Sierra Impeller 18-3039, Replaces Mercury Marine 47-89981

The Sierra 18-3039 is a replacement water pump impeller designed to restore proper cooling flow in marine engines that use the Mercury Marine 47-89981 impeller. The impeller is the core wear component inside a water pump housing, drawing raw water through the pump and circulating it through the engine's cooling passages to prevent overheating. Over time, impeller vanes lose flexibility, crack, or wear down, reducing pump output and putting the engine at risk of running hot. Replacing a worn impeller with the Sierra 18-3039 restores the pump's ability to move water at the correct rate.

This impeller ships as a single unit and is built to Sierra's standard fit and finish for marine water pump service. It is intended as a direct component replacement where the Mercury Marine 47-89981 impeller is specified, and is commonly installed during routine water pump maintenance or as part of a broader water pump rebuild.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3039
• Product Type: Impeller
• Quantity: 1 impeller
• Weight: 0.03 pounds
• UPC: 030999237149
• Country of Origin: United States
• OEM Cross Reference: 47-89981

Fitment

Fits applications specifying the Mercury Marine 47-89981 impeller.

Replaces (OEM)

• 47-89981

Frequently Asked Questions

What does the Sierra 18-3039 fit? The Sierra 18-3039 impeller is a direct replacement wherever the Mercury Marine 47-89981 impeller is specified.

Is the 18-3039 the same as the Mercury Marine 47-89981? Yes, the Sierra 18-3039 is a cross-reference equivalent to the Mercury Marine 47-89981 impeller.

How many impellers come in the package? One impeller is included with part number 18-3039.

How much does the 18-3039 impeller weigh? It weighs 0.03 pounds.

Where is the Sierra 18-3039 impeller made? The country of origin listed for this impeller is the United States.

Is this a genuine Sierra part or aftermarket? The 18-3039 is a Sierra-branded impeller, sold as a cross-reference equivalent to the OEM Mercury Marine 47-89981 part rather than a Mercury-branded part.

What is the UPC for this part? The UPC for the Sierra 18-3039 impeller is 030999237149.

When should I replace this impeller? An impeller like the Sierra 18-3039 should be replaced when it shows cracked, torn, or stiffened vanes, or when engine cooling water flow drops, since a worn impeller reduces pump output.

Does the 18-3039 include the pump housing or just the impeller? This part number covers the impeller only; it does not include a pump housing.

Can I use the 18-3039 as a routine maintenance replacement? Yes, the 18-3039 is suited for routine water pump maintenance wherever the Mercury Marine 47-89981 impeller is called for.