DETROIT DIESEL 53
1.6 Piston and Piston Rings
Piston in Section 1.6.1. Then refer to Fig. 1 and
Select a feeler gage with a thickness that will require a
install the piston rings.
pull of six pounds to remove. The clearance will be
.001" greater than the thickness of the feeler gage
NOTE: Lubricate the piston rings and piston
used. i.e., a .004" feeler gage will indicate a clearance
of .005" when it is withdrawn with a pull of six
with engine oil before installing the rings.
pounds. The feeler gage must be perfectly flat and free
of nicks and bends.
COMPRESSION RINGS
If any bind occurs between the piston and the liner,
1 . Starting with the bottom ring, install the
examine the piston and liner for burrs. Remove burrs
compression rings with tool J 8128 as shown in Fig. 2.
with a fine hone (a flat one is preferable) and recheck
To avoid breaking or overstressing the rings, do not
the clearance.
spread them any more than necessary to slip them
over the piston.
CAUTlON: When installing the top compression
Fitting Piston Rings
(fire) ring with the tapered face, be sure the
side marked "TOP" is toward the top of the
Each piston is fitted with a fire ring, three compression
piston.
rings and two oil control rings (Fig. 1).
2. Stagger the ring gaps around the piston.
The current top compression (fire) ring can be
identified by the bright chrome on the bottom side
and oxide (rust color) on the top. The former ring had
OIL CONTROL RINGS
a plain metal color on both sides.
The upper and lower oil control rings used on pistons
A two-piece oil control ring is used in both oil ring
for non-turbocharged engines consist of two halves
grooves in the pistons for non-turbocharged (naturally
(upper and lower).
aspirated) engines.
Install the oil control rings as follows:
1. Install the ring expanders in the oil control ring
All new piston rings must be installed whenever a
grooves in the piston.
piston is removed, regardless of whether a new or used
piston or cylinder liner is installed.
CAUTION: When installing the oil control rings,
use care to prevent overlapping the ends of the
Insert one ring at a time inside of the cylinder liner
ring expanders. An overlapped expander will
and far enough down to be within the normal area of
cause the oil ring to protrude beyond allowable
ring travel. Use a piston to push the ring down to be
limits and will result in breakage when the
sure it is parallel with the top of the liner. Then
piston is inserted in the ring compressor during
measure the ring gap with a feeler gage as shown in
installation in the cylinder liner. Do not cut or
Fig. 9. Refer to Section 1.0 for ring gap specifications.
grind the ends of the expanders to prevent
overlapping. Cutting or grinding the ends will
If the gap on a compression ring is insufficient, it may
decrease the expanding force on the oil control
be increased by filing or stoning the ends of the ring.
r i n g s and result in high lubricating oil
File or stone both ends of the ring so the cutting
consumption.
action is from the outer surface to the inner surface.
This will prevent any chipping or peeling of the
chrome plate on the ring. The ends of the ring must
remain square and the chamfer on the outer edge
must be approximately .015"
Check the ring side clearance as shown in Fig. 10.
Ring side clearances are specified in Section 1.0.
Install the upper and lower halves of the lower oil
Install Piston Rings
control ring by hand. Install the upper half with the
gap 180o from the gap in the expander. Then install
Before installing the piston rings, assemble the piston
the lower half with the gap 45o from the gap in the
and rod as outlined under Assemble Connecting Rod to
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