what happens with your car if you put it in D when you are stopped on a slight angle / slope?
will it go by itself forward, without pressing the accelerator pedal? or just stay put because the incline is too much for it?

someone was telling me that if your car moves forward then it means the gearbox is good. if it doesn't move, then maybe there are some issues with the gearbox.

did you guys hear anything like this, could it be true?

 

That is not a great way to begin diagnosing your gearbox condition.

I leave and drive in coastal California region known as "earthquake county" with countless hills.

The vehicle creaping forward on a hill is based on the IDLE RPM and the % incline... and yes if it's a 250kMi gearbox then it'll have more internal losses.

You should learn to recognize how well your gearbox is doing it's up/down shifts :

• Best shifts are short + seemless.
• Poor shifts are long + banging.

Given 1000.Miles the 722.9 adapts perfectly to predictable shifts. You may not be able to get great conditions then take it easy on your gearbox. Else heat cooks the seals that leak ATF pressure.

The best thing you can do for your 722.9 is shorten service interval according to City or Hwy driving.
The so called "filter" is a course strainer unlike engine filter. Clutch particulate is a non-magnetic abrasive... not exactly a lubricant when mixed with thin ATF.

See your user manual reference or service advisor for schedule.

Beyond necessary OE ATF viscosity, poor shift quality are caused by external conditions :

1. Busy CAN-C network cause delays
2. Laggy throttle directly impact gear selection
3. The 722.9 smart boxes are GREAT

My opinion is respect your tranny without abusing it with high heat so it can serve you well.... deal with the engine.

 

Yeah , I have heard it before too . You should be feeling a rolling forward when you engage in D . It's torque converter doing its job as I recall . Well, I engage HOLD when shifting thru the gears on the hills or declines because I know it's not good for the tranny to roll downwards on slip hills at all,

 

Entirely depends on how steep the slope is. Because of the torque converter, the drivetrain is never fully decoupled from the engine, so the fluid slushing around in the torque converter always transfers a little bit of torque at idle rpm. If that torque is higher than the friction and forces pulling the car down the slope, then it will slowly move forward. If it's about equal then it will stay put and if it's smaller, then the car will start rolling backwards down the slope. Always assume there's nothing holding the car on the slope other than the brakes. Not sure from the top of my head if the W212 has Hill Start Assist. This feature will temporarily hold the brakes for you, so you can move your foot to the throttle and start on a steep slope w/o the car rolling backwards. There's also the manual HOLD feature where by stabbing the brake pedal after coming to a full stop, you can engage HOLD, which will stand on the brakes for you while the car is stopped and then release the brakes automatically once you step on the throttle. The word HOLD will light up in the instrument cluster if it's engaged.

 

not a test anymore then stomping gas at redlight and asking engine for full torq to get full acceleration.

IN the old days if you had a manual you could test clutch by putting bumper against big A$$ tree.
Putting car in highest gear and slowly let out clutch.
If engine dies then clutch was still grabbing.... if it kept running then clutch was slipping and hurry up and press in clutch to keep it from burning up worse so you can drive to mechanic.

 

Side note question on the 212 trans now that many are accumulating lots of miles along the years: what is a generally good interval for a trans oil change for a car regularly driven in the city? Sure, mixed with hwy miles, but a general-use car that sees >50% city streets? In the interest of increasing gearbox longevity ...TIA, all!

Edward

 

mercedes recommends every 4 years / 60k km. but changing earlier does not hurt