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TM 5-4320-304-14
TM 08922A-14/1
5-12. lNSPECT/REPAIR/REPLACE PISTON (Continued)
5
Measure 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 than 0.0843 inch (2.143 mm), replace
piston.
6
Measure piston ring groove (2) width. Measure-
ment should be 0.0811 to 0.0908 inch (2.060 to
2.310 mm). If measurement is greater than
0.0908 inch (2.310 mm), replace piston.
7
Measure 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 than 0.1599 inch (4.060 mm), replace piston.
Dry cleaning solvent P-D-680 (safety or Stoddard’s Solvent)
is potentially dangerous. Avoid repeated and prolonged
breathing of vapors and skin contact with the liquid. Do
not use near open flame, arcing equipment, or other ignition
sources. Always wear eye protection and protective cloth-
ing, The flash point of P-D-680 is 100° to 138° F (38° to
59°C).
Death or serious injury could occur if compressed air is
directed against the skin. Do not use compressed air for
cleaning or drying unless the pressure is/has been reduced
to 30 psi (2.06 bar) or less. When working with com-
pressed air, always use chip guards, eye protection, and
other personal protective equipment.
8
If any ring groove width measurements are smaller than the minimum values given above, piston
ring grooves may be clogged with carbon
with compressed air. Take measurements
9
Inspect gudgeon pin for scoring, fretting,
damaged, replace gudgeon pin.
deposits. Clean piston
again.
pitting, or indications
with dry cleaning solvent. Dry
of overheating. If severely
REPAIR:
Remove slight scoring or fretting on piston. Clean and repeat procedure if necessary.
5-42
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