diameter, a b l a c k o x i d e f i n i s h , o r
a dull cast iron color. These rings
can be mixed in an engine.
The
former steel rings, identified by a
very shiny appearance, must not
be used for service.
Figure 11B-114. Checking Fire Ring
G r o o v e Using J 24599
Inspection of the connecting rod, piston
pin and piston pin bushing are covered
in this subsection.
Other factors that may contribute to pis-
t o n failure include oil leakage into the air
box, oil pull-over from the air cleaner,
dribbling injectors, combustion blow-by
and low oil pressure (dilution of the lu-
bricating oil).
Figure 11B-115. Installing Seal Ring
A s s e m b l e Piston
3. Compress the seal ring with ring com-
pressor J 23453 and push the skirt into
1. Install the bearing (bushing) in the
position on the piston crown.
piston crown.
It should slide into the
piston crown without force.
With new
NOTE
parts, there is 0.0005" to 0.0105" clear-
ance between the edge of the bushing
Before completely assembling the
and the groove in the piston crown.
piston, c h e c k t o m a k e s u r e t h e
seal ring does not stick in the ring
groove.
It is imperative for satis-
NOTE
factory engine operation that the
The bearing must be installed be-
s e a l r i n g is
free
in
the
piston
fore assembling the piston skirt
c r o w n g r o o v e . Check the full 360
and crown.
circumference of the groove to be
sure
that
are
no
tight
spots.
When the piston crown, seal ring
and piston skirt are assembled,
2. Lubricate the metal seal ring
the skirt should spin freely on the
(Figure 11B-115) with engine oil and in-
crown ( c r o w n t o p d o w n o n t h e
stall it with the chamfer or counterbore
directed toward the bottom of the piston.
bench).
If the seal ring sticks,
remove high spots or nicks in the
groove with a flat file.
If this
NOTE
does not relieve sticking, replace
the piston crown.
T h e s e a l r i n g s a r e m a d e of cast
iron a n d a r e i d e n t i f i e d b y t h e
outside
tin-plating on
the
11B-73
E n g i n e (Less Major Assemblies)