TM 5-1940-322-24
0152 00
PISTON AND CONNECTING ROD MAINTENANCE (Contd)
CLEANING AND INSPECTION (Contd)
CAUTION
Do not use bead blast to clean pistons. Pistons will be damaged by
blast material embedded in the aluminum.
Do not clean pistons and rods in an acid tank. Failure to comply
may result in damage to equipment.
2.
Soak piston (1) overnight in Skysol 100.
3.
Wash piston (1) and connecting rod (2) in a strong solution of detergent and hot water.
CAUTION
Do not use a ring groove cleaner. Use caution when cleaning
grooves. Failure to comply may result in scratches on the ring
sealing surface in the piston groove.
4.
Clean excess deposits from ring grooves (6), (7), and (8) with square end of broken ring.
WARNING
Compressed air source must not exceed 30 psi (207 kPa). Wear
eyeshields when cleaning with compressed air. Failure to comply
may result in injury to personnel.
5.
Wash piston (1) and rod (2) in strong solution of detergent and hot water. Rinse piston (1) and
connecting rod (2) and dry with compressed air.
6.
Inspect connecting rod (2) for deep scratches. Replace connecting rod (2) if damaged.
7.
Inspect piston (1) for damage and excessive wear. Check top of piston (1), ring grooves (6), (7), and (8),
skirt (3), and pin bore (9). Replace piston (1) if damaged.
8.
Using micrometer, measure piston skirt (3) diameter 0.500 in. (12.7 mm) from bottom of piston. For
measurements, refer to table 1, Piston and Connecting Rod Wear Limits. Replace piston (1) if worn
past limits.
9.
Inspect upper groove (8) of piston (1) for damage. Replace piston (1) if damaged.
10.
Using feeler gauge and piston ring (4), measure intermediate ring groove (7) clearance. For
measurements, refer to table 1, Piston and Connecting Rod Wear Limits.
11.
Using feeler gauge and piston ring (5), measure oil ring groove (6) clearance. For measurements, refer
to table 1, Piston and Connecting Rod Wear Limits. Replace piston (1) if worn past limits.
12.
Using telescopic gauge, measure piston pin bore (9) in two locations. For measurements, refer to
table 1, Piston and Connecting Rod Wear Limits. Replace piston (1) if worn past limits.
13.
Inspect piston pin (10) for nicks, gouges, and excessive wear. Replace piston pin (10) if nicked, gouged,
or excessively worn.
14.
Using micrometer, measure piston pin (10) diameter on 90 axis in three locations. For measurements,
refer to table 1, Piston and Connecting Rod Wear Limits. Replace piston pin (10) if worn past limits.
CAUTION
The I-beam section of the rod cannot have dents or other damage.
Damage to this part can cause stress risers which will progress to
breakage.
15.
Inspect connecting rod (2) for damage and wear. Replace connecting rod (2) if damaged or worn.
16.
Using telescopic gauge, measure connecting rod pin bore (11) in two locations on 90 axis. For
measurements, refer to table 1, Piston and Connecting Rod Wear Limits. Replace connecting rod (2) if
worn past limits.
0152 00-4