Sierra Water Pump Repair Kit 18-3470 for Yamaha F225A/F225B/F250A/F250B (4.2L) Outboards

The Sierra 18-3470 is a water pump repair kit engineered for Yamaha 4.2L four-stroke outboard engines. Marine water pumps rely on impellers, plates, and seals to circulate raw water through the cooling system, and these wear components degrade over time from heat, friction, and mineral buildup, eventually leading to overheating or reduced coolant flow. This kit supplies the wear parts needed to service the water pump on covered Yamaha outboards without requiring replacement of the pump housing itself, making it a cost-effective option when the housing is still in serviceable condition.

This is a kit-without-housing configuration, meaning it is intended for pumps where the housing does not need to be replaced. It is designed specifically for the Yamaha F225A/LF225A, F225B/LF225B, F250A/LF250A, and F250B/LF250B outboards equipped with the 4.2L engine, across the model years listed below. Using the correct kit for your specific engine and year range helps ensure proper fit and reliable cooling performance after installation.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3470
• Product Type: Water Pump Repair Kit
• Kit Configuration: Kit without Housing
• Engine Compatibility: Yamaha 4.2L four-stroke outboards
• UPC: 808282374358
• Weight: 1 pound

Fitment

• Yamaha F225A/LF225A (4.2L), 2010-17
• Yamaha F225B/LF225B (4.2L), 2016-17
• Yamaha F250A/LF250A (4.2L), 2014-17
• Yamaha F250B/LF250B (4.2L), 2016-17

Frequently Asked Questions

What engines does the Sierra 18-3470 water pump kit fit? The Sierra 18-3470 fits Yamaha F225A/LF225A (2010-17), F225B/LF225B (2016-17), F250A/LF250A (2014-17), and F250B/LF250B (2016-17) outboards, all with the 4.2L engine.

Does the 18-3470 kit include a new water pump housing? No, the Sierra 18-3470 is a kit-without-housing configuration, meaning it is intended for water pumps where the existing housing is still serviceable and does not need to be replaced.

How much does the 18-3470 water pump kit weigh? The Sierra 18-3470 weighs 1 pound.

What is the UPC for the Sierra 18-3470 water pump kit? The UPC for the Sierra 18-3470 water pump repair kit is 808282374358.

Will the 18-3470 kit work on a 3.3L Yamaha F225 or F250? No. The 18-3470 kit is specific to the 4.2L engine versions of the F225A/B and F250A/B; the 3.3L versions of these Yamaha outboards use a different Sierra kit part number.

Is there a version of this kit that includes the housing? Yes, Sierra offers a corresponding kit-with-housing option for the same 4.2L Yamaha engines, which is a separate part number from the 18-3470 kit-without-housing version.

Is the Sierra 18-3470 a genuine Yamaha part or an aftermarket replacement? The 18-3470 is a Sierra-branded water pump repair kit manufactured for the specified Yamaha 4.2L outboard applications, not an OEM Yamaha part.

What year range does the F225B/LF225B application cover with the 18-3470 kit? For the F225B/LF225B (4.2L), the Sierra 18-3470 kit covers model years 2016-17.

What year range does the F250A/LF250A application cover with the 18-3470 kit? For the F250A/LF250A (4.2L), the Sierra 18-3470 kit covers model years 2014-17.

Why would I choose a kit without housing instead of a full housing kit? A kit-without-housing option like the Sierra 18-3470 is typically chosen when the existing water pump housing is not damaged or worn, allowing you to service only the wear components rather than replacing the entire pump housing assembly.