45. Crankshaft and Bearing Installation

- TOOLS REQUIRED
- SA9140NE Torque Angle Meter
- SA9178NE Cylinder Bore Checking Gauge

IMPORTANT: If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft or connecting rod bearing bores.





Inspect the connecting rod bearing bores or crankshaft main bearing bores using the following procedure:
^ Tighten bearing cap to specification.
^ Measure bearing bore for taper and out-of-round.
- No taper or out-of-round should exist.

BEARING SELECTION





1. Measure bearing clearance to determine the correct replacement bearing insert size. There are two methods to measure bearing clearance.
- Method A gives more reliable results and is preferred. Method A yields measurement from which the bearing clearance can be computed.
- Method B yields the bearing clearance directly. Method B does not give any indication of bearing run-out.

IMPORTANT: Do not mix inserts of different nominal size in the same bearing bore.

2. To measure bearing clearance using Method A, use the following procedure:
a. Measure crankshaft bearing journal diameter with a micrometer in several places, 90 degrees apart. Average the measurements.
b. Measure crankshaft bearing journal taper and runout.
c. Install lower crankcase and tighten bearing cap bolts to specification.
d. Measure bearing I.D. in several places 90 degrees apart, average measurements.
e. Subtract journal measurement from bearing I.D. measurement to determine clearance.
f. Determine whether clearance is within specification. If out of specification choose different inserts.
g. Measure connecting rod inside diameter in same direction as the length of rod with an inside micrometer.
h. Measure crankshaft main bearing inside diameter with an inside micrometer.
i. Select a set of bearing inserts that will produce desired clearance.
j. If specified clearances cannot be met, the crankshaft journals must be reconditioned and undersized bearing inserts installed.





3. To measure bearing clearance using Method B. use the following procedure:
a. Clean used bearing inserts.
b. Install used bearing inserts.
c. Place a piece of gaging plastic across the entire bearing width.
d. Install bearing caps.

NOTICE: In order to prevent the possibility of cylinder block or crankshaft bearing cap damage, the crankshaft bearing caps are tapped into the cylinder block cavity using a brass, lead, or a leather mallet before the attaching bolts are installed. Do not use attaching bolts to pull the crankshaft bearing caps into the seats. Failure to use this process may damage a cylinder block or a bearing cap.

e. Install the bearing cap bolts.

IMPORTANT: Do not rotate the crankshaft.

f. Remove bearing cap, leaving the gaging plastic in place. It does not matter whether gaging plastic adheres to the journal or to the bearing cap.
g. Measure gaging plastic at its widest point with the scale printed on the gaging plastic package.
h. Remove gaging plastic.
i. Select a set of bearing inserts that will produce the desired clearance.