Mercury MERCRUISER, Service Manual, Page: 219 / 566

Crankshaft Installation
Main Bearing Tension
IMPORTANT: Ensure that the main bearing is installed under tension. It should require firm pressure to fit the bearing into
position.
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Main bearing tension
Main Bearings and Crankshaft
1. Remove the timing sprocket from the old crankshaft and install on the new crankshaft.
2. On the driveshaft extension models—if the old pilot bushing is to be reused, the bushing can be removed without damage
as follows:
a. Fill the pilot bushing cavity with grease.
b. Insert an old transmission input shaft in the bore of the bushing and hit it with a hammer. This will create hydraulic
pressure in the pilot bushing cavity that should force the bushing out.
IMPORTANT: Ensure that all bearings and crankshaft journals are clean.
3. Install the upper main bearing inserts in the engine block.
a - Upper insert
b - Oil groove
a
b
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Engine Inspection and Assembly
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 3B-17