M274 engine vibrations

[arana]

Hello everyone.

Apologies if this has been discussed but after having the thermostat sensor changed at Mercedes Watford, a new problem has developed.

The engine vibrates violently and sounds like an old diesel engine.

It is worse when in gear stopped at junction or lights.

Has anyone else faced this vibration issue?

 

[markjay]

I had the thermostat changed on my W204 with the M274 engine, and it involved a lot of dismantling and reassembly due to poor access (MB originally quoted nearly £800, most of it for labour costs).

The only thing I can think of is that they didn't assemble something properly, e.g. a sensor or a wire or a connector or a vacuum hose became loose.

Take the car straight back to the dealer who did the job ...

 

[markjay]

Also, on a general note, a noisy petrol engine is typically caused by incorrect timing or failed timing chain, problem with the hydraulic tappets or valves, or leaking exhaust manifold. Vibration is typically caused when the engine isn't firing on all cylinders, or when there's internal damage (pistons, conrods, crank), or failed engine mounts.