Zinc, Aluminum and Magnesium Anodes
To ensure that the propeller and the drive are protected against corrosion (rust), an anode (also called sacrificial block) is of great importance. The anode ensures that the screw or the drive doesn't rust, but the anode itself. An anode must be replaced when about 50% of the volume has disappeared. Volvo Pentaparts sells magnesium, aluminum and zinc anodes. Aluminum anodes are suitable for use in fresh water (and in some cases in sea water). So ideally suited for brackish water. Zinc anodes are only suitable for salt water. Magnesium anodes offer optimal protection when sailing in fresh water. Incorrect material selection can cause serious corrosion.
Operation of the anode
The anode prevents galvanic corrosion between 2 different materials. The anode corrodes and thus sacrifices itself to protect the surrounding metal. For the anode to function as it should it must have good contact with the housing and it mustn't corrode beyond 50%. An anode in poor condition, covered with paint, or in poor contact with the housing can cause damage.
Replacing the anode
In general, anodes last 2 to 3 years, but this depends on the voltage differences. We recommend replacing the anode when it is half worn. When installing the anode, the mounting surface must be entirely free of paint and contaminants so that optimal electronic contact can be made. When mounting the anode, care must be taken that there is good contact between the anode and the surface on which it is mounted. When your anode hasn't yet been eaten away so much, but is dirty, you can brush it off with a wire brush.
Note: Anodes may never be painted!
Nordicar Marine: Spare parts suitable for Volvo Penta
We are looking forward to helping you to give you the proper advise for your Volvo Penta engine.
E-mail us at: webshop@nordicar.com
Or give us a call at: +31 (0)72 5753202
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