(4) and remove the piston from the
(7) Check the piston pin sleeve bearing
for wear, scoring, and out-of-round.
The clearance between the piston pin
(2) Remove the piston rings (1, 2, and 3)
and bearing should not exceed 0.001
from the piston.
inch. Replace a defective bearing.
(3) Press the sleeve bearing (11) out of
(8) Inspect the bearing halves for wear or
the connecting rod if defective or un-
scoring. Replace both bearing halves
if either is unserviceable. Measure the
(4) Disassemble the other pistons and con-
bearing-to-crankshaft clearance by in-
necting rods in the same manner.
stalling a piece of 0.001 inch shim
c. Cleaning, Inspection, and Repair.
stock on each bearing half. Assemble
(1) Clean carbon from the top of the pis-
t h e connecting rod and cap with
tons. Wash all parts with an approved
s h i m m e d bearing to its respective
cleaning solvent and dry thoroughly.
crankshaft journal and tighten the
nuts to a torque of 14 to 18 ft-lb. A
(2) Use an inside micrometer to measure
slight drag on the shaft, when turned
the cylinder bores for wear. All cylin-
by hand indicates proper clearance.
ders should measure 3.504 to 3.505
The connecting rod bearing should not
inches. Remove, rebore, and hone the
bind using shim stock with a minimum
the cylinder blocks (par. 199) whose
thickness of 0.0005 inch.
measurement exceeds the allowable
wear of 0.005 inch and install oversize
pistons and rings.
(1) Press the sleeve bearing (11, fig. 36)
into the connecting rod (12). Ream
(3) To measure the piston ring gap, place
and hone new bearings (11) to provide
the ring in the cylinder bore in the ap-
a clearance of from 0.0005 to 0.001
proximate operating position and
inch between the piston (6) and the
measure the gap with a feeler gage.
The piston ring gaps should meas-
Note. Be sure to aline the oil holes of the
ure between 0.010 and 0.015 inch. If
connecting rod and bearing.
the gap is too great replace the piston
(2) Position the piston on the connecting
ring with an oversize ring. If the gap
rod and install the piston pin (6) and
is too small remove stock by filing.
the two retaining rings (5).
(4) Place two strips of 0.002 inch shim
(3) Install the oil piston ring (3) in the
stock 1/2 inch wide, on opposite sides
bottom groove of the piston (4) with
of the piston. Invert the piston and
its scraper edge down. Install the
slide it into the cylinder bore. Attach
scraper piston ring (2) in the adja-
a spring pull scale to one of the pieces
c e n t groove with its scraper edge
of shim stock and pull up on the scale.
down. Install the two remaining pis-
A pull of 4 to 8 pounds should be re-
ton rings (1) in the upper grooves.
quired to pull the stock out. If the
Stagger the ring gaps around the pis-
shim stock pulls out too freely replace
the piston with an oversized one. Re-
(4) Reassemble the three remaining pis-
bore and rehone the cylinder bore as
tons and connecting rods in a similar
(5) Measure the piston ring side clear-
ance. Replace the piston when clear-
ance exceeds 0.003 inch in the three
(1) Place a ring compressor on the piston.
top grooves or 0.004 inch in the bot-
(2) Insert the connecting rod (12, fig. 36)
with attached piston in its respective
(6) Measure the piston pin fit in the pis-
cylinder bore and push piston out of
ton. If the clearance exceeds 0.0005
the ring compressor into the cylinder
inch, replace the piston and piston pin.