Standard Procedure - Main Bearing Selection

WARNING: This page is about a different variant/trim than selected.

NOTE:

There are three different possibilities for the upper main bearings and five different lower main bearings. The upper and lower bearing shells are not interchangeable.

NOTE:

Crankshaft thrust bearings are not selectable and are only available in a single thickness.

Bearing oil clearance can also be determined by using Plastigage or equivalent. Refer to MEASURING BEARING CLEARANCE USING PLASTIGAGE .

Courtesy of CHRYSLER GROUP, LLC

1 - Crankshaft Main Bearing Diameter Grade Markings

2 - Connecting Rod Bearing Journal Diameter Grade Markings

The upper and lower main bearings are "select fit" to achieve proper oil clearances. The lower crankshaft main bearing journal diameter grade markings are stamped into the nose of the crankshaft. These marks are read from left to right (clockwise), corresponding with journal number 1, 2, 3, 4 and 5.

Crankshaft lower main bearing journal diameter grade markings correspond to specific journal diameters. The chart below identifies the five crankshaft grade markings and their associated journal diameters.

Crankshaft Marking	Journal Diameter mm (in.)
0	49.985 - 49.988 mm (1.9679 - 1.9680 in.)
1	49.982 - 49.985 mm (1.9678 - 1.9679 in.)
2	49.979 - 49.982 mm (1.9677 - 1.6978 in.)
3	49.976 - 49.979 mm (1.9676 - 1.9677 in.)
4	49.973 - 49.976 mm (1.9674 - 1.9676 in.)

Courtesy of CHRYSLER GROUP, LLC

1 -Lower Main Bearing Shell

The lower main bearing shells are marked with a color code indicating bearing thickness. The bearings are available in five different thickness sizes in order to achieve the desired oil clearance.

Crankshaft lower main bearing shells are available in five thickness sizes. The chart below identifies the five sizes.

Bearing Marking	Thickness mm (in.)
0 (Yellow)	2.497 - 2.500 mm (0.0983 - 0.0984 in.)
1 (Green)	2.500 - 2.503 mm (0.0984 - 0.0985 in.)
2 (Brown)	2.503 - 2.506 mm (0.0985 - 0.0987 in.)
3 (Black)	2.506 - 2.509 mm (0.0987 - 0.0988 in.)
4 (Blue)	2.509 - 2.512 mm (0.0988 - 0.0989 in.)

Courtesy of CHRYSLER GROUP, LLC

1 - Cylinder Bore Diameter Grade Markings

2 - Upper Main Bearing Journal Diameter Grade Markings

Engine block upper main bearing journal diameter grade markings are stamped into the exhaust side of the engine block near the oil pump. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4 and 5.

Engine block lower main bearing journal grade markings correspond to specific journal diameters. The chart below identifies the three engine block grade markings and their associated journal diameters.

Engine Block Marking	Journal Diameter mm (in.)
1	55.000 - <55.006 mm (2.1653 - <2.1656 in.)
2	55.006 - <55.012 mm (2.1656 - <2.1658 in.)
3	55.012 - 55.018 mm (2.1658 - 2.1661 in.)

Courtesy of CHRYSLER GROUP, LLC

1 - Upper Main Bearing Shell Color Code

The upper main bearing shells are marked with a color code indicating bearing thickness. The bearings are available in three different thickness sizes in order to achieve the desired oil clearance.

Crankshaft upper main bearing shells are available in three thickness sizes. The chart below identifies the three sizes.

Bearing Marking	Thickness mm (in.)
1 (Yellow)	2.494 - 2.500 mm (0.0982 - 0.0984 in.)
2 (Brown)	2.500 - 2.506 mm (0.0984 - 0.0987 in.)
3 (Green)	2.506 - 2.512 mm (0.0987 - 0.0989 in.)