Upgrade your outboard motor's electrical system with confidence using this high-performance replacement alternator. Designed for marine environments, it delivers reliable power to keep your engine running smoothly during long days on the water. Whether you're charging batteries, powering electronics, or supporting ignition demands, this unit steps up to ensure consistent output without the guesswork.

Engineered for Marine Demands

Crafted to match original equipment manufacturer standards, this alternator produces output that meets or surpasses factory specifications. Its robust construction handles the harsh conditions of saltwater exposure and constant vibration. Key highlights include:

• Corrosion-resistant plating on fans, pulleys, and hardware to extend service life in wet, salty environments.
• Integrated marine flame arrestor screens that prevent open sparks, reducing risks of explosions or fires—a critical safety feature for boating enthusiasts.
• Application-specific wiring harnesses included, simplifying the swap from your old unit without custom fabrication.

These elements combine to provide not just a part, but a dependable upgrade that minimizes downtime and maximizes your time enjoying the waves.

Superior Performance in Real-World Use

Boaters know alternators take a beating from heat, moisture, and heavy loads. This model addresses common failure points head-on. Expect higher amperage delivery under load compared to worn OEM parts, helping maintain optimal battery charge even with trolling motors or fish finders drawing power. Users report quicker recovery times after starting and steadier voltage for sensitive electronics like GPS and VHF radios.

Backed by a comprehensive Sierra warranty, it offers peace of mind. No more worrying about intermittent charging issues that strand you mid-trip— this alternator keeps the juice flowing reliably.

Effortless Installation for DIY Mechanics

Swapping out a failing alternator doesn't have to be a headache. The included harness plugs right in, matching your engine's setup for a plug-and-play experience. Most installations take under an hour with basic tools: disconnect the battery, remove the old unit, bolt in the new one, and reconnect. Pro tip: Inspect belts and tensioners while you're in there to prevent future issues.

For those troubleshooting low output or dim lights, this is often the fix. Symptoms like sluggish starts or undercharged batteries? A fresh alternator restores full electrical health.

Long-Term Maintenance Tips

To get the most from your investment:

1. Regularly rinse with fresh water after saltwater use to protect plated components.
2. Check belt tension seasonally—too loose, and output drops; too tight, and bearings wear prematurely.
3. Monitor voltage output with a multimeter (aim for 13.8-14.4V at idle) to catch issues early.
4. Avoid overloading with excessive accessories without upgrading wiring.

These simple habits ensure years of trouble-free operation, saving you from costly repairs down the line.

Frequently Asked Questions

Equip your outboard with power you can trust—reliable, safe, and built to last through every adventure.

These all NEW replacement alternators meet OEM specs and meet or exceed OEM output for guaranteed performance. Fans, pulleys and hardware are plated to resist corrosion and special marine flame arrestor screens eliminate open sparks which can cause explosions and fire. Wiring harnesses are supplied as required by application for ease of installation. All alternators are fully backed by the Sierra warranty.
See Sierra's catalog for current application information.


SKU: NVN-4003411
MPN: 18-6844
UPC: 808282311605