GHmarine water pump impeller repair kit for Mercury outboard, 2 Stroke 4-9.8 HP, full seal and hardware kit

GHmarine 70941A3 is a complete water pump impeller repair kit engineered to replace the worn impeller and related components on Mercury/Mariner/Force 4–9.8 HP outboards.

If your small outboard is losing cooling flow, smoking, or running hot, a damaged impeller or degraded seal in the lower unit is a common cause. The GHmarine 70941A3 kit contains the impeller and all the associated components needed to restore proper raw-water circulation on many Mercury Marine 1975–1986 4hp through 9.8hp engines. It’s sold as a direct-fit aftermarket replacement for Mercury part number 46-70941A3 and Sierra 18-3446, and includes the pieces mechanics typically replace during a pump rebuild.

Which engines and years does this kit fit?

This repair kit is intended for older Mercury/Mariner/Force outboard models spanning small horsepower ranges. It matches the OEM geometry and mounting pattern used on many vintage lower units, so it fits units where the original parts list cites 46-70941A3 or Sierra 18-3446.

• Compatible with Mercury Marine 4hp, 4.5hp, 7.5hp, and 9.8hp outboards
• Covers model years approximately 1975–1986
• Designed as a replacement for Mercury 46-70941A3 and Sierra 18-3446
• Good for Mariner and Force-branded variants sharing the same pump layout

What parts are included and why they matter?

The kit provides a full set of pump components typically replaced during a routine impeller service. Replacing the impeller alone can help, but renewing plates, seals, and hardware restores proper clearances and reduces the chance of repeat failure.

• Rubber impeller — the impeller blades move coolant through the engine
• Impeller plate and housing assembly — maintains correct pump clearance
• Seal and cover assembly — prevents leaks and keeps pressure steady
• Key and mounting hardware — secures the impeller to the shaft for correct timing

How do I know if my water pump needs this kit?

Signs of a failing pump include reduced cooling flow at the telltale, engine overheating, or visible damage to the old impeller during inspection. Routine maintenance intervals on older outboards often call for inspecting and replacing the impeller every season or every 100 hours, whichever comes first.

• Low or no telltale stream at idle indicates worn impeller blades
• Engine running hotter than normal under load suggests reduced coolant flow
• Visible cracks, missing blades, or hardened rubber on the removed impeller confirm replacement is needed
• Replace other pump components when performing impeller service to ensure longevity

How easy is installation and what should I prepare?

Installation requires basic mechanical skills and common tools. It’s a straightforward job for anyone comfortable removing the lower unit and handling shaft alignment, but a service manual or step-by-step guide is helpful for torque specs and proper reassembly.

• Lower unit removal and pump cover disassembly are necessary steps
• Lubricate the new impeller and align the key on the driveshaft as directed
• Replace gaskets and seals to avoid leaks; torque fasteners to manufacturer specs
• If unsure, consult a qualified marine mechanic for correct installation

Who this is for: The GHmarine 70941A3 kit is aimed at boat owners, marina technicians, and DIY mechanics who maintain older Mercury, Mariner, or Force outboards in the 4–9.8 HP range. It’s ideal for those restoring vintage small engines, performing seasonal maintenance, or replacing a failed pump with a direct-fit aftermarket alternative to Mercury 46-70941A3 and Sierra 18-3446. If you’re uncertain about compatibility with your specific model year or numbering, contact the seller with your engine serial number for precise fitment guidance.