just in the process of rebuilding my engine,is a my99 turbo 2000 thats done 89k,was in good running order just upgrading the pistons and rods,on removing the pistons i found that all 4 have light scoring marks on the piston skirts below the rings on the inlet side,does anyone know what could have caused this,was a standard engine running standard boost etc.

 

 

just looks like standard wear in the molybendium coating caused mainly by the fact its on the exact thrust point/side from the rod- where the highest contact pressure is.

 

thanks for that buddy