Measure the main bearing shell thickness with an outside micrometer that has a ball tip.
Discard a bearing shell if its thickness is below the minimum specifications.
NOTE: Main bearings are identified with a part number and size stamped on the back side.
If replacing the bearings, determine the size of the removed main bearings and obtain a set of the same size.
Oversize service main bearings are available for use with crankshafts that have been machined undersize. See the
appropriate parts catalog.
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.
• A depth micrometer (preferred method for accuracy)
• A machinist’s rule.
If the measurement is above the maximum specification, the main bearing capscrew must be replaced.
Install
Upper Main Bearing
NOTE: Make sure the main bearing being installed is the same size as the main bearing removed, if the crankshaft
has not been machined. The size is engraved on the back of the main bearing.
NOTE: Install the upper main bearing cap after each upper main bearing is installed to keep the main bearing
in place while the other upper main bearings are installed.
Apply assembly lube, Part Number 3163086, to the upper main bearings.
NOTE: The crankshaft thrust bearing must be installed in the number 6 main bearing position.
NOTE: Some engines use a thrust bearing for the upper and lower main bearing (360 degree), while other engines
only have a thrust bearing for the upper main bearing (180 degree). Always replace like for like.
NOTE: The upper and lower main bearing shells are not interchangeable. The backs of the main bearings are marked with the proper orientation.
Install the upper main bearings.
Insert the side of the main bearing opposite the tang first in between the crankshaft journal and block. Install the
bearing as far as possible by hand.
When installing the thrust bearing, it may be necessary to push the crankshaft to the front or rear of the cylinder block.
Follow this step to finish installing the upper main bearings, except for the number 1 front main bearing.
Use the main bearing replacer, Part Number 3823818, finish installing the main bearing. Rotate the crankshaft,
using the barring tool, part number 3824591.
Make sure the tang (1) on the main bearing is located in the notch (2) of the cylinder block. Finish pushing the main
bearing into position.
NOTE: The front main, number 1, does not have a hole in the journal so the pin can not be used to replace the bearing.
Install the number 1 main bearing.
Insert the side of the main bearing opposite the tang first and install as far as possible by hand.
Use a flat blade screwdriver to push the main bearing into position while rotating the crankshaft.
Make sure the tang on the main bearing is located in the notch of the cylinder block.
Lower Main Bearings
Make sure the backside of the bearings are clean and free of debris.
Install the lower main bearings into the main bearing caps.
Make sure to align the tangs of the bearings with tangs on the main bearing caps.
NOTE: Some engines use a thrust bearing for the upper and lower main bearing (360 degree), while other engines
only have a thrust bearing for the upper main bearing (180 degree). Always replace like for like.
If equipped, install the lower crankshaft thrust bearing.
Six-cylinder engines- the number 6 main bearing position.
Apply a coat of assembly lube, Part Number 3163087, to the crankshaft side of the main bearings and thrust
bearing surfaces.
Make sure the main bear cap surfaces between the main bearing cap and block are clean and free of debris.
Install the main bearing cap into position, aligning the main bearing cap dowel rings with the cylinder block.
The main bearing caps are/were numbered during the removal process for their location. Number 1 starts with
the front of the block.
NOTE: The caps must be installed so the numbers on the caps match the bearing saddle in the block. The lock tangs
in the main bearing saddle and bearing cap must be on the same side.
Install the main bearing caps. Make sure to align the ring dowels on the main bearing cap with the corresponding
drillings in the cylinder block.
Lubricate the main bearing capscrew threads and underside of the head with clean engine oil.
Gently tap the main bearing cap into position with a plastic or rubber mallet.
When seated, install the main bearing capscrews and tighten.
Torque Value: 50 N•m [ 37 ft-lb]
Do not tighten to the final torque value at this time. Final torque should be applied after all main bearing caps are
installed.
Use the barring tool, Part Number 3824591, the crankshaft must rotate freely after installing the main bearing caps.
While applying final torque to the main bearing capscrews, frequently check that the crankshaft rotates freely.
If the crankshaft does not rotate freely:
• Check if the crankshaft is contacting one of the connecting rods
• Check if the correct main bearing caps where installed correctly
• Check if the main bearing cap ring dowels or mounting surfaces were damaged during installation
• Check if the correct main bearings where installed.
NOTE: The sequence to the right is for a six cylinder
engine. For a four cylinder engine, use the same sequence for the 5 main bearing caps.
Tighten the main bearing capscrews evenly and in sequence.
6.7L Main Bearing Capscrews
NOTE: The dimensions of the thrust bearing and crankshaft journal determine end play.
Measure the crankshaft end play using dial indicator, Part Number 3824564 and magnetic base, Part Number 3377399.
If the crankshaft end play is not within specification:
• If the crankshaft end play is below specification, check if there are any obstructions limiting the crankshaft’s travel (lubricating oil pump, connecting rod, etc.)
• If the crankshaft end play is above specification, inspect the crankshaft thrust bearing surface. Also check if the correct thrust bearing(s) were installed.
NOTE: Oversize thrust bearings are available if the end play is not within specifications. Oversize thrust bearings
of 0.25 to 0.51 mm [0.010 to 0.020 in] are available.
