Alternator 18-5957 Sierra

The Sierra 18-5957 alternator is a popular replacement part specifically designed for Mercruiser Stern Drives. It offers a reliable and cost-effective solution to upgrade your boat's electrical system and ensure your battery stays charged. Here's a comprehensive breakdown of the Sierra 18-5957 alternator:

Key Features:

Voltage: 12 volts (standard for marine electrical systems)
Amperage: Variously reported as 65 amps or 68 amps. Refer to specific applications or product details for confirmation.
Design:
Three-wire design (might require additional wiring modifications compared to one-wire alternators)
Includes a fan and drive pulley for complete installation
Built with durable materials to withstand harsh marine environments
Applications: Compatible with various Mercruiser Stern Drive models (refer to compatibility information below for details)
Replaces Part Numbers:
Mercury Marine: 69729 (and possibly others)
Compatibility:

It's crucial to verify exact compatibility with your specific Mercruiser Stern Drive model before purchasing the Sierra 18-5957 alternator. Here's how to ensure a perfect fit:

Consult your boat's manual: This will list the original equipment manufacturer (OEM) alternator part number for your Mercruiser Stern Drive.
Check Sierra Marine's parts finder tool: Look up compatible parts based on your engine model and year on Sierra's website: https://catalog.sierraparts.com/
Contact Sierra Marine or a marine parts specialist: They can definitively confirm compatibility based on your boat's specifics.
Advantages of Sierra 18-5957 Alternator:

Reliable performance: Delivers sufficient amperage to meet your boat's electrical needs.
Durable construction: Built to last in saltwater environments.
Cost-effective solution: Offers a reliable alternative to OEM alternators at a competitive price point.
Complete solution: Includes a fan and pulley for a straightforward installation (though wiring might require adjustments).