Draining Instructions - Mercury 350 Mag MPI Manual

CC946

Draining Instructions

CARBURETED MODELS
If boat is to remain in water after draining, seawater inlet hose must be removed and plugged to prevent
a siphoning action that may occur, allowing seawater to flow from the drain holes or removed hoses.
IMPORTANT: Boat must be as level as possible to ensure complete draining of cooling system.
Seawater section of cooling system MUST BE COMPLETELY drained for winter storage, or immediate-
ly after cold weather use, if the possibility of freezing temperatures exist. Failure to comply may result
in trapped water causing freeze and/or corrosion damage to engine.
1
Ensure engine is as level as possible to ensure complete draining of cooling system.
2
Remove drain plugs from following locations:
A
Port Side - from cylinder block.
Avoid product damage. Do not disturb the Y-fitting when removing the drain plug. There is an ignition
control "Knock Sensor" in the upper hole of the fitting. This sensor must not be loosened or removed.
It is tightened to a critical specification at the factory.
B
Starboard Side - from Y-fitting.
C
Bottom of exhaust manifolds (port and starboard).
3
Repeatedly clean out drain holes using a stiff piece of wire. Do this until entire system is drained.
NOTE: It may be necessary to lift or bend hoses to allow water to drain completely. Crank engine over slightly
to purge any water trapped in seawater pickup pump. Do not allow engine to start.
4
Models equipped with circulating pump hose drain plug: Remove drain plug.
5
Models without circulating pump hose drain plug: Loosen hose clamps and disconnect hose from
thermostat housing or circulating pump. Allow water to drain.
6
Loosen hose clamps and remove the hose:
A
From the transmission cooler.
B
From the water inlet (bottom) of the seawater pickup pump.
After cooling system has been drained completely, install drain plugs, reconnect hoses and tighten all hose
clamps securely.
IMPORTANT: MerCruiser recommends that propylene glycol (a nontoxic and environmentally safe) an-
tifreeze be used in the seawater 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 recommendations.
7
For additional assurance against freezing and rust, remove the thermostat cover and thermostat. Fill the en-
gine seawater cooling system with a mixture of antifreeze and tap water mixed to manufacturer's recommenda-
tion to protect engine to the lowest temperature to which it will be exposed during cold weather or extended stor-
age. Using a new gasket, reinstall thermostat and cover. Tighten cover bolts securely.
CAUTION
CAUTION
CAUTION
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