Bearing Selection
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
- Measure the bearing clearance to determine the correct replacement bearing insert size. There are 2 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.
- To measure bearing clearance using Method A, use the following procedure:
- Measure the crankshaft bearing journal diameter with a micrometer (1) in several places, 90 degrees apart. Average the measurements.
- Measure the crankshaft bearing journal taper and runout.
- Install the lower crankcase and tighten the bearing cap bolts to specification.
- Measure bearing inside diameter (ID) in several places 90 degrees apart, average measurements.
- Subtract journal measurement from bearing ID measurement to determine clearance.
- Determine whether clearance is within specification.
- If out of specification, choose different inserts.
- Measure the connecting rod inside diameter in the same direction as the length of the rod with an inside micrometer.
- Measure the crankshaft main bearing inside diameter with an inside micrometer.
- To measure bearing clearance using Method B, use the following procedure:
- Clean the used bearing inserts.
- Install the used bearing inserts.
- Place a piece of gaging plastic across the entire bearing width.
- Install the bearing caps.
- Install the bearing cap bolts to specification.
- Remove the bearing cap, leaving the gaging plastic in place. It does not matter whether the gaging plastic adheres to the journal or to the bearing cap.
- Measure the gaging plastic at its widest point with the scale (1) printed on the gaging plastic package.
- Remove the gaging plastic.
CAUTION: 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.NOTE: Do not rotate the crankshaft.
NOTE:
Do not mix inserts of different nominal size in the same bearing bore.