Buick LeSabre 1965 Service Manual page 62

2 - 4 0 BEARINGS
ENGINE
5. Using the scale printed on the
Plastigage envelope, measure the
flattened Plastigage at its widest
point. The number within t h e
graduation which m o s t closely
corresponds to the width of Plas-
tigage i n d i c a t e s the bearing
clearance in thousandths of an
inch. See Figure 2-39, View B.
6. The desired clearance with a
new bearing is .0002" to .0023".
If bearing has been in service it
is advisable to install a new bear-
ing if the clearance exceeds .003";
however, if bearing is in good
condition and is not being checked
because of bearing noise, it is not
necessary to replace the bearing.
7. If a new bearing is being se-
lected, try a standard size, then
each undersize bearing in turn
until one is found that is within
the specified limits when checked
for clearance with Plastigage.
NOTE: Each undersize bearing
shell has a number stamped on
outer surface on or near the tang
to indicate amount of undersize.
See Figure 2-40.
8. After the proper size bearing
has been selected, clean off the
Plastigage, oil the bearing thor-
oughly, reinstall cap with bearing
shell and tighten bolt nuts to 40-
45 ft. lbs. torque. See NOTE in
Step 2.
UNDERSIZE MARK —y
TANG
Figure 2-40—Location of Undersize
Mark on Bearing Shell
9. With selected bearing installed
and bolts tightened, it should be
possible to move connecting rod
freely back and forth on crankpin
as allowed by end clearance. If
rod cannot be moved, either the
bearing is too much undersize or
a misaligned rod is indicated.
2 - 1 8 REPLACEMENT OF
CRANKSHAFT
BEARINGS
A crankshaft bearing consists of
two halves or shells which are
alike and interchangeable in cap
and crankcase. The first four
bearings are identical, but the
rear bearing is longer and flanged
to take crankshaft end thrust.
When the shells are placed in
crankcase and bearing cap the
ends extend slightly beyond the
parting surfaces so that when cap
bolts are tightened the shells will
be clamped tightly in place to
insure positive seating, and to
prevent turning. The e n d s of
shells must never be filed flush
with parting surface of crankcase
or bearing cap.
If a thrust bearing shell is dis-
turbed 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 several
times with the bearing cap bolts
finger tight.
Crankshaft bearings are the pre-
cision type which do not require
reaming to size or other fitting.
Shims are not provided for ad-
justment since worn bearings are
readily replaced with new bear-
ings of proper size. Bearings for
s e r v i c e replacement are fur-
nished in s t a n d a r d size and
undersizes. Under no circum-
stances should crankshaft bearing
caps be filed to adjust for wear
in old bearings.
a. Inspection of Crankshaft
Bearings and Crankshaft
After removal of lower crankcase,
oil pump and bell housing cover
perform the following removal,
inspection and installation oper-
ations on each crankshaft bearing
in turn so that the crankshaft will
be well supported by the other
bearings.
NOTE: If crankshaft has been re-
moved to check straightness the
following procedure is suggested.
Rest crankshaft on "veeblocks"
at number one and number five
main bearing journals. Check in-
dicator runout at No. 2, 3 and 4
main bearing journals. Total in-
dicator readings at each journal
should not exceed .003".
While checking runout at each
journal note relation of "high"
spot (or maximum eccentricity)
on each journal to the others.
" High'
;
spot on all journals should
come at the same angular loca-
tion. If "high" spots do not come
at nearly the same angular lo-
cation, crankshaft has a "crook"
or "dogleg" in it and is unsatis-
factory for service.
1. Since any service condition
which affects the crankshaft bear-
ings may also affect the connect-
ing rod bearings, it is advisable
to inspect connecting rod bearings
first (par. 2-17). If crankpins are
worn to the extent that crankshaft
should be replaced or reground,
replacement of crankshaft bear-
ings only will not be satisfactory.
2. Remove one bearing cap, then
clean and inspect lower bearing
shell and the crankshaft journal.
If journal surface is scored or
ridged, the crankshaft must be
replaced or reground to insure
satisfactory operation with new
bearings. Slight roughness may
be polished out with fine grit
polishing cloth thoroughly wetted
with engine oil, and burrs may
be honed off with a fine stone.