Crankshaft Main Bearing: Testing and Inspection

VISUAL INSPECTION
Visually inspect each bearing for peeling, melt, seizure and improper contact. Replace any defective bearings.

OIL CLEARANCE MEASURING
Micrometer Gauge Method.









Using suitable gauges, measure outside diameter of the crankshaft journal and the crank pin and inside diameter of the bearing.
The clearance measurement is the difference between the measured outside and inside diameters.

Plastigauge Method
1. Remove oil, grease and any other dirt from bearings and journals.
2. Cut plastigauge to the same length as the width of the bearing and place it in parallel with the journal, off oil holes.






3. Install the crankshaft, bearings, and caps.
4. Tighten them to the specified torques. During this operation, do not turn the crankshaft.
5. Remove the caps.
6. Measure the width of the plastigauge at the widest point using the scale printed on the gauge package.
7. If the clearance exceeds the repair limit, replace the bearing.

OIL CLEARANCE DIMENSIONS:
Standard value:
Crankshaft main bearing: 0.02-0.05 mm (0.0008-0.0020 inch).
Connecting rod bearing: 0.02-0.05 mm (0.0008-0.0020 inch).
Wear Limit:
Crankshaft main bearing: 0.1 mm (0.004 inch).
Connecting rod bearing: 0.1 mm (0.004 inch).