Mercury MERCRUISER, Service Manual, Page: 228 / 566

IMPORTANT: When assembling the pistons and connecting rods, the following must be kept in mind:
•
If the original pistons or connecting rods are being used, install them into the cylinder from which they were removed.
• The connecting rod bearing tangs are always oriented toward the outside of the engine block.
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• The marking on the top of the piston must be positioned toward the front of the engine (water pump end).
a - Piston marking
1. Cylinder bore preparation:
a. Clean the cylinder bores with a light honing oil, as necessary.
b. Clean with hot water and detergent.
c. Rinse thoroughly.
d. Lightly oil the cylinder bores with a clean, lint free white cloth, with engine oil. Repeat until the cloth remains clean.
e. Wipe down the cylinder bores a final time with a clean, lint free white cloth.
Tube Ref No. Description Where Used Part No.
139
Mercury 25W-40
Synthetic Blend 4-Stroke
Engine Oil
Cylinder walls 92-8M0078629
2. Rotate the crankshaft until the crankpin is at before dead center (BDC) for the cylinder that is ready for the first piston to be
installed.
3. Carefully wipe any foreign material from the connecting rod bearings and the connecting rod bearing fitting surfaces.
IMPORTANT: Do not apply oil to the back of the bearings or the connecting rod bearing mating surfaces.
a
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Engine Inspection and Assembly
Page 3B-26 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015