c. Place the crankshaft carefully in place.
Tape upper and lower main bearing shells
d. 'Roll the upper thrust rings into position with
together and identify by cylinder number.
the grooved sides facing the crankshaft flanges e.
Install the lower bearing shells.
4-75. Cleaning, Inspection and Repair
a. Clean all parts with an approved cleaning
Position the lower thrust rings over the
solvent and dry thoroughly.
dowels on No. 7 main bearing cap.
b. Inspect crankshaft gear. If chipped, cracked
g. Lubricate the threads of the capscrews and
or broken, replace.
lockplates with clean lubricating oil.
c. Inspect crankshaft journals and if worn more
h. Install the caps with the numbers
than 0.002 inches below low limit or are out-of-round in
(corresponding to the upper main bearings) toward the
camshaft side of the engine.
d. Remove all pipe plugs and clean all drilled oil
Install capscrews by tightening alternately and
passages with a rod and rag.
slowly to seat the caps in position.
e. Perform a magnetic inspection on crankshaft
for cracks, breaks, or signs of fatigue.
Inspect bearing shells for chipped, flaked, or
scored condition and wear exceeding 0.002 inch.
Driving the main bearing caps into
Replace defective or worn bearing shells.
position may jar lower main bearing
g. Regrind or replace a worn or defective
shells out of position.
crankshaft as necessary.
allowable wear tolerances).
Tighten the main bearing capscrews
alternately to 65/75 ft-lbs. to set shells, caps and
lockplates, then advance to 140/150 ft.-lbs.
To regrind the crankshaft the
k. Loosen completely to remove all tension.
operation must be performed by a
Retighten to 45/50 foot-pounds.
Scribe capscrew heads to coincide with
permanent mark on cap or scribe each cap in line with
hex corner. Advance each bolt 600 (one hex) from
position described in step (e) above. This will align
scribed mark (or next corner) with mark on main bearing
4-76. Reassembly and Installation
cap. Tighten each side of bearing a little at a time and
as evenly as possible until operating position is reached.
reassemble and install crankshaft and main bearings.
by barring crankshaft toward front and rear. Total gauge
Coat main bearing shells thoroughly with an approved
reading should be 0.004/0.015 inch. If end clearance
high pressure grease.
exceeds 0.022 inch, new thrust rings and/or crankshaft
b. Lay the upper main bearing shells in the block
must be installed.
bores, engaging the locking tangs with the recesses in
the block bores. Index the drilled oil passage holes in
the block and shells.