Sierra 18-5708 Rectifier for Evinrude/OMC Outboards 50-85 HP, Replaces OMC 582399 583408

The Sierra 18-5708 is a voltage rectifier built for Evinrude/OMC outboard motors, converting the alternating current from the engine's stator into direct current to charge the battery and power onboard electrical systems. As the charging system fails to keep the battery topped off, or the engine shows signs of an overcharging or no-charge condition, the rectifier is one of the first components to inspect, and the 18-5708 is a direct replacement for the original units used across a wide range of Evinrude/OMC outboard horsepower classes.

This rectifier is finished in white and is a compact, sealed component designed to mount in the original location using the factory hardware pattern. It carries the Sierra part number 18-5708 and cross-references directly to OMC part numbers 582399 and 583408, so it can be ordered as a like-for-like replacement without modification to the surrounding wiring harness. Sierra backs the part with its standard limited warranty coverage, and every unit is manufactured to fit the outboard applications listed below without further adaptation.

Fitment spans a broad range of Evinrude/OMC outboards by horsepower and model year, including 50, 55, 60 (including the SST60), 65, 70, 75, and 85 HP engines produced across multiple production years. Always confirm the horsepower and model year of the outboard against the fitment list before ordering to ensure the 18-5708 is the correct rectifier for the application.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5708
• Category: Outboard Rectifier
• Color: White
• Weight: 0.15 pounds
• UPC: 030999236722
• OEM Cross Reference: OMC 582399, OMC 583408

Fitment

• Evinrude/OMC 50 HP, 1971-75
• Evinrude/OMC 55 HP, 1976-77
• Evinrude/OMC 60 HP, 1970, 1971
• Evinrude/OMC 60 HP, 1989-91
• Evinrude/OMC SST60, 1989-90
• Evinrude/OMC 65 HP, 1972-73, 1988-91
• Evinrude/OMC 70 HP, 1992-01
• Evinrude/OMC 75 HP, 1975-88
• Evinrude/OMC 85 HP, 1970-80

Replaces (OEM)

• OMC 582399
• OMC 583408

Frequently Asked Questions

What does the Sierra 18-5708 rectifier do? It converts the alternating current produced by an Evinrude/OMC outboard's stator into direct current, which is what charges the battery and runs the boat's electrical system.

Which outboards fit the Sierra 18-5708? The 18-5708 fits Evinrude/OMC outboards including 50 HP (1971-75), 55 HP (1976-77), 60 HP (1970, 1971 and again 1989-91), SST60 (1989-90), 65 HP (1972-73, 1988-91), 70 HP (1992-01), 75 HP (1975-88), and 85 HP (1970-80).

Is the Sierra 18-5708 a genuine OEM part or an aftermarket replacement? It is a Sierra-manufactured aftermarket rectifier built to replace the original OMC unit, cross-referencing directly to OMC part numbers 582399 and 583408.

What OEM part numbers does the 18-5708 replace? The Sierra 18-5708 replaces OMC 582399 and OMC 583408.

How much does the Sierra 18-5708 rectifier weigh? The 18-5708 rectifier weighs 0.15 pounds.

What color is the Sierra 18-5708? It is finished in white.

Does the SST60 outboard use the same rectifier as the standard 60 HP model? Yes, the SST60 (1989-90) uses the same Sierra 18-5708 rectifier as the 60 HP Evinrude/OMC outboards from 1989-91.

What are the signs a rectifier like the 18-5708 needs to be replaced? A failing rectifier typically shows up as a battery that will not hold a charge, an overcharging condition, or erratic charging system readings on an Evinrude/OMC outboard.

Is installation of the 18-5708 straightforward? The Sierra 18-5708 is designed as a direct replacement for the original OMC 582399 or 583408 rectifier, mounting in the factory location using the existing wiring connections.

What is included when I order the 18-5708? Each order includes one Sierra 18-5708 rectifier.

Does Sierra offer a warranty on the 18-5708 rectifier? Yes, the 18-5708 is covered under Sierra's standard limited warranty.