Mercury MerCruiser O-Ring 8M0204684
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Mercury MerCruiser O-Ring – 8M0204684
Maintain a proper seal in your marine engine or drive system with the Mercury MerCruiser O-Ring 8M0204684. This genuine Mercury OEM sealing ring is used in various engine and sterndrive assemblies to prevent fluid leaks and maintain system pressure.
Manufactured to Mercury Marine specifications, this O-ring provides reliable sealing performance in demanding marine environments where exposure to oil, water, and temperature changes can cause seals to wear over time. Replacing worn O-rings during routine service helps maintain engine reliability and prevent leaks.
Key Features
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Genuine Mercury Marine OEM O-ring
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Designed to maintain leak-free sealing in engine and drive assemblies
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Resistant to oil, water, and marine operating conditions
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Direct replacement for original Mercury sealing components
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Ideal for routine maintenance and seal replacement during service
Part Details
OEM Part Number: 8M0204684
Also Referenced As: 25-8M0204684
Supersedes: 805726
Product Type: O-ring seal
Material: Marine-grade rubber sealing compound
Compatible Mercury & MerCruiser Engines
This O-ring is used in various Mercury and MerCruiser engine and drive assemblies, including components such as seawater pumps, gear housings, and drive systems. Applications include:
MerCruiser Sterndrives
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MerCruiser Alpha One (Gen II) drive assemblies
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MerCruiser Bravo One
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MerCruiser Bravo Two
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MerCruiser Bravo Three
MerCruiser V-8 Marine Engines
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MerCruiser 7.4L (454 CID) V8
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MerCruiser 8.2L (502 CID) V8
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MerCruiser 454 EFI / MAG engines
Mercury Racing Sterndrive Engines
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Racing Sterndrive 420
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Racing Sterndrive 425
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Racing Sterndrive 465
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Racing Sterndrive 500
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Racing Sterndrive 525 SC
Mercury / Mariner Outboards (Gear Housing Applications)
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Mercury 8HP
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Mercury 10HP
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Mercury 25HP
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Mariner 6HP
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Mariner 9.9HP
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Mariner 15HP
These engines use the O-ring in gear housing, driveshaft housing, or seawater pump assemblies depending on the model and configuration.
Function
O-rings provide a tight seal between two mating components, preventing fluid leaks and maintaining proper pressure in marine systems such as pumps, gear housings, and lubrication passages.
Over time, O-rings can harden, crack, or lose elasticity due to heat and exposure to oil or seawater. Replacing worn seals helps:
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Prevent oil or water leaks
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Maintain proper system pressure
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Protect engine and drive components from contamination
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Ensure reliable engine operation
Important Compatibility Note
O-rings are used in many different assemblies depending on engine model, serial number range, and component design. Always verify compatibility using the engine model and serial number or parts diagram before ordering to ensure the correct replacement seal.
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.