Noisy engine 220 CDI

[John Kerr]

I have a MY06 220CDI CLK.When it gets over 2k rpm it sounds very harsh.I drove a CLC recently same engine and auto box which was quiet and smooth.I wonder if this is linked to the poor fuel consumption.Milage is 58k
Many thanks

 

[recardo]

is it a "knocking" noise? could be injectors, stuck EGR valve amongst other things