Mercury OEM Nut 859135 5-Pack

Part Number: 859135 (Mercury catalog prefix: 11-859135)
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 859135 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 Mercurys specifications and built from corrosion-resistant materials suited to both saltwater and freshwater marine environments. 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 failure.

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 across multiple assembly locations in 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

859135 current Mercury OEM part number
11-859135 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, replacing fasteners during major service intervals rather than reusing corroded hardware is a sound practice that prevents seized fasteners at the next service.

Technical FAQ

Q: How is 859135 different from Mercury nut 859116?
These are two distinct Mercury OEM nut part numbers used in different assembly locations. They may differ in thread pitch, diameter, depth, or finish. Do not substitute one for the other always order by the part number shown in the Mercury parts diagram for your specific assembly position. See also: Mercury OEM Nut 859116 5-Pack.

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. 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: 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.

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 youre never waiting on a single nut to complete a job. Its also a smart buy when doing a full service on a saltwater boat where replacing all fasteners in the assembly rather than reusing corroded originals is the right call for long-term reliability.

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. A second frequent issue is reusing corroded fasteners to save a few dollars, then dealing with a seized or stripped nut at the next service. In saltwater environments especially, fresh hardware at each major service is inexpensive compared to the cost of extracting a seized fastener.

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