Hi all.
Since buying this XJR 4.0 its been plaqued with issues revolving around the electrical system and mainy the Merc auto box.


After many hours over many months i THINK ive resolved them.......
however, the car is just on my driveway for now and its very slow to select the gears, as if you were very slowly letting the clutch out on a manual car. it will rev like hell then slowly creap away.....


im also quite sure its not changing up through the gears as a test drive last week showed it wasnt going above 3rd gear....i think...50mph and 4000rpm.....


No error code are showing, the box is correctly filled with ATF........i think its just had it...


Has anyone had simular faults with their box and how was it resolved, will a full overhaul be required??

 

That sounds like low fluid. Do you have a dipstick.

 

yes mate, and its been checked at the dealers, its as it should be as far as fluid goes..

 

I would expect a problem with the conductor plate speed sensors and solenoids would result in a code and reduced performance. Considering how reliable the Merc is, the least expensive way to solve the problem might be to replace it with a used unit at a independent shop.

 

i have another unit, its got 153k on it and its condition is unclear.....but of course the dealer that sold me it swears its spot on......even after i caught him out lying about the milage, he advertised it as 78k, but i then bought the dash clocks that showed its true milage!...it looks quite i big job to swap the box and im just getting too old for that kind of thing.
there are no codes showing, it just isnt performing right........

 

I'd want to check the fluid myself, not take someone else's word for it.

 

I have, several times and i was there when it was dipped at the main dealers....the fluid isnt the issue ...as i posted in my main post!

 

Your symptoms are similar to mine when I had to replace my stretched gear selector cable. I would put the car in "D" and have delays and it would shift thru the gears with very delayed/slow shifts. On the cables last legs it would not shift past 1st gear and feel as you described ''as if you were very slowly letting the clutch out on a manual car''. I never got any fault codes just drivability issues.

 

See my post and video links as Jagpilot in the Benz World Forums. The C280 and the XJR have the same 722.6 transmission. The fault lies in the valves. While you are at it change out the electrical conductor board and the transmission harness adaptor.

See: 722.6 Gearbox issue - Mercedes-Benz Forum

I did my transmission valve & valve body clean up this weekend on the Mercedes and the tranny issue was resolved.