Procedures

Main Bearing Fitting





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

Crankshaft main bearing journal diameter grade markings correspond to specific journal diameters. The chart below identifies the 19 crankshaft grade markings and their associated journal diameters.










Engine block main bearing bore diameter grade markings are stamped into the right side of the engine block. These marks are read from front to rear, corresponding with journal number 1, 2, 3, 4, 5.

Engine block main bearing bore grade markings correspond to specific bore diameters. The chart below identifies the 14 engine block grade markings and their associated bore diameters.






For upper and lower main bearing selection, obtain the grade identification marks from the crankshaft and engine block. Main bearings are available in three sizes (red, blue, yellow). Upper and lower sizes can be mixed on a journal in order to achieve the desired oil clearance. The chart below identifies the three sizes available and how they should be selected based on crankshaft and engine block grade markings.










The main bearing shells are color coded (1) on the edge of the bearing. The bearings are available in three different sizes and can be mixed on a journal in order to achieve the proper oil clearance.

Main bearing shells are available in three sizes. The chart below identifies the three bearing sizes.











NOTE: Crankshaft thrust washers are not selectable and are only available in a single thickness as part of the center upper main bearing.


Bearing oil clearance can also be determined by using Plastigage or equivalent Measuring Bearing Clearance Using Plastigage