Mercury OEM Nut 859116 – 5-Pack
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Mercury OEM Nut 859116 – 5-Pack
Part Number: 859116 (Mercury catalog prefix: 11-859116)
Brand: Mercury Marine
Official Product Type: OEM Nut / Fastener
Pack Quantity: 5 nuts per pack
System: Engine & Drive Assembly Hardware
Condition: New OEM
What It Does
The Mercury 859116 is a genuine OEM nut used in Mercury and MerCruiser engine and drive assemblies. Sold as a convenient 5-pack, this nut is precision-threaded to Mercury’s specifications and constructed from corrosion-resistant materials suited to the demands of the marine environment. OEM fasteners are manufactured to the exact thread pitch, hardness, and finish required for the assembly — substituting generic hardware in critical fastening locations can lead to improper torque retention or accelerated corrosion.
Compatible Applications
- Mercury outboard engine assemblies — verify position by parts diagram and serial number
- MerCruiser sterndrive assemblies — verify position by parts diagram and serial number
Note: This nut is used in multiple assembly locations across Mercury and MerCruiser product lines. Always confirm the correct part number and thread specification against the Mercury parts diagram for your specific engine model and serial number before ordering.
Supersedes / Alternate Part Numbers
- 859116 — current Mercury OEM part number
- 11-859116 — full catalog format with hardware prefix
Kit Contents
5 OEM nuts per pack. No washers, bolts, or additional hardware included.
Service Interval
Inspect fasteners whenever the assembly is opened for service. Replace any nut that shows corrosion, thread damage, rounding, or deformation. In saltwater environments, it is good practice to replace fasteners during major service intervals rather than reusing hardware that has been exposed to corrosion cycles.
Technical FAQ
Q: Can I substitute a standard hardware store nut of the same thread size?
For non-critical locations, a grade-matched stainless or zinc-plated nut of the correct thread pitch may be acceptable. However, for critical fastening points — such as those securing engine mounts, drive components, or structural assemblies — Mercury OEM hardware is recommended to ensure the correct hardness, thread class, and corrosion resistance for the application.
Q: How do I confirm the thread specification for this nut?
The thread specification is not printed on the nut itself. Refer to the Mercury service manual for your engine model, or measure the mating bolt with a thread gauge. The Mercury parts diagram will also identify the correct fastener for each assembly position.
Q: Why buy a 5-pack instead of a single nut?
Fasteners in marine environments are often replaced in sets during service — particularly when corrosion is present. Having spares on hand avoids a second parts order mid-job and is especially useful for recurring maintenance tasks where the same hardware is removed and replaced regularly.
Related Products
Parts Desk Insights
Best Use Case: This 5-pack is ideal for shops doing repeat service work on Mercury engines where the same fastener position is accessed regularly — keeping a pack in the parts bin means you’re never waiting on a single nut to complete a job. It’s also a smart buy when you’re doing a full service on a saltwater boat and want to replace all fasteners in the assembly rather than reusing corroded hardware.
Common Issues: The most common problem is ordering by part name rather than part number. Mercury uses many similar-looking nuts across different assemblies with different thread pitches and hardness grades — always confirm by part number from the diagram. The second common issue is reusing corroded fasteners to save a few dollars, then dealing with a seized or stripped nut at the next service interval. In saltwater environments especially, fresh hardware at each major service is cheap insurance.
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.