Buick LeSabre 1965 Service Manual page 61

ENGINE BEARINGS 2 - 3 9
SECTION 2-E
REPLACEMENT OF CRANKSHAFT AND CONNECTING ROD
BEARINGS, PISTONS AND RINGS
Paragraph Subject
CONTENTS OF SECTION 2-E
Page Paragraph
Subject
2-17 Replacement of Connecting
Rod Bearings 2-39
2-18 Replacement of Crankshaft
Bearings 2-40
2-19 Replacement of Pistons, Rings,
and Connecting Rods . . . .
Page
2-43
2 - 1 7 REPLACEMENT OF
CONNECTING ROD
BEARINGS
A connecting rod bearing consists
two halves or shells which are
alike and interchangeable in rod
and cap. When the shells are
placed in rod and cap the ends
extend slightly beyond the parting
surfaces so that when rod bolts
are tightened the shells will be
clamped tightly in place to insure
positive seating and to prevent
turning. The ends of shells must
never be filed flush with parting
surface of rod or cap.
If a precision type connecting rod
bearing becomes noisy or is worn
so that clearance on crankpin
is excessive, a new bearing of
proper size must be selected and
installed since no provision is
made for adjustment. Under no
circumstances should the con-
necting rod or cap be filed to
adjust the bearing clearance.
a. Inspection of Connecting
Rod Bearings and
Crankpin Journals
After removal of lower crankcase,
disconnect two connecting rods at
a time from crankshaft and in-
spect the bearings and crankpin
journals. While turning crank-
shaft it is necessary to tempo-
rarily r e c o n n e c t the rods to
crankshaft to avoid possibility of
damaging t h e journals through
contact with loose rods.
If connecting rod bearings are
chipped or scored they should be
replaced. If bearings are in good
physical c o n d i t i o n check for
proper clearance on crankpins
as described in subparagraph b,
below.
If crankpin journals are scored
or ridged the crankshaft must be
replaced, or reground for under-
size bearings, to insure satis-
factory life of connecting r o d
bearings. Slight roughness may
be polished out with fine grit
polishing cloth thoroughly wetted
with engine oil. Burrs may be
honed off with a fine oil stone.
Use an outside micrometer to
check crankpins for out-of-round.
If crankpins are more than .0015"
out-of-round, satisfactory life of
new bearings cannot be expected.
b. Checking Clearance and
Selecting Replacement
Connecting Rod Bearings
Service bearings are furnished in
standard size and several under-
sizes (including undersizes for
reground crankpins).
The clearance of connecting rod
(and crankshaft) bearings may be
checked by use of Plastigage,
Type PG-1 (green), which has a
range of .001" to .003". Plasti-
gage is manufactured by Perfect
Circle Corporation, and is avail-
able through General Motors parts
warehouses.
1. Remove connecting rod cap
with bearing shell. Wipe oil from
bearing and crankpin journal, also
blow oil out of hole in crankshaft.
NOTE; Plastigage is soluble in
oil,
2. Place a piece of Plastigage
lengthwise along the bottom cen-
ter of the lower bearing shell
(Figure 2-39, view A), then install
cap with shell and tighten bolt
nuts to 40-45 ft. lbs. torque.
NOTE: The rib on edge of cap
and the conical boss on web of
rod must be toward rear of engine
on all rods in right bank or
toward front of engine in left
bank.
3. DO NOT TURN CRANKSHAFT
with Plastigage in bearing.
4. Remove b e a r i n g cap with
bearing shell, the flattened Plas-
tigage will be found adhering to
either the bearing shell or the
crankpin. Do not remove it.
Figure 2-39—Checking Bearing
Clearance with Plastigage