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2 3 1 V 6 ENGINE V.I. CODE C
6A3-15
L
Fig. 6A3-29 Removal and Installation of Crankshaft
Bearing Upper Shell
9. Before installation of bearing shells make sure that
crankshaft journal and the bearing seats in crankcase and cap
are thoroughly cleaned.
10. Coat inside surface of upper bearing shell with engine
oil and place shell against crankshaft journal so that tang on
shell will engage notch in crankcase when shell is rotated into
place. Upper bearing shells have an oil groove in their center,
while lower shells are not grooved. They must not be
interchanged.
11. Rotate bearing shell into place as far as possible by
hand, then insert Installer J 8080 in crankshaft oil hole and
rotate crankshaft to push shell into place. Bearing shells
should move into place with very little pressure. If heavy
pressure is required, shell was not started squarely and will
be distorted if forced into place.
12. Place lower bearing shell in bearing cap, then check
clearance with plastic-type gage, as previously described.
13. The desired clearance with a new bearing is
.OW''
to .0015". If this clearance cannot be obtained with a standard
size bearing, insert an undersize bearing and check again with
plastic-type gage.
Each undersize shell has a number stamped on outer
surface on or near the tang to indicate amount of undersize.
14. When the proper size bearing has been selected, clean
out all plastic-type gages, oil the lower shell and reinstall
bearing cap. Clean the bolt holes and lube bolts, then torque
cap bolts to specification.
The crankshaft should turn freely at flywheel rim;
however, a very slight drag is permissible.
15. If the thrust bearing shell is disturbed or replaced
it is necessary to line up the thrust surfaces of the bearing shell
before the cap bolts are tightened. To do this, move the
crankshaft fore and aft the limit of its travel serveral times
(last movement fore) with the thrust bearing cap bolts finger
tight.
16. After bearing is installed and tested, loosen all
bearing cap bolts 1/2 turn and continue with other bearings.
When bearings have been installed and tested, tighten all
bearing cap bolts to specified torque.
17. Replace rear main bearing oil seals.
18. Install oil pan bame, pipe and screen assembly, and
oil pan.
Installation of Rear Bearing Oil Seals
Braided fabric seals are pressed into grooves formed in
crankcase and rear bearing cap to rear of the oil collecting
groove, to seal against leakage of oil around the crankshaft.
See Fig. 6A3-30.
Fig. 6A3-30 Installing Rear Bearing Oil Seals
A new braided fabric seal can be installed in crankcase
only when crankshaft is removed, but it can be repaired while
crankshaft is installed, as outlined under Rear Main Bearing
Upper Oil Seal Repair. The seal can be replaced in cap
whenever the cap is removed. Remove old seal and place new
seal in groove with both ends projecting above parting surface
of cap. Force seal into groove by rubbing down with hammer
handle or smooth stick until seal projects above the groove
not more than 1/16". Cut ends off flush with surface of cap,
using sharp knife or razor blade. See Fig. 6A3-30.
The engine must be operated at slow speed when first
started after a new braided seal is installed.
Neoprene composition seals are placed in grooves in the
sides of bearing cap to seal against leakage in the joints
between cap and crankcase. The neoprene composition swells
in the presence of oil and heat. The seals are undersize when
newly installed and may even leak for a short time until the
seals have had time to swell and seal the opening. See Fig.
6A3-30.
The neoprene seals are slightly longer than the grooves
in the bearing cap. The seals must not be cut to length. Before
installation of seals, soak for 1 to 2 minutes in light oil or
kerosene. After installation of bearing cap in crankcase,
install seal in bearing cap.
To help eliminate oil leakage at the joint where the cap
meets the crankcase, apply silastic sealer to the rear main
bearing cap split line. When applying sealer, use only a thin
coat as an over abundance will not allow the cap to seat
properly. See Fig. 6A3-3 1.
After seal is installed, force seals up into the cap with
a blunt instrument to be sure of a seal at the upper parting
line between the cap and case.
REAR M A I N BEARING UPPER OIL SEAL
REPAIR
1. Remove oil pan.
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