DETROIT DIESEL 53
1.6 Piston and Piston Rings
8. Reassemble the bearing cap and lower bearing shell
The compression rings may be Inspected through the
to the connecting rod.
ports in the cylinder liners after the air box covers
have been removed. If the rings are free and are not
worn IO the extent that the plating or grooves are
gone. compression should be within operating
Disassemble Piston and Connecting Rod
specifications. Refer to Section 15.2 for the procedure
Note the condition of the piston and rings. Then
for checking compression pressure.
remove the rings and connecting rod from the piston
as follows:
Remove Piston and Connecting Rod
1. Secure the connecting rod in a vise equipped with
soft jaws and remove the piston rings with tool J 8128
1. Drain the cooling system.
as shown in Fig. 2.
2. Drain the oil and remove the oil pan.
2. Punch a hole through the center of one of the piston
pin retainers with a narrow chisel or punch and pry
3. Remove the oil pump and inlet and outlet pipes, if
the retainer from the piston, being careful not to
necessary (Section 4.1).
damage the piston or bushings.
3. Withdraw the piston pin from the piston, then
4. Remove the cylinder head (Section 1.2).
remove the connecting rod.
5. Remove the carbon deposits from the upper inner
4. Drive the remaining piston pin retainer out from
surface of the cylinder liner.
the inside with a brass rod or other suitable tool.
6. Use a ridge cutter to remove any ridge in the
cylinder liner at the top of the piston ring travel.
Clean Piston
NOTE: Move the piston to the bottom of its
Clean the piston components with fuel oil and dry
travel and place a cloth over the top of the
them with compressed air. If fuel oil does not remove
piston to collect the cuttings. After the ridge has
the carbon deposits, use a chemical solvent (Fig. 3)
been removed, turn the crankshaft to bring the
that will not harm the piston pin bushings or the tin-
piston to the top of its stroke and carefully
plate on the piston.
remove the cloth with the cuttings.
T h e upper part of the piston, including the
7. Remove the bearing cap and the lower bearing shell
compression ring lands and grooves, is not tin-plated
from the connecting rod. Then push the piston and
and may be wire-brushed to remove any hard carbon.
rod assembly out through the top of the cylinder block.
However, use care to avoid damage to the tin-plating
The piston cannot be removed from the bottom of the
on the piston skirt. Clean the ring grooves with a
cylinder block.
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 and the oil
drain holes in the piston skirt. Exercise care to avoid
enlarging the holes while cleaning them.
Inspection
If the tin-plate on the piston and the original grooves
in the piston rings are intact, it is an indication of very
little wear.
Excessively worn or scored pistons, rings or cylinder
liners may be an indication of abnormal maintenance
or operating conditions which should be corrected to
avoid recurrence of the failure. The use of the correct
types and proper maintenance of the lubricating oil
filters and air cleaners will reduce 10 a minimum the
Fig. 3 - Cleaning Piston
amount of abrasive dust and foreign material
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