Piston And Piston Pin

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Check the piston and piston pin for wear or crack.
Check the snap ring for distortion or wear.
Check the piston ring groove for damage.
Check the circlip groove (A) for burr.
NOTE: If the burr is found, remove the burr from groove.

Fig 1: Identifying Circlip Groove
Courtesy of SUBARU OF AMERICA, INC.
Check that the piston pin can be inserted into the piston pin hole with a thumb at 20°C (68°F).
Check the clearance between piston pin hole and piston pin. Check the clearance between piston pin hole and piston pin by measuring respectively the inner diameter of piston pin hole and the outer diameter of piston pin.
1. Using a caliper gauge, measure the inner diameter of piston pin hole.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - Record the measured value.
    
    Fig 2: Measuring Inner Diameter Of Piston Pin Hole Using Caliper Gauge
    Courtesy of SUBARU OF AMERICA, INC.
2. Measure the outer diameter of piston pin with a micrometer.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - Record the measured value.
    
    Fig 3: Measuring Outer Diameter Of Piston Pin With Micrometer
    Courtesy of SUBARU OF AMERICA, INC.
3. Calculate the clearance between piston pin hole and piston pin. If it is not within the standard, replace the piston and piston pin as a set.
  Clearance between piston pin hole and piston pin:
  
  Standard
  
  0.004 - 0.008 mm (0.0002 - 0.0003 in)