Sierra Water Pump Kit with Housing 18-3408, Replaces 6H4-W0078-00-A0, for Yamaha 40/50/Pro50 HP Outboards (1984-1987)

The Sierra 18-3408 is a complete water pump kit with housing, engineered as a direct replacement for the factory water pump assembly on select Yamaha outboard engines. The kit is built around a new water pump housing along with the mounting hardware needed to complete the water pump service, so the cooling system component that fails most often on these outboards can be replaced without sourcing individual pieces separately. Sierra assembles its water pump kits to meet or exceed original equipment specifications, giving boaters a dependable way to restore proper raw-water cooling flow to the engine.

This kit is designed to fit Yamaha 40 HP (1984-1987), 50 HP (1984-1987), and Pro50 (1987) outboard engines. It replaces the OEM Yamaha water pump components identified below, and the housing itself is a metal construction for durability in the marine cooling system environment. Regular water pump service is a key part of outboard maintenance, and using a housing kit matched to the correct OEM part numbers helps ensure proper fit and sealing against the powerhead.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3408
• Product Type: Water Pump Kit with Housing
• Includes Housing: Yes
• Material: Metal
• Weight: 0.89 pounds
• UPC: 808282286989
• Fitment: Yamaha 40 HP (1984-1987), 50 HP (1984-1987), Pro50 (1987) outboards
• OEM Cross Reference: 6H4-W0078-00-A0, 663-44311-02
• Kit Contents: Water Pump Housing (O.E. 6J8-44311-00-00), Bolt (O.E. 97095-08045-00)

Fitment

• Yamaha 40 HP outboard, 1984-1987
• Yamaha 50 HP outboard, 1984-1987
• Yamaha Pro50 outboard, 1987

Replaces (OEM)

• 6H4-W0078-00-A0
• 663-44311-02

Frequently Asked Questions

What does the Sierra 18-3408 water pump kit include? The kit includes a water pump housing (O.E. Equivalent 6J8-44311-00-00) and a mounting bolt (O.E. Equivalent 97095-08045-00). It is sold as the 18-3408 water pump kit with housing.

Does the 18-3408 kit include the pump housing? Yes, the Sierra 18-3408 is a water pump kit that comes with the housing included, not just internal service parts.

Which Yamaha outboard motors fit the Sierra 18-3408 water pump kit? It fits Yamaha 40 HP (1984-1987), 50 HP (1984-1987), and Pro50 (1987) outboard engines.

What OEM Yamaha part numbers does the 18-3408 kit cross-reference to? The 18-3408 replaces Yamaha OEM numbers 6H4-W0078-00-A0 and 663-44311-02.

How much does the Sierra 18-3408 water pump kit weigh? The Sierra 18-3408 water pump kit weighs 0.89 pounds.

What material is the water pump housing made of? The housing in the 18-3408 kit is constructed of metal.

Is the Sierra 18-3408 a genuine replacement for factory Yamaha parts? The 18-3408 is a Sierra-manufactured replacement built to match the fit and function of the original Yamaha water pump housing and hardware it replaces, rather than a Yamaha-branded part.

Does the 18-3408 kit include mounting bolts? Yes, a bolt (O.E. Equivalent 97095-08045-00) is included with the Sierra 18-3408 water pump housing kit.

Will the 18-3408 fit a Yamaha Pro50 outboard? Yes, the Sierra 18-3408 water pump kit is listed for the Yamaha Pro50 (1987) outboard engine.

What years of Yamaha 40 HP and 50 HP outboards does this kit fit? The 18-3408 fits Yamaha 40 HP and 50 HP outboards from 1984 through 1987.

Where is the Sierra 18-3408 water pump kit assembled? Sierra water pump kits, including the 18-3408, are assembled at Sierra's Illinois factory.

What is the UPC for the Sierra 18-3408 water pump kit? The UPC for the Sierra 18-3408 water pump kit is 808282286989.