Water Pump Impeller – Fits Mercury/Mariner 4–9.8 HP Outboards (Replaces 47-89981)
Water Pump Impeller – Fits Mercury/Mariner 4–9.8 HP Outboards (Replaces 47-89981) 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 4–9.8 HP Outboards (Repl...
Water Pump Impeller – Fits Mercury/Mariner 4–9.8 HP Outboards (Replaces 47-89981) is backordered and will ship as soon as it is back in stock.
Product Details
This replacement Water Pump Impeller – Fits Mercury/Mariner 4–9.8 HP Outboards (Replaces 47-89981) is designed for Mercury and Mariner 2-stroke outboard models from 3.9 HP to 10 HP (1965–1986) with an 11.60 mm shaft diameter. It ensures reliable engine cooling and performance.
It serves as a direct interchange for Mercury 47-89981, Sierra 18-3039, GLM 12270, CEF 500314, and Mallory 9-45305.
- Engineered as a direct-fit replacement for specified models.
- Constructed with a durable brass hub and neoprene blades.
- Note: This part is not compatible with 5 HP Mercury Mariner engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 47-89981 |
| Sierra | 18-3039 |
| GLM | 12270 |
| CEF | 500314 |
| Mallory | 9-45305 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 39 1-Cylinder | 3.9 | 2-Stroke | 1965–1986 | 47-89981 | Serial number 2278851 and up |
| Mercury | 40 (4 HP) 1-Cylinder | 4 | 2-Stroke | 1965–1986 | 47-89981 | Serial number 2278851 and up |
| Mercury | 4 HP 1-Cylinder USA | 4 | 2-Stroke | 1965–1986 | 47-89981 | Inside diameter 0.456 inch |
| Mercury | 45, 4.5 1-Cylinder | 4.5 | 2-Stroke | 1965–1986 | 47-89981 | Inside diameter 0.456 inch |
| Mercury | 60 (6HP) | 6 | 2-Stroke | 1965–1986 | 47-89981 | Serial number 1916139 thru 2529894 |
| Mercury | 7.5 HP | 7.5 | 2-Stroke | 1965–1986 | 47-89981 | Inside diameter 0.456 inch |
| Mercury | 75 (7.5HP) | 7.5 | 2-Stroke | 1965–1986 | 47-89981 | Inside diameter 0.456 inch |
| Mercury | 9.8 HP | 9.8 | 2-Stroke | 1965–1986 | 47-89981 | Inside diameter 0.456 inch |
| Mercury | 110 (10hp) | 10 | 2-Stroke | 1965–1986 | 47-89981 | Serial number 1865779 and up |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct-fit replacement
- Fuel Type
- Gasoline
- Housing Material
- Brass Hub with Neoprene Blades
- Housing Color
- Black
- Dimensions
- Height: 14.40 mm (0.57"), External Diameter: 32.00 mm (1.26"), Internal Shaft Diameter: 11.60 mm (0.456")
- Weight
- 11 g (0.39 oz)
- Number of Blades
- 6
- Warranty
- Manufacturer warranty may apply
- Other Attributes
- Not compatible with 5 HP Mercury Mariner engines
What’s in the Box
- 1 x Water Pump Impeller (47-89981)
Installation Notes
- Disconnect the battery and remove the engine cover.
- Drain the lower unit gear lube.
- Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing.
- Gently separate the lower unit from the upper housing. Be mindful of the shift shaft.
- Locate and unbolt the water pump housing.
- Slide the old impeller off the driveshaft, noting the keyway alignment.
- Clean the housing and inspect for wear or damage. Lightly grease the new impeller and interior of the housing.
- Install the new impeller onto the driveshaft, ensuring the key is in place and the blades are oriented correctly (typically bent in the direction of shaft rotation).
- Reassemble the water pump housing, reattach the lower unit, and refill the gear lube with the correct type and amount.
- Test the engine in water, confirming a steady stream from the tell-tale port.
Troubleshooting & FAQ
How do I know if this impeller fits my specific engine?
This impeller fits a wide range of Mercury/Mariner 2-stroke outboards from 3.9 to 9.8 HP made between 1965 and 1986. Please check the "Engine & Model Compatibility" table and verify your engine's model, horsepower, and serial number range. Crucially, this part is NOT for 5 HP models.
What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alerts or steam, and reduced engine performance. An impeller should be inspected regularly and replaced as part of routine maintenance.
How often should I replace my impeller?
For preventative maintenance, it's recommended to replace the impeller every 1-2 years or every 100-200 hours of use, whichever comes first. Frequency should increase if operating in saltwater or sandy/silty conditions.
Does this include the housing or gaskets?
No, this listing is for the impeller only, as shown in the "What's in the Box" section. It does not include the full water pump kit with housing, wear plate, or gaskets.
Is this an OEM or aftermarket part?
This listing is for an aftermarket replacement part, not an original equipment manufacturer (OEM) component. It is engineered to meet or exceed OEM specifications using comparable materials and is manufactured in an ISO 9001 certified facility, with batch inspections for quality control.
How much is shipping and how fast is it?
We ship worldwide quickly, with a typical transit time of 5–15 days for most regions. Standard shipping is free. If available for your location, expedited shipping options and costs will be presented at checkout.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal use conditions. Should you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard return window for items that are unused and in their original condition. See our full policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against 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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