make a brief whirring almost whistling sound like it was trying to down shift.....a couple seconds later, same sound...no downshift but this time I got a message on the dash under the speedo about a transmission fault. After turning the car off, the message goes away.
I proactively replaced the transmission fluid and filter hoping the problem would be resolved.....it was not. Again, while going up a longer hill, the car made the whirring sound once, then a second time right about where you would expect a downshift in the transmission. Again, the message came up so I drove the car home and after turning it off, the message is gone.
Has anyone had a similar experience? I am pretty handy with cars and have watched a few You tube videos on servicing the transmission (replace plug adapter, valve body bridge seal, mactronic sleeves and fluid). All look to be very simple tasks. Any advice would be greatly appreciated. Happy Dave

 

Welcome Happy Dave to the ZF Transmission Twilight Zone. Much is awaiting you. You have made a good start in replacing the ATF and filter. But make ABSOLUTELY sure that the transmission was refilled to the correct level per the specified procedure (don't ask how I know). The next step is to have any residual transmission error codes read out on a scan tool. I too had the transmission fault message extinguish itself after my turning off the engine, but the original fault codes were still there in the system to be discovered by the scan tool (otherwise known as "the sharp pointy stick in the eye"). An excellent summary of the faults that might potentially be there can be found in:
http://jagrepair.com/JaguarXK8TransmissionTrouble.htm
Let us know what you find. Others, much more capable than I, might point you in the right direction. You might find similar woes in my thread:
https://www.jaguarforums.com/forum/x...ission-275636/
Just keep telling yourself: this is fun!