Water Pump Impeller Repair Kit – Fits Mercury/Mariner 8-9.9 HP 4-Stroke Outboards (Replaces 803748Q01, 803750A03, 853792A5)
Water Pump Impeller Repair Kit – Fits Mercury/Mariner 8-9.9 HP 4-Stroke Outboards (Replaces 803748Q01, 803750A03, 853792A5) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Water Pump Impeller Repair Kit – Fits Mercury/Mariner 8-9.9 HP 4-St...
Water Pump Impeller Repair Kit – Fits Mercury/Mariner 8-9.9 HP 4-Stroke Outboards (Replaces 803748Q01, 803750A03, 853792A5) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Repair Kit is designed for listed Mercury and Mariner 8-9.9 HP 4-Stroke, 209cc outboards from 2005 and newer, specifically applications with serial number R042475 and up. The kit provides the water-pump components needed to service the lower-unit cooling system and help maintain proper engine water circulation.
It is listed as a replacement for Mercury part numbers 803748Q01, 803750A03, 853792A5, 47-803748Q01, 47-803750A03, and 803748K01, with QuickMarine reference 803750A03 also associated with the application.
- Installation Location: Lower unit of the outboard.
- Complete Service Kit: Includes the impeller, housing, wear plate, insert cup, gaskets, and installation instructions listed below.
- Construction: Neoprene impeller with a hardened nylon hub and marine-grade nylon water-pump housing.
Part Number Matrix
Use the following references to compare the listed replacement numbers with the part identified for your engine.
| Brand | Part Number |
|---|---|
| Mercury | 803748Q01 |
| Mercury | 803750A03 |
| Mercury | 853792A5 |
| Mercury | 47-803748Q01 |
| Mercury | 47-803750A03 |
| Mercury | 803748K01 |
| QuickMarine | 803750A03 |
Engine & Model Compatibility
Confirm the engine brand, displacement, stroke, model year, and serial number before ordering. The detailed applications listed for this kit are non-Bigfoot Mercury and Mariner 4-Stroke models with serial number R042475 or higher.
| Brand | Model / Displacement | Rated HP | Stroke | Years / Serial Condition | Listed Reference | Notes |
|---|---|---|---|---|---|---|
| Mercury | 4-Stroke, 209cc | 8 | 4-Stroke | 2005 and newer; S/N R042475 and up | 803748Q01 | Non-Bigfoot models |
| Mercury | 4-Stroke, 209cc | 9.9 | 4-Stroke | 2005 and newer; S/N R042475 and up | 803748Q01 | Non-Bigfoot models |
| Mariner | 4-Stroke, 209cc | 8 | 4-Stroke | 2005 and newer; S/N R042475 and up | 803748Q01 | International models |
| Mariner | 4-Stroke, 209cc | 9.8 | 4-Stroke | 2005 and newer; S/N R042475 and up | 803748Q01 | International models |
| Mariner | 4-Stroke, 209cc | 9.9 | 4-Stroke | 2005 and newer; S/N R042475 and up | 803748Q01 | International models |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Application
- Lower-unit water pump service
- Housing Material
- Marine-grade nylon
- Housing Color
- Black
- Impeller Material
- Neoprene with hardened nylon hub
- Impeller Design
- 6-blade design
- Dimensions
- Impeller overall diameter: 1.587 inches (40.3 mm)
Impeller height: 0.709 inch (18 mm)
Shaft/hub size: 0.472 inch (12 mm) - Approximate Weight
- 20 g
- Warranty
- 1 year against manufacturing defects under normal operating conditions
What’s in the Box
- 1 x Water Pump Impeller (47-8037481)
- 1 x Water Pump Housing (803750A02)
- 1 x Insert Cup (8037511)
- 1 x Wear Plate (8037531)
- 1 x Gasket (161585)
- 1 x Gasket (161586)
- 1 x Gasket (161587)
- 1 x Installation Instructions
Installation Notes
- Disconnect the battery and place the outboard in neutral.
- Drain the gearcase oil from the lower unit.
- Remove the bolts securing the lower unit to the midsection and carefully lower the unit.
- Unbolt and remove the old water-pump housing assembly from the driveshaft.
- Clean the mounting surfaces and inspect the driveshaft for wear or corrosion.
- Install the new wear plate, gaskets, insert cup, and impeller in the housing. Make sure the impeller key is correctly seated.
- Slide the water-pump assembly down the driveshaft, aligning the impeller blades with the direction of shaft rotation.
- Secure the housing with the original fasteners and tighten them to the engine manufacturer’s specified torque.
- Reinstall the lower unit, ensuring that the water tube and shift shaft are properly aligned.
- Refill the gearcase with fresh oil and test the engine in water, confirming a steady tell-tale stream.
Troubleshooting & FAQ
How do I confirm this kit fits my specific engine?
Check the engine identification plate for brand, model, displacement, stroke, year, and serial number. This listing is for the detailed Mercury and Mariner 8-9.9 HP 4-Stroke, 209cc applications shown above, with serial number R042475 and up. Confirm the original impeller and water-pump components before ordering, especially for Bigfoot and other variants.
What are the signs of a failing water-pump impeller?
Common symptoms include a weak or missing tell-tale stream, an overheating alarm, elevated operating temperature, or reduced engine performance. A visual inspection may show cracked, brittle, or broken impeller blades.
How often should I replace the impeller?
Impeller replacement is a preventative-maintenance task. A commonly used service interval is every 1-2 years or 100-200 operating hours, whichever comes first. Saltwater, sand, silt, and long periods of storage may require more frequent inspection or replacement.
What is included in this repair kit?
This listing includes the impeller, housing, insert cup, wear plate, three listed gaskets, and installation instructions. Replace the complete water-pump service components when the housing or wear plate shows scoring, distortion, or heat damage.
Is this an OEM or aftermarket part?
This is an aftermarket replacement kit, not a Mercury or Mariner original-equipment part. The listed component dimensions, materials, and replacement references are intended to match the specified applications.
What are the shipping speed and cost?
Typical international transit time is 5-15 days. Standard shipping is free for most regions. Expedited options, when available for your location, are shown at checkout.
What is the warranty and return policy?
The product is covered by a 1-year warranty against manufacturing defects under normal operating conditions. Returns are accepted within the standard return window for unused items in their original condition. Contact support with your order details for assistance.
Safety & Important Info
- Verify the engine model, year, stroke, displacement, serial number, and original component before installation.
- Do not rely on horsepower alone, because different engine variants may use different water-pump components.
- This is an aftermarket replacement kit, not an original equipment manufacturer part.
- Professional installation is recommended if you are not familiar with lower-unit removal, shift-shaft alignment, gearcase service, or water-pump maintenance.
- After installation, run the engine safely and confirm a steady tell-tale stream before normal operation.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts designed for dependable real-world service.
- Fast Global Fulfillment — Standard delivery is available to most regions, with typical transit times of 5-15 days.
- Manufacturer-Direct Value — Our replacement parts provide practical value while maintaining attention to materials and quality control.
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