Mercury Quicksilver Gimbal Housing Cover Gasket — 818305 — Alpha One Gen II and Bravo
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Mercury Quicksilver Gimbal Housing Cover Gasket 818305
Genuine Mercury Marine OEM gasket for the water-passage block-off cover on selected MerCruiser transom assemblies. It seals the cover to the gimbal housing when the gasket, cover, and surrounding hardware match the applicable drive and transom diagram.
Compatible Applications
- Selected MerCruiser Alpha One Gen II transom assemblies
- Selected Bravo One transom assemblies
- Selected Bravo Two transom assemblies
- Selected Bravo Three transom assemblies
- Selected Bravo XR and XZ applications
- Selected integrated-transom assemblies where the parts diagram specifies 818305
Confirm the sterndrive and transom serial number before ordering. Surrounding gimbal-housing components can vary by drive generation and production range.
Part Details
- OEM part number: 818305
- Full service number: 27-818305
- Brand: Mercury Quicksilver
- Product type: Gimbal housing cover gasket
- System: Transom assembly and gimbal housing
- Diagram quantity: One gasket per applicable assembly
- UPC: 745061324367
Key Features
- Genuine Mercury Marine OEM gasket
- Seals the water-passage block-off cover to the gimbal housing
- Used across selected Alpha One Gen II and Bravo-family assemblies
- Fitment depends on drive family, serial number, and diagram position
Replacement Guidance
Replace the gasket whenever the block-off cover is removed, or if the existing gasket is torn, compressed, leaking, or damaged during service. A fresh gasket helps restore the intended seal at the cover and gimbal-housing interface.
Installation Notes
Clean both sealing surfaces before installation and follow the current service manual for orientation, tightening sequence, and torque. Applicable assemblies may use block-off plate kit 8M0095447, two 1/4-20 × 3/4 in. screws such as 28636, and two 1/4 in. stainless lockwashers such as 26992.
Technical FAQ
Does 818305 fit every Alpha One or Bravo drive?
No. It is used in selected Alpha One Gen II and Bravo-family transom assemblies. Confirm the complete drive and transom serial number against the current parts diagram.
Where is this gasket installed?
It sits beneath the water-passage block-off cover on the applicable gimbal housing or transom assembly.
Can I reuse the old gasket?
Replacement is recommended whenever the cover is removed, especially if the gasket is compressed, torn, contaminated, or no longer seals correctly.
What related cover is used with 818305?
Applicable diagrams may use block-off plate kit 8M0095447. Confirm the complete cover and hardware assembly for the installed drive.
Related Parts
- Mercury MerCruiser Quicksilver Alpha Block-Off Kit 8M0095447
- 1/4-20 × 3/4 in. screws 28636
- 1/4 in. stainless lockwashers 26992
Parts Desk Insights
Best use: Use 818305 when servicing the water-passage block-off cover on a compatible Alpha One Gen II, Bravo, or integrated-transom assembly.
Most common mistake: Treating the gasket as a universal MerCruiser transom seal. Nearby gimbal-housing components vary by drive generation, so the serial number and diagram position matter.
Fitment and sizing: Match the complete 27-818305 service number, one-gasket quantity, drive family, transom serial number, and block-off-cover diagram before ordering.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 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.