Connecting Rod Bearing: Testing and Inspection

Visual Inspection
Visually inspect each bearing for peeling, melt, seizure and improper contact. Replace the defective bearings.

Oil Clearance Measurement
To check the oil clearance, 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.
Standard value:
Connecting rod bearing: 0.024-0.044 mm (0.0009-0.0017 inch)
Limit: 0.1 mm (0.0039 inch)

Oil Clearance Measurement (Plastigauge Method)
Plastigauge may be used to measure the clearance.
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, away from oil holes.





3. Install the crankshaft, bearings, and caps. Tighten them to the specified torques. During this operation, do not turn the crankshaft. Remove the caps. Measure the width of the plastigauge at the widest point using the scale printed on the gauge package. If the clearance exceeds the repair limit, the bearing should be replaced or an undersize bearing be used. When installing a new crankshaft, be sure to use standard size bearings. Should the standard clearance not be obtained even after bearing replacement, the journal should be ground to a recommended under size, and a bearing of the same size should be installed.