Piston and block stamps - Q for the mechs
 

Dear All,

(posting is about my 1983 380SEC).
In the Mercedes manual for my engine (116.963) it says that the piston marking (e.g., 1,1+,or 2) should correspond with the respective marking on the engine block. ("The group number is also stamped into the crankcase mating surface. The piston group number (e.g., 2) must correspond with the group number of the cylinder bores (series manufacture)").

Now here is the problem: All my pistons are stamped 1+; about half of my cylinders are stamped 2 and the other half 1+ (in a seemingly random order). I doubt that this engine was ever disassambled before. Could you guys who have (not) seen anything like this before comment? Is this serious - if yes, how is it possible?

Thanks!

ON a 23+ year old car...... Not important at all!

The piston to block clearance is select fit & anly a few 0.0001" difference between those sizes.