Mercury 100 FourStroke, Service Manual

Page: 263 / 574

90-830234R3 DECEMBER 1997 POWERHEAD - 4-51
Pistons must be installed very carefully into cyl-
inders. Piston rings cannot be inspected thru ex-
haust ports.
6. Bottom end of cylinder bore has taper which per-
mits the insertion of the piston into block without
using a piston ring compressor. Place piston
carefully into cylinder.
Check rings by viewing through exhaust ports while
depressing rings with a screwdriver. If no spring ten-
sion is there (ring fails to “spring” back), the ring is
probably broken and must be replaced before instal-
ling the crankshaft.
51087
20338
Crankshaft Installation
•
If Lower Bearing and Gear were removed from
crankshaft, reassemble using arbor press and
suitable mandrel for bearing; gear slides on.
(NOTE keyway and key in gear to crankshaft as-
sembly.)
•
Install main bearing retaining ring after pressing
main bearing tight against the oil gear.
NOTE: There is NO main bearing retaining ring or re-
taining ring groove in the crankshaft on the following
outboards:
75/90/100/115/125 - Serial Number 0C 259434 and
above
b
e
d
c
d
a
b
51084
25949
a - Lower Bearing
b - Gear
c - Retaining Ring
d - Seal Carrier
e - Key
•
If Seal Carrier above was removed, replace by
placing a piece of wood on carrier and tapping
gently with a mallet, keeping carrier “square” dur-
ing insertion, seal fully to crankshaft. See page
4-39 -- (Powerhead Disassembly, this Section),
for wear-sleeve reinstallation, if so equipped.