Water Pump Impeller Kit – Fits Yamaha, Mercury/Mariner 20-30 HP (Replaces 689-W0078-A6)
Water Pump Impeller Kit – Fits Yamaha, Mercury/Mariner 20-30 HP (Replaces 689-W0078-A6) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Impeller Kit – Fits Yamaha, Mercury/Mariner 20-30 HP (Re...
Water Pump Impeller Kit – Fits Yamaha, Mercury/Mariner 20-30 HP (Replaces 689-W0078-A6) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha 20/25/30 HP (Replaces 689-W0078-A6) provides the essential components to service the cooling system on a range of outboard motors. It is designed for select Yamaha 2-stroke (1985–2001) and 4-stroke (1986–1997) models, as well as various Mercury/Mariner 2-stroke engines from 1984–1998. Proper installation restores cooling efficiency and helps prevent engine overheating.
This kit is a direct aftermarket replacement and interchanges with numerous OEM and other aftermarket part numbers, including Yamaha 689-W0078-A6-00, Sierra 18-3427, and GLM 12059.
- Engineered as a direct replacement for a straightforward installation.
- Manufactured in an ISO 9002 certified facility to meet or exceed OEM specifications.
- Designed for use in gasoline-fueled marine engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Yamaha | 689-W0078-A6-00 |
| Yamaha | 689-W0078-06-00 |
| Yamaha | 689-W0078-05-00 |
| Yamaha | 689-W0078-A4-00 |
| Yamaha | 689-W0078-04-00 |
| Yamaha | 689-W0078-A3-00 |
| Yamaha | 662-44352-01-00 |
| Sierra | 18-3063 |
| Sierra | 18-3427 |
| Sierra | 18-3426 |
| GLM | 12059 |
| GLM | 12058 |
| Mercury | 47-42431M |
| Mercury | 47-81242M |
| Mercury | 47-95611M |
| Mercury | 47-95661M / 47-95661T |
| Mercury | 47-97793M / 47-97793T |
Engine & Model Compatibility
Confirm your engine model and year in the tables below. Verify against the OEM part number for your specific engine before ordering.
Yamaha Compatibility
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | 20C | 20 | 2-Stroke | 1985–2002 | 689-W0078-A6 |
| Yamaha | 25D | 25 | 2-Stroke | 1985–2001 | 689-W0078-A6 |
| Yamaha | 30A | 30 | 2-Stroke | 1985–1992 | 689-W0078-A6 |
| Yamaha | 25 HP | 25 | 4-Stroke | 1986–1987 | 689-W0078-A6 |
| Yamaha | C25 HP | 25 | 4-Stroke | 1991–1997 | 689-W0078-A6 |
| Yamaha | CV25 HP | 25 | 4-Stroke | 1990 | 689-W0078-A6 |
| Yamaha | 30 HP | 30 | 4-Stroke | 1986 | 689-W0078-A6 |
| Yamaha | C30 HP | 30 | 4-Stroke | 1991–1992 | 689-W0078-A6 |
| Yamaha | CV30 HP | 30 | 4-Stroke | 1989–1990 | 689-W0078-A6 |
Mercury/Mariner Compatibility
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 20C | 20 | 2-Stroke | 1984–1998 | 47-42431M | With Thru-Prop Exhaust |
| Mercury | 25C | 25 | 2-Stroke | 1984–1998 | 47-81242M | With Thru-Prop Exhaust |
| Mercury | 28 | 28 | 2-Stroke | 1984–1998 | 47-95611M | |
| Mercury | 30A | 30 | 2-Stroke | 1984–1998 | 47-95661M/47-95661T |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct Replacement
- Fuel Type
- Gasoline
- Weight
- 9.7 oz (275 g)
- Other Attributes
- Manufactured to OEM specifications; Produced in ISO9002 certified factory
What’s in the Box
Kit contents vary by the specific model selected. Common components include:
- 1 x Impeller (Replaces 662-44352-01-00 / 689-44352-02-00)
- 1 x Impeller Key (Replaces 664-44338-00)
- 1 x Upper Water Tube Seal (Replaces 664-44365-01)
- 1 x Pump Housing (Included in complete housing kits, replaces 689-44311-03)
- 1 x Cartridge Insert (Included in complete housing kits, replaces 689-W4432-01)
- 1 x Outer Plate (Included in complete housing kits, replaces 682-44323-00-00)
- Gaskets, Seals, and Bolts as required by kit model
Installation Notes
Professional installation is recommended. The following are general, non-model-specific steps:
- Disconnect the negative battery terminal and shift the engine to neutral.
- Remove the bolts securing the lower unit (gearcase) to the engine.
- Carefully lower the gearcase, potentially disconnecting a speedometer tube if present.
- Unbolt the water pump housing to access the impeller. Note the rotational direction of the old impeller vanes.
- Remove all old impeller parts, gaskets, seals, and wear plates.
- Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
- Install the new components from the kit. Lightly grease the new impeller and insert it while turning the driveshaft in its normal rotational direction.
- Secure the new housing, ensuring bolts are torqued to manufacturer specifications.
- Reinstall the lower unit, ensuring the driveshaft, shift shaft, and water tube are correctly aligned.
- Once assembled, start the engine in a water source and confirm a steady stream of water from the tell-tale port.
Troubleshooting & FAQ
What are the signs of a failing water pump impeller?
The most common signs are a weak or inconsistent water stream from the "tell-tale" outlet, an engine overheating alarm, or visible steam from the exhaust. Reduced cooling can cause severe engine damage, so these symptoms should not be ignored.
How often should I replace my water pump impeller?
As a preventative maintenance item, most manufacturers recommend replacing the impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. The interval can be shorter if you operate in sandy, silty, or saltwater environments.
How do I confirm this kit will fit my engine?
Cross-reference your engine's model number and year against the compatibility tables on this page. For the most accurate fitment, match the OEM part number from your engine's service manual to the numbers listed in our Part Number Matrix.
What is the difference between the basic and complete housing kits?
The contents depend on the kit model chosen. Basic kits typically include the impeller, key, and gaskets. Complete kits also include the metal housing, cartridge insert, and wear plate, which should be replaced if the old ones are scored, warped, or corroded.
Is this an OEM part?
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component. It has been engineered to meet or exceed OEM specifications for fit, form, and function and is produced in an ISO 9002 certified facility to ensure quality and consistency.
What are your shipping speed and cost?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most regions, with expedited options available at checkout where applicable.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition. See our full policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not install the part.
- This is an aftermarket replacement component, not an OEM part. Brand names and part numbers are used for reference purposes only.
- Professional installation is highly recommended for safety and to ensure proper performance. Incorrect installation can lead to engine damage.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world durability and performance.
- Fast Global Fulfillment — With partners across the globe, we offer free standard delivery to most regions with an average transit time of 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we offer fair pricing without compromising on materials, quality control, or performance.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
