TM 55-1930-209-14&P-21
(6)
Remove four piston and connecting rod assemblies as follows:
(a) Remove bearing cap and lower bearing shell from connecting rod.
(b) Push piston and rod assembly out through top of cylinder block.
b.
Disassembly
(1)
Secure connecting rod in a vise equipped with soft jaws and remove rings using a ring expander.
(2)
Punch a hole through center of one of pin retainers with a narrow chisel or punch and pry retainer from
piston being careful not to damage piston or bushings.
(3)
Withdraw piston pin from piston, then remove connecting rod.
(4)
Drive remaining piston pin retainer out from inside with a brass rod or other suitable tool.
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Piston and connecting rod cleaning, inspection and repair
a.
Cleaning
WARNING
Cleaning solvents are toxic and additional hazard is posed when compressed air is used
to dry off parts cleaned with solvents. This type of maintenance requires the use of
safety goggles and a well-ventilated work area.
Observe all precautions stated on the
container, and never put solvents in unmarked containers.
(1)
Clean all parts with cleaning solvent and dry thoroughly with compressed air.
(2)
Clean carbon from top of piston using a wire brush.
(3)
Use diesel oil or kerosene to clean carbon from piston ring grooves.
(4)
Use a twist drill of a diameter corresponding to holes to clean carbon from eight oil control holes in bottom
of piston oil ring grooves.
b.
Inspection and repair
(1)
Inspect pistons for scoring, overheating, cracks, or damaged ring grooves. A piston with light score marks
can be cleaned up and reused.
(2)
Refer to Table 1-1 and inspect and measure piston pins and pin bushings.
(3)
Replace piston bushings as follows:
(a) Place piston in a holding fixture and drive bushings from piston.
(b) Place fixture spacer in counterbore of holding fixture, small end up. Place piston on holding fixture
so that spacer protrudes into piston pin bushing bore.
(c) Locate joint in bushing toward bottom of piston, insert installer handle, and drive bushing in until it
bottoms on spacer.
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