Measuring piston

Check 

• Position micrometer in area (A) and measure piston installation clearance transversely to piston pin.
  TECHNICAL DATA - PISTON DIAMETER SPECIFICATION
  
  

  Measure the piston diameter at distance (A) from the lower end of the piston skirt. Courtesy of BMW OF NORTH AMERICA, INC.	Distance (A) to the lower end of the piston skirt
  	10 mm Nominal dimension of piston diameter 31.958 mm... 81.996 mm

  Courtesy of BMW OF NORTH AMERICA, INC.

  Result 

• Piston does not correspond to the specifications.

Measure 

• Replace the piston.