TM 10-4320-310-14
5-12.
INSPECT/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. Measurement
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 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 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
compressed air always use chip guards, eye protection, and other personal
equipment.
8
If any ring groove width measurements are smaller than the minimum values given above, piston ring grooves may
be clogged with carbon deposits. Clean piston with dry cleaning solvent. Dry with compressed air. Take
measurements again.
9
Inspect gudgeon pin for scoring, freting, pitting, or indications of overheating. If severely damaged, replace
gudgeon pin.
REPAIR:
Remove slight scoring or fretting on piston. Clean and repeat procedure if necessary.
5-32
