Mercury – Water Pump Kit | Cooling System | 46-42579A07

Overview

This kit restores the heart of the cooling system—something you really notice after a few seasons of sand, silt, and shallow-water runs. When the impeller starts wearing down, the engine can run hotter than it should, especially during long idle periods or slow trolling. Swapping the whole kit gives the motor a fresh, steady flow of water again. It’s a job most boaters take on themselves, and this kit has what you need to get the pump back to full strength.

Key Features

  • Complete Pump Assembly – Provides all core components needed for a full rebuild.
  • High-Quality Impeller – Delivers consistent water movement for stable engine temps.
  • Durable Housing Components – Holds up to sand, heat, and debris over repeated runs.
  • OEM-Spec Seals – Maintains proper sealing to prevent pressure loss.

Engine & Boat Compatibility

  • Mercury outboard cooling systems
  • Multi-cylinder platforms
  • Standard mechanical cooling layouts
  • Classic Mercury service series

Performance & Practical Benefits

A fresh pump usually brings the engine temps back to a more relaxed, predictable range. You’ll feel more confident running shallow water or long no-wake zones since the motor won’t drift toward overheating. Throttle transitions feel steadier because the cooling flow keeps the block from heat-soaking. Overall, it brings back that clean, dependable feel you expect from a healthy outboard.

Why Buy OEM

OEM pump kits match Mercury’s clearances and flow design, which helps the motor hold stable temperature across all speeds. The materials resist swelling and wear better than budget parts, so the system stays consistent from one season to the next. It’s a straightforward way to avoid cooling problems that can sneak up later.

FAQ

1. How can I tell the water pump is getting weak?
Reduced tell-tale flow, higher running temps, or steam at idle are common signs.

2. Do I need any calibration after installing this kit?
No, once the pump is rebuilt, the system operates normally without adjustments.

3. How does this kit handle sandy or silty water?
The impeller and housing materials are built for typical wear, but regular inspections help in gritty environments.

4. Any installation tips?
Take note of the impeller’s vane direction and lightly lube the new one before sliding it into the housing.

5. What happens when the pump starts failing?
The engine may run hotter, lose water pressure, or show weak tell-tale flow.

• Supersessions
  46-8M0077148, 46-8M0077148