These are pictures of my C36 AMG M104 engine with the heads removed.

Please take a look at the color and slight build-up on the top of the pistons.

Is this normal? The sides are smooth with no nicks or burrs.

Should the piston tops be lightly finished?

Does the color and pattern indicate anything?

What else should be checked or done while doing a valve-job and head-gasket?

Thanks in advance,

:-) neil
1988 360TE AMG
1993 500E