C230 Kompressor, 2003, automatic. -- Last year during a regularly schedule maintenance visit, I complained about an intermittent problem where my C230 runs rough and has an occasional "sputtering vibration" when I'm slowing to a stop. The car was still under warranty but the problem never occurred while the dealer had it. I took the car back about 6-7 months later to try again because it seemed like the problem was occurring more frequently. Again, the dealer could not reproduce. Last month, I took my car in for the next Service A and requested that they look again for this problem as it was occurring nearly everytime I drove the car. This time, they reproduced the problem. They told me that coolant was leaking into my transmission. They replaced the radiator and flushed-the transmission. I picked the car up and drove it home. It seemed a little rough (test drove with the mechanic) but the mechanic told me that was normal and was due to "carbon build-up".
The next morning, I started my car and when I put it into reverse, the car started rocking from side to side and cycling through the short bursts of vibrations/sputtering. When I attempted to drive the car, it literally bucked like a bronco. So, I put the car in park and just let it run until the jerking stopped. After a couple of minutes, the car drove fine. However, I returned it to the dealer the next business day. They reiterated that this was due to carbon build-up. It didn't seem to matter that the vehicle has NEVER done this before.
At this point, the car has been into the shop twice to clean all carbon from the fuel injection system and replace all plugs.
The "bucking like a bronco" behavior has not recurred but the behavior is still the same each morning: rocking from side to side and cycling through the short bursts of vibration until the engine gets warmed-up. It takes about two minutes.
The service manager at the dealer is now telling me that I have to replace the engine mounts (~$900) and then "it will be much better".
This doesn't make sense to me. I would imagine a general roughness, always, due to collapsed engine mounts, not just this weirdness every morning. The rocking and sputtering is very pronounced. You can see it if you're standing across the street.
I'm reluctant to spend this amount of money on another "guess". Can anyone tell me more about this issue? This car is less than 5 years old and only has 60,000 miles on it. My manual says that carbon build-up must be cleaned and the plugs replaced at 80,000 miles. It doesn't say anything about replacing engine mounts every 3-4 years. This is my first Mercedes and I was always under the impression that an MB was a much higher quality vehicle. I'm starting to think that's just hype given this problem first occurring when the car was only 3.5 years old and less than 40,000 miles.

 

MB uses a softer engine mount than most to isolate more vibration from the passengers. These mounts do go bad but at 60000 miles and 5 years I would question that. You mentioned having carbon removed from the fuel injection system. There should be no carbon here except perhaps on the injector tips themselves and a good day of high speed driving should take care of much of that. This particular enging was never the smoothest that MB made although it is quite durable and provides a nice amount of power for its displacement thanks to the supercharger. I do suggest that perhaps you should try another dealer they seem to be at odds in correcting your problem

 

I assume that this rocking from side to side is while the vehicle is still in park. I believe that your engine is the 271 engine, black cover on top not white and red, which was well known to build up carbon on the valves. Usually if the vehicle was not driven "hard" somewhat often.

I have seen motor mounts go out at well before 5 years and 60,000 miles, but never seen motor mounts that absorb vibration better the warmer the vehicle got.

If I were you I would go on a nice long ride while holding the rpm's at least above 4,000rpm's. This would possibly help if minor carbon build-up on the valves is the problem.

Hopefully this helps.

 

Thank you for the replies to my posting. My engine starts rocking only after put into gear (reverse or drive). The cycling of the short bursts of vibration will continue even if I switch back into Park but if I leave it in Park for a few minutes upon cold start, none of the symptoms occur.
As for driving long periods at high speeds, I commute 25 miles to work each morning and back again in the afternoon. The average speed is 50 miles per hour with a stretch of road (about 5 miles) where I can legally drive 60-65 MPH. I ALWAYS use Chevron 93 octane gasoline with techron.
The nearest alternative dealer is 60 miles away. I'm not sure what I should do next.

 

Ok. I would assume that it is still transmission related then, not motor mount related. I would let them replace the motor mounts with the agreement that if the motor mounts don't resolve the issue, you won't pay for the motor mounts. Be willing to leave the vehicle there over night and ask that a shop foreman start the vehicle in the morning. Explain to the shop foreman your exact routine for starting the vehicle and driving away in the morning.

Good luck.

 

Thanks for the suggestion. I tried it. But the service manager said "if the problem isn't better, he'll put the old motor mounts back on the car". Frankly, I think he was being very rude to suggest such a thing. I'm sure that most of the cost for this repair is labor and not the actual motor mounts. Also, this response gives me no recourse to correct the problem that occurs EVERY morning. Now, it has worsened. When I start the car and put it in reverse, if I switch it back into Park to wait-out the rocking and sputtering, its very stiff when I try to put it back into Reverse. But the service manager at the dealership is telling me that this is NORMAL behavior on a cold start. When I explain that I've been driving this car for 4.5 years and have never had it behave this way before, he tells me its NORMAL for a car this AGE. Four and half years old?
I guess I'm now wondering how to contact MB directly because there's no one higher-up at the dealership. Does anyone on this forum know a point of contact if you can't get help from your dealer? The only other dealership is 70 miles away.

 

Call his bluff.....he'll have to absorb not only the cost of the labor twice but also the cost of the part. If you just pay for the part (to leave it in) he'll be way ahead.

 

Sounds to me like a fuel issue. Bucking bronco is usually associated with a rich mixture, but - that should show a check engine light. You say the problem goes away when you let it sit a min or two to warm. Trannys warms best as you drive them.
When cold and you select R, the sudden load and wrong mixture causes the misfire, and once warm, usually within a minute, the computer starts to run a different program with a leaner fuel curve, so the problem abates.
Try that angle with the NEW DEALER

 

I would try a combination of the 2. This way if the new dealer finds that the issue is related to the coolant contaminatin issue you can trace it back to the original repairing dealer, and MBUSA will be aware of the issue.

 

1) I don't understand how engine mounts would be time related and then heal. You stated that it would be rough on start up then clear up. If a mount is broken, then it won't get better as the engine warms up.

2) Fuel injector. might be a miss fire on start up if it sticks but if it opens any there will be enough fuel for a weak fire and not major rocking of the engine.

3) Transmission in neutral doesn't really load up the engine. So if it is not running correctly in neutral I would not suspect the transmission. Good thing though to get the water out,, that is really bad.

4) My thoughts are carbon under a valve preventing it from seating properly resulting in miss fire when cold and after running and heating up it begins to seat.

I would recommend using Chevron Techron gas and immediately add enough Techron additive for a "treatment dose". Then you should drive the car at sustained highway speeds (won't say how fast I think). To allow the carbon time to clear up some. IF this doesn't work, I would use the clean/decarbon system through the fuel injectors.

All this is based on your plugs and wires are in good shape.

But for the engine mounts causing this,, 1:100 shot IMO since it clears up as the engine runs. Best of luck