Water Pump Impeller for Mercury/Mariner 20 HP and Johnson/Evinrude 20–35 HP 2-Stroke Outboards
Water Pump Impeller for Mercury/Mariner 20 HP and Johnson/Evinrude 20–35 HP 2-Stroke Outboards is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Water Pump Impeller for Mercury/Mariner 20 HP and Johnson/Evinrude ...
Water Pump Impeller for Mercury/Mariner 20 HP and Johnson/Evinrude 20–35 HP 2-Stroke Outboards is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller is a replacement impeller for selected Mercury/Mariner and Johnson/Evinrude 2-stroke outboard applications. It is supplied as a single impeller and is intended to restore water-pump circulation and help maintain proper engine cooling.
Company application data identifies this impeller for Mercury/Mariner 20 HP applications and for Johnson/Evinrude 2-stroke outboards rated 20, 25, 28, 30, and 35 HP. Always compare the exact engine model, year, serial number, existing impeller, and water-pump housing before ordering.
- Single aftermarket water pump impeller; not a complete water pump kit.
- Designed for selected 2-stroke Mercury/Mariner and Johnson/Evinrude outboards.
- Cross-reference numbers are provided for identification and application checking only.
- Replace the impeller whenever it is worn, cracked, hardened, damaged, or unable to maintain a strong cooling-water flow.
Part Number References
The following manufacturer and aftermarket references are associated with this impeller in the available product records. They are not a guarantee of fitment by number alone.
| Brand or Reference Type | Part Number |
|---|---|
| Mercury/Mariner OEM references | 47-65958, 47-89982, 47-56780, 47-89982T1 |
| Johnson/Evinrude/OMC/BRP OEM references | 0763982, 0388702, 0389983, 763982, 388702, 389983 |
| Sierra Marine | 18-3052 |
| CEF Marine | 500311 |
| Mallory Marine | 9-45311 |
| GLM Marine | 89820 |
| SEI Marine | 96-299-03F |
Engine Compatibility
Use the complete model and year conditions below as a guide. A horsepower match by itself is not sufficient because impeller fitment can vary by engine design, model, year, and serial-number range.
| Brand | Engine Type | Rated HP | Stroke | Year Condition | Associated OEM References |
|---|---|---|---|---|---|
| Mercury/Mariner | Selected outboard applications | 20 HP | 2-Stroke | Verify the exact model and serial range | 47-65958, 47-89982, 47-56780, 47-89982T1 |
| Johnson/Evinrude | Selected outboard applications | 20 HP | 2-Stroke | 1982 and newer | 0763982, 0388702, 0389983 |
| Johnson/Evinrude | Selected outboard applications | 25 HP | 2-Stroke | 1979 and newer | 0763982, 0388702, 0389983 |
| Johnson/Evinrude | Selected outboard applications | 28 HP | 2-Stroke | 1978 and newer | 0763982, 0388702, 0389983 |
| Johnson/Evinrude | Selected outboard applications | 30 HP | 2-Stroke | 1984 and newer | 0763982, 0388702, 0389983 |
| Johnson/Evinrude | Selected outboard applications | 35 HP | 2-Stroke | 1978 and newer | 0763982, 0388702, 0389983 |
Technical Specifications
- Product Type
- Water pump impeller
- Product Configuration
- Single replacement impeller
- Application
- Selected Mercury/Mariner and Johnson/Evinrude 2-stroke outboard water-pump applications
- Replacement Status
- Aftermarket replacement; not a genuine OEM component
- Water Pump Kit Contents
- This listing is for the impeller only; a water-pump housing, gaskets, wear plate, screws, and other service parts are not included unless separately stated.
What's in the Box
- 1 x Water pump impeller
Installation Notes
- Stop the engine, disconnect the battery where applicable, and follow the service manual for safe lower-unit removal.
- Remove the water-pump housing and carefully take out the old impeller. Note the position of the drive key and the direction of the vanes before disassembly.
- Inspect the housing, wear plate, key, seals, and related components for scoring, distortion, corrosion, or damage. Replace damaged parts before installation.
- Install the impeller with the correct drive key and seat it in the housing according to the engine manufacturer's service procedure.
- Reassemble the water pump and reinstall the lower unit using the correct fasteners and torque specifications for the engine.
- Run the engine only in an appropriate test tank or with the correct flushing equipment. Confirm a steady cooling-water tell-tale stream and monitor for overheating.
Troubleshooting & FAQ
How do I confirm that this impeller fits my outboard?
Check the exact brand, model, horsepower, stroke, year, and serial number against your engine service information. Then compare the removed impeller and water-pump housing with the product references shown above. Do not rely on horsepower alone.
What symptoms indicate a worn impeller?
Common symptoms include a weak or missing tell-tale stream, overheating at idle or under load, reduced cooling-water flow, damaged or brittle vanes, and visible cracking or deformation. Stop operating the engine if it overheats.
Is this a complete water-pump kit?
No. This listing contains one replacement impeller only. Other water-pump service parts are not included.
Does the impeller include a drive key?
No drive key is stated as included in the company package information. Reuse the correct serviceable key or purchase the correct key separately for your exact engine if required.
Is this an OEM part?
No. This is an aftermarket replacement impeller. The listed OEM numbers are reference numbers used to help identify applications and are not a claim that the product is manufactured by Mercury, Mariner, Johnson, Evinrude, OMC, BRP, or any other OEM brand.
How often should the impeller be replaced?
Inspect the impeller during scheduled water-pump service and replace it when the service manual specifies, or sooner if it shows wear, cracking, hardening, deformation, or cooling-flow problems. Service life depends on operating hours, water conditions, storage, and the condition of the pump housing.
Safety & Important Information
- Verify the exact engine model, year, serial number, and water-pump configuration before ordering.
- Inspect the replacement part against the original part before installation. Do not install a part that differs in critical dimensions, keyway, vane design, or housing fit.
- Never operate an outboard without an adequate cooling-water supply.
- Professional installation is recommended if you are not familiar with lower-unit or water-pump service.
- This is an aftermarket replacement and is not an OEM component.
About Sea Sierra
- Marine Replacement Parts — Practical replacement components for routine outboard maintenance and repair.
- Application-Focused Listings — Product references and fitment conditions are provided to support careful part-number and model verification.
- Service-Ready Support — Always use the engine manufacturer's service information for installation procedures, torque values, and maintenance intervals.
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