Volvo Penta 21182210, Operator'S Manual

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Sacrificial Anodes
Sacrificial anodes are used in various locations on the
engine, transom shield, and drive to provide protection
against galvanic corrosion. Anodes are slowly eroded
away by galvanic action and require inspection. Addi-
tionally, anodes that are subjected to frequent wetting
and drying require periodic scraping with sandpaper
to remove scale and oxidation to maintain their effec-
tiveness. Do not paint anodes, as this will destroy their
effectiveness.
When you need to purchase new anodes, see your
Volvo Penta dealer. The material composition of Volvo
Penta anodes meets U.S. Military Specification
18001-H. Some after-market anodes may not meet
mil-specs.
Reference Anodes
51416
Reference anodes B , attached to the manifold and
exhaust raw water drain plugs A , serve as an indica-
tion of the amount of erosion that has occurred on var-
ious anodes in the exhaust system.
These anodes must be checked (at least once every
six months or whenever you drain the raw water sys-
tem) to determine the amount of erosion that has
occurred. If there is a substantial amount of erosion
between checks, this could be an indication that the
exhaust system is not adequately protected against
corrosion.
NOTICE! It is extremely important that the reference
anodes are checked on a regular basis to ensure that
no corrosion has occurred in the exhaust system.
If the diameter of the anode is less than 7/32 in.
(5.3 mm) and/or the length is less than 7/16 in.
(11.3 mm), be sure to have the exhaust system
inspected at a Volvo Penta dealer at your earliest con-
venience. Be sure that new anodes are installed to
replace the old.
When checking the anodes, also be sure to check the
condition of the O-ring
C . Inspect the O-ring for nicks,
cuts, and wear. Replace as necessary.
The reference anodes are manufactured using alumi-
num only. These anodes will function properly in salt-
water or freshwater.
Maintenance
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