Mariner Mercury 105/140 JET, Service Manual

Page: 411 / 797

4A-40 - POWERHEAD 90-824052R3 JUNE 2002
Piston Installation (Standard and
High Performance Models)
1. Before installing new piston rings, check gap
between ring ends by placing each ring in its
respective cylinder, then pushing ring about 1/2
in. (12.7mm) into cylinder using piston to assure
proper position.
2. Check end gap of each new piston ring with a
feeler gauge. End gap must be within .018 in. to
.025 in. (0.45mm to 0.64mm). If end gap is
greater, check other piston rings in cylinder bore,
until rings (within tolerance) are found.
c
d
a
b
51852
a - Piston Ring
b - Dots (Faces Up)
c - Feeler Gauge
d - Ring End Gap
IMPORTANT: Piston ring side with dot or letter
must be facing up.
a
b
a - Dot or Letter
b - Piston Ring
3. Use Piston Ring Expander (91-24697) and install
piston rings (dot side up) on each piston. Spread
rings just enough to slip over piston.
4. Check piston rings to be sure that they fit freely
in ring groove.
5. Lubricate piston, rings and cylinder wall with
2-Cycle Outboard Oil.
a
b
51081
a - Piston Ring Expander
b - Dot Side “Up” on Piston Ring
6. Rotate each piston ring so end of ring is aligned
with locating pin as shown.
7. Install Piston Ring Compressor.
8. Remove screws and connecting rod cap from
piston rod assembly being installed.
IMPORTANT: Piston must be correctly installed
and positioned as shown.
Pistons marked with the word “UP” and with the letter
“P” or “S” on top of piston.
Pistons with the letter “P” must be installed in the port
side of engine and the word “UP” facing toward top
of engine.
Pistons with the letter “S” must be installed in the
starboard side of engine and the word “UP” toward
top of engine.
CYL 2
CYL 4
CYL 6
CYL 1
CYL 3
CYL 5
UP
P
UP
P
UP
P
UP
S
UP
S
UP
S