Mercury – Quicksilver Upper Water Pump Housing | Reinforced Nylon Construction | 803750A05

Overview

A strong, leak-free cooling system starts with quality components. The Mercury Marine 803750A05 Quicksilver Upper Water Pump Housing is built from reinforced nylon to handle heat, pressure, and long hours on the water without warping or cracking. Designed for Mercury and Mariner F8/9.9HP FourStroke BigFoot, F15/20HP FourStroke, and select 9.9HP–18HP TwoStroke outboards, this OEM housing ensures consistent water flow and a reliable seal within your cooling system. It’s the right part to keep your outboard running cool and protected season after season.

Key Features

• Purpose: Serves as the upper section of your engine’s water pump, maintaining proper water flow and system pressure.
• Construction: Made from reinforced nylon, providing strength, heat resistance, and durability in marine conditions.
• Design: Built to maintain a tight seal, ensuring proper cooling performance.
• Performance: Resists wear and deformation caused by heat, vibration, and salt exposure.
• Ease of Use: OEM-quality fit for straightforward installation using standard tools.

Engine & Boat Compatibility

• Mercury/Mariner F8 & F9.9HP FourStroke BigFoot (2005 and newer)
• Mercury/Mariner F15 & F20HP FourStroke (serial number 0R235168 and higher)
• Mercury/Mariner 9.9HP TwoStroke (serial number 0N059858 and higher)
• Mercury/Mariner 15HP & 18HP TwoStroke (serial number 0N001590 and higher)

Performance & Real-World Benefits

The 803750A05 upper water pump housing plays a crucial role in maintaining steady cooling water circulation through your engine. Over time, housings can wear or deform, leading to poor water flow or leaks that compromise cooling efficiency. Replacing it with a genuine Quicksilver housing restores proper water pressure and ensures the pump runs smoothly.

The reinforced nylon construction offers the best mix of strength and flexibility — it’s lightweight, corrosion-resistant, and built to handle marine heat cycles without cracking. With an OEM fit, you can expect a clean installation and long-lasting reliability.

Why Choose Mercury OEM

The Quicksilver 803750A05 is a genuine Mercury Marine component, built to the same standards used in factory assemblies. While aftermarket housings might claim compatibility, they often use cheaper plastics that can warp, causing leaks or uneven water flow.

Mercury’s OEM design is tested under real marine conditions for precision fit, strength, and consistent performance. When it comes to your cooling system, the right fit matters — and this one is built to last.

FAQ

Q1: What’s included in this part?
It includes the upper water pump housing ready for installation.

Q2: Why replace the upper housing?
Cracked or worn housings can cause water leaks or uneven cooling flow, leading to overheating.

Q3: What material is it made from?
It’s constructed from reinforced nylon for strength, durability, and corrosion resistance.

Q4: Is it difficult to install?
No — it’s a direct-fit OEM part that installs easily using basic tools.

Q5: Why go with OEM instead of aftermarket?
OEM components ensure exact fitment, long service life, and dependable performance, something generic parts can’t match.