Sierra 18-3055 Water Pump Impeller, Replaces OMC 389589, for 50-60 HP Evinrude/OMC Outboards

The Sierra 18-3055 is a water pump impeller built to circulate raw water through the cooling system of compatible outboard motors, keeping the engine block and powerhead running at safe operating temperatures. As the wearing component inside the water pump housing, the impeller's flexible vanes draw water in and push it through the cooling passages every time the engine runs; over time these vanes flatten, crack, or shed material from heat and dry-running, which reduces flow and can lead to overheating. Replacing the impeller on the recommended service interval, or as soon as overheating or reduced water discharge is noticed, protects the powerhead from costly heat damage.

This impeller is made of metal-reinforced construction and is designed as a direct equivalent to OMC 389589, so it installs into the original water pump housing without modification. It is intended for 2 stroke Evinrude/OMC outboard engines used in general boating activities such as fishing, water sports, and cruising. Fitment covers 50 HP model years 1979-1985, 55 HP model years 1979-1985, and 60 HP model years 1980-1985.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3055
• Item Type: Impeller
• OEM Equivalent Part Number: OMC 389589
• Engine Type: 2 Stroke
• Fuel Type: Gasoline
• Mounting Type: Transom Mount
• Material: Metal
• Color: Black
• Weight: 0.17 pounds
• Package Length: 14.478 centimeters
• Package Width: 7.874 centimeters
• Package Height: 2.286 centimeters
• Unit Count: 1 count
• UPC: 030999315113

Fitment

• 50 HP, model years 1979-1985
• 55 HP, model years 1979-1985
• 60 HP, model years 1980-1985

Replaces (OEM)

• OMC 389589

Frequently Asked Questions

What does the Sierra 18-3055 impeller fit? It fits 50 HP outboards from model years 1979-1985, 55 HP outboards from model years 1979-1985, and 60 HP outboards from model years 1980-1985 on Evinrude/OMC engines.

Is the Sierra 18-3055 an OEM part or an equivalent replacement? It is an aftermarket equivalent to OEM part OMC 389589, built to install into the original water pump housing without modification.

What material is the 18-3055 impeller made from? The impeller is constructed of metal with black-colored vanes, per Sierra's part specifications.

How much does the Sierra 18-3055 impeller weigh? The Sierra 18-3055 weighs 0.17 pounds.

What are the package dimensions of the 18-3055? The Sierra 18-3055 ships in packaging measuring 14.478 centimeters long, 7.874 centimeters wide, and 2.286 centimeters high.

How many impellers come in one Sierra 18-3055 package? One package of the Sierra 18-3055 contains a single impeller.

What engine type is the 18-3055 impeller designed for? This impeller is designed for 2 stroke, gasoline-fueled outboard engines.

Does the 18-3055 impeller work with transom-mounted outboards? Yes, the Sierra 18-3055 is designed for transom mount outboard applications.

Why would a boat owner need to replace the 18-3055 impeller? Water pump impellers like the Sierra 18-3055 wear out over time as their flexible vanes flatten or crack, reducing raw water flow and risking engine overheating, so periodic replacement is needed to keep the cooling system working properly.

What OEM number does the Sierra 18-3055 cross-reference to? The Sierra 18-3055 impeller cross-references to OMC 389589.