Water Pump Impeller Kit – Fits Yamaha 2-Stroke 25-30HP, Mercury/Mariner 20-30HP (Replaces 689-W0078-A6-00)

$29.00

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You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Water Pump Impeller Kit provides all necessary components for servicing the water pump on Yamaha 2-stroke 25HP and 30HP outboard models (including CV25, C25, C30, CV30) and select Mercury/Mariner 20HP to 30HP motors. It is engineered as a direct-fit replacement to restore cooling system performance and prevent engine overheating.

This kit serves as a direct interchange for Yamaha part numbers 689-W0078-A6-00, 689-W0078-06-00, 689-W0078-05-00, and 689-W0078-04-00, as well as Mercury/Mariner equivalents including 47-42431M, 47-84829M, 47-97793M, and others.

Designed for direct, hassle-free installation.
Includes all essential gaskets, seals, and hardware for a complete service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Yamaha	689-W0078-A6-00
Yamaha	689-W0078-06-00
Yamaha	689-W0078-05-00
Yamaha	689-W0078-04-00
Mercury/Mariner	47-42431M / 47-84829M / 47-97793M / 47-97793T / 47-81242M / 47-95661M

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Fits select Yamaha 2-stroke 25HP and 30HP outboards.

Also compatible with certain Mercury/Mariner 2-stroke outboards originally manufactured by Yamaha.

Brand	Model	Rated HP	Stroke	OEM Part No.
Yamaha	CV25, C25	25	2-Stroke	689-W0078-A6-00
Yamaha	CV30, C30	30	2-Stroke	689-W0078-A6-00
Mercury/Mariner	20C	20	2-Stroke	47-42431M, 47-84829M, 47-97793M, 47-97793T, 47-81242M, 47-95661M
Mercury/Mariner	25C	25	2-Stroke	47-42431M, 47-84829M, 47-97793M, 47-97793T, 47-81242M, 47-95661M
Mercury/Mariner	28	28	2-Stroke	47-42431M, 47-84829M, 47-97793M, 47-97793T, 47-81242M, 47-95661M
Mercury/Mariner	30A	30	2-Stroke	47-42431M, 47-84829M, 47-97793M, 47-97793T, 47-81242M, 47-95661M

Technical Specs

Product Type: Water Pump Impeller Kit
Installation: Direct replacement
Kit Type: Complete water pump service kit
Weight: 275 g (9.7 oz)

What’s in the Box

1 x Water Seal Damper (626-44365-01-00)
1 x Woodruff Key (664-44338-00-00)
1 x Water Pump Housing (689-44311-03-00)
1 x Water Pump Gasket (689-44316-A0-00)
1 x Cartridge Outer Plate (689-44323-03-00)
1 x Cartridge Gasket (689-44324-A0-00)
1 x Impeller (689-44352-02-00)
1 x Cartridge Insert (689-W4432-02-00)
3 x Bolts, With Washers (90119-06M07-00)

Installation Notes

Disconnect the battery and ignition coil leads for safety.
Place a drain pan under the lower unit and remove the gearcase oil drain screw to empty the oil.
Remove the bolts securing the lower unit (gearcase) to the engine housing and carefully lower it.
Unbolt and remove the old water pump housing to access the impeller and other components.
Clean all mating surfaces, removing any old gasket material or sealant residue.
Install the new components from the kit in the reverse order of removal, ensuring the new impeller vanes are oriented correctly.
Re-install the water pump housing, torquing bolts to the manufacturer's specification.
Re-attach the lower unit, refill the gearcase with fresh oil, and start the engine to test for proper water flow from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?

This kit is for specific Yamaha (CV25, C25, C30, CV30) and Mercury/Mariner (20C, 25C, 28, 30A) 2-stroke models. The best way to ensure fitment is to match your engine's original part number to the cross-references in our Part Number Matrix. Always compare the parts in our photos to your old ones before installing.

What are signs of a failing water pump impeller?

Common symptoms include the engine overheating at idle or low speeds, a weak or intermittent water stream from the "tell-tale" pisser outlet, or a high-pitched whining sound from the pump area. Upon inspection, a worn impeller may be brittle, cracked, or have missing vanes.

How often should the water pump be serviced?

For preventative maintenance, most manufacturers recommend inspecting the impeller annually and replacing the entire water pump kit every 1-2 years or 100-200 hours of use. Service intervals should be shorter in saltwater or silty/sandy conditions.

Is this an OEM part?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for consistency and quality.

How fast is shipping?

We ship worldwide quickly—typical transit time is 5–15 days for most locations. Standard shipping is free, with expedited options available at checkout where applicable.

What is the warranty and return policy?

This part is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, contact our support team with your order details. Returns are accepted within our standard window provided the item is unused and in its original condition. Please see our policy page or contact us for instructions.

Safety & Important Info

Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement component, not an original equipment manufacturer (OEM) part.
Professional installation is recommended for safety and optimal performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions, typically arriving in 5–15 days.
Manufacturer-Direct Value — Fair pricing on quality components without compromising on materials or quality control.

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