Honda 8–20 HP 4-Stroke Outboard Water Pump Impeller with Key – Replaces 19210-ZW9-A31/A32
Honda 8–20 HP 4-Stroke Outboard Water Pump Impeller with Key – Replaces 19210-ZW9-A31/A32 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Honda 8–20 HP 4-Stroke Outboard Water Pump Impeller with Key – Repl...
Honda 8–20 HP 4-Stroke Outboard Water Pump Impeller with Key – Replaces 19210-ZW9-A31/A32 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller with key is designed for Honda Marine 4-stroke outboards in the 8, 9.9, 15, and 20 HP ranges. According to the applicable fitment information, it is intended for Honda 8 HP and 9.9 HP models from 2001 and newer, and Honda 15 HP and 20 HP models from 2003 and newer.
The impeller is a replacement for Honda OEM part numbers 19210-ZW9-A31 and 19210-ZW9-A32. It is also listed as an aftermarket interchange for Sierra Marine 18-32455. A matching key is included with the impeller.
- Replacement water pump impeller for specified Honda 4-stroke outboards.
- Supplied with the impeller key required for the applicable installation.
- Helps restore water-pump circulation and support normal engine cooling when correctly matched and installed.
- Aftermarket component; not manufactured or sold by Honda or Sierra Marine.
Part Number Matrix
Use the following references to compare the replacement part with your original impeller. Part-number references do not replace verification of the exact engine model and application.
| Brand | Part Number | Reference Type | Notes |
|---|---|---|---|
| Honda | 19210-ZW9-A31 | OEM reference | Replacement reference for the impeller |
| Honda | 19210-ZW9-A32 | OEM reference | Replacement reference for the impeller |
| Sierra Marine | 18-32455 | Aftermarket interchange | Impeller reference; this product includes a key |
Engine & Model Compatibility
Keep the horsepower, stroke, model designation, and model year together when checking fitment. The company fitment information for this product is limited to the following Honda Marine applications:
| Brand | Rated HP | Stroke | Model Year | OEM Part No. | Fitment Scope |
|---|---|---|---|---|---|
| Honda Marine | 8 | 4-Stroke | 2001 and newer | 19210-ZW9-A31 / 19210-ZW9-A32 | Honda 8 HP outboards |
| Honda Marine | 9.9 | 4-Stroke | 2001 and newer | 19210-ZW9-A31 / 19210-ZW9-A32 | Honda 9.9 HP outboards |
| Honda Marine | 15 | 4-Stroke | 2003 and newer | 19210-ZW9-A31 / 19210-ZW9-A32 | Honda 15 HP outboards |
| Honda Marine | 20 | 4-Stroke | 2003 and newer | 19210-ZW9-A31 / 19210-ZW9-A32 | Honda 20 HP outboards |
Model suffixes, shaft configurations, and production details can vary within a horsepower range. Confirm the complete model designation, year, original impeller dimensions, key arrangement, and OEM part number before ordering.
Technical Specs
- Product Type
- Water pump impeller with key
- Application
- Honda Marine 4-stroke outboards
- Rated Horsepower Range
- 8, 9.9, 15, and 20 HP
- Installation
- Replacement water-pump component
- Included Key
- Yes, one matching impeller key is included
- Aftermarket Status
- Aftermarket replacement; not an OEM Honda component
- OEM References
- 19210-ZW9-A31 and 19210-ZW9-A32
- Aftermarket Reference
- Sierra Marine 18-32455
What’s in the Box
- 1 x Water pump impeller
- 1 x Impeller key
Installation Notes
- Verify the complete engine model, horsepower, stroke, year, and original part number before beginning work.
- Disconnect the battery or follow the engine manufacturer’s safety procedure to prevent accidental starting.
- Place the outboard in a stable service position and remove the lower unit according to the applicable service manual.
- Remove the water-pump housing and note the original impeller-vane orientation and key position.
- Remove the old impeller and key. Clean the pump housing and inspect the housing, wear surfaces, seals, and drive components for damage.
- Install the supplied key in the shaft keyway and align the new impeller with the key before seating it.
- Lubricate the impeller and housing with a lubricant recommended for the application. Do not use a lubricant that can damage the impeller material.
- Reinstall the water-pump housing, lower unit, and related hardware. Tighten fasteners according to the manufacturer’s service specifications.
- Run the engine only in an appropriate water supply or with the correct flushing equipment, then verify a steady cooling-water tell-tale stream and normal operating temperature.
Troubleshooting & FAQ
How do I know if the water-pump impeller needs replacing?
Common warning signs include a weak or missing tell-tale stream, overheating, an overheating alarm, steam, or impeller vanes that are cracked, brittle, damaged, or permanently bent. Cooling-system blockages and damaged pump components can produce similar symptoms, so inspect the complete system.
Which Honda outboards does this impeller fit?
The stated application is Honda Marine 4-stroke outboards: 8 HP and 9.9 HP models from 2001 and newer, plus 15 HP and 20 HP models from 2003 and newer. Verify the exact model designation and OEM part number before purchase.
Does the product include the impeller key?
Yes. This product is sold as an impeller with one matching impeller key. It does not include a complete water-pump service kit, gasket set, O-ring, or water-pump housing unless separately stated.
Is this an OEM Honda part?
No. This is an aftermarket replacement referenced to Honda OEM part numbers 19210-ZW9-A31 and 19210-ZW9-A32. Honda and Sierra Marine are used only to identify application and reference numbers.
My engine is overheating, but the tell-tale stream looks normal. Could it still be the impeller?
Yes. A worn or partially damaged impeller may provide some visible flow while failing to deliver sufficient cooling-water volume under load. Also inspect the water passages, thermostat, pump housing, seals, and related cooling-system components.
How often should an impeller be inspected or replaced?
Inspect the impeller during scheduled maintenance and replace it when the service manual recommends or whenever the vanes show wear, cracking, hardening, or deformation. Service intervals can be shorter in saltwater, silty water, or high-debris environments.
Safety & Important Information
- Confirm the exact engine model, year, horsepower, stroke, OEM number, and original part configuration before ordering.
- Do not operate an outboard without an adequate water supply or the manufacturer-approved flushing equipment.
- Inspect the complete water-pump assembly during installation; a new impeller cannot correct a damaged housing, blocked passage, failed seal, or other cooling-system fault.
- Professional installation is recommended if you are not familiar with lower-unit or water-pump service.
About Sea Sierra
- Marine Replacement Parts — Practical aftermarket components for routine maintenance and repair.
- Application-Focused Listings — Product references and fitment information are provided to help you compare your original part.
- Service Support — Verify the complete engine information before ordering to help ensure the correct replacement.
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