MerCruiser Alpha One Gen II Magnesium Anode Kit – 18-6158M / 47-6158M
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MerCruiser Alpha One Gen II Magnesium Anode Kit – 18-6158M / 47-6158M
This magnesium sacrificial anode kit is designed to protect MerCruiser Alpha One Generation II sterndrives from galvanic corrosion in freshwater environments. Magnesium is the preferred anode material for freshwater use — it is more electrochemically active than aluminum or zinc, which means it sacrifices itself more readily to shield submerged sterndrive components from corrosion.
The kit covers Alpha One Gen II drives from 1991 and newer, subject to drive configuration and serial-number verification. Cross-references to Mercury/Quicksilver part 888755Q03 and several superseded numbers.
Specifications
- Part Numbers: 18-6158M / 47-6158M
- Anode Material: Magnesium
- Application: Freshwater use only
- Drive Compatibility: MerCruiser Alpha One Generation II (1991 and newer)
- Weight: 803 g (1.77 lbs)
- UPC: 808282277260
Cross-Reference / Superseded Part Numbers
- 18-6158M
- 47-6158M
- 888755Q03
- 888755Q01
- 97-888755K01
- 888755A1
Features
- Magnesium construction — more active than aluminum or zinc for superior freshwater protection
- Complete drive-anode service kit for applicable Alpha One Gen II configurations
- Sacrificial design — protects sterndrive housing and components by corroding in their place
- Cross-references to current Mercury/Quicksilver Alpha Gen II magnesium kit (888755Q03)
Compatible Applications
- MerCruiser Alpha One Generation II sterndrives, 1991 and newer
- Freshwater lakes, rivers, and inland waterways
- Seasonal anode replacement during sterndrive service or winterization
Fitment Note
Alpha One Gen II applications can vary by production range and drive configuration. Always confirm the sterndrive model and serial number before ordering, especially when replacing an older kit or matching individual anodes already on the drive. Magnesium anodes are for freshwater use only — they are too active for sustained saltwater or brackish-water use.
Related Products
- MerCruiser Alpha One Gen II Aluminum Anode Kit
- MerCruiser Alpha One Gen II Zinc Anode Kit
- Mercury OEM Aluminum Anode Kit – Alpha One (818298Q1)
- Seachoice Alpha One Gen II Magnesium Anode Kit (95031)
- Seachoice Alpha One Gen II Aluminum Anode Kit (95021)
Parts Desk Insights
Best use case: This kit is the right choice for boats kept exclusively in freshwater — lakes, rivers, and inland waterways. Magnesium anodes are more active than aluminum or zinc, which makes them effective in the low-conductivity environment of fresh water where less active materials can become passive and stop protecting the drive.
Two things matter most at installation: anode material selection and electrical contact. Magnesium is correct for freshwater, but it degrades quickly in salt or brackish water — if your boat moves between environments, aluminum is the safer all-around choice. Regardless of material, the anode cannot protect the drive if paint, corrosion, or sealant breaks the metal-to-metal contact between the anode and the housing. Clean the mounting surfaces to bare metal before installing, and never coat the exposed anode face.
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.