TM 5-3895-346-14
PISTON AND PISTON RINGS
ENGINE OVERHAUL
The compression rings may be inspected through the ports in the cylinder liners after the air box covers have
been removed. If the rings are free and are not worn to the extent that the plating or grooves are gone,
compression should be within operating specifications. Refer to Troubleshooting (Engine) for the procedure for
checking compression pressure.
Remove Piston and Connecting Rod
1.
Drain the cooling system.
2.
Drain the oil and remove the oil pan.
3.
Remove the oil pump and inlet and outlet pipes, if necessary (Oil Pump).
4.
Remove the cylinder head (Cylinder Head).
5.
Remove the carbon deposits from the upper inner surface of the cylinder liner.
6.
Remove the bearing cap and the lower bearing shell from the connecting rod. Then push the piston
and rod assembly out through the top of the cylinder block. The piston cannot be removed from the bottom of
the cylinder block.
7.
Reassemble the bearing cap and lower bearing shell to the connecting rod.
Disassemble Piston and Connecting Rod
Note the condition of the piston and rings. Then remove the rings and connecting rod from the piston as
follows:
1.
Secure the connecting rod in a vise equipped with soft jaws and remove the piston rings with tool J
8128 as shown in Fig. 2.
Figure 2. Removing or Installing Piston Ring using Tool J 8128
2.
Punch a hole through the center of one of the piston pin retainers with a narrow chisel or punch and
pry the retainer from the piston, being careful not to damage the piston or bushings.
3.
Withdraw the piston pin from the piston, then remove the connecting rod.
4.
Drive the remaining piston pin retainer out from the inside with a brass rod or other suitable tool.
Clean Piston
Clean the piston components with fuel oil and dry them with compressed air. If fuel oil does not remove the
carbon deposits, use a chemical solvent (Fig. 3) that will not harm the piston pin bushings or the tinplate on the
piston.
The upper part of the piston, including the compression ring lands and grooves, is not tin-plated and may be
wirebrushed to remove any hard carbon. However, use care to avoid damage to
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