Water Pump Repair Kit for Mercury 175–300 HP and 450R 4-Stroke Outboards – Replaces 8M0205803 and 8M0142980
Water Pump Repair Kit for Mercury 175–300 HP and 450R 4-Stroke Outboards – Replaces 8M0205803 and 8M0142980 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Water Pump Repair Kit for Mercury 175–300 HP and 450R 4-Stroke Outb...
Water Pump Repair Kit for Mercury 175–300 HP and 450R 4-Stroke Outboards – Replaces 8M0205803 and 8M0142980 is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Repair Kit is intended for selected Mercury Marine 175–300 HP 3.4L V6 and 4.6L V8 four-stroke outboards, including 450R models, from 2019 and newer with serial number 2B529482 and above.
The kit is listed as a replacement for Mercury part numbers 8M0205803, 8M0142980, 47-8M0205803, and 98-8M0142980. Verify the model, year, serial number, and original water-pump configuration before ordering.
- Replacement water-pump service kit for applicable Mercury four-stroke outboards.
- Includes an impeller, gaskets, seals, a key, a face plate, and a face-seal installation tool.
- Supports restoration of proper water-pump and cooling-system operation when installed correctly.
Part Number Matrix
Use these references to compare the replacement kit with the part number on your original component.
| Brand | Part Number |
|---|---|
| Mercury | 8M0205803 |
| Mercury | 8M0142980 |
| Mercury | 47-8M0205803 |
| Mercury | 98-8M0142980 |
Engine and Model Compatibility
The following application details describe the listed fitment scope. Model, year, stroke, and serial-number conditions must be confirmed together.
| Brand | Model or Engine Family | Rated HP | Stroke | Years | Reference Part No. | Serial Condition |
|---|---|---|---|---|---|---|
| Mercury | 3.4L V6 | 175 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 3.4L V6 | 200 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 3.4L V6 | 225 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 4.6L V8 | 200 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 4.6L V8 | 225 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 4.6L V8 | 250 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 4.6L V8 | 300 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
| Mercury | 450R | 450 | 4-Stroke | 2019 and newer | 8M0205803 | 2B529482 and above |
Technical Specifications
- Product Type
- Water pump repair kit
- Application
- Selected Mercury four-stroke outboards
- Installation
- Replacement installation in the water-pump assembly
- Fitment Requirement
- Applicable Mercury V6, V8, and 450R four-stroke models with serial number 2B529482 and above
- Replacement References
- 8M0205803, 8M0142980, 47-8M0205803, and 98-8M0142980
- Product Status
- Aftermarket replacement, not a Mercury-branded OEM component
What's in the Box
- 2 x Water pump gasket
- 1 x Face plate
- 1 x Face plate gasket
- 1 x Impeller key
- 1 x Impeller
- 1 x Face seal
- 1 x Drain plug seal
- 1 x O-ring
- 1 x Actuator seal
- 1 x Face seal tool
Installation Notes
- Disconnect the battery and remove the lower unit according to the manufacturer's service procedure.
- Remove the existing water-pump housing, impeller, gaskets, and seals.
- Clean the mating surfaces and remove old gasket material, debris, and corrosion.
- Install the replacement gaskets, face plate, impeller with key, and seals supplied in the kit.
- Use an appropriate marine lubricant during assembly where specified by the service procedure.
- Reinstall the water-pump housing and tighten fasteners to the manufacturer's specified torque.
- Reattach the lower unit and verify proper cooling-water flow before returning the engine to service.
Troubleshooting and FAQ
How do I know if this kit fits my Mercury outboard?
Compare your engine's exact model, horsepower, stroke, year, serial number, and original part number with the fitment information above. This listing is intended for the specified 3.4L V6, 4.6L V8, and 450R four-stroke applications with serial number 2B529482 and above. If any of these details differ, confirm compatibility before ordering.
What are common signs of a failing water pump?
Possible symptoms include overheating at idle or low speed, a weak or missing telltale-water stream, or an engine warning alarm. These symptoms can have other causes, so inspect the complete cooling system before replacing parts.
How often should the impeller be inspected?
Inspect the impeller as part of routine maintenance and replace it when it shows wear, cracking, deformation, brittleness, or other damage. Service intervals depend on the engine manufacturer's schedule and operating conditions, including saltwater use and debris exposure.
Is professional installation recommended?
Yes. Installation requires removal of the lower unit and correct assembly of the water-pump components. Use the applicable service manual and manufacturer torque specifications, or have the work completed by a qualified marine technician.
Is this an OEM part?
No. This is an aftermarket replacement kit intended for the applications and reference numbers listed on this page. It is not manufactured or branded by Mercury Marine.
Safety and Important Information
- Verify the engine model, year, horsepower, stroke, serial number, and original part number before purchase.
- Compare the replacement components with the original water-pump assembly before installation.
- Do not operate the engine if cooling-water flow is inadequate or overheating occurs.
- Follow the applicable service manual and use professional installation if you are not experienced with lower-unit removal.
- This product is an aftermarket replacement, not an OEM component.
About Sea Sierra
- Marine replacement parts selected for practical service and repair applications.
- Parts support for boat owners, technicians, and marine maintenance projects.
- Customer-focused fulfillment and product information for replacement-part ordering.
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