MerCruiser 8.1 MAG, Owner'S Manual

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Section 5 - Maintenance
90-864839070 AUGUST 2007 Page 111
6. Crank the engine over slightly with starter motor to purge any water trapped in the
seawater pickup pump. Do not allow the engine to start.
7. Prior to launching the boat or starting the engine, close the drain system by installing
the two blue drain plugs.
Draining the Sterndrive
NOTE: This procedure is needed only for salty, brackish, mineral laden, or polluted water
applications; and for freezing temperatures or extended storage.
1. Insert a small wire repeatedly to make sure that vent holes, water drain holes, and
passages are unobstructed and open.
b
a
d
e
f
c
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Sterndrive Water Drain Holes
a - Speedometer pitot tube
b - Trim tab cavity vent hole
c - Trim tab cavity drain passage
d - Gear housing water drain hole (1
each ‑ port and starboard)
e - Gear housing cavity vent hole
f - Gear housing cavity drain hole
NOTICE
The universal joint bellows may develop a set when stored in a raised or up position,
causing the bellows to fail when returned to service and allowing water to enter the boat.
Store the sterndrive in the full down position.
2. Lower the sterndrive unit to the full down/in position.
3. For additional assurance against freezing and rust, after draining, fill the cooling system
with propylene glycol mixed to the manufacturer's recommendation to protect engine
to the lowest temperature to which it will be exposed during freezing temperatures or
extended storage
IMPORTANT: Mercury MerCruiser requires that propylene glycol antifreeze, mixed to the
manufacturers instructions, be used in the seawater section of the cooling system for
freezing temperatures 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 recommendations.
Manual Drain System ‑ 8.1 Models
NOTE: If air actuated drain system fails, use the blue drain plugs to drain engine.
NOTE: It may be necessary to lift, bend or lower hoses to allow water to drain completely
when hoses are disconnected.
1. Remove blue drain plugs from the seawater pump