Sierra 18-3713 Lock Nut - Mercruiser
Sierra 18-3713 Lock Nut - Mercruiser — Product description
Discover the Reliability of the Sierra 18-3713 Lock Nut for Mercruiser Engines
Keeping your Mercruiser engine running smoothly on the water starts with the right fasteners. The Sierra 18-3713 lock nut steps in as a dependable replacement for the OEM 11-22339 nut, designed specifically for marine environments where vibration, saltwater exposure, and constant motion demand unyielding performance. Crafted from high-grade materials, this lock nut resists loosening over time, ensuring your propeller shaft, drive components, or other critical assemblies stay secure during every outing.
Unlike basic hardware store options, the Sierra 18-3713 incorporates a nylon insert that provides consistent locking torque, even after repeated installations. Boat owners and mechanics alike trust it for its precise fit and corrosion-resistant finish, which holds up against the harsh marine conditions that can quickly degrade lesser parts.
Key Features That Set the Sierra 18-3713 Apart
- Precision Engineering: Matches OEM specifications for the 11-22339 nut, ensuring seamless compatibility without modifications.
- Nylon Locking Mechanism: Delivers reliable self-locking action to prevent vibration-induced loosening, a common issue in high-RPM sterndrive applications.
- Corrosion Resistance: Zinc-plated steel construction fights off rust and galvanic corrosion from saltwater immersion.
- Standard Sizing: Hex head design (typically 5/16-18 thread) allows for easy wrench access in tight engine compartments.
- Aftermarket Quality: Sierra's rigorous testing mirrors OEM standards, offering peace of mind at a fraction of dealer costs.
Whether you're prepping for a weekend cruise or tackling a full engine rebuild, this lock nut integrates effortlessly into your maintenance routine.
Perfect Fit for Popular Mercruiser Models
The Sierra 18-3713 shines in a wide array of Mercruiser setups, particularly Alpha One, Bravo sterndrives, and inboard engines. It's commonly used to secure:
- Propeller nuts on shaft assemblies.
- Trim tab rams and hydraulic fittings.
- Exhaust manifold studs and accessories.
- Power steering components.
Always cross-reference with your engine's service manual to confirm fitment, but this part covers generations from the 1980s through modern configurations. Its versatility makes it a staple in boatyards everywhere.
Pro Tips for Installing Your Sierra 18-3713 Lock Nut
Installation is straightforward, but following these steps maximizes longevity:
- Clean threads thoroughly to remove old sealant, debris, or corrosion—use a wire brush and marine solvent.
- Apply a thin layer of anti-seize compound to prevent galling, especially in aluminum housings.
- Torque to manufacturer specs (typically 20-30 ft-lbs for similar applications—check your manual).
- After initial run-in, re-torque to confirm hold, as nylon inserts may settle slightly.
- Inspect annually or every 100 hours of operation for wear.
Pro tip: In saltwater use, pair with stainless washers for added protection against electrolysis.
Why Sierra Lock Nuts Boost Long-Term Engine Health
Secure fasteners like the 18-3713 prevent catastrophic failures that could lead to propeller damage or drive shaft issues. By choosing Sierra, you're investing in parts that undergo vibration testing equivalent to thousands of sea miles. This reduces downtime, cuts repair costs, and keeps your vessel ready for adventure. Marine enthusiasts report fewer comebacks compared to generic imports, thanks to Sierra's focus on marine-specific durability.
Frequently Asked Questions
What does the Sierra 18-3713 lock nut replace?
It directly replaces the Mercruiser OEM 11-22339 nut, offering identical fit and function for sterndrive and inboard applications.
Is the Sierra 18-3713 suitable for saltwater boats?
Yes, its zinc plating and nylon insert provide excellent corrosion resistance, making it ideal for brackish or saltwater environments.
How do I know if this lock nut fits my Mercruiser engine?
Check your engine serial number against Sierra's compatibility charts or your service manual. It's commonly used in Alpha and Bravo drives.
Can I reuse the Sierra 18-3713 lock nut multiple times?
The nylon insert allows limited reuse (2-3 times), but for safety, replace after removal to maintain full locking power.
What's the difference between this and a regular hex nut?
The locking feature prevents loosening from engine vibration, crucial for marine props and drives where standard nuts would fail.
Do I need special tools to install the 18-3713?
No, a standard 1/2-inch wrench or socket works fine. Use a torque wrench for precise application.
How often should I inspect this lock nut?
Check at every oil change or 50-100 hours, especially after heavy use or trailering.
SKU: NVN-4003627
MPN: 18-3713
UPC: 808282244033
Technical specifications
| Brand | Sierra Engine Parts |
| Model | Sierra 18-3713 Lock Nut - Mercruiser |
| SKU / MFR# | 4003627 |
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