Hey all!

I've had an issue with the transmission ever since I got my car. The car is a 2017 W205 c220d with 7-G tronic. Here is what happens:

Sometimes (frequently) when I am on 1st, 2nd or 3rd gear and accelerate, then lift my foot off the gas quickly I can feel a "kick". These kicks sometimes are very hard and are more noticable on the driver seat. This also happens when I put the car in reverse - it kicks. Some people suggested that it might be because of the torque converter.

I had my transmission fluid changed recently. The kicks were happening before and after the transmission fluid change.

Has anyone had the same problem?

 

How as the condition of the fluid?
Sounds normal for the 7G, I mean, it needs to take time to process what you just done. So you were braking, the TCU assumed you wanted to come to a stop but you suddenly let go of the brake and try to accelerate, it needs time to transition from downshifting to upshifting again.

 

I mean, you could try going through an adaptation with the tool XENTRY but what you described is what I experienced on many MBs and MB transmissions, that is just how these work from experience, or you never know, it might be my driving style or the ones I driven all had broken transmissions. Which the latter is unlikely.

 

The old fluid was in a very bad condition. I did notice some improvement once we changed it but around 3,000km after the change, I still experience the kicks.
I am not braking at all, I just accelerate on (for example) second gear and then lift off the gas pedal and it just does a kick.

 

Are you referring to the gearbox "reset" that you can do like this - ?

 

That is not the same as resetting using XENTRY, I mean you could try that but like I said there is unlikely anything wrong with the transmission. Especially if there are no codes in the computer.

 

Oh, then that is nothing what I thought and not how I experienced with MB transmissions. In your case, the vehicle was trying to upshift and you let go so it got stunned and not sure what you want to do. Another possibility, the transmission mount.

 

How many miles were the fluid?

 

I did try resetting it using the method from the video but sadly didn't help. I don't have any error codes when I diagnosed it.

Yeah its a very strange issue. We did inspect below the vehicle and nothing seemed out of the ordinary except for a bit strange noise coming from the Torque converter which brings me to the idea that the issue comes from it.

Around 30,000kms

 

30,000 KMs on the fluid isn't that bad, how many years was the fluid? You usually change it every 5-6 years regardless of mileage.

How was the transmission mounts?

 

I was told by the dealer that the fluid was changed before they sold me the car. I changed it after ~30,000km (1.5 years) just to be sure and turned out to be a good decision since the fluid was in a very bad shape. Most likely they used some cheap one

 

Uh oh, I think they lied. If the fluid is as bad as you described, 30,000 KMs to turn that bad, is just wrong, there is no way they changed the fluid when you got it 30,000 KMs before. How many KMs in total on the vehicle?

 

Got it at ~200,000. Now it's at 240K. A lot I know, but here this is the situation with almost all vehicles older than 5 years

 

I am worried, if they actually did lie about changing the fluid before to make the sale, then it is overdue by a lot of mileage. Do you still have the fluid by chance? If so, you could send it to Blackstone labs for analysis.

 

Sadly I don't. We got rid of it.

 

I see, don't worry about it. Right now we need to figure out if it is normal behaviour for this vehicle.

 

Most likely its the torque converter. I am around 80% sure, however, this thing is pretty expensive. Here brand new is around $1000 and second hand is $700.

 

What about oem reman?

 

I don't really know. Its kinda hard to get OEM parts here. Maybe ebay is a good option but didnt have the chance on searching yet. I need to see the part number

 

Beware of counterfeits though.

 

Yeah, this is the downside of buying from eBay. I will consult with a mechanic before making purchases.

 

I see good luck : )