jerking in gear

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IFFY100

Active Member
Joined
Jun 8, 2020
Messages
326
Location
SCOTLAND
Car
Cls 350 cdi 2010 grand edition
Apologies for bringing up an old topic. I have a cls 350cdi 2010 with a 7gtronic box. Car has covered 90k. I bought the car at 52k. The issue I experience is a vibration when I accelerate around 1300rpm (most noticeable in gear 3 or 4). I have done various things to try to solve this issue, and although the vibration defo decreased, it is still there. The vehicle will NOT produce the vibration when cold. Only when hot and has been running for say about 45 mins. Firstly please note what has been done to resolve the issue:

  1. full gearbox service
  2. throttle body and egr clean
  3. engine service
  4. Engine adaption reset via STAR
  5. STAR diagnostics by MERC master tech
  6. mass air flow clean, intake manifold clean

Till recent I had thought that this may just be a characteristic of the vehicle, but I had the chance to drive an identical car to find the other vehicle doesn't behave in the same way. The other car has covered 150k.
I am wondering whether the box may start to behave with age, or could damage have been done with late service? I doubt the previous owner would of have carried out the gearbox service as per schedule, thus making the service 12 k miles late. Another box service is due. Should I perhaps look to remove any part in the box to service ? Also what would be more sensible - carry out gearbox services every 40k from the last time done, or over service to compensate for late service?
 
Do you notice a bump when you move directly into reverse out of forward. I had a similar problem at a time and went through everything thing and ended up a cheap gearbox mounting. Don’t know if you’ll be that lucky but worth a check only thing needs checked on a ramp.
 
Do your crank sensor before anything else. 50 quid from Mercedes.

If you do not have A642905000 installed, the old ones were recalled/superseeded.

If you already have that part number, maybe it has failed. These engines run very hot, and the engine computer is super tolerant of a bad sensor.
 
Might be worth having a think about engine and gearbox mounts, and less likely but maybe the rubber prop coupling donut?
I have a 350CDI of this era, and this sort of age and mileage is a common time where replacement is required.
 
Might be worth having a think about engine and gearbox mounts, and less likely but maybe the rubber prop coupling donut?
I have a 350CDI of this era, and this sort of age and mileage is a common time where replacement is required.
Yes, to be fair 90k miles is a lot for the factory mounts.

In my experience,1300 rpm is where the EGR fades out in low torque demand. Essentially all of these engines vibrate/stumble at ~1300rpm. Only usually noticeably if you sit on that fence of the performance envelope.
 
Have the codes been read on star
This behaviour does not register any faults. It's nothing wrong as far as the engine software is concerned.
 

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