Piston And Piston Pin

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Check the piston and piston pin for damage, cracks or wear. Replace if faulty.
Check the piston ring groove for wear or damage. Replace if faulty.
Make sure that the piston pin can be inserted into the piston pin hole with a thumb at 20°C (68°F). Replace if faulty.
Clearance between piston pin hole and piston pin:

Standard

0.004 - 0.008 mm (0.0002 - 0.0003 in)

Fig 1: Measuring Clearance Between Piston Pin Hole And Piston Pin
Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Measuring Piston Pin Diameter Using Micrometer
Courtesy of SUBARU OF AMERICA, INC.
Check the snap ring installation groove (A) on the piston for burr. If necessary, remove burr from the groove so that the piston pin can lightly move.

Fig 3: Identifying Snap Ring Installation Groove
Courtesy of SUBARU OF AMERICA, INC.
Check the snap ring for distortion, cracks and wear.