Mercury MerCruiser Quicksilver — Engine & Gearcase Oil Seal — 8M0214939
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Mercury MerCruiser Quicksilver Oil Seal 8M0214939
Mercury MerCruiser Quicksilver 8M0214939 is a genuine OEM oil seal used in select Mercury Marine engine and gearcase assemblies. It replaces Mercury 66302 and is used at specified shaft or housing locations to help maintain separation between lubricated internal components and the surrounding environment.
Compatible Applications
- Select Mercury 25 HP outboards, including documented 1996 and 1997 applications
- Select lower-crankcase sealing locations originally using 66302
- Select Mercury outboard gearcase bearing-carrier assemblies
- Select Mercury and MerCruiser drive assemblies whose OEM diagram specifies 66302 or 8M0214939
Serial-number fitment: Verify the engine or drive serial number and exact OEM diagram before ordering. Some gearcase carrier assemblies use two 8M0214939 seals together, making quantity and installation orientation application-specific.
Part Details
- Current OEM part number: 8M0214939
- Mercury prefix reference: 26-8M0214939
- Brand: Mercury MerCruiser Quicksilver
- Product type: Engine and gearcase oil seal
- Supersedes: 66302
- Additional legacy references: 56394 and 66302B
- Condition: New
Key Features
- Genuine OEM oil seal
- Used as a lower-crankcase oil seal in select applications
- Also shown in select gearcase bearing-carrier assemblies
- Current replacement for earlier Mercury 66302 applications
- Some carrier assemblies require two seals at the same location
When to Replace This Seal
Replace the seal when oil or gear-lubricant leakage is visible, water is found in the gear lubricant, the bearing carrier or associated shaft has been removed, the sealing lip is worn or damaged, or an engine or gearcase rebuild exposes the existing seal. A used seal is generally best replaced while the surrounding assembly is apart.
Installation Notes
Confirm the seal location, required quantity, and installation orientation using the applicable service manual or OEM diagram. For gearcase applications, inspect the shaft sealing surface, clean the carrier bore, protect the sealing lip from sharp edges, and follow the specified installation depth and orientation. Pressure-test the gearcase after major sealing work when required by the service procedure.
Technical FAQ
Is this seal limited to one engine model?
No. It appears in both select engine and gearcase assemblies, so fitment must be matched to the serial-specific diagram.
How many seals are required?
Quantity varies by application. Some bearing-carrier diagrams show two 8M0214939 seals installed together.
Can installation orientation be assumed?
No. Confirm the direction and depth specified for the exact assembly before installation.
Parts Desk Insights
Best use case: Replacing the specified oil seal during lower-crankcase, shaft, or bearing-carrier service when the OEM diagram calls for 66302 or 8M0214939.
Most common mistake: Assuming one seal is enough or installing it in the wrong direction. Some carrier assemblies use two identical seals with an application-specific orientation.
Fitment guidance: Check the engine or drive serial number, diagram location, required quantity, and installation orientation before ordering or fitting the seal.
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.