Mercury 305 CID, Service Manual, Page: 47 / 967

1B-30 - MAINTENANCE 90-823225--1 1096
(2) On Alpha Drive Equipped Models: In-
sert a small wire (repeatedly) to make
sure that vent holes and water drain holes
and passages (as shown) are unob-
structed and open.
71216
70134
b
c
d
e
f
a
c
f
a - Speedometer Pitot Tube
b - Trim Tab Cavity Vent Hole
c - Trim Tab Cavity Drain Passage
d - Gear Housing Water Drain Hole (One Each - Port and
Starboard)
e - Gear Housing Cavity Vent Hole
f - Gear Housing Cavity Drain Hole
i. Crank engine over slightly with starter motor
to purge any water trapped in seawater pick-
up pump. DO NOT ALLOW ENGINE TO
START.
! CAUTION
If boat is in the water or is to remain in the water,
seacock (if so equipped) must remain closed un-
til engine is to be restarted, to prevent water from
flowing back into cooling system. If boat is not
fitted with a seacock, seawater inlet hose must
remain disconnected and plugged, to prevent
water from flowing into cooling system and/or
boat. As a precautionary measure, attach a tag to
the ignition switch or steering wheel with the
warning that the seacock must be opened or the
seawater inlet hose reconnected prior to starting
the engine.
j. After seawater section of cooling system has
been drained completely, coat threads of
drain plugs with Quicksilver Perfect Seal and
reinstall. Tighten drain plugs securely. Re-
connect hoses and tighten all hose clamps
securely. If NOT equipped with seacock:
seawater inlet hose must remain discon-
nected and plugged until engine is to be re-
started.
IMPORTANT: MerCruiser recommends that pro-
pylene glycol antifreeze (nontoxic and biode-
gradable, which makes it friendly to lakes and riv-
ers) be used in sea-water section of the cooling
system for cold weather or extended storage.
Make sure that the propylene glycol antifreeze
contains a rust inhibitor and is recommended for
use in marine engines. Be certain to follow the
propylene glycol manufacturer’s recommenda-
tions.
k. For additional assurance against freezing
and rust, remove the thermostat cover and
thermostat. Fill the engine seawater cooling
system with a mixture of antifreeze and tap
water mixed to manufacturer’s recommenda-
tion to protect engine to the lowest tempera-
ture to which it will be exposed during cold
weather or extended storage. Using a new
gasket, reinstall thermostat and cover. Tight-
en cover bolts to 30 lb. ft. (41 N·m).