ive got a 2000 yr clk 320 which has lost compresion in one cylinder, on inspection its has clearly scored, ive been told its either a nikisil bore problem as with the jags or bmws caused by poor fuel or it could be the catalytic converter is breaking up and bits are finding there way into the cylinder. i asked if it could be rebored but the garage said no its got to have a whole new block. can someone give me some advise as i wasnt aware that mercedes suffered with this problem ?

 

What could have caused the scorring ?