Piston Installation - Mercury 15 EFI FourStroke Service Manual

2. Lubricate the rings with 4‑Stroke 10W‑30 Outboard Oil, after the rings are installed on the piston.
110
c
b
a - Top oil control ring
b - Expander
c - Bottom oil control ring
d - Second ring
e - Top ring
f - End gap ‑ Top ring
g - End gap ‑ Bottom oil control ring
h - End gap ‑ Second ring
i - End gap ‑ Top oil control ring
Tube Ref No.
4-Stroke 10W-30 Outboard
110
Oil

Piston Installation

IMPORTANT: The cylinder bores must be clean before installing the pistons. Clean the bore with a light honing as necessary.
After honing, clean the cylinder bores with water and mild detergent. After cleaning, swab out the cylinder bores with engine oil
and a clean cloth. Wipe the cylinder bore with a clean dry cloth.
1. Lubricate the piston, rings, and cylinder bores with 10W‑30 4‑Stroke Marine Engine Oil.
2. Use a piston ring compressor tool to compress the piston rings.
3. Using the piston ring compressor tool, install the piston/connecting rod assembly into the cylinder block.
4. Push down on the piston compressor tool to ensure that the tool is firmly seated against the block.
90-8M0125265 eng NOVEMBER 2017
T
a
d
e
Description
a
b
c
110
f
i
T
Where Used
Piston rings
© 2018 Mercury Marine
Cylinder Block/Crankcase
d
45 o
45
o
UP
3150
Part No.
92-8M0078625
Page 4A-25
e
g
h