Engine Seawater Pump Inspection; Replacing The Engine Coolant In The Closed-Cooling System; System; Draining The Closed-Cooling System - Mercury 2.8 Diesel Operation & Maintenance Manual

5. Place the remote control in neutral, idle speed position and start the engine.
Operating the engine out of the water at high speeds creates suction, which can collapse the water supply hose and overheat
the engine. Do not operate the engine above 1400 RPM out of the water and without sufficient cooling water supply.
6. Operate the engine at idle speed in neutral for about ten minutes or until the discharge water is clear.
7. Observe the water temperature gauge to ensure that the engine is operating in the normal range.
8. Stop the engine.
9. Shut off the water tap.
10. Remove the adapter from the seawater pump inlet hose connection.
11. Do not open the seacock or reconnect the water inlet hose at this time to prevent water from siphoning into the boat or
engine.
12. Place an appropriate tag on the key switch stating that the seacock must be opened or the seawater inlet hose must be
reconnected before operating the engine.

Engine Seawater Pump Inspection

IMPORTANT: Mercury strongly recommends that this service be performed by a Mercury Diesel authorized repair facility.
Remove and inspect the engine seawater pump at the interval specified in the Maintenance Schedule. See your Mercury
Diesel authorized repair facility.
Replacing the Engine Coolant in the Closed‑Cooling System
Draining the Closed‑Cooling System
Discharge of oil, coolant, or other engine/drive fluids into the environment is restricted by law. Use caution not to spill oil,
coolant, or other fluids into the environment when using or servicing your boat. Be aware of the local restrictions governing
the disposal or recycling of waste, and contain and dispose of fluids as required.
NOTE: For instructions on draining the seawater section, refer to Draining the Seawater System in this section.
IMPORTANT: Observe the following points.
• Ensure that the engine is as level as possible to promote complete draining of the cooling system.
• The closed‑cooling section must be filled year‑round with the required coolant. If the engine will be exposed to freezing
temperatures, ensure that the closed‑cooling section is filled with a solution of ethylene glycol antifreeze and water properly
mixed to protect the engine to the lowest temperature to which it will be exposed.
• Do not use propylene glycol antifreeze in the closed‑cooling section of the engine.
A sudden loss of pressure can cause hot coolant to boil and discharge violently resulting in serious injury from burns. Allow
the engine to cool down before removing the coolant pressure cap.
1. Allow the engine to cool.
2. Remove the pressure cap from the expansion tank and coolant reservoir.
NOTE: Drain coolant into a suitable container. Dispose of old coolant properly.
3. Remove the intake and exhaust manifold drain plug.
90-8M0113987 DECEMBER 2015
eng
NOTICE
NOTICE
CAUTION
!
Section 4 - Maintenance
Page 67