SeaSierra Outboard Water Pump Kit for Mercury 30–60 HP — Complete Rebuild Kit with Impeller & Seals

The SeaSierra 812966A12 outboard water pump kit is a complete replacement kit designed to rebuild the cooling pump assembly on Mercury 4-stroke 30–60 HP engines.

When your Mercury outboard shows signs of reduced cooling flow or the impeller is worn, replacing the water pump components with a full kit restores reliable circulation through the lower unit. This SeaSierra kit matches OEM and common aftermarket part numbers so you get the parts needed to service the gearcase cooling system without hunting for individual pieces.

What parts are included and why are they important?

The kit supplies every primary wear item required to rebuild the water pump housing and restore a proper seal and impeller action. Replacing worn seals, the impeller, gaskets, and fasteners together prevents future leaks and avoids repeat labor.

• Housing 14334A3 and water pump base assembly 812966A7 for structural replacement
• Impeller 19453T and guide tube 893857 to renew water flow and fit
• O-ring 805726, seals 830749, and gaskets (19701, 822189) to stop leaks
• Key 19699, faceplate 19700A2, washers and other hardware for reassembly

Which Mercury outboards is this kit compatible with?

This SeaSierra kit is built for Mercury Marine 4-stroke outboards in the 30, 35, 40, 50 and 60 horsepower range. It cross-references a range of OEM numbers and commonly used aftermarket SKUs, making it suitable for most service needs on those models.

• Compatible horsepower: 30HP, 35HP, 40HP, 50HP, 60HP 4-stroke Mercury outboards
• Replaces OEM part numbers including 46-812966A12 and related variants
• Matches aftermarket references such as Sierra 18-3690 and GLM 12124

How does installing the full kit help compared with replacing only the impeller?

Replacing only the impeller can lead to premature failure if adjacent seals or the housing are compromised. A complete kit ensures mating surfaces, fasteners, and seals are renewed so the repaired pump functions like a properly serviced unit and reduces the chance of follow-up repairs.

• Ensures damaged housings or guide tubes are addressed alongside the impeller
• Prevents leaks by replacing gaskets, O-rings and the shaft seal simultaneously
• Includes hardware and faceplate so no missing parts delay reassembly

What should I prepare for installation and routine inspection?

Gather basic marine tools, a clean workspace, and marine-grade grease or approved lubrication as specified by Mercury. Inspect the driveshaft, keyway, and pump bore for scoring before installing new components to ensure proper seating and longevity.

• Tools: socket set, screwdrivers, seal puller, torque wrench for correct fastener tightening
• Check the lower unit bore, guide tube fit, and key alignment during assembly
• Plan for a brief sea trial after installation to verify steady water flow from the telltale

Who is this for: The SeaSierra 812966A12 pump kit is intended for boat owners, DIY mechanics, and marine technicians who service Mercury 4-stroke outboards from 30 to 60 HP. If you need a complete, cross-referenced replacement set that includes housings, seals, impeller and all necessary hardware to restore your lower unit cooling system, this kit provides the parts required to perform a thorough rebuild and get the engine circulating coolant reliably again.