TM 5-3810-300-24&P-3
1.6
Piston and Piston Rings
piston cannot be removed from the bottom of the cylinder
Remove Piston and Connecting Rod
block.
1. Drain the cooling system.
8. Re-assemble the bearing cap and lower bearing
2. Drain the oil and remove the oil pan.
shell to the connecting rod.
3. Remove the oil pump and inlet and outlet pipes, if
Disassemble Piston and Connecting Rod
necessary (Section 4.1).
Note the condition of the piston and rings. Then remove
4. Remove the cylinder head (Section 1.2).
the rings and disassemble the piston as follows:
5. Remove the carbon deposits from the upper inner
1. Secure the connecting rod in a vise equipped with
surface of the cylinder liner.
soft jaws and remove the piston rings with tool J 8128 as
shown in Fig. 16.
6. Use a ridge cutter to remove any ridge in the cylinder
liner at the top of the piston ring travel.
2. Punch a hole through the center of one of the piston
pin retainers with a narrow chisel or punch and pry the
NOTE: Move the piston to the bottom of its
retainer from the piston, being careful not to damage the
travel and place a cloth over the top of the
piston or bushing. Remove the opposite retainer in the
piston to collect the cuttings. After the ridge
same manner.
has been removed, turn the crankshaft to
bring the piston to the top of its stroke and
3. Remove the two bolts and spacers which secure the
carefully remove the cloth with the cuttings.
connecting rod to the piston pin and remove the
connecting rod.
7. Remove the bearing cap and the lower bearing shell
from the connecting rod. Then push the piston and rod
4. Withdraw the piston pin.
assembly out through the top of the cylinder block. The
5. Separate the piston skirt from the piston crown.
6. Remove the metal seal ring from the piston crown.
CAUTION: Do not remove the bushings
from the pistons used in series "N" engines
because they are not serviced separately.
Cleaning
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 that will not
harm the piston pin bushing or the tin-plate on the piston.
The piston crown, including the compression ring
grooves, is not tin-plated and may be wire-brushed to
remove any hard carbon. Do not wire-brush the piston
skirt. Clean the ring grooves with a suitable tool or a
piece of an old compression ring that has been ground to
a bevel edge.
Clean the inside surfaces of the piston crown and skirt
and the oil drain holes in the lower half of the piston skirt.
Exercise care to avoid enlarging the holes while cleaning
them.
Fig. 16 - Removing or Installing Piston Rings
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