TM 10-4320-310-145-12.INSPECT/REPAIR/REPLACE PISTON (Continued)5Measure piston compression ring groove (1) width.Measurement should be 0.0826 to 0.0843 inch(2.100 to 2.143 mm). If measurement is greater than0.0843 inch (2.143 mm), replace piston.6Measure piston ring groove (2) width. Measurementshould be 0.0811 to 0.0908 inch (2.060 to 2.310mm). If measurement is greater than 0.0908 inch(2.310 mm), replace piston.7Measure piston oil control ring groove (3) width.Measurement should be 0.1582 to 0.1599 inch(4.020 to 4.060 mm). If measurement is greater than0.1599 inch (4.060 mm), replace piston..Dry cleaning solvent P-D-680 (safety or Stoddard's Solvent) Is potentiallydangerous. Avoid repeated and prolonged breathing of vapors and skincontact with the liquid. Do not use near open flame, arcing equipment, orother Ignition sources. Always wear eye protection and protective clothing.The flash point of P-D-680 is 100°F to 138°F (38°C to 59°C).Death or serious Injury could occur if compressed air is directed against theskin. Do not use compressed air for cleaning or drying unless the pressureis/has been reduced to 30 psi (2.06 bar) or less. When working withcompressed air always use chip guards, eye protection, and other personalequipment.8If any ring groove width measurements are smaller than the minimum values given above, piston ring grooves maybe clogged with carbon deposits. Clean piston with dry cleaning solvent. Dry with compressed air. Takemeasurements again.9Inspect gudgeon pin for scoring, freting, pitting, or indications of overheating. If severely damaged, replacegudgeon pin.REPAIR:Remove slight scoring or fretting on piston. Clean and repeat procedure if necessary.5-32
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