Sierra 18-3003 Impeller, Replaces OMC 377178, for Evinrude Outboard Water Pumps

The Sierra 18-3003 is a water pump impeller built for Evinrude outboard water pump applications. The impeller is the component inside your outboard's water pump housing that draws raw water in and circulates it through the engine's cooling system, so a worn or cracked impeller is one of the most common causes of overheating on outboard motors. This impeller is black in color and is supplied as a single unit (quantity of 1) for use when rebuilding or servicing your outboard's water pump.

Because impellers wear out from normal use, dry-running, or age-related hardening of the material, replacing the impeller at recommended service intervals or at the first sign of reduced water flow helps protect the engine from overheating damage. The Sierra 18-3003 is manufactured as a direct cross-reference replacement for the original equipment part, making it a straightforward like-for-like swap during a water pump service.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3003
• Application: Evinrude Outboard Water Pumps & Impellers
• Color: Black
• Item Dimensions: 3 x 3 x 1 inches
• Weight: 0.09 pounds
• Quantity: 1 impeller
• UPC: 030999314994
• OEM Cross Reference: OMC 377178

Fitment

• Evinrude outboard water pump applications

Replaces (OEM)

• OMC 377178

Frequently Asked Questions

What does the Sierra 18-3003 impeller fit? The Sierra 18-3003 is designed for Evinrude outboard water pump applications.

What OEM part number does the Sierra 18-3003 replace? It cross-references to OMC part number 377178, so it is a direct replacement for that original equipment impeller.

What color is the Sierra 18-3003 impeller? It is black.

How much does the Sierra 18-3003 impeller weigh? This impeller weighs 0.09 pounds.

What are the dimensions of the Sierra 18-3003? The impeller measures 3 x 3 x 1 inches.

How many impellers come in the package? The Sierra 18-3003 is sold as a single impeller, quantity 1.

Is the Sierra 18-3003 a genuine Sierra part? Yes, it is manufactured and sold under the Sierra brand as part number 18-3003.

Why would I need to replace the impeller in my outboard's water pump? A worn, cracked, or hardened impeller reduces raw water flow through the cooling system, which can lead to engine overheating; the Sierra 18-3003 impeller is used to restore proper water pump function.

What is the UPC for the Sierra 18-3003 impeller? The UPC for the Sierra 18-3003 impeller is 030999314994.

Can the Sierra 18-3003 be used as a direct swap for OMC 377178? Yes, Sierra 18-3003 is the cross-referenced replacement for OMC 377178.