Inspection

MAIN BEARINGS

Engine crankshaft bearing clearances can be determined by use of Plastigage or equivalent. The following is the recommended procedure for the use of Plastigage:

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 may be accomplished with the engine on an engine stand. Rotate the engine upside down, so the crankshaft weight is being supported by the engine block.
3. Plastigage is available in a variety of clearance ranges. The 0.025-0.076 mm (.001-.003 inch) is usually the most appropriate for checking engine bearing proper specifications.