Mercury F4ZZ-6303-AARM Crankshaft Assembly

Carefully scrape all traces of the Plastigage material off the main bearing journals or the bearing faces. Don't nick or scratch the bearing faces.

Check the main bearing caps to see if they are marked to indicate their locations. They should be numbered consecutively from the front of the engine to the rear. If they aren't, mark them with number stamping dies or a center-punch.

Clean the crankshaft with solvent and dry it with compressed air. Use a stiff brush to clean the oil holes and flush them with solvent.

Push the crankshaft all the way to the rear and zero the dial indicator. Next, pry the crankshaft to the front as far as possible and check the reading on the dial indicator. The distance that it moves is the endplay. If it's greater than the limit, check the crankshaft thrust surfaces for wear. If no wear is evident, new main bearings should correct the endplay.

Check crankshaft endplay again and verify that it is correct.