Crankshaft and Bearing Installation
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Crankshaft and Bearing Installation
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Note
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If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft or connecting rod bearing bores.
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Inspect the connecting rod bearing bores or crankshaft main bearing bores using the following procedure:
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Tighten the bedplate to specification using the
EN-45059
angle meter.
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Measure the bearing bore for taper and out-of-round using the
EN-8087
gauge (1).
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No taper or out-of-round should exist.
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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.
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Method A yields measurement from which the bearing clearance can be computed.
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Method B yields the bearing clearance directly. Method B does not give any indication of bearing run-out.
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Note
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Do not mix inserts of different nominal size in the same bearing bore.
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To measure bearing clearance using Method A, use the following procedure:
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1.
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Measure the crankshaft bearing journal diameter with a micrometer (1) in several places, 90 degrees apart. Average the measurements.
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2.
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Measure the crankshaft bearing journal taper and runout.
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3.
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Install the lower crankcase and tighten the bearing cap bolts to specification.
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4.
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Measure bearing inside diameter (ID) in several places 90 degrees apart, average measurements.
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5.
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Subtract journal measurement from bearing ID measurement to determine clearance.
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6.
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Determine whether clearance is within specification.
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7.
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If out of specification, choose different inserts.
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8.
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Measure the connecting rod inside diameter in the same direction as the length of the rod with an inside micrometer.
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9.
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Measure the crankshaft main bearing inside diameter with an inside micrometer.
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To measure bearing clearance using Method B, use the following procedure:
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1.
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Clean the used bearing inserts.
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2.
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Install the used bearing inserts.
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3.
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Place a piece of gaging plastic across the entire bearing width.
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4.
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Install the bearing caps.
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5.
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Warning
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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.
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Install the bearing cap bolts to specification.
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6.
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Note
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Do not rotate the crankshaft.
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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.
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7.
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Measure the gaging plastic at its widest point with the scale (1) printed on the gaging plastic package.
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8.
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Remove the gaging plastic.
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