INSTALLATION MANUAL
90-864198020 Page 67 of 77
3 POINT MANUAL DRAIN SYSTEM
NOTE: Use this procedure if your engine is not equipped with an air actuated single point
drain system or if the single point drain system fails.
1. Remove three blue drain plugs: One from the distribution housing (lower front, port side)
and two from the seawater pickup pump (front, starboard side).
77908
77917
a
a
a-Blue Drain Plug
2. Verify that water is draining from each opening.
3. Allow the system to drain for a minimum of 5 minutes. Mercury MerCruiser recommends
leaving the plugs out while transporting the boat or while performing other maintenance
to ensure that all water is drained.
4. Crank engine over slightly with starter motor to purge any water trapped in seawater
pickup pump. DO NOT allow engine to start.
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.
5. Prior to launching boat or starting the engine, close the drain system by re-installing the
three blue drain plugs.
All Models
1. For additional assurance against freezing and corrosion, fill the cooling system with a
mixture of propylene glycol 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 propylene glycol coolant until block
and head are full. If thermostat housing was removed, reinstall and tighten cover
bolts securely.
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