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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Delivery and Shipping
Delivery and Shipping
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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 replacement Water Pump Impeller – Fits Mercury/Mariner 4–9.8HP Outboards is engineered for a precise fit on select 2-stroke engines from 1975–1986, specifically models with a 0.456" (11.6mm) drive shaft diameter. It is a crucial component for maintaining proper engine cooling performance by circulating water through the outboard's cooling system.
This part serves as a direct interchange for OEM numbers Mercury 47-89981, 47-65957, and 47-39074, and aftermarket equivalents including Sierra 18-3039, GLM 89810, and Mallory 9-45305.
- Installs via a direct press-fit on the drive shaft.
- Constructed from durable neoprene with a brass hub for corrosion resistance.
- Critically designed for models using the larger 0.456" diameter drive shaft.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 47-89981 |
| Mercury | 47-89981B |
| Mercury | 47-65957 |
| Mercury | 47-39074 |
| Sierra | 18-3039 |
| GLM Marine | 89810 |
| Mallory Marine | 9-45305 |
| Mallory Marine | 9-45305-10 |
| SEI Marine | 96-260-03B |
| CEF | 500310 |
| CEF | 500314 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury and Mariner owners: Please measure your drive shaft diameter. This impeller is only compatible with the 0.456-inch shaft. It will not fit models with the smaller shaft diameter, even if your model and year fall within the listed ranges.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 4 HP | 4 | 2-Stroke | 1975–1986 | 47-89981 | S/N 2498136-4107219 (1 cylinder) |
| Mercury | 4 HP | 4 | 2-Stroke | 1979–1986 | 47-89981 | S/N 5595532-9075838 (USA model) |
| Mercury | 4.5 HP | 4.5 | 2-Stroke | 1975–1986 | 47-89981 | S/N 4107220 and up |
| Mercury | 6 HP | 6 | 2-Stroke | 1976–1979 | 47-89981 | S/N 1916139-2193817 |
| Mercury | 6 HP | 6 | 2-Stroke | 1979–1983 | 47-89981 | S/N 2193818-2529894 |
| Mercury | 7.5 HP | 7.5 | 2-Stroke | 1976–1986 | 47-89981 | S/N 4131610-5226934 |
| Mercury | 9.8 HP (110) | 9.8 | 2-Stroke | 1976–1986 | 47-89981 | S/N 2196389-5206549 |
| Mariner | 4 HP | 4 | 2-Stroke | 1977–1986 | 47-89981 | With 0.456" drive shaft |
| Mariner | 4.5 HP | 4.5 | 2-Stroke | 1977–1986 | 47-89981 | With 0.456" drive shaft |
| Mariner | 6 HP | 6 | 2-Stroke | 1977–1983 | 47-89981 | With 0.456" drive shaft |
| Mariner | 7.5 HP | 7.5 | 2-Stroke | 1977–1986 | 47-89981 | With 0.456" drive shaft |
| Mariner | 9.8 HP | 9.8 | 2-Stroke | 1977–1986 | 47-89981 | With 0.456" drive shaft |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct Replacement
- Fuel Type
- Gasoline
- Connection
- Press-fit on Drive Shaft
- Housing Material
- Neoprene with Metal (Brass) Hub
- Housing Color
- Black
- Dimensions
- Overall Diameter: 32.0mm (1.26"), Height: 14.4mm (0.57"), Hub Shaft Diameter: 11.6mm (0.456")
- Weight
- ~11g (0.4 oz)
- Number of Blades
- 6
- Operating Temperature
- -29°C to 82°C (-20°F to 180°F)
What’s in the Box
- 1 x Water Pump Impeller (47-89981)
Installation Notes
- Disconnect the battery and spark plug wires for safety.
- Drain the lower unit gear lube.
- Remove the bolts securing the lower unit (gearcase) and carefully separate it from the upper housing.
- Unbolt and remove the water pump housing cover to access the old impeller. Note the orientation of the blades.
- Remove the old impeller. Clean the housing interior and inspect it for wear or damage.
- Lubricate the new impeller and housing with a suitable marine grease or soapy water.
- Install the new impeller, ensuring the blades are oriented in the correct rotational direction (typically by turning the driveshaft clockwise while pushing down).
- Reinstall the water pump housing, using new gaskets where applicable, and tighten bolts to the manufacturer's specified torque.
- Reattach the lower unit, refill the gear lube, and reconnect the battery/spark plugs.
- Start the engine in water and verify a strong, steady stream from the "tell-tale" water outlet.
Troubleshooting & FAQ
How do I know if this impeller will fit my Mercury or Mariner engine?
First, confirm your model and year in the compatibility chart. Most importantly, you must verify your engine has the 0.456-inch (11.6mm) diameter drive shaft. Mercury used two different shaft sizes on these HP ranges, so physical measurement is the only way to be certain.
What are the signs of a failing water pump impeller?
Common signs include the engine running hotter than normal, a weak or non-existent water stream from the "tell-tale" outlet, or a melted water pump housing. If you notice any of these symptoms, shut down the engine immediately to prevent overheating and severe damage.
How often should I replace my impeller?
For preventative maintenance, it is best practice to replace the impeller every year or every 100 hours of operation, whichever comes first. This is especially important if you operate in saltwater or sandy/silty conditions.
Is this part compatible with Mercury 5HP engines?
No, it is not. Mercury/Mariner 5HP outboards typically use a different impeller, part number 47-16154-3.
Why is verifying the shaft diameter so critical?
During the same production years, Mercury produced 4, 4.5, and 7.5 HP motors with two different drive shaft diameters. An impeller designed for the wrong shaft size will not fit or function, leading to immediate engine overheating. Always measure before ordering.
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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