Mercury Alpha One Zinc Anode CMT-821631Z
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You have 30 days to request a return. All sale items are final sale.
The CMT-821631Z is a zinc gimbal/block anode designed for Mercury Alpha One sterndrives, protecting the gimbal housing, transom plate, and surrounding drive components from galvanic corrosion. It is a direct replacement for OEM Mercury/Quicksilver part 821631.
Manufactured from marine-grade zinc alloy, this anode is intended for saltwater applications, where it sacrifices itself to protect more valuable aluminum and steel components.
Key Features
- Direct replacement for Mercury 821631 / 821631Q1
- Marine-grade zinc (saltwater optimized)
- Block-style / gimbal housing anode
- Protects transom and sterndrive mounting components
- Cast to MIL-spec corrosion standards
Engine / Drive Compatibility
Designed for:
- Mercury / MerCruiser Alpha One sterndrives
- Compatible with:
- Alpha One Gen I
- Alpha One Gen II
- Some Bravo applications (gimbal use)
✔ Installed on:
- Gimbal housing / transom plate
✔ Protects:
- Gimbal ring and housing
- Transom assembly
- Adjacent bonded metals
Serial Number Fitment Notice
Always confirm:
- OEM reference (821631)
- Drive generation (Gen I vs Gen II)
- Mounting hole spacing and casting shape
When This Part Needs Replacement
- Anode is 50% or more consumed
- Uneven wear or pitting
- Visible corrosion on gimbal housing
- Routine seasonal service
Installation Notes
- Install on clean, bare metal surface
- Ensure full contact with mounting surface
- Do not paint the anode
- Replace mounting hardware if corroded
- Inspect regularly in saltwater
Alternate / Superseded Part Numbers
- Mercury / Quicksilver: 821631 / 821631Q1 / 821631B1
- Camp Company: CMT-821631Z
- Martyr: CM821631Z
- Aluminum version: CMT-821631A
- Magnesium version available
Parts Desk Insight
This is one of the most important single anodes on an Alpha drive. If it’s gone, corrosion targets the gimbal housing first, which is a high-cost repair—so it’s one you never want to let fully deplete.
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.