Sudden "cut in power" issue.
Discussion
I have an old (2010) C350 with all the trimmings. It has gone everywhere and until recently never missed a beat. It then started to suffer from a sudden and drastic cut in power. It seems to go into a limp home mode (not indicated by diagnostics). Sometimes if you pulled over and reset, the problem would rectify for 20 or so miles. Mostly it didn't. After a visit to my local specialist who cleaned up some connectors and bunged it back at me the problem wasn't solved.
Alarmingly, a long hard study of the forums across the world, didn't cast any light on the problem. The few threads found, ended by either just fading out with no conclusion, someone spending a massive amount on another engine or getting pissed off and ditching the vehicle.
I took it to a main dealer. They have replaced a lot. Turbo switch gear. Turbo electronics (you have to replace the whole turbo unit) the intake butterfly valves. They brought in specialist diagnostics from Germany. There was a lack of fault codes and the ones presented did not agree or point to the problems with the car. Endoscopes were prodded in parts of the car never before seen. The file for the investigation grew and grew.
After 16 months the Mercedes guru visited the car (for a second time). He noticed that the brand new turbo was in the wrong position and was raised. Looking at the intake side showed considerable damage to the impeller. Using an endoscope the intake manifold was examined and it was shown to be disintegrating, throwing material at the turbo under acceleration and shutting it down. The intake manifold is double skinned so the issue was very hard to see and diagnose.
A second turbo and a new intake manifold was fitted and the problem has been resolved. Be aware, this was £2800 for the manifold replacement and £2000 for the turbo (not what I ended up paying) from a main dealer. The intake manifold is £425 as a part (if you are interested).
I do have to put a caveat on this. I have found the guys in the main dealer very trustworthy. They found I could understand technically what they were doing so proper conversations were held. That said, I specifically requested that all parts removed from the car to be returned with the car so I could verify what has happened. This did not happen so I have to take their word for it.
I hope this helps someone who has suffered this issue and been unable to find a resolution. The repair is costly and there is a lot of labour involved.
Alarmingly, a long hard study of the forums across the world, didn't cast any light on the problem. The few threads found, ended by either just fading out with no conclusion, someone spending a massive amount on another engine or getting pissed off and ditching the vehicle.
I took it to a main dealer. They have replaced a lot. Turbo switch gear. Turbo electronics (you have to replace the whole turbo unit) the intake butterfly valves. They brought in specialist diagnostics from Germany. There was a lack of fault codes and the ones presented did not agree or point to the problems with the car. Endoscopes were prodded in parts of the car never before seen. The file for the investigation grew and grew.
After 16 months the Mercedes guru visited the car (for a second time). He noticed that the brand new turbo was in the wrong position and was raised. Looking at the intake side showed considerable damage to the impeller. Using an endoscope the intake manifold was examined and it was shown to be disintegrating, throwing material at the turbo under acceleration and shutting it down. The intake manifold is double skinned so the issue was very hard to see and diagnose.
A second turbo and a new intake manifold was fitted and the problem has been resolved. Be aware, this was £2800 for the manifold replacement and £2000 for the turbo (not what I ended up paying) from a main dealer. The intake manifold is £425 as a part (if you are interested).
I do have to put a caveat on this. I have found the guys in the main dealer very trustworthy. They found I could understand technically what they were doing so proper conversations were held. That said, I specifically requested that all parts removed from the car to be returned with the car so I could verify what has happened. This did not happen so I have to take their word for it.
I hope this helps someone who has suffered this issue and been unable to find a resolution. The repair is costly and there is a lot of labour involved.
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