Mercury 5L2Z-6303-AA Crankshaft Assembly

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Rub a penny across each journal several times. If copper rubs off and is embedded in the crankshaft, the journals should be reground. If a journal picks up copper from the penny, it indicates that it is too rough and must be reground.

Push the crankshaft all the way to the rear and zero the dial indicator. Then, pry the crankshaft to the front as far as possible and check the reading on the dial indicator. The distance 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.

Rub a penny across each journal several times. If a journal picks up copper from the penny, it's too rough and must be reground.

Mount a dial indicator with the stem in line with the crankshaft and just touching one of the crank throws. 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.

Install the bolts and tighten all except the thrust bearing cap bolts to the specified torque, working from the center out and approaching the final torque in three steps.

Rotate the crankshaft by hand to check for binding; it should rotate with a running torque of 50 in-lbs or less.

Carefully scrape all traces of the Plastigage material off the main bearing journals or the bearing faces using your fingernail or the edge of a credit card, avoiding nicks or scratches.

Clean the faces of the bearings in the caps and install the caps in their respective positions with the arrows pointing toward the front of the engine.

Check the oil seal journals at each end of the crankshaft for wear and damage. If the seal has worn a groove in the journal, or if it's nicked or scratched, the new seal may leak when the engine is reassembled. An automotive machine shop may be able to repair the journal by pressing on a thin sleeve. If repair isn't feasible, a new or different crankshaft should be installed.

Mount a dial indicator with the stem in line with the crankshaft and just touching the end of the crankshaft. 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 end play. 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 end play.