QUICKMARINER Outboard Water Pump Impeller Rebuild Kit Mercury 4-9.8 HP with Housing, Complete Seal and Plate

QUICKMARINER 70941A3 is a complete water pump impeller rebuild kit designed to restore cooling flow for Mercury and Mariner 4–9.8 HP outboards with a 0.456-inch impeller insert.

If your small outboard is running hotter than usual or shows signs of reduced water flow, this kit supplies the parts needed to rebuild the lower unit water pump. It replaces OEM and aftermarket references such as Mercury Marine 46-70941A3 and Sierra 18-3446, and fits select 1975–1986 Mercury/Mariner 4, 4.5, 6, 7.5 and 9.8 HP models. The package includes the impeller, plate, seal, cover, housing, and key to get the pump back to factory-style operation.

How do I know this kit fits my outboard?

Compatibility hinges on the impeller insert size and the lower unit model range. This QUICKMARINER kit specifically fits pumps that accept an impeller insert measuring 0.456 inches and aligns with Mercury/Mariner lower units produced between 1975 and 1986.

• Checks: confirm your motor model and year against Mercury/Mariner 4–9.8 HP lists.
• Measure: verify the impeller insert diameter is 0.456 inches.
• Cross-reference: compatible with Mercury 46-70941A3 and Sierra 18-3446 replacements.

What parts come inside the QUICKMARINER 70941A3 kit?

This kit provides all core components required to rebuild the water pump section of the lower gearcase, so you won’t need separate small parts or seals for a standard rebuild. Parts are matched to fit together and restore pump clearance and function.

• Flexible rubber water pump impeller sized for the 0.456-inch insert.
• Impeller plate and pump cover seal to re-establish a water-tight housing.
• Complete cover assembly, housing assembly and drive key for correct installation.

How will installing this kit affect engine performance?

Replacing worn impeller components restores designed coolant flow through the engine, which helps maintain consistent operating temperature and prevents cavitation-related loss of pressure. While it doesn’t change horsepower, it protects engine components from overheating and long-term damage.

• Restores steady water circulation to the cooling jacket.
• Reduces risk of overheating or heat-related wear.
• Improves reliability for regular boating and seasonal storage starts.

What should I prepare before installing the kit?

Basic mechanical tools and a clean workspace are needed, plus knowledge of lower unit removal and reassembly or access to a repair manual. Inspect the driveshaft and housing for scoring or corrosion before fitting new parts.

• Have a service manual or step guide specific to your motor handy.
• Gather common tools: socket set, screwdrivers, seal puller, torque wrench.
• Clean the lower unit interior and inspect for metal debris or excessive wear.

Who is this for: The QUICKMARINER 70941A3 kit is aimed at DIY boat owners, marine mechanics, and service shops working on Mercury and Mariner small outboards from 1975–1986. It’s ideal for anyone needing a full water pump rebuild where the impeller insert measures 0.456 inches and who wants a cost-effective, ready-to-install parts solution that mirrors OEM replacements.