Mercury MerCruiser Quicksilver O-Ring 31986
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Mercury MerCruiser Quicksilver 25-31986 is a genuine Mercury Marine O-ring used as a sealing ring in select Mercury, Mariner, MerCruiser, and older sterndrive / outboard assemblies. Mercury parts references list this as 25-31986 O-RING, with manufacturer part number 31986 and GTIN / UPC 745061135390. It is a broad-use OEM sealing part best matched by the exact Mercury parts diagram callout.
Key Features
- Genuine Mercury Marine / Quicksilver O-ring reference
- OEM part number: 25-31986
- Base part reference: 31986
- GTIN / UPC reference: 745061135390
- Catalog package reference: approximately 3.50 in. x 3.50 in. x 0.75 in.
- Catalog weight reference: approximately 0.02 lb
- Aftermarket size reference: 2.635 in. / 67 mm I.D. x 0.210 in. / 5.3 mm width
Engine Compatibility
This O-ring appears in Mercury parts references across many older Mercury / Mariner outboard applications, including select 35 HP, 40 HP, 45 HP, 50 HP, 60 HP, 65 HP, 70 HP, and related 350, 400, 402, 450, 500, and 650 model-family listings depending on serial number range. Mercury where-used data also lists older MerCruiser-related applications including ā0ā sterndrive 1965ā1966 and 60 Renault 68 I/L4 1965ā1968 references.
Serial Number Fitment Notice
O-ring fitment depends on the exact engine, drive, gear housing, component group, and serial number range. Always confirm compatibility using the Mercury or MerCruiser serial number and the exact parts diagram before ordering, especially because 25-31986 appears across many different assemblies.
When This Part Needs Replacement
Replace this O-ring whenever the related assembly is opened, or if the original seal is flattened, cut, brittle, swollen, cracked, missing, or no longer sealing properly. Reusing an old compressed O-ring can lead to leaks and repeat service.
Installation Notes
Clean the O-ring groove and mating surface before installation. Lightly lubricate the O-ring with the service-manual-approved lubricant where specified, and make sure it seats evenly without twisting, stretching, pinching, or rolling during assembly. Confirm the exact diagram location before installation because this O-ring has broad Mercury and MerCruiser usage.
Alternate/Superseded Part Numbers
- 25-31986
- 31986
- Sierra 18-7160
- GLM 83340
- Mallory 9-76545
- Volvo Penta 3852866 ā related cross-reference in supported applications
- OMC / Johnson / Evinrude 0508490, 0913850, 3852866 ā related cross-reference references
Parts Desk Insight
This is a broad-use sealing ring, so the safest match is the exact diagram callout rather than engine horsepower alone. The size can help confirm the part, but serial number and diagram location are the most reliable way to avoid ordering the wrong O-ring.
Shipping: Ships same or next day for fast Canada wide shipping. ā
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3ā4 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 ā 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 ā 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.