82
1
FIGURE
14.
PISTON GROOVE CLEANING
Inspection
Follow the procedures given below when inspecting
pistons and connecting rods.
Piston Inspection:
1.
Inspect the pistons for fractures at the ring
lands, skirts and pin bosses. Check for wear at
the ring lands using a new ring and feeler gauge
as shown in Figure
15.
Replace the piston when
the side clearance of the top compression ring
exceeds that specified in
DIMENSIONS AND
CLEARANCES.
2.
Replace pistons showing signs of scuffing,
scoring, worn ring lands, fractures or damage
from preignition. Excessive piston wear near
the edge
of
the top ring land indicates
preignition.
Connecthg
Rod
Inspection:
1.
Replace connecting rod bolts and nuts with
damaged threads. Replace connecting rods
FIGURE
15.
CHECKING RING
SIDE
CLEARANCE
with deep nicks, signs of fractures, scored
bores or bores out of round more than
0.002
inch.
2.
Use a new piston pin to check connecting rod
for wear.
A
push fit clearance is required and
varies from engine to engine. If a new piston
pin falls through a dry rod pin bore as a result
of its own weight, replace the rod.
Fitting Pistons:
1.
Proper piston tolerances must be maintained
for satisfactory operation.
.
2.
Refer to
DIMENSIONS AND CLEARANCES
to
determine where to measure piston to be sure
the total clearance follows specifications.
1
I
I
I
Io
0
0
0
01
c
MEASURECLEARANCEHERE
FIGURE
16.
MEASURING
PISTON
CLEARANCE
10.9
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