722.9 Auto box problem. No drive at all. Any help appreciated.

[Jobsworth]

And how difficult is to access the flex plate to unbolt it from the TC?

722.9, six bolts arranged in three pairs. Accessed from the gearbox side of the bellhousing through an aperture at the six o’clock position. On the 722.6 there are also six bolts, but 60 degrees apart and accessed from the engine side of the flywheel through an aperture in the sump, also at the six o’clock position

 

[Justintyme]

Very easy. Black cover on the bottom of the gearbox about 20mm by 50mm. Spin the engine on the front pully and undo the 4 bolts 14mm if I remember correctly. I know now as I've learnt my lesson.

Experience being the best teacher Brian....you would not be the first ( or will be the last either... ) to learn the hard way...I've done it myself many times.....but generally only once !!!

 

[Miller19]

Hi Iv read though all of this as I have a similar problem I have a 2011 c220 with 722.9 car was driving fine but aggressive changes from 3rd to 4th was driving home from work driving fine slowed down for a roundabout pulled away went into 1st 2nd 3rd then went to go into 4th and nothing just reving I was told high chances of it being the tcm so took it out send it off to be rebuilt, I got it back re rutted it and no change still only have 1st 2nd and 3rd if there any chance it could be the same problem? Thanks.

 

[G7Wagen]

Kudos to Jobsworth for the diagnosis and advice to the OP..
I helped a friend remove the cover plate and TC bolts on a 722.3 autobox.. on a Gwagen w463 to remove the box. My friend never explained why it was done this way.. now we all know why .
Every day is a school day

 

[blueikon]

Hi, Sorry to jump on here. we've got very similar symptoms on a 722.9 transmission but is not the pump gear.
Engine was replaced about 2k miles ago.
While driving suddenly lost all drive with no warning. Trans is giving no Drive at all.
Connected on to star and gives stored faults of Implausible gear/slipping for all ratios.
Star doesn't show an oil pressure option on the live data, but it is showing turbine speed so there must be oil pressure for it to spin.
1st gear engages, live data shows turbine speed increasing and TC slip reducing to nil as the accelerator is pressed.
Wouldnt have thought it would be the control unit with giving some codes
Any ideas anyone before i pull and strip the box??

 

[Jobsworth]

How do you know it isn’t the pump? The turbine spins on a spline drive directly from the torque converter. It doesn’t need fluid pressure for that. The fluid pressure is used to lock the various clutches and engage the gears.

 

[blueikon]

How do you know it isn’t the pump? The turbine spins on a spline drive directly from the torque converter. It doesn’t need fluid pressure for that. The fluid pressure is used to lock the various clutches and engage the gears.

Yes you're right, it would still spin. I'm thinking of torque converter lockup when it applies fluid to the TC.
Anyway, it is engaging 1st and reverse so must have some pressure from the pump. is it enough pressure? Annoyingly no way of seeing on Xentry that I can see.

 

[Jobsworth]

If it was engaging 1st and reverse you would have some drive. If you jack up the rear so the wheels are off the ground do you have 1st and reverse? Even if the clutches are slipping you’ll usually show some forward and reverse motion on the rear wheels if they have no load. If it doesn’t turn the wheels forward and reverse jacked up I’d suspect the pump

 

[blueikon]

If it was engaging 1st and reverse you would have some drive. If you jack up the rear so the wheels are off the ground do you have 1st and reverse? Even if the clutches are slipping you’ll usually show some forward and reverse motion on the rear wheels if they have no load. If it doesn’t turn the wheels forward and reverse jacked up I’d suspect the pump

I'll have to jack the rear in the morning and check. Xentry is saying it is engaging the gear. It has a gear requested and gear selected in the data.
How it is determining it has engaged though? just from an open solenoid perhaps? I know there is a pressure sensor on the valve body, but what is it using it for if not to throw faults or determine if there is pressure and the solenoid is open for a specific gear.
Xentry really is pretty useless on these 722.9 transmissions.

 

[Jobsworth]

In the absence of any drive you can disconnect one of the lines that goes out to the oil cooler and run the engine. If no oil is pumped out either the transmission has no oil in it or the pump is defective

 

[blueikon]

In the absence of any drive you can disconnect one of the lines that goes out to the oil cooler and run the engine. If no oil is pumped out either the transmission has no oil in it or the pump is defective

I managed to find in Xentry where it gives you details on some of the solenoids. (Hidden under a module that the vehicle doesn’t have)
There is definitely oil pressure there although is 2bar enough for hydraulics? I’ve tried to find the correct operating pressures everywhere to no avail. That’s only like 30psi.
Engaging and disengaging D changes the pressure and values on the first solenoid but no effect on the second

 

[blueikon]

Found it in WIS. Pressure is regulated to a maximum of 8bar.
Is 2 bar showing at regulator solenoid low pump pressure or a valve block fault?

 

[Jobsworth]

Have you removed the sump and checked for blocked filter or drawing air from the filter O ring maybe?

 

[blueikon]

Have you removed the sump and checked for blocked filter or drawing air from the filter O ring maybe?

Sump removed, Filter OK, Filter O-ring fine and seated correctly.
No debris in the oil, still blue/green with just a little fine material on the sump magnet
Removed the Valve Block, stripped it. no debris or anything untoward in the block. Tested all the hydraulic valve movements against another valve block. All look ok.
Metered all of the solenoids. All showing 4.6 Ohms with no blocked meshes.
Next job will be to pressurise the clutches from the sump to check for any that don't actuate or audible leaks

 

[Markypuk]

Mercedes 2012 W212 E220 212 7G Tronic 722.9 No Drive diagnostic Fix / Fixed

As Jobsworth said mine was also a Primary Oil Pump problem

The last owner had split the engine and to do a cam chain replacement although I have not took the box off untill tommorow I have been through Star and adapted his atempt of changing the ISM / Electrical/Mechanical gear changer

How wrong he was after hours of diagnosis with Star i have learned there is nothing to tell you that you have no oil pressure!!
The unit will only tell you oil Temps which come in handy for setting the oil level at 45 degres

You are able to split the auxilary oil pump and refit the pump and valve half only and energise the pump with 12v

The pump situated with one bolt and energised will give the gearbox the pressure it needs to perform its actions..
Plug in the aux pump circuit board back into the original pump plug and socket.

One energised you will hear the pump.
Go through the gears with foot on brake, Drive To Reverse and back to park a few times and purge and bleed the system
You will then feel the car dropping into gear and then regain movement.

This is a fix to satisfy yourself about Primary oil pump concerns I wouldnt suggest running the aux pump for anty considerable time thats not is job..