Main Bearing Fitting
Crankshaft thrust washers 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 STANDARD PROCEDURE .
The upper and lower main bearings are "select fit" to achieve proper oil clearances. Crankshaft main bearing journal diameter grade markings (1) are stamped into the front crankshaft counterweight. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4.
Crankshaft 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 Size mm (in.) |
|---|---|
| 1 | 71.9870 - 71.9905 mm (2.8341 - 2.8343 in.) |
| 2 | 71.9906 - 71.9941 mm (2.8343 - 2.8344 in.) |
| 3 | 71.9942 - 71.9977 mm (2.8344 - 2.8345 in.) |
| 4 | 71.9978 - 72.0013 mm (2.8346 - 2.8347 in.) |
| 5 | 72.0014 - 72.0050 mm (2.8347 - 2.8348 in.) |
Engine block main bearing journal diameter grade markings (2) are stamped into the left side of the engine block. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4.
Engine block main bearing journal grade markings correspond to specific journal diameters. The chart below identifies the five engine block grade markings and their associated journal diameters.
| Engine Block Marking | Journal Size mm (in.) |
|---|---|
| 1 | 77.0055 - 77.0090 mm (3.0317 - 3.0318 in.) |
| 2 | 77.0019 - 77.0054 mm (3.0316 - 3.0317 in.) |
| 3 | 76.9983 - 77.0018 mm (3.0314 - 3.0316 in.) |
| 4 | 76.9947 - 76.9982 mm (3.0313 - 3.0314 in.) |
| 5 | 76.9910 - 76.9946 mm (3.0311 - 3.0313 in.) |
For upper and lower main bearing selection, obtain the grade identification marks from the crankshaft and engine block. Main bearings are available in five sizes. Upper and lower sizes can be mixed on a journal in order to achieve the desired oil clearance. The chart below identifies the five sizes available and how they should be selected based on crankshaft and engine block grade markings.
| Engine Block Marking | Crankshaft Marking | ||||
| 1 | 2 | 3 | 4 | 5 | |
| 1 | 1/1 | 1/2 | 2/2 | 2/3 | 3/3 |
| 2 | 1/2 | 2/2 | 2/3 | 3/3 | 3/4 |
| 3 | 2/2 | 2/3 | 3/3 | 3/4 | 4/4 |
| 4 | 2/3 | 3/3 | 3/4 | 4/4 | 4/5 |
| 5 | 3/3 | 3/4 | 4/4 | 4/5 | 5/5 |
| UPPER/LOWER Main Bearings to Achieve 0.024 - 0.050 mm (0.0009 - 0.0020 in.) Oil Clearance | |||||
The upper main bearing shell (2) and lower main bearing shell (1) are marked with the bearing size (3) on the bearing lining surface. The upper and lower bearings are available in five different sizes and can be mixed on a journal in order to achieve the proper oil clearance.
Upper and lower main bearing shells are available in five sizes. The chart below identifies the five bearing sizes.
| Bearing Marking | Size mm (in.) |
|---|---|
| 1 | 2.4951 - 2.4987 mm (0.0982 - 0.0984 in.) |
| 2 | 2.4915 - 2.4951 mm (0.0981 - 0.0982 in.) |
| 3 | 2.4879 - 2.4915 mm (0.0979 - 0.0981 in.) |
| 4 | 2.4843 - 2.4879 mm (0.0978 - 0.0979 in.) |
| 5 | 2.4807 - 2.4843 mm (0.0977 - 0.0978 in.) |