Cleaning and Inspection
CLEANING1. Remove any deposits from the piston surfaces.
CAUTION: Do not use caustic compounds or a wire brush to clean the pistons.
NOTE: Always replace the piston ring with a piston ring expander. Clean gum or varnish from the piston skirt, piston pins and piston rings with solvent.
2. Use Piston Ring Groove Cleaner D81L-6002-D or equivalent to clean the ring grooves. Ensure the oil ring slots (holes) are clean.
INSPECTION
Carefully inspect the pistons for fractures at the ring lands, skirts and pin bosses. Checked for scuffed rough, or scored skirts. If the lower inner portion of the ring grooves have high steps, replace the piston. This step will interfere with piston ring operation and cause excessive piston ring side clearance.
Spongy, eroded areas near the top of the piston are usually caused by detonation or premature ignition. A shiny thrust surface, offset from the centerline between the piston pin holes, can be caused by a bent connecting rod. Replace pistons showing signs of excessive wear, irregular or fractured ring lands, or damage from detonation and premature ignition.
Check the piston-to-cylinder bore clearance by measuring the piston and bore diameters.
Inspect the outer circumferences of all pistons for seizure or scoring. Replace the piston if necessary.
If a new piston is to be used, check the clearance of the piston to the cylinder bore before assembling the piston and piston pin to the connecting rod.