Mercury 2.8 Diesel, Operation & Maintenance Manual

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Section 4 - Maintenance
90-8M0113987
eng
DECEMBER 2015 Page 69
IMPORTANT: Use only the specified coolant.
2. If the coolant is being replaced or the level is low, slowly add the specified coolant to the level indicated in the table.
Coolant level in expansion tank
All models
Within 25 mm (1 in.) of the bottom of the filler neck, or between the upper and lower marks, if marked
Description Where Used Part Number
Mercury Extended Life Antifreeze Closed‑cooling system 92‑877770K1
NOTICE
Without sufficient cooling water, the engine, the water pump, and other components will overheat and suffer damage. Provide
a sufficient supply of water to the water inlets during operation.
3. Ensure that the seawater pickup pump is supplied cooling water.
4. Do not install the pressure cap. Start and operate the engine at fast idle (1500–1800 RPM). Add coolant if necessary to
maintain the coolant at the level specified previously.
IMPORTANT: When installing the pressure cap, be sure to tighten it securely to avoid coolant loss.
5. Install the pressure cap after the engine has reached normal operating temperature (with the thermostat fully open) and the
coolant level remains constant.
6. Test the engine operation. Observe the temperature gauge and check the engine for coolant leaks. If the temperature
gauge indicates excessive temperature or if the coolant is leaking, stop the engine immediately and inspect for the cause.
7. After the first operation, allow the engine to cool.
8. Remove the pressure cap and add the specified coolant to the level indicated in the table.
Coolant level in expansion tank
All models
Within 25 mm (1 in.) of the bottom of the filler neck, or between the upper and lower marks, if marked
9. Install and securely tighten the pressure cap.
Corrosion Protection
General Information
Whenever two or more dissimilar metals (such as those found on this power package) are submerged in a conductive solution
such as saltwater, polluted water, or water with a high mineral content, a chemical reaction takes place causing electrical
current to flow between metals. The electrical current flow causes the metal that is most chemically active, or anodic, to erode.
This erosion is known as
galvanic corrosion
and, if it is not controlled, it will eventually cause the need for replacement of power
package components exposed to water.
To help control the effects of galvanic corrosion, Mercury power packages come with several sacrificial anodes and other
corrosion protection devices. For a more comprehensive explanation of corrosion and corrosion protection refer to the
Marine
Corrosion Protection Guide
.
IMPORTANT: Replace sacrificial anodes if eroded 50% or more. Mercury strongly recommends avoiding the use of anodes
from other manufacturers. Refer to your Mercury Diesel authorized repair facility for additional information.
Engine Corrosion Protection Components
The engine is equipped with a sacrificial anode located on top of the aftercooler end cover to assist in protecting the engine and
the seawater cooling system from corrosion. 4.2 models contain a second sacrificial anode assembly on the stern end of the
fluid cooler.
Removal
1. Allow the engine to cool.
NOTICE
Failure to close the seawater inlet or seacock when removing or replacing the anode plugs can lead to water damage. Close
the seacock or remove and plug the seawater inlet hose to prevent water from entering the anode plug holes.
2. With the engine off, close the seacock, if equipped, or remove and plug the seawater inlet hose.
3. Drain the seawater system. See
Draining the Seawater System
.