There are no liners in the original engines. Mercedes does not offer oversized pistons. They expect you to have the block bored out about 1/8" and install a sleeve which has to be bored out to the original dimesions. The top of the sleeve then has to be surfaced removing a small amount from the block. You may have to install thicker precombustion chamber seals to prevent the piston from striking it. I think that this is archaic. I did this once on a '68 220D. Very labor intensive. I had tried to get aftermarket oversized pistons at the time. None were available.