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Sierra 18-6455 Alternator 50 Amp 5S/I for Mercury Mariner Outboard

Manufacturer

Sierra

<p>For nearly six decades, Sierra has established itself as one of the marine industry's most trusted names in aftermarket engine and drive parts. Founded as a specialized marine parts manufacturer, Sierra has grown into a comprehensive supplier of replacement components, instrumentation, and accessories for both recreational and commercial boating applications. Operating from their 300,000-square-foot distribution center in Litchfield, Illinois, Sierra serves boat owners and marine technicians worldwide with an extensive catalog of parts engineered specifically for the harsh saltwater environment.</p><h3>Marine Engine Excellence</h3><p>Sierra's reputation was built on delivering precision-engineered internal engine components and drive system parts that meet or exceed OEM specifications. Their <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> provide critical sealing solutions for inboard and outboard motors, while their <a href="/7570-sierra-engine-complete-assembly-15341">engine complete assemblies</a> offer comprehensive replacement options for major overhauls. Each component undergoes rigorous testing to ensure reliability in demanding marine conditions, from corrosion resistance to temperature cycling performance.</p><h3>Instrumentation and Monitoring Systems</h3><p>Accurate instrumentation is essential for boat operators to monitor engine health and prevent costly breakdowns on the water. Sierra's comprehensive line of <a href="/7570-sierra-gauges-200483">gauges</a> includes everything from fuel pressure and temperature indicators to voltmeters and trim gauges, all designed with marine-grade materials that withstand vibration, moisture, and UV exposure. Their <a href="/7570-sierra-tachometer-gauge-1488">tachometer gauges</a> deliver precise RPM readings critical for optimizing engine performance and fuel efficiency. Supporting these instruments, Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> ensure proper signal conditioning and accurate readings across various sensor types and engine configurations.</p><h3>Expanded Product Portfolio</h3><p>In 2022, Sierra significantly broadened its scope beyond traditional marine engine parts to encompass a wider range of boating accessories and even outdoor power equipment components. This strategic expansion brought established marine brands like Shields and Moeller under the Sierra umbrella, creating a one-stop resource for marine maintenance and replacement parts. The company now offers fuel systems, electrical components, battery charging solutions, and NMEA electronics alongside their traditional engine parts lineup.</p><h3>Quality Backed by Industry-Leading Warranties</h3><p>What sets Sierra apart in the crowded aftermarket marine parts market is their commitment to standing behind every component they manufacture. Their warranty coverage extends beyond simple part replacement—it includes shop labor, haul-out fees, towing charges, and related incidental costs should a warrantied part fail. This comprehensive protection reflects the company's confidence in their manufacturing processes and quality control standards. For boat owners facing repairs far from shore or mechanics working on customer vessels, this peace of mind is invaluable. Whether you're maintaining an outboard motor, rebuilding an inboard engine, or upgrading your boat's instrumentation, Sierra's decades of marine industry experience and commitment to quality make them a reliable choice for keeping your vessel running at peak performance.</p>

Part Number

18-6455
06/04/2036 12:30 PM
Sale Price

$460.28

4 left at this price

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Usually delivered within 2 days

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-6455 is a 50-amp alternator designed specifically for Mercury and Mariner outboard motors. This reliable replacement alternator features 5-stator/inducer (5S/I) construction, delivering consistent charging performance for marine electrical systems.

Key Features:

  • 50-amp output capacity for dependable battery charging
  • 5S/I (5-stator/inducer) design for efficient power generation
  • Direct replacement for Mercury/Mariner OEM alternators
  • Marine-grade construction for corrosion resistance
  • Precision-engineered to OEM specifications

Sierra Marine is known for producing high-quality aftermarket parts that meet or exceed original equipment standards. This alternator provides reliable performance for keeping your outboard's battery system charged during operation, ensuring you have power for electronics, starting, and accessories.

Products specifications

Compatibility

5S/I 50 Amp for Mercury/Mariner Outboard Motors. Fits 1.5L and 3.0L. For 200 DFI200 DFI/DTS225 EFI225 EFI Sea Pro225 DFI/DTS250 EFI. Replaces Mercury 875286T875286A1881247A18M0064020

Type

Alternators

Fast shipping on purchased item. Had in stock when other's did not.

wish you had this size in black

The order was very easy to place

so far so good

make it work right and I'll be back!

Good so far

It was ok

Easy

Quick and easy. Good prices, too

This was my first time using autoplicity and I was very happy with their service. Great prices and fast shipping.

Great product at a a great price!

Good prices free shipping

Unbeliveable customer service and super fast shipping. I had a question about my order and I was able to use the online chat function to instantly connect with a customer service agent that was quick to answer all my questions regarding my order. I am very pleased with the level of service I received not to mention the great price they offered on the item I purchased. I will be sure to continue doing business with Autoplicity for my automotive needs. Thanks so much. A+

so far - so good

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