Draining The Seawater System; Drain System Identification; Air Actuated Single-Point Drain System - Mercury 4.3 MPI SeaCore Operation & Maintenance Manual

Section 5 - Storage
Water trapped in the seawater section of the cooling system can cause corrosion or freeze damage. Drain the seawater
section of the cooling system immediately after operation or before any length of storage in freezing temperatures. If the boat
is in the water, keep the seacock closed until restarting the engine to prevent water from flowing back into the cooling system.
If the boat is not fitted with a seacock, leave the water inlet hose disconnected and plugged.
12. Fill the seawater cooling system with propylene glycol mixed to the manufacturer's recommendation to protect the engine
to the lowest temperature to which it will be exposed during freezing temperatures or extended storage. This will also
prevent the formation of exfoliating rust in the cooling system passages.
13. Store the battery according to the manufacturer's instructions.

Draining the Seawater System

Water can enter the bilge when the drain system is open, damaging the engine or causing the boat to sink. Remove the boat
from the water or close the seacock, disconnect and plug the seawater inlet hose, and ensure the bilge pump is operational
before draining. Do not operate the engine with the drain system open.
IMPORTANT: Only drain the seawater section of the closed cooling system.
IMPORTANT: The boat must be as level as possible to ensure complete draining of the cooling system.
Your power package is equipped with a drain system. Refer to Drain System Identification to determine which instructions
apply to your power package.
IMPORTANT: The engine must not be operating at any point during the draining procedure.
IMPORTANT: Mercury MerCruiser requires that propylene glycol antifreeze, mixed to the manufacturer's instructions, be used
in the seawater section of the cooling system for freezing temperatures or extended storage. Ensure 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.

Drain System Identification

NOTE: All drain plugs are fitted with blue wing nuts.

Air Actuated Single-Point Drain System

NOTE: The blue air pump is mounted on the engine on V8 models, but is stored off the engine on V6 models. Ask your dealer
for the location.
b
a
Page 92
NOTICE
CAUTION
!
c
Closed cooling models (V8 shown)
a - Blue drain plug location
b - Blue air pump
c - Air manifold
d - Green indicators
d
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