B) Piston sliding surface

B) Piston sliding surface

Repair seizing mark and/or scratch area with pneumatic grinder stone, oilstone and/or emery paper. NOTE! Using breaker with unrepaired condition will eventually destroy cylinder. Repair at early failure stage before too late. NOTE! Polish to perpendicular direction only. If not, circularity will be spoiled. NOTE! Wash repaired piston before reassemble.

Caution on using pneumatic grinder stone, oilstone and/or emery paper

Fault type Condition Remedy

Vertical scratch

Scratch in the grooves Striped scratches to the direction of piston striking.

Repair at early stage as scratches may develop to a fatal failure.

Vertical scratch or rust pit on lower part of piston

Chipped corner of sliding section

Remove burrs by polishing to the circumferential direction.

Remove burrs sticking out of grooves and finish edges.

Remove burrs by polishing machine to the circumferential direction. NO polishing more than 0.05 mm in depth from normal diameter. Replace the piston if scratches and rust pits are not removed by that much polishing.