Specifications

MAINTENANCE
Page 82 90-860168040 JANUARY 2004
0161.04
Corrosion Protection
Whenever 2 or more dissimilar metals (like those found on the sterndrive) 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 is known as galvanic corrosion and, if not controlled, it will in time cause the need
for replacement of power package components exposed to water.
To help control the effects of galvanic corrosion, Mercury MerCruiser sterndrive units come
withe 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
(90-88181301).
71176
a
b
c
d
e
f
a-Gearcase anodic plate
b-Anodic plate
c-Drive mounted anodic block
d-Anode kit
e-Trim cylinder anodes
f-Bearing carrier anode
IMPORTANT: Replace sacrificial anodes if eroded 50 percent or more.
Gearcase Anodic Plate - Is mounted on the underside of the lower gearcase and serves
as a sacrificial anode.
70134
a
Alpha
a-Anode