General Information
The crankshaft uses forged counterweights.
Oversize main bearings, thrust bearings, and connecting rod bearings are available for service. Cummins Inc.
recommends regrinding all of the main or the connecting rod journals when one requires regrinding. See the
appropriate parts catalog.
Remove
NOTE: Lift the crankshaft straight up to avoid damage to the crankshaft and cylinder block.
Install nylon lift sling, Part Number 3375957, around the number 3 and number 4 rod bearing journals.
Attach the sling to a hoist and remove the crankshaft.
Remove the upper main bearings.
Use an awl to mark the bearing position in the tang area.
NOTE: Mark the bearing location for future identification or possible failure analysis.
Measure
Measure the crankshaft main and connecting rod journals.
Out-of-Round: 0.050 mm [0.002 in]
Taper: 0.013 mm [0.0005 in]
NOTE: If crankshaft journals are not within the given specification, the crankshaft must be reground. Always
grind all of the journals when one is not within specifications.
Measure and record the diameter of the connecting rod journal on the crankshaft.
NOTE: If the crankshaft connecting rod journals are not within the given specification, the crankshaft must be
ground. Select the target undersize journal diameter and its corresponding oversize bearing. Machine the
crankshaft to the maximum journal diameter specified in the table above. Then finish the crankshaft to the target
diameter. Always grind all the journals when one is not within specifications.
Measure and record the diameter of the connecting rod crankshaft bore with the bearings installed. The following
procedure contains information for measuring the connecting rod crankshaft bore (with bearing).
Refer to Procedure 001-014 in Section 1.
Calculate the connecting rod bearing to crankshaft journal clearance.
Bearing clearance equals the connecting rod crankshaft bore (with bearing) minus the crankshaft connecting rod
journal diameter.
Bearing clearance can also be determined with plastigauge during crankshaft installation.
NOTE: If the clearance is found to be out of specification:
1. Replace or try another set of connecting rod bearings
2. Measure and inspect the connecting rod crankshaft bore with the bearings removed. Refer to Procedure Refer toย ย ย ย ย ย Procedure 001-014 in Section 1.
NOTE: If the crankshaft connecting rod journals are not within the given specification, the crankshaft must be
reground. Select the target undersize journal diameter and its corresponding oversize bearing. Machine the
crankshaft to the maximum journal diameter specified in the table above. Then finish the crankshaft to the target
diameter. Always grind all of the journals when one is not within specifications.
Install the main bearing caps with the upper and lower main bearings. Refer to Proc~dure 001-006 in Section 1.
Tighten the main bearing cap capscrews.
Measure the main bearing bore with the bearings installed.
Calculate the main bearing to crankshaft journal clearance.
Bearing clearance equals the main bearing crankshaft bore (with bearing) minus the crankshaft main bearing
journal diameter.
Bearing clearance can also be determined with plastigauge during engine assembly.
NOTE: If the clearance is found to be out of specification:
1. Replace or try another set of connecting rod bearings
2. Measure and inspect the connecting rod crankshaft bore with the bearings removed. Refer to Procedure
001-014 in Section 1.
Main Bearing Capscrew Reuse Measurement
To check if a main bearing capscrew can be reused, the length must be measured by performing the following:
For each main bearing capscrew that has been removed, measure the length from underneath the head of the
capscrew to the tip of the capscrew, as illustrated, using one of two methods.
1. A depth micrometer (preferred method for accuracy)
2. A machinist’s rule.
If the measurement is above the maximum specification, the main bearing capscrew must be replaced.
Check the thrust bearing surfaces for damage or excessive wear. Minor scratches are acceptable. Use a
fine crocus cloth to polish the machined surfaces.
The thrust bearing surfaces are located at the number 6 crankshaft main bearing journal.
Measure the thrust distance.
NOTE: Oversize thrust bearings are available if the thrust distance is not within specifications. Oversize thrust
bearings of 0.25 and 0.50 mm [0.01 0 to 0.020 in] are available.
Use a light preservative oil to lubricate the crankshaft to prevent rust.
NOTE: If the crankshaft is not going to be used immediately, use a heavy preservative oil. Protect the crankshaft with a cover to prevent dirt from sticking to the oil.
Install
Upper Main Bearings
Do not lubricate the side of the main bearing that is against the cylinder block.
Apply a coat of assembly lubricant, Part Number 3163087 or equivalent, to the crankshaft side of the upper main
bearings.
NOTE: Make sure the main bearing being installed is the same size as the main bearing that was removed. The size
is engraved on the back of the main bearing.
NOTE: The crankshaft thrust bearing must be installed in the number four position.
NOTE: The upper and lower main bearing shells of some engines are not interchangeable. The backs of the main
bearings are marked with the proper orientation, if required.
NOTE: If used bearing shells are to be installed, they must be installed in their original locations, as marked
during disassembly.
Use a hoist and nylon list sling, Part Number 3375957.
Install the sling around the number 3 and number 4 connecting rod bearing journals.
Install the crankshaft.
