Draining the Seawater System
Draining the Raw Water
!
CAUTION
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 raw water section of the closed cooling system. Raw water is sometimes referred to as seawater.
IMPORTANT: The boat must be as level as possible to ensure complete draining of the cooling system.
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 raw water section of the cooling system during freezing temperatures or for 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.
Air Actuated Single‑Point Drain System—Closed Cooling
The following instructions apply to draining procedures performed on engines in vessels that are in the water. For vessels that
are not in the water, you do not need to close the seacock (if equipped) or remove and plug the water inlet hose.
1. Close the seacock (if equipped) or remove and plug the water inlet hose.
2. Remove the blue plug from the heat exchanger.
3. Remove the cap from the air actuated valve assembly.
a - Blue plug
b - Cap
4. Ensure that the lever on top of the pump is flush with the handle (horizontal).
5. Install the air pump on the actuator fitting.
6. Pull the lever on the air pump (vertical) to lock the pump onto the fitting.
a - Actuator fitting
b - Green indicators
c - Manual release valve
d - Air pump
e - Lever (locking)
7. Pump air into the system until both green indicators extend out of the actuator assembly.
8. Check to ensure water drains out of the distribution housing.
8293
b
d
e
a
c
Section 5 - Storage
Page 90 90-8M0128973 eng MAY 2017
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