Procedures

Carefully inspect the pistons for fractures at the ring lands, skirts, oil ring slot corners, and pin bosses. Also inspect for scuffed, rough or scored skirts. If the lower inner portion of the ring grooves have a high step, replace the piston. The step will interfere with ring operation and cause excessive ring side clearance.

Spongy, eroded areas near the edge of the top of the piston are usually caused by detonation or preignition. A shiny surface on the thrust surface of the piston, offset from the centerline between the piston pin holes, can be caused by a bent connecting rod. Replace pistons showing signs of excessive wear, wavy ring lands or fractures or damage from detonation or pre-ignition.

Replace pistons showing signs of fracture, etching or wear. Check the piston pin fit in the piston and connecting rod.