Aftermarket Water Pump Impeller with Key for Mercury/Mariner 2-Stroke 3.5–9.8 HP, 0.438 in Shaft – Replaces 47-68988, 47-89980
Aftermarket Water Pump Impeller with Key for Mercury/Mariner 2-Stroke 3.5–9.8 HP, 0.438 in Shaft – Replaces 47-68988, 47-89980 is backordered and will ship as soon as it is back in stock.
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Aftermarket Water Pump Impeller with Key for Mercury/Mariner 2-Stro...
Aftermarket Water Pump Impeller with Key for Mercury/Mariner 2-Stroke 3.5–9.8 HP, 0.438 in Shaft – Replaces 47-68988, 47-89980 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller with key is designed for selected Mercury and Mariner 2-stroke outboard applications from 3.5 HP through 9.8 HP. It is intended to restore water-pump circulation and help maintain proper engine cooling when the original impeller is worn, damaged, or hardened.
The impeller is specified for a 0.438-inch shaft fit and replaces the listed Mercury references 47-68988, 47-89980, and 47-89980T1. The aftermarket reference associated with this product is Sierra 18-3054.
- Aftermarket replacement impeller for selected Mercury and Mariner 2-stroke outboards.
- Includes the matching key supplied with this product.
- Designed for applications using a 0.438-inch shaft or impeller bore specification.
- Confirm the exact model, serial-number range, shaft size, and original impeller before installation.
Part Number Matrix
Use the following references to compare the impeller against your original part and service information. These numbers identify reference or interchange applications; they do not replace the need to verify the engine model and shaft specification.
| Brand or Reference | Part Number | Reference Type |
|---|---|---|
| Mercury | 47-68988 | OEM reference |
| Mercury | 47-89980 | OEM reference |
| Mercury | 47-89980T1 | OEM reference |
| Sierra | 18-3054 | Aftermarket interchange reference |
| Mercury | 89980 / 68988 | Short-form reference numbers |
Engine & Model Compatibility
The company fitment record specifies Mercury and Mariner 2-stroke engines rated at 3.5, 3.6, 4, 4.5, 7.5, and 9.8 HP, provided the engine uses the required 0.438-inch shaft specification. Model names and serial-number ranges can vary within these horsepower groups, so verify the complete engine identification before ordering.
| Brand | Engine Type | Rated HP | Shaft Specification | OEM Reference | Fitment Note |
|---|---|---|---|---|---|
| Mercury / Mariner | 2-Stroke | 3.5 | 0.438 in | 47-89980 | Verify model and serial number. |
| Mercury / Mariner | 2-Stroke | 3.6 | 0.438 in | 47-89980 | Verify model and serial number. |
| Mercury / Mariner | 2-Stroke | 4 | 0.438 in | 47-89980 | Verify model and serial number. |
| Mercury / Mariner | 2-Stroke | 4.5 | 0.438 in | 47-89980 | Verify model and serial number. |
| Mercury / Mariner | 2-Stroke | 7.5 | 0.438 in | 47-89980 | Verify model and serial number. |
| Mercury / Mariner | 2-Stroke | 9.8 | 0.438 in | 47-89980 | Verify model and serial number. |
Technical Specs
- Product Type
- Water pump impeller with key
- Application
- Selected Mercury and Mariner 2-stroke outboards
- Rated Horsepower
- 3.5, 3.6, 4, 4.5, 7.5, and 9.8 HP applications
- Shaft or Bore Specification
- 0.438 inch
- Replacement References
- Mercury 47-68988, 47-89980, and 47-89980T1
- Aftermarket Reference
- Sierra 18-3054
- Product Status
- Aftermarket replacement; not an OEM Mercury or Quicksilver part
What’s in the Box
- 1 x Water pump impeller
- 1 x Matching impeller key
Installation Notes
- Verify fitment first: Confirm that your engine is a compatible Mercury or Mariner 2-stroke model rated at 3.5, 3.6, 4, 4.5, 7.5, or 9.8 HP and that the required shaft or bore specification is 0.438 inch.
- Disconnect the battery, shut down the engine, and allow all components to cool before servicing.
- Remove the lower unit and water-pump cover according to the engine manufacturer's service procedure.
- Remove the old impeller and key. Inspect the pump housing, wear surfaces, seals, and shaft for damage or excessive wear.
- Install the supplied key and impeller in the correct orientation. Lubricate the impeller and housing only with a lubricant approved for the application.
- Reassemble the water-pump components and lower unit using the correct service-manual procedures and torque specifications.
- After installation, run the engine in a safe water supply and confirm a strong cooling-water discharge before normal operation.
Troubleshooting & FAQ
How do I know if this impeller fits my specific engine?
Check all fitment conditions together: Mercury or Mariner brand, 2-stroke engine type, rated horsepower of 3.5, 3.6, 4, 4.5, 7.5, or 9.8 HP, the correct model and serial-number range, and the 0.438-inch shaft or bore specification. Do not rely on horsepower alone.
Does this product include the key?
Yes. This product is supplied as a water pump impeller with the matching key.
Which part numbers does this impeller replace?
The listed Mercury references are 47-68988, 47-89980, and 47-89980T1. Sierra 18-3054 is an aftermarket reference associated with the same application. Always compare the original part and shaft specification before installation.
Will this impeller fit a 5 HP Mercury outboard?
A 5 HP rating is not included in the supplied fitment record. Do not assume compatibility based on nearby horsepower ratings; verify the exact model, serial number, and shaft specification before ordering.
What are the signs of a failing water-pump impeller?
Common signs include overheating, reduced cooling-water flow, or little to no water discharge from the telltale. Stop using the engine if it overheats and inspect the cooling system before further operation.
Is this an OEM Mercury or Quicksilver part?
No. This listing is for an aftermarket replacement impeller with key. Mercury and Quicksilver names and part numbers are used only to identify compatible reference applications.
Safety & Important Information
- Verify the original impeller, shaft or bore size, engine model, and serial-number range before purchase.
- Do not operate an outboard with inadequate cooling-water flow.
- Follow the engine manufacturer's service procedures and use appropriate marine-safety practices during installation.
- This is an aftermarket replacement part, not an OEM Mercury or Quicksilver component.
- Professional installation is recommended when the correct lower-unit or water-pump service procedure is unfamiliar.
About Sea Sierra
- Pro-Grade Standards — We supply marine replacement parts selected for practical fitment and reliable service.
- Application-Focused Support — Clear model, horsepower, and shaft-size information helps you select the correct replacement part.
- Manufacturer-Direct Value — We offer aftermarket marine components at competitive prices.
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