The only bearing that is pressed onto the crank is the upper main bearing. Item 21 in the diagram below. I usually put a dab of red Locktite to make sure it stays put. Also the crank seals item 11 are easy to break when installing the crank into the block. They look like piston rings and seal each section of the crankcase from each other. This is a 2-stroke motor and each section of the crankcase is momentarily pressurized to force the fuel mixture into the cylinder. I always have a few spare ones on hand just in case. Don't ask me how I know that! LOL! The other crank bearings are split in half and have a split wire ring that hold them around the crank journal.
http://www.crowleymarine.com/mercury-outboard/parts/1310_100.cfm
Inspect the bearings and bearing journals on the crank and rods. Look closely for signs of discoloration caused by overheating and lack of lubrication, usually blue color, and or pitting.
http://www.crowleymarine.com/mercury-outboard/parts/1310_100.cfm
Inspect the bearings and bearing journals on the crank and rods. Look closely for signs of discoloration caused by overheating and lack of lubrication, usually blue color, and or pitting.