UANOFCN Outboard Water Pump Impeller Kit for Mercury 30–70 HP — 77177A3 Complete Rebuild Kit, Impeller + Gaskets

The UANOFCN 77177A3 is a complete outboard water pump impeller kit engineered to restore cooling flow on Mercury 2‑cycle 30–70 HP engines quickly and affordably.

If your Mercury outboard is running hot or showing reduced cooling circulation, the problem is often a worn or damaged impeller and related pump components. This kit supplies the impeller and all the mating parts you need to rebuild the water pump assembly for a range of Mercury 2‑cycle engines, matching OEM cross‑references so you can repair with confidence without buying individual parts.

Which Mercury engines and part numbers does this kit match?

The UANOFCN 77177A3 kit is made for Mercury Marine 2‑cycle outboards in the 30–70 HP range, including JET and standard models used across several years. It replaces several OEM and aftermarket part numbers, making it a direct fit for common service needs.

• Compatible with Mercury 30, 35, 40, 45, 50, 60, 65 and 70 HP 2‑cycle outboard models (including 30 JET).
• Direct replacement for Mercury 46‑77177A3 and aftermarket numbers such as Sierra 18‑3324, Mallory 9‑48312, GLM 12100.
• Requires the 26‑38452 seal and 26‑38453 washer kit to complete installation (sold separately).

What components are included and why each matters?

This kit bundles the impeller and the pump hardware that commonly fail together, so you can perform a reliable rebuild instead of piecemeal repairs. Each part restores the pump’s sealing, alignment, and the impeller’s ability to move cooling water effectively.

• Water pump impeller and impeller plate — core moving parts for coolant displacement.
• Impeller key, housing, base, and multiple gaskets — ensure correct positioning and leak‑free seals.
• Lower and upper pump gaskets, drain screw gasket, rubber washer, O‑ring — prevent external leaks and maintain pressure.

How difficult is installation and what should I prepare?

Installation is a typical moderate DIY marine repair if you have basic hand tools and some mechanical experience; however some models require partial lower unit removal. Prepare to replace the recommended seal and washer kit for a fully reliable rebuild and follow the engine’s service manual torque and alignment specs.

• Tools: standard sockets, torque wrench, pliers, gasket scraper, and marine grease.
• Time: plan 1–3 hours depending on experience and whether the lower unit must be dropped.
• Tip: replace 26‑38452 seal and 26‑38453 washer kit at the same service to avoid repeat disassembly.

Will this kit improve cooling performance and longevity?

Replacing a worn impeller and restoring the pump gaskets renews the water flow that cools the engine, reducing overheating risk caused by degraded components. While results depend on overall engine condition and intake flow, a proper rebuild is a key maintenance step to maintain designed cooling performance.

• Fresh impeller restores pumping efficiency that declines with wear and cracking.
• New gaskets and O‑rings prevent bypass and external leaks that reduce pressure and flow.
• Using correct seal and washer kits prevents basement leaks and extends service intervals.

Who is this for: Marine DIYers, small boat owners, and technicians who service Mercury 2‑cycle 30–70 HP outboards and want a complete, cost‑effective pump rebuild kit that matches common OEM cross‑references. Choose this kit when you need a full set of impeller components in one package and plan to replace the companion seals and washers for a dependable repair.