Measurement
Install the connecting rod bearing cap (3) with the connecting rod bearing shells (2) onto the connecting rod.
Note: Do not change the connecting rod bearing cap and connecting rod during installation, and ensure that the contact surfaces are clean
Note: Old bolts can be reused for testing.
Tighten the 2 bolts to 13 Nm, then turn further by +60° +15°.
The connecting rod center diameter is measured with an internal micrometer in positions I, II, and arithmetically. The formula and example for calculating the connecting rod bearing diameter: I + II + III.
I – 43, 026 mm.
II – 43, 027 mm.
III – 43, 031 mm.
129.084 mm: 3 = 43.028 mm.
The average inner diameter of the connecting rod bearing is 43.028 mm.
The journal diameter of the connecting rod bearing shaft is measured with an outside micrometer in positions I and II. Formula and example for calculating the journal diameter of the connecting rod bearing shaft:
I + II / 2;
I – 42.977 mm + II – 42.985 mm.
85.962 mm: 2 = 42.981 mm.
The average diameter of the connecting rod bearing shaft journal is 42.981 mm.
Determine the connecting rod bearing clearance using the connecting rod bearing mean inside diameter and the connecting rod bearing journal mean diameter.
Average inner diameter of connecting rod bearing: 4.028 mm.
Average diameter of connecting rod bearing journal: 2.981 mm.
Connecting rod bearing clearance: 0.047 mm.
The calculated connecting rod bearing clearance is 0.047 mm in this example. The allowable connecting rod bearing clearance is 0.013 mm to 0.061 mm.
Note: The check is carried out using a tool for measuring clearances in plain bearings.
Mark the installation position of the connecting rod bearing cap.
Disconnect the connecting rod bearing shells and the connecting rod bearing cap by unscrewing the 2 mounting bolts.
Measure the connecting rod bearing clearance using a plain bearing clearance measuring tool (plastic wire).
Note: The plain bearing clearance measuring tool is available in different measuring ranges.
Cut the wire to a length that matches the width of the connecting rod bearing.
Place the wire along the axis between the crankshaft main journal of the connecting rod bearing and the connecting rod bearing shell.
Install the connecting rod bearing cap
Note: To prevent the wire from breaking when removing the connecting rod bearing cap, remove the grease from the crankshaft journal and lightly lubricate the connecting rod bearing shell - do not turn the crankshaft.
Tighten the 2 bolts to 13 Nm and turn them further by +60° and +15°.
Remove the connecting rod bearing cover, unscrew the 2 bolts.
Attention! Do not confuse decimal and metric scale information.
Measure the width of the flattened section of plastic wire using a measuring scale.
Permissible clearance in the connecting rod bearing: from 0.013 mm to 0.061 mm.
Install the connecting rod bearing shell and connecting rod bearing cap.
Clean the crankshaft bearing journal and connecting rod bearing shell.
Lightly lubricate the connecting rod bearing shells.
Tighten the 2 bolts to 13 Nm and turn them further by +60° and +15°.
Caution: Always use M6.5 bolts. Use new bolts.
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