Mercury MerCruiser Quicksilver Gear Housing Oil Passage Seal 455771
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Gear Housing Oil Passage Seal — OEM Reference 455771 / 26-455771
Part Number: 455771 | Service format: 26-455771
Brand: Mercury Marine / Quicksilver
Official Product Type: Quad-Ring Oil Passage Seal
Supersedes: 455771 / 26-455771
Replaced By: 8M0204680 — View current replacement: Mercury MerCruiser Seal 8M0204680
System: Sterndrive Gear Housing — Internal Oil Passage Sealing
Diagram Position: Internal lubricant passage between mating gear housing sections
What This Seal Does
This genuine Mercury Marine / Quicksilver quad-ring seal sits at the oil-passage interface between mating sections of the MerCruiser gear housing. It seals internal lubricant passages and prevents gear oil from escaping or water from entering the gearcase at that junction. Although it closely resembles a standard O-ring, it is a quad-ring profile — substituting a round O-ring will change how the seal compresses between the housings and increases the risk of lubricant loss or water intrusion.
Compatible Applications
Fitment depends on exact sterndrive model and serial number. Confirm against your MerCruiser parts diagram before ordering.
- MC-1 sterndrive
- R / MR sterndrives
- Alpha One sterndrive
- Alpha One Gen II sterndrive
- Bravo One, Two, Three sterndrives
- Bravo X / XR / XZ drive families
- Selected Vazer drive applications
This seal appears in multiple gear-housing diagrams, including Bravo III assemblies. Because Mercury uses several similar small seals in the same gear housing, the correct diagram callout must be confirmed before ordering.
Serial Number Fitment Notice
Verify fitment using your exact sterndrive model and serial number in the correct MerCruiser parts diagram. Similar seals appear in nearby locations within the same gear housing, and appearance alone does not confirm interchangeability.
When to Replace This Seal
Replace whenever the gear housing is opened at the location this seal protects, or if the existing quad-ring is flattened, cut, hardened, swollen, or otherwise damaged. A compromised seal can allow gear lubricant to escape or permit water to enter the drive.
Service Interval
Replace at every gear housing separation or complete sterndrive service. Mercury recommends inspecting all drive seals any time the housing is opened — reusing a disturbed quad-ring is not recommended.
Dimensions
Approximate inner diameter: 0.3125 in. | Approximate outer diameter: 0.4375 in. | Profile: Quad-ring (X-ring)
Installation Notes
- Clean the seal groove and mating surfaces thoroughly before installation.
- Lightly lubricate the new seal with the lubricant specified in the applicable MerCruiser service procedure.
- Confirm the seal remains properly seated as the gear housing is reassembled.
- Do not substitute a standard round O-ring — the quad-ring profile is required for correct compression and sealing.
Kit Contents
Single seal. Not a kit. Order related drive seals and O-rings separately for a complete service.
Alternate and Superseded Part Numbers
- Original: 455771 / 26-455771
- Related: 45577 / 26-45577, 45577B / 26-45577B, 45577B1 / 26-45577B1
- Current OEM replacement: 8M0204680
- Aftermarket cross-reference: Sierra 18-2944, GLM 85140
GTIN (8M0204680): 745061776937
Related Parts
- Mercury MerCruiser Seal 8M0204680 — current OEM replacement for this seal
- MerCruiser gear housing O-ring set — verify by drive model and serial number
- Sterndrive gear lube — required for seal lubrication during installation
Parts Desk Insights
The most common mistake with this seal is ordering by size or appearance alone. MerCruiser gear housings contain several small seals in close proximity, and they can look nearly identical. Always match by diagram callout and serial number — not by visual comparison to the old seal. This part is also a quad-ring, not a standard O-ring; using the wrong profile changes how it seals between the housings and can result in a leak after reassembly. Order the current replacement 8M0204680 unless you have confirmed availability of the original 455771 stock.
Technical FAQ
Q: Can I use a standard O-ring instead of this seal?
No. This is a quad-ring (X-ring) profile. A standard round O-ring will not compress the same way and may not seal reliably in this application.
Q: Is 8M0204680 the same seal as 455771?
Yes — 8M0204680 is the current OEM replacement for 455771. It may differ visually while performing the same sealing function.
Q: How do I confirm this is the right seal for my drive?
Use your MerCruiser sterndrive serial number to look up the correct parts diagram and confirm the diagram specifically calls for 455771 or 8M0204680 at the oil-passage location in your gear housing.
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.
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