GASOLINE STERNDRIVE INSTALLATION MANUAL
90-860172011
Page 121 of 137
IMPORTANT: Mercury MerCruiser recommends that propylene glycol (a nontoxic
and environmentally safe) antifreeze 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.
9. For additional assurance against freezing and rust, fill the cooling system with a mixture
of antifreeze and tap water mixed to manufacturer’s recommendation to protect engine
to the lowest temperature to which it will be exposed during cold weather or extended
storage.
a. Remove thermostat housing or hose and fill with coolant until block and head are
full. If thermostat housing was removed, reinstall and tighten cover bolts securely.
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b. Remove water hose from exhaust manifold and fill manifold with coolant. Reinstall
hose and tighten clamp securely.
Store boat with sterndrive unit in full DOWN/IN position.