Sierra 18-3398 Water Pump Kit with Housing, Replaces Yamaha 6F5-W0078-A0-00, for Yamaha Outboard Motors

The Sierra 18-3398 Water Pump Kit with Housing is a complete outboard water pump rebuild kit designed for Yamaha outboard motors. Unlike a standard impeller-only kit, this version includes the water pump housing itself, giving you everything needed to fully renew the cooling system's pump assembly in one purchase rather than sourcing the housing separately. The kit is built around a Sierra impeller along with the gaskets, seal, wear plate, bolts, washers, and insert cup required for a complete, correct reinstallation.

Inside the kit you will find the impeller, an impeller key, the water pump housing, a water seal damper, three water pump gaskets, a wear plate, mounting bolts with bolt washers, and an insert cup. This gives an installer every wear component in the water pump assembly at once, which reduces the chance of a repeat failure from reusing an old gasket or worn wear plate after replacing only the impeller. The kit is manufactured by Sierra to meet or exceed the specifications of the original equipment components it replaces, and it is backed by Sierra's standard customer satisfaction warranty.

This kit is intended for Yamaha outboard applications and directly replaces the OEM water pump kit part numbers listed below. Because it includes the housing, it is the correct choice when the housing is worn, cracked, or otherwise in need of replacement in addition to the impeller and gasket set.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3398
• Product Type: Water Pump Kit with Housing
• Compatible Engine Brand: Yamaha Outboard
• Weight: 0.91 pounds
• Includes Housing: Yes
• Kit Contents: Impeller, Impeller Key, Water Pump Housing, Water Seal Damper, 3 Water Pump Gaskets, Wear Plate, Bolts, Bolt Washers, Insert Cup
• OEM Cross Reference: 6F5-W0078-A0-00, 6F5-W0078-00-00

Fitment

Designed for Yamaha outboard motors.

Replaces (OEM)

• 6F5-W0078-A0-00
• 6F5-W0078-00-00

Frequently Asked Questions

What does the Sierra 18-3398 water pump kit include? The Sierra 18-3398 kit includes an impeller, impeller key, water pump housing, water seal damper, three water pump gaskets, a wear plate, bolts, bolt washers, and an insert cup, giving a complete water pump assembly for Yamaha outboard motors.

Does the 18-3398 kit come with the water pump housing? Yes, the 18-3398 kit includes the water pump housing, which distinguishes it from housing-less water pump kits that only cover the impeller and gasket set.

What OEM Yamaha part numbers does the 18-3398 replace? This kit replaces Yamaha OEM numbers 6F5-W0078-A0-00 and 6F5-W0078-00-00.

How much does the Sierra 18-3398 water pump kit weigh? The 18-3398 water pump kit weighs 0.91 pounds.

Is the Sierra 18-3398 an aftermarket or genuine Yamaha part? The 18-3398 is a Sierra-manufactured aftermarket kit engineered to meet or exceed the specifications of the original Yamaha equipment it replaces, not a genuine Yamaha part.

Will the 18-3398 kit fit any Yamaha outboard? The 18-3398 is designed for Yamaha outboard motors that use the 6F5-W0078-A0-00 or 6F5-W0078-00-00 water pump kit, so confirm your engine calls for one of those OEM numbers before ordering.

What is the difference between the 18-3398 and 18-3397 kits? The Sierra 18-3398 includes the water pump housing, while the related 18-3397 kit does not include the housing.

Does the kit include the gaskets needed for installation? Yes, the 18-3398 kit includes three water pump gaskets along with the wear plate and other hardware needed to reseal the pump assembly.

Is Sierra 18-3398 covered by a warranty? Yes, the Sierra 18-3398 water pump kit is covered under Sierra's standard customer satisfaction warranty.

When should I replace the water pump housing along with the impeller? If the housing is cracked, corroded, or worn, the 18-3398 kit is the right choice since it includes a replacement housing along with the impeller and gasket set, unlike impeller-only kits.

What is the impeller key used for in this kit? The impeller key included in the 18-3398 kit secures the impeller to the water pump drive shaft so it rotates properly to circulate cooling water.