Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP (Replaces 47-89981Q1)
Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP (Replaces 47-89981Q1) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP...
Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP (Replaces 47-89981Q1) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Water Pump Impeller Kit is a direct replacement for Mercury and Mariner 2-stroke outboard engines, including 3.9HP, 4HP, 4.5HP, 6HP, 7.5HP, and 9.8HP models. It is specifically designed for engines primarily from the 1970s and 1980s that utilize a driveshaft with a 0.456" inner diameter connection.
This component serves as a direct interchange for Mercury OEM parts 47-89981Q1, 47-89981T1, and 89981T2, as well as aftermarket equivalents like Sierra 18-3039, GLM 12270, and Mallory 9-45035.
- Engineered for direct-fit installation.
- Constructed from durable neoprene rubber with a brass hub for corrosion resistance.
- Includes the essential impeller needed for a water pump rebuild.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 47-89981Q1 |
| Mercury | 47-89981T1 |
| Mercury | 89981T2 |
| Sierra | 18-3039 |
| GLM | 12270 |
| Mallory | 9-45035 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury engines, compatibility is often determined by the serial number range, which can indicate the manufacturing location (USA, Canada, Belgium, Australia) and production years. Please verify your serial number against the listed ranges.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Outboard (USA) | 4 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 4126460-5206549 |
| Mercury | Outboard (USA) | 7.5 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 4131610-5226934 |
| Mercury | Outboard (USA) | 4.5 | 2-Stroke | 1975–1979 | 47-89981Q1 | Serial Range: 4107220-5595531 |
| Mercury | Outboard (USA) | 9.8 | 2-Stroke | 1979–1985 | 47-89981Q1 | Serial Range: 5206550 & Up |
| Mercury | Outboard (USA) | 7.5 | 2-Stroke | 1979–1986 | 47-89981Q1 | Serial Range: 5206550 & Up |
| Mercury | Outboard (USA) | 4.5 | 2-Stroke | 1980–1985 | 47-89981Q1 | Serial Range: 5595532 & Up |
| Mercury | Outboard (USA) | 4 | 2-Stroke | 1982–1986 | 47-89981Q1 | Serial Range: 5595532 & Up |
| Mercury | Outboard (CAN) | 9.8 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 7049108-7125387 |
| Mercury | Outboard (CAN) | 7.5 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 7050206-7136037 |
| Mercury | Outboard (CAN) | 4.5 | 2-Stroke | 1975–1979 | 47-89981Q1 | Serial Range: 7045758-7147237 |
| Mercury | Outboard (CAN) | 9.8 | 2-Stroke | 1979–1985 | 47-89981Q1 | Serial Range: 7125388 & Up |
| Mercury | Outboard (CAN) | 7.5 | 2-Stroke | 1979–1986 | 47-89981Q1 | Serial Range: 7125388 & Up |
| Mercury | Outboard (CAN) | 4.5 | 2-Stroke | 1980–1985 | 47-89981Q1 | Serial Range: 7147238 & Up |
| Mercury | Outboard (CAN) | 4 | 2-Stroke | 1982–1986 | 47-89981Q1 | Serial Range: 7143688 & Up |
| Mercury | Outboard (BEL) | 9.8 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 9078139-9217755 |
| Mercury | Outboard (BEL) | 7.5 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 9079489-9219255 |
| Mercury | Outboard (BEL) | 4.5 | 2-Stroke | 1975–1979 | 47-89981Q1 | Serial Range: 9072179-9258280 |
| Mercury | Outboard (BEL) | 9.8 | 2-Stroke | 1979–1985 | 47-89981Q1 | Serial Range: 9217756 & Up |
| Mercury | Outboard (BEL) | 7.5 | 2-Stroke | 1979–1986 | 47-89981Q1 | Serial Range: 9217756 & Up |
| Mercury | Outboard (BEL) | 4.5 | 2-Stroke | 1980–1985 | 47-89981Q1 | Serial Range: 9258281 & Up |
| Mercury | Outboard (BEL) | 4 | 2-Stroke | 1982–1986 | 47-89981Q1 | Serial Range: 9258281 & Up |
| Mercury | Outboard (AUS) | 7.5 | 2-Stroke | 1974–1977 | 47-89981Q1 | Serial Range: 8028840-8058019 |
| Mercury | Outboard (AUS) | 9.8 | 2-Stroke | 1974–1978 | 47-89981Q1 | Serial Range: 8028440-8057554 |
| Mercury | Outboard (AUS) | 4.5 | 2-Stroke | 1975–1979 | 47-89981Q1 | Serial Range: 8026540-8068064 |
| Mercury | Outboard (AUS) | 9.8 | 2-Stroke | 1979–1985 | 47-89981Q1 | Serial Range: 8057545 & Up |
| Mercury | Outboard (AUS) | 7.5 | 2-Stroke | 1979–1986 | 47-89981Q1 | Serial Range: 8057545 & Up |
| Mercury | Outboard (AUS) | 4.5 | 2-Stroke | 1980–1985 | 47-89981Q1 | Serial Range: 8068065 & Up |
| Mercury | Outboard (AUS) | 4 | 2-Stroke | 1982–1986 | 47-89981Q1 | Serial Range: 8068065 & Up |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct replacement
- Connection
- 0.456" ID (Driveshaft)
- Dimensions
- 32mm diameter × 14.4mm height (1.26" × 0.57")
- Weight
- 11g (0.458 oz)
- Material
- Neoprene rubber with brass hub
- Number of Blades
- 6
- Warranty
- 90 Days (Aftermarket)
What’s in the Box
- 1 x Water Pump Impeller (47-89981Q1/47-89981T1/89981T2)
Installation Notes
- Disconnect the battery and ensure the engine is off.
- Remove the lower unit (gearcase) from the outboard motor.
- Locate and unbolt the water pump housing.
- Remove the old impeller, noting the direction of the blades.
- Clean the housing interior and inspect it for wear or damage.
- Install the new impeller, using a slight twisting motion in the direction of engine rotation.
- Apply a marine-grade lubricant to the housing and impeller.
- Reassemble the water pump housing and torque bolts to manufacturer specifications.
- Reinstall the lower unit, ensuring all connections are secure.
- Start the engine in a water supply and verify water is exiting the tell-tale port.
Troubleshooting & FAQ
How do I confirm this impeller fits my specific Mercury engine?
The most reliable method is to match your engine's serial number to the ranges listed in the compatibility table. While HP and year are good indicators, serial numbers provide definitive application data.
What is the difference between this 0.456" ID impeller and similar models?
This impeller has a 0.456-inch inner diameter for the driveshaft. A similar part (47-89980) exists with a 0.438-inch ID for other applications. It is critical to measure your driveshaft or old impeller to ensure you purchase the correct one.
How often should I replace my water pump impeller?
As a general maintenance rule, it is recommended to replace your impeller every 1-2 years or every 100-200 hours of use, whichever comes first. This interval can change based on operating conditions (e.g., saltwater vs. freshwater).
What are the signs of a failing impeller?
Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, and a dry, cracked, or brittle appearance on the old impeller upon inspection.
Is a new water pump housing required for installation?
This kit includes only the impeller. You should always inspect the water pump housing for scoring, warping, or corrosion. If significant wear is present, the housing should be replaced to ensure a proper seal and efficient cooling.
What materials are used in this impeller?
It is made from a durable, high-quality neoprene rubber compound designed for marine environments, with a solid brass hub for a secure fit on the driveshaft and resistance to corrosion.
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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