Sierra 18-4547 Marine Water Pump Insert Cup

The Sierra 18-4547 is a marine water pump insert cup designed as a precision aftermarket replacement for outboard engine cooling systems. This component seats inside the water pump housing to form the critical interface that channels cooling water flow through the impeller assembly, helping maintain proper engine operating temperature.

Key Features:

• Engineered to meet or exceed original equipment manufacturer (OEM) specifications for fit, form, and function
• Manufactured from marine-grade materials engineered to resist corrosion and deterioration in harsh saltwater and freshwater environments
• Direct OEM replacement — installs without modification using original hardware
• Backed by Sierra's limited lifetime warranty covering defects in materials and workmanship
• Part of Sierra's comprehensive water pump component line, compatible with select Johnson/Evinrude outboard applications

Sierra is the marine aftermarket industry's leading supplier of replacement engine parts, covering over 6,000 marine components across all major engine brands. The 18-4547 insert cup is typically serviced as part of a complete water pump rebuild — replacing the insert cup along with the impeller, housing, and seals helps restore full cooling system performance and extend engine life.