C43 Facelift Transmission slipping/issues
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C43 Facelift Transmission slipping/issues
Hello guys,
I have a C43 Coupe Facelift, with around 135.000 km now. I have owned it for a year now, put over 30.000 km in it, and for half a year now, when the engine is cold, the first shift between 3-4 sounds like its slipping. If i gently accelerate, the revs go up as it shifts, but after this first case of this, it's normally fine. If i accelerate not gently, just firmly, then it's okay, but still not perfect. When the car is warm, around 60+c for the trans, it's mostly fine. HOWEVER, i must also add: When not giving enough gas, sometimes the shift feels really weird, like it punches the gear into 4th with a big jerk. This doesnt happen all the time, but with more firm gas normally the shifting is fine.
Also, whenever the car automatically downshifts, 4->3->2, i hear bubbling or sort of burbling, but not from the engine or exhaust, more kind of from the transmssion. It's not crunchy, it's not metal sounding, it's more fluid i think.
The fluid was changed over 15.000 km ago, with a TCU reset via a Mercedes authorized workshop.
Anyone experience similar?
I have a C43 Coupe Facelift, with around 135.000 km now. I have owned it for a year now, put over 30.000 km in it, and for half a year now, when the engine is cold, the first shift between 3-4 sounds like its slipping. If i gently accelerate, the revs go up as it shifts, but after this first case of this, it's normally fine. If i accelerate not gently, just firmly, then it's okay, but still not perfect. When the car is warm, around 60+c for the trans, it's mostly fine. HOWEVER, i must also add: When not giving enough gas, sometimes the shift feels really weird, like it punches the gear into 4th with a big jerk. This doesnt happen all the time, but with more firm gas normally the shifting is fine.
Also, whenever the car automatically downshifts, 4->3->2, i hear bubbling or sort of burbling, but not from the engine or exhaust, more kind of from the transmssion. It's not crunchy, it's not metal sounding, it's more fluid i think.
The fluid was changed over 15.000 km ago, with a TCU reset via a Mercedes authorized workshop.
Anyone experience similar?
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I’ll try and get a video out here tomorrow
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2018 C43 Coupe
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Thanks for posting the video OP I can see what you mean, sorry that now I realized I am not able to help since I have the pre-facelift and the programming is different to the facelift I can't say if yours is normal or not, hopefully someone else chimes in. Sorry about that.
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Hello guys,
I have a C43 Coupe Facelift, with around 135.000 km now. I have owned it for a year now, put over 30.000 km in it, and for half a year now, when the engine is cold, the first shift between 3-4 sounds like its slipping. If i gently accelerate, the revs go up as it shifts, but after this first case of this, it's normally fine. If i accelerate not gently, just firmly, then it's okay, but still not perfect. When the car is warm, around 60+c for the trans, it's mostly fine. HOWEVER, i must also add: When not giving enough gas, sometimes the shift feels really weird, like it punches the gear into 4th with a big jerk. This doesnt happen all the time, but with more firm gas normally the shifting is fine.
Also, whenever the car automatically downshifts, 4->3->2, i hear bubbling or sort of burbling, but not from the engine or exhaust, more kind of from the transmssion. It's not crunchy, it's not metal sounding, it's more fluid i think.
The fluid was changed over 15.000 km ago, with a TCU reset via a Mercedes authorized workshop.
Anyone experience similar?
I have a C43 Coupe Facelift, with around 135.000 km now. I have owned it for a year now, put over 30.000 km in it, and for half a year now, when the engine is cold, the first shift between 3-4 sounds like its slipping. If i gently accelerate, the revs go up as it shifts, but after this first case of this, it's normally fine. If i accelerate not gently, just firmly, then it's okay, but still not perfect. When the car is warm, around 60+c for the trans, it's mostly fine. HOWEVER, i must also add: When not giving enough gas, sometimes the shift feels really weird, like it punches the gear into 4th with a big jerk. This doesnt happen all the time, but with more firm gas normally the shifting is fine.
Also, whenever the car automatically downshifts, 4->3->2, i hear bubbling or sort of burbling, but not from the engine or exhaust, more kind of from the transmssion. It's not crunchy, it's not metal sounding, it's more fluid i think.
The fluid was changed over 15.000 km ago, with a TCU reset via a Mercedes authorized workshop.
Anyone experience similar?
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
... me too ??
Anyway you can be more specific?
This will help you to get the service you need.
MB Specialist can :
Is your issue specific to "3 to 4th" upshifts banging/slipping with partial throttle somewhat randomly when hot ??
FYI: when you output high-power into a poorly shifted set of clutches, the high friction heats up the thin oil to the point the valve body has a hard time working with.
Take it easy!
This will help you to get the service you need.
MB Specialist can :
- replace genuine ATF
- refresh learned shifts adaptations.
- various firmware tweaks may help
- Beyond that options are rebuilt jobs
Is your issue specific to "3 to 4th" upshifts banging/slipping with partial throttle somewhat randomly when hot ??
FYI: when you output high-power into a poorly shifted set of clutches, the high friction heats up the thin oil to the point the valve body has a hard time working with.
Take it easy!
Last edited by CaliBenzDriver; Mar 18, 2026 at 04:45 PM.
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C43 2020
Yes,
The car in comfort mode from 3rd to 4th increases rpm, about 200. It only happens with light throttle, but quite sporadically. In sport mode it didn't happened. No jerk.
Sometimes I hear a small bang from the front.
The oil in the automatic transmission is new, it was done directly at the MB, a new car battery helped for a month, then it started doing it again. Pump valve is new.
The car in comfort mode from 3rd to 4th increases rpm, about 200. It only happens with light throttle, but quite sporadically. In sport mode it didn't happened. No jerk.
Sometimes I hear a small bang from the front.
The oil in the automatic transmission is new, it was done directly at the MB, a new car battery helped for a month, then it started doing it again. Pump valve is new.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Yes,
The car in comfort mode from 3rd to 4th increases rpm, about 200. It only happens with light throttle, but quite sporadically. In sport mode it didn't happened. No jerk.
Sometimes I hear a small bang from the front.
The oil in the automatic transmission is new, it was done directly at the MB, a new car battery helped for a month, then it started doing it again. Pump valve is new.
The car in comfort mode from 3rd to 4th increases rpm, about 200. It only happens with light throttle, but quite sporadically. In sport mode it didn't happened. No jerk.
Sometimes I hear a small bang from the front.
The oil in the automatic transmission is new, it was done directly at the MB, a new car battery helped for a month, then it started doing it again. Pump valve is new.
To be practical, if you found that "fresh battery did help" you could try "CTEK Float" to keep your battery in top shape. Chassis performance is directly affected by voltage!
Yes indeed select the "Sport mode" rather than "Comfort mode" around town.
Comfort is best on Hwy to uses a torque converter 2-level clutch that produces heat by unnecessary frictions ... S BEST CITY COURSE.
The S/C option won't "fix 3/4 shifts" issues but help output overall.
Last edited by CaliBenzDriver; Mar 18, 2026 at 05:47 PM.
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C43 2020
what new "pump valve" is that ??
To be practical, if you found that "fresh battery did help" you could try "CTEK Float" to keep your battery in top shape. Chassis performance is directly affected by voltage!
Yes indeed select the "Sport mode" rather than "Comfort mode" around town.
Comfort is best on Hwy to uses a torque converter 2-level clutch that produces heat by unnecessary frictions ... S BEST CITY COURSE.
The S/C option won't "fix 3/4 shifts" issues but help output overall.
To be practical, if you found that "fresh battery did help" you could try "CTEK Float" to keep your battery in top shape. Chassis performance is directly affected by voltage!
Yes indeed select the "Sport mode" rather than "Comfort mode" around town.
Comfort is best on Hwy to uses a torque converter 2-level clutch that produces heat by unnecessary frictions ... S BEST CITY COURSE.
The S/C option won't "fix 3/4 shifts" issues but help output overall.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
