Corrosion And Corrosion Protection - MerCruiser Alpha One V6 Operation And Maintenance Manual

MAINTENANCE
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3A
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MerCruiser V6/V8
CORROSION AND CORROSION
PROTECTION
Whenever two or more dissimilar metals
(like those found on the stern drive) 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 elec-
trical 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.
/
( IMPORTANT: Replace zinc sacrificial
anodes if eroded 50% or more.
In addition to the corrosion protection
devices, the following steps should be
taken to inhibit corrosion.
• Paint all exposed metal surfaces below
water line on boat, transom assembly
and drive unit (except drain holes, zinc
anodes, MerCathode system, and items
specified by boat manufacturer) with
good quality marine paint.
IMPORTANT: If antifouling protection is
required, Tri-Butyl- Tin-Adipate (TBTA)
base antifouling paints are recommended
on MerCruiser boating applications. In
areas where Tri-Butyl- Tin-Adipate base
paints are prohibited by law, copper base
paints can be used on the boat hull and
transom. Do not apply paint to the Mer-
Cruiser drive unit or transom assembly. In
addition, care must be taken to avoid an
electrical interconnection between the
MerCruiser Product and the paint. Corro-
sion damage that results from the improper
application of copper base paint will not be
covered by the limited warranty.
IMPORTANT: Do not paint zinc anodes
or MerCathode system.
• Spray power package components on
inside of boat every 2-3 weeks with
MerCruiser V6/V8
Quicksilver Corrosion Guard to protect
finish from dulling and corrosion. Ex-
ternal power package components may
also be sprayed.
• All lubrication points (especially
steering system, shift and throttle
linkages) should be kept well lubricated.
• Flush cooling system periodically
(preferably after each use).
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Zinc Trim Tab - serves as a sacrificial
anode. Remove plug from drive shaft
housing to access attaching screw and
insert 3/8" allen wrench. Unthread
attaching screw and remove trim tab. Do
not remove screw. Install new trim tab
(Trailing edge of trim tab must be set
straight back) and tighten screw securely.
Install plug.
2
Zinc Heads - serve as sacrificial
anodes. Unscrew anodic heads counter-
clockwise with pliers. Using new gaskets,
install new anodic heads and tighten
securely.
3
Zinc Block - is mounted to underside
of gimbal housing and serves as a
sacrificial anode. Remove two bolts to
change block.
3A
MerCathode System (if so equipped)
- Electrode assembly replaces zinc block
on bottom of gimbal housing. Also replace
anodic bolt heads with plastic caps.
System should be tested to ensure
adequate output.
Test should be made where boat is
moored, using Quicksilver Reference
Electrode and Test Meter. Contact your
Authorized MerCruiser Dealer to arrange
for this test.
4
Zinc Anode Kit (if so equipped) -
Mounted to boat transom. Acts as a
sacrificial anode. Replace as required.
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