722.9 jerk / jolt 4th to 5th

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phobos

Active Member
Joined
Feb 17, 2019
Messages
223
Location
Farnborough - Hampshire
Car
W221 S350cdi
Hi everyone, recently I had the ATF fuild changed on my W221 S350CDI at my local mechanic ( trusted mechanic for over 10 years) as the car's odometer is 96k and the ATF fluid had only been changed at 40k
All parts used were genuine Mercedes and the oil on the torque converter was also been drained.
The mechanic followed the procedure as Mercedes guidelines and checked the temperature with a STAR machine ( 45C to check the oil level)

Car seems fine, shifts up and down very smoothly, except on the upshif from 4th to 5th where we have a jollt, especailly if the shift is performed at lower rpm and you remove your feet. from the accelarator so:

drive normally - in 4th gear - changed to 5th - keep feet on the accelarator - Jolt but not so noticable

drive normally - in 4th gear - changed to 5th - REMOVE feet on the accelarator- Big jolt that you can feel acrross the whole car ( even the missus notices it)

Took it back t the mechanic and we have ran through the procedure again putting brand new oil and checking the level, but still the jolt it there?
Any ideas?
 
Which oil did he use?

There are two for the 7 speed gearbox. The 7G + is different to that used in the older type 7G.
 
Hi everyone, recently I had the ATF fuild changed on my W221 S350CDI at my local mechanic ( trusted mechanic for over 10 years) as the car's odometer is 96k and the ATF fluid had only been changed at 40k
All parts used were genuine Mercedes and the oil on the torque converter was also been drained.
The mechanic followed the procedure as Mercedes guidelines and checked the temperature with a STAR machine ( 45C to check the oil level)

Car seems fine, shifts up and down very smoothly, except on the upshif from 4th to 5th where we have a jollt, especailly if the shift is performed at lower rpm and you remove your feet. from the accelarator so:

drive normally - in 4th gear - changed to 5th - keep feet on the accelarator - Jolt but not so noticable

drive normally - in 4th gear - changed to 5th - REMOVE feet on the accelarator- Big jolt that you can feel acrross the whole car ( even the missus notices it)

Took it back t the mechanic and we have ran through the procedure again putting brand new oil and checking the level, but still the jolt it there?
Any ideas?
Was a flush done ?
 
The mechanic drained the TC and the oil pan, so wh did NOT use any of those flush machines.
That could be the problem then . Shifts should be smoother if done correctly but I’ve heard that sometimes there isn’t much difference
 
There are two different height “fill towers” that go into the sump drain plug and set the level correctly , one is green the other white . Depends on 7g or 7g+ box
 
That could be the problem then . Shifts should be smoother if done correctly but I’ve heard that sometimes there isn’t much difference
Thanks Woody, I have only ever seen ATF fuild draining from TC and oil pan by removing the plugs and let it drain out. The mechanic has a printout form WIS that he showed me before the 2nd attempt which only mentions draining.
 
How did the mechanic put brand new oil in to re check everything without knocking the sump plastic tower thingy out the way to get the old oil out ??
 
There are two different height “fill towers” that go into the sump drain plug and set the level correctly , one is green the other white . Depends on 7g or 7g+ box
Hi W1ghty, mine was white, also checked by the Mercedes delarship as the right one.
 
How did the mechanic put brand new oil in to re check everything without knocking the sump plastic tower thingy out the way to get the old oil out ??
Hi W1ghty, he did know the sump plastic tube to drain the oil out. Afterwards he removed the olug from the TC to drain the oil from the TC. Finally he removed the oil sump ( to replace gasket / magets and clean the sump)
 
Hi W1ghty, he did know the sump plastic tube to drain the oil out. Afterwards he removed the olug from the TC to drain the oil from the TC. Finally he removed the oil sump ( to replace gasket / magets and clean the sump)
And replace filter ?
 
Thanks Woody, I have only ever seen ATF fuild draining from TC and oil pan by removing the plugs and let it drain out. The mechanic has a printout form WIS that he showed me before the 2nd attempt which only mentions draining.
It’s always worth flushing the tranny as it helps to remove any deposits from the old oil. Chances are there’s still a lot of the older deposits still present..
 
It’s always worth flushing the tranny as it helps to remove any deposits from the old oil. Chances are there’s still a lot of the older deposits still present..
How was it shifting before having the atf changed ?
 
It’s always worth flushing the tranny as it helps to remove any deposits from the old oil. Chances are there’s still a lot of the older deposits still present..
HI Woody, what do you understand as a flush? you mean with the machine connected creating a circuit trying to push all the oil out?
 
How was it shifting before having the atf changed ?
Shifting was good, with no nasty kicks but on cold you feel tha tyou had to press on a bit more on the accelarator to drive the car from stopped. Likt it was starting for a higher gear. After the ATF change the start is much better.
 
Shifting was good, with no nasty kicks but on cold you feel tha tyou had to press on a bit more on the accelarator to drive the car from stopped. Likt it was starting for a higher gear. After the ATF change the start is much better.
I experienced a similar sensation on my 7g + box after a tranny service it would kick from 5th to 6th but all other gear changes were seamless as it was before I had the atf change. I had it carried out a few months ago and feels like it is becoming smoother from 5th to 6th as time goes on. My feeling is yours will also get better but keep an eye on it.
 
I experienced a similar sensation on my 7g + box after a tranny service it would kick from 5th to 6th but all other gear changes were seamless as it was before I had the atf change. I had it carried out a few months ago and feels like it is becoming smoother from 5th to 6th as time goes on. My feeling is yours will also get better but keep an eye on it.
Thanks Woody, I just read that there is a STAR transmissing adaptation process for shifting.. Maybe I will read a little bit more and see if it worth doing
 
Thanks Woody, I just read that there is a STAR transmissing adaptation process for shifting.. Maybe I will read a little bit more and see if it worth doing
There is also a software update available for some 7G type gearboxes, worth asking your MB specialist
 

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