Volvo Penta D4 Operator's Manual page 95

Tie rod anode, twin installations (DPR)
7748934 04-2008
Corrosion protection, checking and
changing
Check the sacrificial anodes regularly. Replace with
new anodes when approximately 1/3 of an anode has
corroded away.
When the boat is stored ashore, corrosion protection
deteriorates due to sacrificial anode oxidization. Even
new anodes may have surface oxidation. Before
launching the sacrificial anodes must be cleaned or
polished with emery cloth.
IMPORTANT!
Use emery paper. Do not use a wire brush or other
steel tools when cleaning, as these may damage the
galvanic protection.
The stern drive is fitted with zinc anodes as standard,
intended for use in salt water. If the stern drive is to be
used principally in freshwater the sacrificial anodes
must be magnesium.
Use sacrificial anodes thus:
• Zinc in salt water.
• Magnesium in freshwater.
• Aluminum when the boat is used primarily in salt
water and sometimes in brackish water.
Replacing corrosion protection
1 Remove all the anode retaining screws.
2 Clean the contact surface.
3 Install the new sacrificial anodes and fasten them
to ensure good metallic contact.
Maintenance
93