Hi, i have a 159 with the 2.0jtdm engine. Recently it has developed a noise that sounds like a dry metallic rattle, almost a normal diesel sound but louder. This can only be heard between approx 1700rpm and 2500 rpm. Either side of this and the engine sounds perfectly normal. The rattle can also sound louder if you accelerate harder, and is more noticeable in lower gears, i'm thinking this is due to less road noise.
I'm leaning towards it being a injector issue? so far i have used added wurth fuel cleaner in about 3/8ths of a tank of fuel and have covered a few hundred miles and still the noise is there.
The car is on 69k and had a cambelt kit and new aux belt fitted about 1k ago. I did notice while poking about under the bonnet the drive pully has a slight wobble, would this be anything to do with the problem?

Thank you in advance, Jon.