Sierra 18-3083 Impeller, OMC 377230 Replacement for Evinrude 40 HP (1960-70) and 50 HP (1971-78) Outboards

The Sierra 18-3083 is a water pump impeller engineered for Evinrude outboard motors, designed to keep the engine's cooling system circulating water reliably. As a wear item inside the lower unit water pump, the impeller pushes raw water through the cooling passages to prevent overheating, and it should be inspected and replaced on a regular service interval or any time cooling performance drops off. This impeller is built from metal components and is finished in black. It is a direct application-specific part for Evinrude 40 HP outboards from 1960-70 and 50 HP outboards from 1971-78, and it cross-references to OMC part numbers 377230 and 777213, so it can be ordered as a drop-in equivalent using either the Sierra part number or the original OMC numbers. The impeller ships as a single unit and is the correct replacement for boaters who need to restore proper water flow to the engine's cooling system without hunting down a discontinued OEM part. Because engine overheating from a worn or cracked impeller can lead to serious damage, keeping a spare on hand or replacing it proactively during routine maintenance is common practice among outboard owners running these engine and year combinations.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3083
• Item Type: Impeller
• Material: Metal
• Color: Black
• Weight: 0.14 pounds
• Package Length: 5.588 cm
• Package Width: 5.588 cm
• Package Height: 3.81 cm
• Mounting Type: Engine Mount
• Fuel Type: Gasoline
• Unit Count: 1
• Included Components: Impeller
• OEM Equivalent Part Number: OMC 377230, 777213
• UPC: 030999315359

Fitment

• Evinrude 40 HP outboards, 1960-70
• Evinrude 50 HP outboards, 1971-78

Replaces (OEM)

• OMC 377230
• OMC 777213

Frequently Asked Questions

What does the Sierra 18-3083 impeller fit? The Sierra 18-3083 is built for Evinrude 40 HP outboards from 1960-70 and Evinrude 50 HP outboards from 1971-78.

Is the 18-3083 impeller a genuine OMC part? It is an aftermarket impeller manufactured by Sierra, sold as a direct equivalent to OMC part numbers 377230 and 777213, not an original OMC-branded part.

What OEM part numbers does the 18-3083 cross-reference to? This impeller replaces OMC 377230 and OMC 777213 on the applicable Evinrude 40 and 50 HP outboards.

How much does the 18-3083 impeller weigh? The Sierra 18-3083 impeller weighs 0.14 pounds.

What material is the 18-3083 impeller made from? The 18-3083 is made from metal and has a black finish.

How many impellers come in one order of 18-3083? Each order of the Sierra 18-3083 includes one impeller.

Why does an outboard impeller need to be replaced? An impeller like the 18-3083 wears down over time and can crack or lose vanes, reducing water flow through the cooling system and risking engine overheating, so it is a routine maintenance replacement part.

Will the 18-3083 impeller fit any Evinrude outboard? No, the 18-3083 is specific to Evinrude 40 HP outboards from 1960-70 and 50 HP outboards from 1971-78; other Evinrude engines and years use different Sierra part numbers.

What are the package dimensions of the 18-3083 impeller? The Sierra 18-3083 impeller has a package length of 5.588 cm, package width of 5.588 cm, and package height of 3.81 cm.

Does the 18-3083 impeller include mounting hardware? The 18-3083 order includes the impeller itself; no additional components are listed with it.

What color is the Sierra 18-3083 impeller? The 18-3083 impeller is black.

Can the 18-3083 be identified by its UPC code? Yes, the Sierra 18-3083 impeller carries UPC 030999315359.