Piston And Piston Pin

WARNING: This page is about a different variant/trim than selected.

Check the piston and piston pin for damage, cracks or wear. And check the piston ring groove for wear or damage. Replace if faulty.
Measure the clearance between piston and cylinder in each cylinder. Ref. to CYLINDER AND PISTON , INSPECTION, Cylinder Block. If the clearance exceeds the standard, replace the piston, or rebore the cylinder so that an oversize piston can be used.
Make sure the piston pin can be inserted into the piston pin hole by 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 Piston Pin Hole Diameter
Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Measuring Piston Pin Diameter
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 Circlip Installation Groove On Piston
Courtesy of SUBARU OF AMERICA, INC.
Check the piston pin snap ring for distortion, cracks and wear.