ANODO LAPIZ GM Ø12 41mm (ZN)

Function and technical context

This zinc pencil anode with a diameter of 12 mm and a length of 41 mm acts as cathodic protection in outboard motors and powertrains of the GM brand, sacrificing itself electrochemically to prevent galvanic corrosion in the metal parts of the engine submerged in salt or brackish water. It works within the seawater cooling system, installing directly in the ducts or engine blocks where the flow of seawater is in contact with metal alloys susceptible to corrosion. Its function is to absorb galvanic current that would otherwise attack critical components such as the heat exchanger, cylinder liners or cylinder head. If this anode is completely consumed without being replaced, the engine's noble metals are exposed to electrolytic corrosion, which can lead to deep pitting, coolant leaks and serious engine block failures.

When to replace this part?

The most obvious symptom that this pencil anode needs replacement is a reduction in its mass by more than 50%, visible when it is removed during the seasonal inspection: an excessively worn, fragmented or completely consumed anode indicates that the engine metals have been unprotected. It is recommended to inspect and replace the pencil anodes at least once per nautical season, or every 200-300 hours of navigation in waters with high conductivity. Preventively replacing the anode at the beginning of each season is the most economical and effective measure to avoid costly repairs to the block or the engine's internal cooling system.