80-100km/h noise from the back / 3rd to 4th hard shift
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Joined: Nov 2025
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C43 2020
80-100km/h noise from the back / 3rd to 4th hard shift
I have a C43 2020 with 70,000 miles on it. I recently had the oil changed in the automatic transmission and differential, but it still didn't help.
1, From 3 to 4 it sometimes jerks/kicks, or the revs jump slightly (about 200-300) and then shifts. It happens in the city in Comfort when I'm driving slower. The other gears are fine.
2, When driving 80-100km/h, there is a humming/wind current/like something is spinning from behind. It only happens under the gas regardless of the mode. The car was on a jack and there was no play anywhere. I suspect the differential, but I've read that sometimes it doesn't help. Few people figured it out. It's at the beginning and end of the video.
Thanks for any advice,
1, From 3 to 4 it sometimes jerks/kicks, or the revs jump slightly (about 200-300) and then shifts. It happens in the city in Comfort when I'm driving slower. The other gears are fine.
2, When driving 80-100km/h, there is a humming/wind current/like something is spinning from behind. It only happens under the gas regardless of the mode. The car was on a jack and there was no play anywhere. I suspect the differential, but I've read that sometimes it doesn't help. Few people figured it out. It's at the beginning and end of the video.
Thanks for any advice,
Out Of Control!!
Joined: Apr 2019
Posts: 11,931
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
tranny + dif concerns
I have a C43 2020 with 70,000 miles on it. I recently had the oil changed in the automatic transmission and differential, but it still didn't help.
1, From 3 to 4 it sometimes jerks/kicks, or the revs jump slightly (about 200-300) and then shifts. It happens in the city in Comfort when I'm driving slower. The other gears are fine.
2, When driving 80-100km/h, there is a humming/wind current/like something is spinning from behind. It only happens under the gas regardless of the mode. The car was on a jack and there was no play anywhere. I suspect the differential, but I've read that sometimes it doesn't help. Few people figured it out. It's at the beginning and end of the video.
Thanks for any advice,
1, From 3 to 4 it sometimes jerks/kicks, or the revs jump slightly (about 200-300) and then shifts. It happens in the city in Comfort when I'm driving slower. The other gears are fine.
2, When driving 80-100km/h, there is a humming/wind current/like something is spinning from behind. It only happens under the gas regardless of the mode. The car was on a jack and there was no play anywhere. I suspect the differential, but I've read that sometimes it doesn't help. Few people figured it out. It's at the beginning and end of the video.
Thanks for any advice,
What did the service technician remark about the oil that came out... ok or extra bad??
-- How are the 3x Pcs Engine-tranny mounts: collapsed or new?
-- The more or less pronounced harsh 3 to 4 shifts are a common feature not out of the ordinary.
You can request your MB service Dealer to :
-1- get the tranny firmware updated and
-2- get the self-adaptations retrained.
Try these 2 above steps than you can consider out of the ordinary procedure to speed up delayed shifts.
This may help for good or temporarily only to return the exact same results in 2500.Miles later.
Last edited by CaliBenzDriver; Nov 8, 2025 at 06:00 PM.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 37
Likes: 0
C43 2020
-- 70kMi interval is either too late or too early.
What did the service technician remark about the oil that came out... ok or extra bad??
-- How are the 3x Pcs Engine-tranny mounts: collapsed or new?
-- The more or less pronounced harsh 3 to 4 shifts are a common feature not out of the ordinary.
You can request your MB service Dealer to :
-1- get the tranny firmware updated and
-2- get the self-adaptations retrained.
Try these 2 above steps than you can consider out of the ordinary procedure to speed up delayed shifts.
This may help for good or temporarily only to return the exact same results in 2500.Miles later.
What did the service technician remark about the oil that came out... ok or extra bad??
-- How are the 3x Pcs Engine-tranny mounts: collapsed or new?
-- The more or less pronounced harsh 3 to 4 shifts are a common feature not out of the ordinary.
You can request your MB service Dealer to :
-1- get the tranny firmware updated and
-2- get the self-adaptations retrained.
Try these 2 above steps than you can consider out of the ordinary procedure to speed up delayed shifts.
This may help for good or temporarily only to return the exact same results in 2500.Miles later.
in comfort mode in the city I find it shifts a lot, the gearbox is sometimes indecisive.
what did you mean by mounts?
that it can then jerk or make a humming noise from back?
Last edited by C43 Fido; Nov 9, 2025 at 05:45 AM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,931
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Tranny being indecisive in the wrong gear is caused by the engine throttle itself, not the TCU. The excellent tranny shifts the wrong gears at the wrong time courtesy of the ECU.
