Sierra 18-6011A Anode, Replaces 31640, Fits R/MR/Alpha One Sterndrive & Transom Assembly (1983-90) and Alpha One Gen II (1991 & up)

The Sierra 18-6011A is a sacrificial anode built for sterndrive and transom assembly applications, protecting underwater metal components from galvanic corrosion caused by electrolysis in fresh and salt water. Mounted on the drive or transom assembly, the anode corrodes preferentially in place of the more expensive surrounding metal parts, extending the service life of the drive unit. Installation is straightforward, making it a routine maintenance item for boat owners performing seasonal upkeep or replacing a worn-out anode.

The Sierra 18-6011A is designed for use on R/MR/Alpha One, Sterndrive & Transom Assembly (1983-90) & prior drives, and Alpha One, Gen II (1991 & up) applications, and it directly replaces a wide range of OEM anode part numbers, so it is a straightforward drop-in for owners servicing these drive systems. Regular inspection and replacement of the anode helps prevent costly corrosion damage to the sterndrive housing, propeller shaft, and other submerged metal components.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-6011A
• Product Category: Mercury Outboard Anodes
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.43 pounds
• UPC: 808282175870

Fitment

• R/MR/Alpha One, Sterndrive & Transom Assembly (1983-90) & prior drives
• Alpha One, Gen II (1991 & up)

Replaces (OEM)

• 31640
• 31640A1
• 97-31640Q4
• 31640T6
• 97-31640B4
• 31640A4
• 31640A2
• 316404
• 316403
• 72436A1

Frequently Asked Questions

What does the Sierra 18-6011A anode fit? The Sierra 18-6011A is designed for use on R/MR/Alpha One, Sterndrive & Transom Assembly (1983-90) & prior drives, as well as Alpha One, Gen II (1991 & up) applications.

What OEM part numbers does the 18-6011A replace? It replaces OEM numbers 31640, 31640A1, 97-31640Q4, 31640T6, 97-31640B4, 31640A4, 31640A2, 316404, 316403, and 72436A1.

How much does the Sierra 18-6011A weigh? This anode weighs 0.43 pounds.

What are the dimensions of the 18-6011A anode? The Sierra 18-6011A measures 0.39 x 0.39 x 0.39 inches.

Is the 18-6011A the same as Sierra part 18-6011? No, 18-6011A is a distinct, current Sierra part number; it is not interchangeable by number with 18-6011 or 18-6012, which are separate anode part numbers with their own fitment and replaces lists.

Why does a sterndrive need an anode like the 18-6011A? Sacrificial anodes such as the 18-6011A corrode in place of the drive's metal components, protecting the sterndrive and transom assembly from galvanic corrosion in the water.

Does the 18-6011A fit Alpha One Gen II drives? Yes, the Sierra 18-6011A is listed for use on Alpha One, Gen II (1991 & up) drives, in addition to R/MR/Alpha One Sterndrive & Transom Assembly (1983-90) & prior drives.

How often should the 18-6011A anode be replaced? The 18-6011A should be inspected regularly and replaced once significantly corroded, since its function is to sacrificially deteriorate in place of the surrounding metal drive components.

Is the Sierra 18-6011A a genuine Sierra part? Yes, 18-6011A is a Sierra-branded anode identified by its own manufacturer part number.

Can the 18-6011A be used to replace 31640A1? Yes, the Sierra 18-6011A anode replaces OEM number 31640A1 along with several other listed cross-reference numbers.