My "08 VDP, 118 K miles, has suddenly started having hard shifts and hunting for low gears. Seems to be resolved as the car warms up, but it is a startling change from the silky-smooth operation I'm accustomed to. My previous X350 stacked up a lot more miles with no transmission issues, so this is quite a surprise. This has been an instant onset, no warning. No CEL, no other alerts.

Anyone with similar experiences? General guidance? I've done trans fluid changes in previous X300s, but this is a real puzzler.

 

1.rear wheel speed sensors ( together with abs dsc speed controle issues) can be one of the culprits causing trouble to the transmission.
2 Low oil level inside the transmission is a major impact.
have a look at the pan itself and at its electrical "connector sleeve" inside tranny) plug for oil loss .
check at radiator left side of car (2 trancooler lines going from left side of tranny to the front then upwards between engine and radiator where it is attached tho the left side of the radiator) those lines are part alu ,part rubber hose and can leak at that joint.
Tranny is ZF6HP26 required oil is Zf lifeguard 6
level procedure is :
rised Leveled car filled with tranny oil engine started , then going through all the gear positions (slowly )at the lever and back to P with your foot on the brake constantly.
open filler hole hole continue filling till it is leaking out... until Oil temp is 40- 50 degrees celcius slightely dripping... level is correct

 

Inner parts bridge seal tube seals and connector sleeve that can be changed during a normal oilchange.
1068.298.062 is a Zf oilchange kit 7 liter pan filter magnets screws
videos are available " zf6hp26 oilchange and level procedure"

 

Thanks for your thoughtful response. I have ZF fluid on hand from my '05, so I'll start by checking all those leaky possibilities, then add fluid if it seems justified.

 

A short 90 degree hex key to open fillerhole right side of tranny barely 2 inches above plastic pan very near to the exhaust

 

Check you have P1111 and then also check fuel trims as engine issues can upset the trans.

 

It took a long 12 hour day, but after removing all the plastic underbody shields, etc, I discovered a loose connection on the transmission cooler line where it exits the radiator. After drying everything off with paper towels, the drip showed up, and the flange nut was actually finger tight. Or perhaps, finger loose. It was too far up for me to actually touch it with my fingers, but the open end wrench showed how loose it was. I was concerned that it might be stripped, or otherwise faulty, but it snugged right up and seated the pipe. clean and dry. I had 2 liters of trans juice, one from JLR, and one from ZF. I used a 25CC syringe with 6 inches of plastic hose, and sent it all in through the filler hole, and it was still not overflowing. I'll check around town for some additional, before I order any, but the trans is definitely happier now. 2L plus is too much to do without.

Side note: Send the car up on the lift, work underneath. Then drop car to crawl in and start the engine, Send it up again to get underneath and find leak. drop car to crawl in to turn off the ignition. raise car up to work on the problem. Rinse and repeat. I lived without a car lift for decades, but now I can't imagine how.

 

Oh good one.
if you open just the drain hole of the tranny there is about 4 liters coming out then close it . Refill with fresh oil. Then the level procedure.