TM 9-2815-225-34&P
3-39. PISTON, CONNECTING ROD, AND BEARING REPAIR (Contd)
LOCATION/ITEM
ACTION
REMARKS
a. Disassembly (Contd)
fingers.
NOTE
Prior to performing steps 3 and 4, clean and inspect rod bushing and connecting rod dowels
(steps 6, 16, and 18). Do not remove rod bushing or connecting rod dowels unless they are
damaged or not within wear limits.
3.
Rod bushing (9)
Using connecting rod bushing
New bushing requires boring out
driver (ST-1242) (11), remove from
of inside diameter.
connecting rod (5).
4.
Two connecting rod
Pull out of connecting rod cap (7).
dowels (6)
b. Cleaning
CAUTION
Do not exceed water boiling point 212°F (100°C) when heating piston during cleaning.
Piston skirt is coated with plating that may blister if overheated.
5.
Piston (1)
Clean.
Use solvent-cleaning bath that
will not attack aluminum, or blast
suitable material that will embed
in or remove material from piston
(1). Refer to para. 3-6 for addition-
al cleaning instructions.
6.
Piston pin (2), two
Clean.
Refer to para. 3-6 for cleaning
retaining rings (3),
information and instructions.
connecting rod assembly (4),
Do not remove dowels from
and two rod bearing
connecting rod cap or rod bushing
halves (10)
from connecting rod during
cleaning.
c. Inspection
7.
Piston (1) and
Check for cracks, breaks,
Discard if damaged.
piston pin (2)
scoring, galling, and scratches.
Small scratches may be removed
with crocus cloth.
8.
Piston (1)
a. Inspect all ring grooves for
Discard if damaged.
missing sections, breaks, cracks,
distortion, and galling.
NOTE
There are two ways to check piston ring grooves. If using piston ring groove gauge ST-560,
perform step 8b. If piston ring groove gauge ST-560 is not available, perform step 8c.
b. Using No. 2 piston ring groove
Ensure ring grooves are clean.
gauge (12), check top and second
Discard piston (1) if shoulder's
ring grooves.
widest part of guide touches it.
c. Hold segment of new piston
Ensure ring grooves are clean.
ring (13) in ring groove, and
Discard piston (1) if gauge enters
insert 0.006 in. (0.15 mm) feeler
groove force or disengaging ring.
3-176
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