Sierra 18-3319 Water Pump Kit with Upper and Lower Housings - Replaces Mercury Marine 46-42579A4

The Sierra 18-3319 Water Pump Kit is a complete replacement water pump kit engineered for Mercury Marine outboard applications, designed to restore proper cooling system function. This kit includes the water pump base (Sierra 18-3419) along with the upper and lower housing components needed for a full water pump rebuild, allowing the raw water cooling circuit to draw and circulate water through the engine as intended. The kit is built to meet or exceed original equipment quality standards, giving installers a direct-fit alternative to the factory Mercury Marine part.

Because water pump components are fit specific, buyers should confirm part numbers against their existing pump assembly before ordering to ensure proper fit. The kit corresponds to Mercury Marine OEM part number 46-42579A4, making it a straightforward cross-reference for anyone replacing a worn or failed pump assembly using the original Mercury part number.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3319
• Product Name: Water Pump Kit w/Upper and Lower Housings - Mercury
• Included Components: Water Pump Kit (includes Water Pump Base 18-3419)
• Weight: 0.9 pounds
• UPC: 030999315816

Fitment

• Mercury Marine outboard applications using OEM part number 46-42579A4

Replaces (OEM)

• Mercury Marine 46-42579A4

Frequently Asked Questions

What does the Sierra 18-3319 Water Pump Kit include? The kit includes a water pump base, identified separately as Sierra 18-3419, along with the upper and lower housing components needed to rebuild the water pump assembly.

What Mercury Marine part number does the Sierra 18-3319 replace? It replaces Mercury Marine OEM part number 46-42579A4.

How much does the Sierra 18-3319 Water Pump Kit weigh? This water pump kit weighs 0.9 pounds.

Is the Sierra 18-3319 a genuine Mercury Marine part or an aftermarket replacement? The Sierra 18-3319 is an aftermarket water pump kit built to meet or exceed original equipment quality, cross-referenced to Mercury Marine part number 46-42579A4 rather than being a Mercury-branded part.

How do I know if the 18-3319 will fit my Mercury outboard? Because water pump components are fit specific, confirm the part number on your existing pump assembly matches Mercury Marine 46-42579A4 before ordering the 18-3319 kit.

Does the 18-3319 kit come with an impeller? The listed included components for the 18-3319 kit are the water pump base (18-3419) and the upper and lower housings; an impeller is not listed among the included components.

What is the UPC for the Sierra 18-3319 Water Pump Kit? The UPC for this Sierra 18-3319 kit is 030999315816.

Can the Sierra 18-3319 be used to replace a full water pump assembly rather than just the impeller? Yes, the 18-3319 is a kit that includes the pump base and upper and lower housings, making it suited to a fuller water pump rebuild rather than an impeller-only replacement.

What is the manufacturer part number for this water pump kit? The manufacturer part number is 18-3319, sold under the Sierra brand.

Why does fit matter so much when ordering a water pump kit like the 18-3319? Water pump components vary by engine and housing design, so the 18-3319 is fit specific; checking that its cross-reference number, Mercury Marine 46-42579A4, matches your current part is the way to ensure proper fit.