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CRANKSHAFT MAIN DESCRIPTION The main bearing caps are not interchangeable and should be marked at removal to insure correct Upper and lower No. 3 bearing halves are flanged to carry the crankshaft thrust loads and are NOT STANDARD PROCEDURE MEASURING CRANKSHAFT MAIN BEARING PLASTIGAGE METHOD Engine crankshaft bearing clearances can be deter- mined by use of Plastigage or equivalent. The follow- (1) Remove oil film from surface to be checked. Plastigage is soluble in oil. (2) The total clearance of the main bearings can only be determined by removing the weight of the crankshaft. This can be accomplished by either of two PREFERRED METHOD (1) Shimming the bearings adjacent to the bearing to be checked in order to remove the clearance • When checking No. 1 main bearing. Shim No. 2 main bearing. • When checking No. 2 main bearing. Shim No.1 and No. 3 main bearing. • When checking No.3 main bearing. Shim No. 2 and No. 4 main bearing. • When checking No. 4 main bearing. Shim No. 3 and No. 5 main bearing. • When checking No. 5 main bearing. Shim No. 4 and No. 6 main bearing. • When checking No. 6 main bearing. Shim No. 5 main bearing. NOTE: REMOVE ALL SHIMS BEFORE REASSEM- ALTERNATIVE METHOD (1) With the weight of the crankshaft being sup- ported by a jack under the counterweight adjacent to (2) Place a piece of Plastigage across the entire width of the bearing shell in the cap approximately Fig. 112 Main Bearing Identification Fig. 113 Placement of Plastigage in Bearing Shell 1 - PLASTIGAGE 9 - 66 ENGINE ZB |