Water Pump Impeller – Fits Mercury/Mariner 4–9.8HP Outboards (Replaces 47-89981, 47-65957, 47-39074)
Water Pump Impeller – Fits Mercury/Mariner 4–9.8HP Outboards (Replaces 47-89981, 47-65957, 47-39074) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller – Fits Mercury/Mariner 4–9.8HP Outboards (Repla...
Water Pump Impeller – Fits Mercury/Mariner 4–9.8HP Outboards (Replaces 47-89981, 47-65957, 47-39074) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller is designed for select Mercury and Mariner 2-stroke outboards using the larger approximately 0.456-inch (11.6 mm) impeller bore. It circulates cooling water through the water-pump system to help maintain proper engine operating temperature.
Catalog references identify this application as a replacement for Mercury OEM numbers 47-89981, 47-65957, and 47-39074. Always verify the original impeller, bore size, engine serial number, and water-pump configuration before ordering.
- Replacement impeller for select Mercury and Mariner outboard cooling systems.
- Designed for the approximately 0.456-inch (11.6 mm) impeller bore application.
- Catalog cross-reference: Sierra 18-3039 and GLM 89810.
- Drive style and water-pump configuration must match the original part; do not rely on horsepower alone.
Part Number Matrix
The following numbers are manufacturer or aftermarket reference numbers associated with this impeller application. They are provided for identification and cross-reference only.
| Brand | Part Number | Reference |
|---|---|---|
| Mercury | 47-89981 | OEM reference |
| Mercury | 47-89981B | Related OEM suffix reference; verify application |
| Mercury | 47-65957 | Replacement reference |
| Mercury | 47-39074 | Replacement reference |
| Sierra | 18-3039 | Aftermarket cross-reference |
| GLM Marine | 89810 | Aftermarket cross-reference |
Engine & Model Compatibility
This impeller is intended for select Mercury and Mariner 2-stroke outboards in the 4–9.8 HP range, including the applications listed below. Model, year, serial number, and impeller bore must be checked together.
Important: Mercury and Mariner outboards in similar horsepower ranges may use different impeller bore sizes. This part is for the approximately 0.456-inch (11.6 mm) application. It is not intended for the smaller approximately 0.438-inch-bore impeller application.
| Brand | Model | Rated HP | Stroke | Years | OEM Reference | Application Notes |
|---|---|---|---|---|---|---|
| Mercury | 4 HP | 4 | 2-Stroke | 1975–1986 | 47-89981 | Verify serial number and approximately 0.456-inch impeller bore. |
| Mercury | 4 HP | 4 | 2-Stroke | 1979–1986 | 47-89981 | USA model range; verify serial number and bore. |
| Mercury | 4.5 HP | 4.5 | 2-Stroke | 1975–1986 | 47-89981 | Verify serial number and approximately 0.456-inch impeller bore. |
| Mercury | 6 HP | 6 | 2-Stroke | 1976–1979 | 47-89981 | Serial range 1916139–2193817; verify the original impeller. |
| Mercury | 6 HP | 6 | 2-Stroke | 1979–1983 | 47-89981 | Serial range 2193818–2529894; verify the original impeller. |
| Mercury | 7.5 HP | 7.5 | 2-Stroke | 1976–1986 | 47-89981 | Serial range 4131610–5226934; verify the original impeller. |
| Mercury | 9.8 HP (110) | 9.8 | 2-Stroke | 1976–1986 | 47-89981 | Serial range 2196389–5206549; verify the original impeller. |
| Mariner | 4 HP | 4 | 2-Stroke | 1977–1986 | 47-89981 | Use only with the approximately 0.456-inch impeller bore application. |
| Mariner | 4.5 HP | 4.5 | 2-Stroke | 1977–1986 | 47-89981 | Use only with the approximately 0.456-inch impeller bore application. |
| Mariner | 6 HP | 6 | 2-Stroke | 1977–1983 | 47-89981 | Use only with the approximately 0.456-inch impeller bore application. |
| Mariner | 7.5 HP | 7.5 | 2-Stroke | 1977–1986 | 47-89981 | Use only with the approximately 0.456-inch impeller bore application. |
| Mariner | 9.8 HP | 9.8 | 2-Stroke | 1977–1986 | 47-89981 | Use only with the approximately 0.456-inch impeller bore application. |
Technical Specs
- Product Type
- Water pump impeller
- Application
- Selected Mercury and Mariner 2-stroke outboard cooling systems
- Impeller Bore
- Approximately 0.456 inch (11.6 mm)
- Outside Diameter
- Approximately 1.250 inches (31.8 mm), subject to manufacturing tolerance
- Drive Style
- Match the original impeller and water-pump shaft configuration before installation
- Fuel Type
- Gasoline outboard engines
- Replacement Type
- Aftermarket direct-replacement impeller
What’s in the Box
- 1 × water pump impeller
No gasket, water-pump housing, wear plate, pin, key, or other water-pump service parts are included unless specifically shown or stated with the selected product.
Installation Notes
- Disconnect the battery and remove the safety lanyard. Follow the engine manufacturer’s service precautions.
- Remove the lower unit according to the service manual for your exact engine and serial number.
- Open the water-pump housing and note the orientation and drive arrangement of the original impeller.
- Remove the old impeller and inspect the housing, wear plate, shaft, pin or key, gaskets, and seals for wear or damage.
- Clean the water-pump cavity and confirm that the replacement bore and drive arrangement match the original part.
- Lubricate the impeller with clean water or a lubricant approved for marine water-pump installation. Do not use a petroleum product that may damage the impeller material.
- Install the impeller with the vanes oriented in the operating direction specified by the service manual. Do not force an incorrect bore or drive style onto the shaft.
- Reassemble the water-pump housing with serviceable gaskets and seals, tightening fasteners to the manufacturer’s specified torque.
- Reinstall the lower unit and verify gear-shift and cooling-water connections before operation.
- Run the engine only in water or with an appropriate flushing attachment, and confirm a steady cooling-water discharge before normal use.
Troubleshooting & FAQ
How do I confirm that this impeller fits my Mercury or Mariner engine?
Check the engine brand, exact model, year, serial number, OEM reference, and impeller bore. The approximately 0.456-inch bore is the key application distinction. Compare the replacement with the old impeller and consult the engine service manual before installation.
What are the signs of a failing water-pump impeller?
Common signs include a weak or missing cooling-water discharge, higher-than-normal operating temperature, an overheating alarm, or visible damage to the impeller or water-pump housing. Stop the engine if overheating occurs and inspect the complete cooling system.
How often should an impeller be replaced?
Replacement intervals depend on engine use, storage, water conditions, and the manufacturer’s maintenance schedule. Replace an impeller when it is damaged, hardened, cracked, deformed, or when cooling-water flow is reduced. Seasonal inspection is recommended for frequently used engines.
Will this impeller fit every Mercury or Mariner engine from 4 to 9.8 HP?
No. Horsepower and model year alone do not establish fitment. Some engines use a different impeller bore or water-pump configuration. Confirm the serial number and approximately 0.456-inch bore before ordering.
Is this an OEM part?
No. This is an aftermarket replacement impeller. Mercury OEM numbers and aftermarket numbers shown on this page are reference numbers used to help identify the application; they do not indicate that this product is manufactured by Mercury, Sierra, or GLM.
Are gaskets or other water-pump parts included?
No. This listing is for one impeller only. Gaskets, seals, wear plates, housings, pins, keys, and other service parts are not included unless specifically stated in the package contents.
What should I do if the impeller does not match my original part?
Do not install it. Compare the bore, outside diameter, height, vane arrangement, and drive style with the original part, then confirm the engine serial number and water-pump diagram before proceeding.
Safety & Important Information
- Verify the engine model, year, serial number, OEM reference, and impeller dimensions before purchase.
- Do not operate an outboard with inadequate cooling-water flow.
- Use the manufacturer’s service manual for torque values, lower-unit removal, and water-pump assembly procedures.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when the correct application or service procedure is uncertain.
About Sea Sierra
- Marine replacement parts selected for practical repair and maintenance applications.
- Clear cross-reference information to help match replacement parts with the original component.
- Customer support is available for product-identification questions before ordering.
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