Crankshaft assembly,  M110

Repairing and squaring connecting rods



03—313 Repairing and squaring connecting rods




Center of conrod bearing bore to
center of conrod bushing bore
Width of conrod at conrod bearing bore and conrod bushing bore
27.890 27.857
Basic bore for conrod bearing shells
51.619 51.600
Basic bore for conrod bushing
26.021 26.000
Conrod bushing inside dia.
23.013 23.007
Peak to valley height on inside of conrod bushing
Permissible stagger of conrod bore to conrod bushing bore in reference to a length of 100 mm


Permissible difference in parallel between axes: conrod bearing bore to conrod bushing bore in reference to a length of 100 mm
dia. 0.015


Permissible deviation of conrod bearing bore from true


Permissible difference in weight of all connecting rods of one engine


5 gr.
Tightening torque



Conrod nuts
Initial torque
40-50 Nm


Torque angle
Conventional tool



Connecting rod checking and straightening tool
Made by Krupp GmbH, e.g. Model CL 6
5309 Meckenheim


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Connecting rods, which are overheated (blue discoloration) due to bearing damage, may not be re-used.
The connecting rod and its cap are marked to fit together. The connecting rod stem must not show cross scoring and notches.
Connecting rods with a machined conrod bushing are delivered as replacement parts.
When renewing conrods pay attention to different weights of rods.
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1 Check conrod bolts and replace if necessary (03-310).


2 Check conrod bolt bores.


Place conrod cap on a conrod bolt. If the conrod cap moves down by its own weight, the connecting rod must be replaced.
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3 Mount connecting rod bearing cap and tighten to 40-50 Nm and 90-100° angle of rotation torque.
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4 Measure conrod bearing basic bore. If a basic bore exceeds the value of 51.62 mm or shows conicity, hone bearing surface of bearing cap on a surface plate up to max. 0.02 mm.


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5   Press in new conrod bushing that oil bores match. Installation pressure 2500 Nm.
6   Mill or ream out conrod bushing.
7   Hone side bearing surfaces of connecting rod on a surface plate.
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8 Square connecting rod with a conrod tester.


9 Align parallel of conrod bore to conrod bushing bore.
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10 Correct stagger of conrod bore to conrod bushing bore.
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