TM 9-2320-272-24-4
5-26. PISTON AND CONNECTING ROD MAINTENANCE
THIS TASK COVERS:
d. Assembly
a. Removal
b. Disassembly
e. Installation
c. Cleaning and Inspection
INITIAL SETUP:
APPLICABLE MODELS
MATERIALS/PARTS
Piston rings (Appendix D, Item 518)
M939A2
Two retaining rings (Appendix D, Item 539)
SPECIAL TOOLS
Connecting rod bearing (Appendix D, Item 40)
Lubricating oil (Appendix C, Item 50)
Engine barring tool (Appendix E, Item 43)
Plastigage (Appendix C, Item 55)
Ring compressor (Appendix E, Item 32)
REFERENCES (TM)
TOOLS
TM 9-2320-272-24P
General mechanic's tool kit (Appendix E, Item 1)
Keystone gauge (Appendix E, Item 54)
EQUIPMENT CONDITlON
Inside micrometer (Appendix E, Item 82)
Cylinder head removed (para. 4-41).
Outside micrometer (Appendix E, Item 80)
Vernier calipers (Appendix E, Item 159)
Oil pan and suction tube removed (para. 4-47).
Torque wrench (Appendix E, Item 144)
Depth gauge (Appendix E, Item 81)
Feeler gauge
Soft-headed hammer
NOTE
All piston assemblies are replaced the same way. This procedure
covers replacement of one piston assembly.
a. Removal
1.
Using engine barring tool, rotate crankshaft (6) to lower pistons (1) enough to remove all carbon
from upper inside wall of each cylinder (3).
2.
Remove two nuts (8) from screws (5) and connecting rod cap (7).
3.
Using soft-headed hammer, tap screws (5) and remove connecting rod cap (7) from crankshaft (6).
CAUTION
Use a tape-protected tool to push piston from cylinder block.
Failure to do so may cause damage to cylinder liners.
NOTE
Assistant will help with step 4.
4.
Using tape-protected tool, push connecting rod (2) and piston (1) from engine block (4).
b. Disassembly
CAUTION
Pistons, connecting rods, and connecting rod caps must be kept together
as an assembly. Missing parts may cause damage to equipment.
1.
Remove two retaining rings (12) from bore of piston (1). Discard retaining rings (12).
2.
Remove piston pin (13) and connecting rod (2) from piston (1).
3.
Remove ring (9), compression ring (10), and oil ring (11) from piston (1). Discard rings (9), (10),
and (11).
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