TM 5-4320-302-14
6-16.
PISTON ASSEMBLY (CONT)
Location/Item
Action
Remarks
9.
Piston pin bore
Measure piston pin bore on X and Y axis with precision bore gage. Measurement should
be 1.3781 to 1.3783 inches (35.004 to 35.01 mm). If bore measurement is larger than
1.3783 inches (35.01 mm) or is out-of-round, replace piston. This is also an indication of
unusual wear. Check cylinder in accordance with paragraph 6-15 and also connecting
rod in accordance with paragraph 6-17.
10. Trapezoidal ring groove
Measure axial clearance with piston ring groove gage No. 130360. Insert gage into ring
groove. If a gap exists between the inserted gage and the piston, the axial ring clearance
is 0.1 to 0.1064 inch (2.54 to 2.702 mm) and the piston is still usable. Do not replace
piston. If the gage contacts the side of the piston with no gap, the axial ring clearance is
too great and the piston must be replaced.
11. Taper piston ring groove
Measure axial ring clearance with standard clearance gage. Measurement should be
0.1016 to 0.1024 inch (2.58 to 2.60 mm). If measurement is greater than 0.1024 inch
(2.6 mm), replace piston.
6-112
