Mercury – Water Pump Impeller Repair Kit | For 8 & 9.9HP FourStroke BigFoot/Command Thrust | 803748K02

Overview

Your engine’s cooling system is the heart of its reliability, and the Mercury Marine 803748K02 Water Pump Impeller Repair Kit keeps it running perfectly. Designed for Mercury 8HP and 9.9HP FourStroke outboards equipped with BigFoot or Command Thrust gearcases (model year 2005 and newer), this OEM kit includes everything you need to restore proper water flow and cooling performance. It’s an easy, straightforward way to maintain your motor’s health and prevent overheating before it starts.

Key Features

• Purpose: Replaces worn cooling system parts to maintain steady water flow and prevent overheating.
• Complete Kit: Includes impeller, seal, key, gasket, plate, and water guide tube.
• Performance: Ensures proper cooling under all load and temperature conditions.
• Ease of Use: Simple installation with standard tools — direct OEM fit, no modifications needed.

Engine & Boat Compatibility

• Mercury 8HP and 9.9HP FourStroke outboards
• With BigFoot/Command Thrust gearcases
• Model year 2005 and newer

Performance & Real-World Benefits

The 803748K02 impeller repair kit restores your engine’s cooling efficiency by replacing critical water pump components that wear over time. A fresh impeller and gasket set maintain strong water circulation, protecting your outboard from overheating and ensuring consistent performance in all conditions.

This complete OEM kit includes everything needed for a proper repair — no missing parts, no guesswork. It’s built to Mercury’s standards for perfect fitment and durability, so you can service your pump confidently and get back on the water knowing your engine is protected.

Why Choose Mercury OEM

The Mercury 803748K02 is an authentic Mercury Marine kit, designed and tested specifically for Mercury engines. Aftermarket kits may look similar, but small differences in size, materials, or tolerances can reduce performance and cause early failure.

Mercury OEM components are built from premium materials to withstand high temperatures, saltwater exposure, and continuous use. It’s the same quality used by Mercury technicians, ensuring the job gets done right the first time.

FAQ

Q1: What engines does this kit fit?
It fits Mercury 8HP and 9.9HP FourStroke outboards with BigFoot or Command Thrust gearcases, 2005 and newer.

Q2: What’s included in the kit?
The kit comes with a replacement impeller, seal, key, gasket, plate, and water guide tube.

Q3: Why should I replace the impeller?
The impeller wears over time and can’t circulate water efficiently, leading to overheating and reduced engine performance.

Q4: Is this a complete repair kit?
Yes — it contains every key component you need for a proper water pump rebuild.

Q5: Why choose Mercury OEM instead of aftermarket?
Because OEM parts fit exactly, last longer, and are tested to perform in real-world marine conditions — no shortcuts or compromises.