ML63 - Autotrans jerk / 4 Matic?

[Badvgood]

ML63 (2007) W164 with the M156 Engine and AMG Speedtronic 7G-Tronic Gearbox (4Matic?)

Symptom:

Cruise control on so steady throttle application (happens without cruise on also), cruising at 70 mph, engine speed 2150 RPM constant with dry smooth motorway conditions.

When you come to a long gradual incline, after a few seconds you sometimes feel a jerk, like a downshift but the gearbox stays in 7th gear.

Could this be a switch in the 4Matic power distribution? At 70 mph?

Other than this the transmission is perfect, no harsh gear changes up or down and all at the right times. No fault codes in anything.

Any thoughts as to what it may be?

 

[Stratman]

Has the transmission fluid ever been changed, or even the level checked?

 

[Badvgood]

Hi, not that I am aware of. I was thinking of doing it anyway so prob will do it sooner rather than later. Cant see how this would cause the symptom I have tho...

 

[Stratman]

Incorrect fluid level can cause all manner of problems, as can old fluid.

I don't know the correct procedure for checking the 7G box, hopefully someone who does will be along soon.

 

[zenman63]

Whats the milage?

Sounds like the chain in the transfer box jumping, cheap enough to fix, chains £100.