Mercury MerCruiser MCM 454 Mag MPI Service Manual page 70

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SERVICE MANUAL NUMBER 23

8. On Horizon Model: Remove drain plugs from fittings on each seawater pump hose.

9. Crank engine over slightly with starter motor to purge any water trapped in seawater

10. After cooling system has been drained completely, coat threads of drain plugs with

IMPORTANT: MerCruiser recommends that propylene glycol antifreeze (nontoxic

and biodegradable, which makes it friendly to lakes and rivers) be used in 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 recom-

11. For additional assurance against freezing and rust, remove the thermostat cover and

NOTE: Hoses shown removed for visual clarity. Do not remove hoses.

90-861326--1 MARCH 1999

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Drain Plugs - One Is Hidden From View

pickup pump. DO NOT ALLOW ENGINE TO START.

Quicksilver Perfect Seal. Install all drain plugs and tighten securely. Reconnect all hoses

and tighten all hose clamps securely.

thermostat. Fill the engine seawater cooling system with a mixture of antifreeze and tap

water mixed to manufacturer's recommendation to protect engine to the lowest temper-

ature to which it will be exposed during cold weather or extended storage. Using a new

gasket, reinstall thermostat and cover. Tighten cover bolts to 30 lb-ft (41 Nm).

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