Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02)
Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02)
Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02) provides the essential components to restore your engine's cooling system. It is engineered for a wide range of Yamaha 2-stroke engines from 25 HP to 70 HP (1984–1995) and select 4-stroke models, ensuring reliable performance and engine protection.
This kit serves as a direct interchange for multiple OEM and aftermarket part numbers, including Yamaha 663-44311-02-00, 663-W0078-A0-00, and 6H4-W0078-A0-00; Sierra 18-3408; and Mercury/Mariner 46-81416T.
- Designed as a drop-in replacement for straightforward installation.
- Includes a new impeller, gaskets, plates, and hardware for a complete service.
- Components are manufactured in an ISO9002 certified facility to ensure quality and fitment.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 663-44311-00 |
| Yamaha | 663-44311-02 |
| Yamaha | 663-44311-02-00 |
| Yamaha | 663W0078A000 |
| Yamaha | 6H4-W0078-A0-00 |
| Yamaha | 6H4W0078A000 |
| Yamaha | 6J8-44311-00 |
| Yamaha | 6J84431100 |
| Sierra | 18-3408 |
| Mercury/Mariner | 46-81416T |
| Aftermarket | AM663-44311-02 |
| Aftermarket | MAL9-43255 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit fits a variety of Yamaha 2-stroke and 4-stroke outboard engines. Please verify your specific model and year, as fitment can vary. Note that models designated with a "6H4" code have specific compatibility.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 25B/BETO | 25 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 40N/H/E | 40 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 40 | 40 | 2-Stroke | 1984–1994 | 6H4-W0078-00 | 6H4 code models |
| Yamaha | 48 | 48 | 2-Stroke | 1995–2000 | 6H4-W0078-00 | 6H4 code models |
| Yamaha | 50G/GEO/GETO | 50 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 50D | 50 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 50 | 50 | 2-Stroke | 1984–1994 | 6H4-W0078-00 | 6H4 code models |
| Yamaha | 55B/BET | 55 | 2-Stroke | 663-44311-02 | ||
| Yamaha | E55CMH | 55 | 2-Stroke | 663-44311-02 | ||
| Yamaha | C55 | 55 | 2-Stroke | 1990–1995 | 663-W0078-A0, 670-W0078-A0 | |
| Yamaha | CV55 | 55 | 2-Stroke | 1989 | 663-W0078-A0 | |
| Yamaha | 55 | 55 | 2-Stroke | 1989–1995 | 6H4-W0078-00 | 6H4 code models |
| Yamaha | 60FEO/FETO/FEDO | 60 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 60BE/BEM/BET | 60 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 70CE | 70 | 2-Stroke | 663-44311-02 | ||
| Yamaha | 55C | 55 | 4-Stroke | 1990 | 663-44311-02 | |
| Yamaha | 60C | 60 | 4-Stroke | 663-44311-02 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Drop-in replacement
- Other Technical Attributes
- ISO9002 certified manufacturing
What’s in the Box
- 1 x Water Pump Gasket (663-44315-A0-00)
- 1 x Cartridge Insert (663-44322-00-00)
- 1 x Cartridge Outer Plate (663-44323-00-00)
- 1 x Cartridge Gasket (663-44324-A0-00)
- 1 x Water Seal Damper 2 (663-44366-00-00)
- 1 x Impeller (6H3-44352-00-00)
- 1 x Woodruff Key (90280-03024-00)
- 2 x Bolts (97095-08045-00)
- 2 x Bolts (97095-08055-00)
Installation Notes
- Disconnect the battery and shift the outboard into neutral.
- Remove the lower unit (gearcase) by unbolting it from the engine's midsection. You may need to disconnect a speedometer tube.
- Place the lower unit on a workbench and remove the bolts securing the water pump housing cover.
- Slide the housing off the driveshaft, exposing the old impeller. Remove the old impeller and woodruff key.
- Clean any debris or gasket residue from the housing, base plate, and driveshaft. Inspect components for scoring or warping.
- Install the new woodruff key, then slide the new impeller onto the driveshaft, rotating clockwise to bed the vanes.
- Install the new gaskets, plates, and housing components as included in the kit.
- Lightly grease the housing interior and re-install it over the impeller. Tighten the bolts to the manufacturer's specified torque.
- Re-install the lower unit, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure all bolts.
- Reconnect the battery and test the engine using a water source (flushing muffs or in water). Confirm a steady stream from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if my water pump needs to be replaced?
The most common sign of a failing water pump is a weak or absent water stream from the engine's tell-tale (peephole) outlet. Other indicators include engine overheating alarms, steam from the exhaust, or a prematurely worn impeller found during routine maintenance. For preventative care, it is recommended to replace the impeller annually or every 100 hours of use.
Why are there two different sizes of bolts included in the kit?
The inclusion of two sets of bolts (97095-08045-00 and 97095-08055-00) accommodates slight variations in water pump housing designs across the wide range of compatible engine years and models. Simply match the new bolts to the size of your original hardware and discard the unused set.
My Yamaha model is listed, but the year range is missing. Will this kit fit?
If your engine model is listed but the year is not specified, this kit is likely a match. However, to guarantee fitment, always compare your original part numbers to those in the Part Number Matrix or check photos against your existing parts before ordering. Yamaha often uses the same core components across many years.
Is this a complete kit, or do I need other parts?
This is a comprehensive repair kit containing the impeller, housing insert, outer plate, gaskets, key, and mounting bolts. It includes all the typical wear items needed for a standard water pump service. You should not need any other parts unless your existing housing is cracked or severely corroded.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and 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 in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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