Johnson Evinrude Aluminum Anode CM983952A

Function and technical context

The aluminum anode CM983952A is a galvanic protection component designed specifically for Johnson and Evinrude outboard motors. Its purpose is to act as a sacrificial electrode: being manufactured from high-purity aluminum, it corrodes preferentially over the structural metals of the engine—such as the aluminum lower gearcase, the drive shaft, or the propeller—protecting these parts from electrolytic corrosion produced by contact with salt water, brackish water, or mineral water. Without effective anodic protection, galvanic corrosion can irreversibly degrade critical engine components, resulting in costly repairs or even propulsion unit failure.

When to replace this part?

Aluminum anodes should be inspected at the beginning and end of each boating season, and replaced when they have lost approximately 50% of their mass or show a severely pitted and irregular surface. On vessels that regularly navigate in salt water or brackish water, wear can be more accelerated, so it is recommended to check the anode condition each time the vessel is removed from the water. Replacing the anode preventively before it is completely depleted is the most economical measure to avoid serious damage to the propulsion system and engine housing.

Equivalent manufacturer part numbers