installed, the crankshaft would be
disassemble the main bearings and crankshaft.
impossible to turn except with a
wrench or bar.
(3) Inspect and measure the connecting rod
journals in a similar manner as described for
Remove the bearing sleeves (2, 4, 6,
the main bearing journals above. The
and 8) from the bearing caps and the
connecting rod journals diameter should be
3.499 to 3.500 inch. When the connecting rod
is perfectly free, with the proper clearance it
Main Bearings and Crankshaft Cleaning,
should have 0.008 to 0.012 in. side play.
Inspection, and Repair
Repair or replace a defective part as required.
The main bearing cap must be torqued to the
correct tightness, 1/2 in. capscrew should be
(1) Clean all parts in an approved cleaning
from 85 to 95 ft-lbs and the 9/16 in. should be
from 100 to 110 ft-lb.
(2) Clean all oil passages in the crankshaft.
Inspect the rear oil seals for cracks, wear, or
Use extreme care in cleaning and
handling the bearing caps, sleeves
and crankshaft journals to avoid
Main Bearings and Crankshaft Reassembly
damaging the machined surfaces.
b. Inspection and Repair.
a. Reassembly. Refer to figure 34 and reassemble
the crankshaft and main bearings in the' reverse order.
(1) Inspect the bearings. Replace the bearing if
there is any indication of wear, flaking out, or
Install the bearing sleeves (2, 4, 6,
If visual inspection appears
and 8) in the bearing caps and the
satisfactory, measure the bearing for
thickness is 0.1237 to 0.1232 inches.
Replace a bearing that is worn more than
(1) Refer to figure 33 and install the crankshaft
and main bearings on the engine.
(2) Inspect the crankshaft journals for wear or
scoring. The diameter of the crankshaft
(2) Install connecting rod bearing caps (par. 99).
journals should be 3.749 to 3.750 inches.
The clearance of each bearing should be
measured with a piece of feeler stock 1/2 in.
wide and s8 in. shorter than the length of the
(4) Install timing gears and front end plate (par.
Dress all edges of the stock
carefully to be sure there are no burrs to
mark the bearing. The thickness of the feeler
Check crankshaft end play before
stock should be equivalent to the maximum
installing front end plate.
clearance, which is 0.003 in., in the bearing.
Place the feeler stock on a film of oil in the
c. Checking Crankshaft End Play. A shim pack
bearing. Install the bearing cap, and torque
containing shims of 0.002 in. and 0.008 in. thickness, is
the capscrews to specified amount (1/2 in.
incorporated in the assembly between the front end of
capscrews, 85-90 ft-lb; 9/16 in. capscrews
the main bearing journal and the crank gear. By
100-110 ft-lb). A definite drag should be felt
removing or adding shims, this end play can be
when the crankshaft is turned.
corrected to fall within the specification (Table 2).
At all times when checking end play,
If a new shaft and new bearings are
the crank gear must be tightened
firmly against the shim pack.
70 AGO 8456A