MerCruiser Alpha One Gen II Zinc Anode Kit - Alpha1G2-Kit-ZN

The Alpha One Gen II Zinc Anode Kit Alpha1G2-Kit-ZN is a complete sacrificial anode kit for MerCruiser Alpha One Generation II sterndrives used in saltwater service. These zinc anodes are designed to help protect the aluminum sterndrive housing, gimbal assembly, trim components, bearing carrier area, and lower-unit hardware from galvanic corrosion by corroding first in the water.

This kit is intended for 1991 and newer Alpha One Gen II sterndrive applications where the drive uses the matching anode layout. Confirm your drive model, serial number, and anode configuration before ordering.

Key Features

• Complete zinc anode kit for Alpha One Gen II sterndrives.
• Part number: Alpha1G2-Kit-ZN.
• Designed for saltwater corrosion protection.
• Fits common 1991 and newer MerCruiser Alpha One Generation II anode layouts.
• Helps protect aluminum drive castings from galvanic corrosion.
• Includes the main external anode locations commonly serviced during annual maintenance.
• Supplied with stainless steel mounting hardware where included in the kit.
• Cross-references common Mercury/Quicksilver, Martyr, Sierra, and Tecnoseal kit layouts.
• Best suited for saltwater use; choose the correct anode material for brackish or freshwater operation.

Kit Contents

Typical Alpha One Gen II zinc kit layout includes:

• Gimbal housing block anode — replaces Mercury/Quicksilver reference 821631
• Ventilation plate anode — replaces Mercury/Quicksilver reference 821629
• Trim tab / skeg anode — replaces Mercury/Quicksilver reference 76214-5
• Propeller bearing carrier collar anode — replaces Mercury/Quicksilver reference 806105
• Trim cylinder ram collar anodes, quantity 2 — replace Mercury/Quicksilver reference 806189
• Mounting hardware — stainless steel fasteners where supplied with the kit

Confirm the exact contents against your drive layout before installation, especially if the sterndrive has been modified, repowered, or previously fitted with a different trim tab/anode style.

Drive Compatibility

Common application context includes:

• MerCruiser Alpha One Gen II sterndrives
• 1991 and newer Alpha One Generation II drive packages where this anode layout is used
• Saltwater boats requiring zinc sacrificial protection
• Sterndrives using the gimbal housing, ventilation plate, trim tab, bearing carrier, and trim ram collar anode configuration listed above

This kit is not for Alpha One Gen I, Bravo, Blackhawk, outboard, or non-MerCruiser drive applications unless a parts diagram confirms the same anode layout.

Fitment Notice

Confirm fitment by sterndrive serial number, drive model, anode material requirement, trim tab style, bearing carrier style, and factory parts diagram before ordering. Alpha One Gen II drives can have different anode layouts depending on model year, drive configuration, propeller setup, and previous service history.

Use zinc for saltwater applications. For brackish water, aluminum anodes are often the better choice. For freshwater-only use, magnesium is typically used instead. Using the wrong anode material can reduce corrosion protection.

When This Kit Needs Replacement

Replace sacrificial anodes when they are heavily pitted, loose, missing, damaged, covered in scale, or approximately half consumed. Anodes should also be inspected during spring commissioning, fall haul-out, winterization, gear lube service, propeller service, and any time corrosion, bubbling paint, white powdering, or unusual metal loss is seen on the drive.

Do not wait until an anode is completely gone. Once the sacrificial metal is consumed, the sterndrive housing and underwater hardware become the next corrosion target.

Installation Notes

Remove the old anodes and clean each mounting surface down to bare metal before installing the new zincs. Sacrificial anodes must have direct metal-to-metal contact with the drive to work properly. Paint, corrosion, marine growth, sealant, or heavy scale under the anode can insulate it and prevent proper protection.

Do not paint anodes. Antifouling paint, primer, clear coat, or heavy coating over the zinc surface prevents the water from contacting the sacrificial metal and can stop the anode from working. Tighten mounting hardware securely and inspect bonding continuity where applicable.

After installation, recheck the anodes after the boat has been back in the water, especially if the vessel is kept in a marina with shore power, nearby steel pilings, or known stray-current issues.

Alternate/Cross-Reference Part Numbers

• Alpha1G2-Kit-ZN — zinc anode kit part number
• Mercury/Quicksilver 97-888756Q03 — OEM anode kit reference; verify by drive serial number
• Mercury/Quicksilver 888756Q01 — OEM anode kit reference; verify by drive serial number
• Martyr ALPHAKITZ — zinc kit reference
• Martyr CMALPHAKITZ — zinc kit reference
• Sierra 18-6158Z — zinc kit reference
• Tecnoseal 20801 — zinc kit reference
• 821631 — gimbal housing block anode reference
• 821629 — ventilation plate anode reference
• 76214-5 — trim tab/skeg anode reference
• 806105 — bearing carrier collar anode reference
• 806189 — trim cylinder ram collar anode reference

Parts Desk Insight

Alpha One Gen II anodes should be selected by both drive model and water type. Zinc is the traditional saltwater choice, but it is not the best material for every boating environment. The cleanest installation is one where every anode contacts bare metal, all hardware is tight, and no anode is painted or insulated from the drive. When corrosion is already visible, inspect the bonding system, shore power ground, drive paint, trim rams, prop hardware, and nearby marina conditions as part of the repair.

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