Supports Consistent Cooling Water Flow
The 6-blade design is intended to restore water movement through compatible small Mercury and Mariner outboard cooling systems when the old impeller is worn, hardened, or damaged.
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47-89980 Water Pump Impeller for Mercury Mariner 3.5-9.8HP | Quickmarine
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47-89980 Water Pump Impeller for Mercury Mariner 3.5-9.8HP | Quickmarine is backordered and will ship as soon as it is back in stock.
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47-89980 Water Pump Impeller for Mercury Mariner 3.5-9.8HP | Quickm...
Regular price
$0.00
Unit price
47-89980 Water Pump Impeller for Mercury Mariner 3.5-9.8HP | Quickmarine is backordered and will ship as soon as it is back in stock.
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Description
Description
Aftermarket Outboard Cooling Replacement Part
47-89980 / 47-68988 Water Pump Impeller for Mercury & Mariner 3.5HP–9.8HP Outboards
This Quickmarine water pump impeller is an aftermarket replacement for Mercury Marine part numbers 47-89980 and 47-68988, and it also cross-references with Sierra Marine 18-3054. It is intended for selected Mercury and Mariner small outboards from the 1979–1985 model range that use a 6-blade impeller with a 0.438 inch / 11.13 mm internal shaft diameter.
Product Overview
A water pump impeller is the flexible rotating component inside an outboard lower-unit water pump. As it turns, the blades move cooling water through the engine so the powerhead can maintain a safe operating temperature. A worn, cracked, or set impeller may reduce water flow and can contribute to overheating, especially after storage or seasonal use.
This aftermarket replacement water pump impeller is designed for selected Mercury and Mariner 1-cylinder and 2-stroke outboard engines in the 3.5HP to 9.8HP range, with an additional fitment group covering certain Mercury 40 / 4HP 2-cylinder applications. The most reliable way to confirm compatibility is to match the original part number and physical measurements rather than relying on horsepower alone.
Buyer fitment rule: Before purchase, compare your old impeller against the listed OEM numbers, internal shaft diameter, outside diameter, height, and your official parts diagram. Small outboards can use different pump components across similar years and horsepower ratings.
Why Choose This Replacement Impeller?
This part is written for boat owners and marine technicians who need a clear replacement option for the Mercury 47-89980 / 47-68988 impeller family. The emphasis is on accurate fitment, practical cooling-system maintenance, and transparent aftermarket identification.
Built with Marine-Appropriate Materials
The neoprene impeller body provides flexible blade action, while the brass hub gives the center bore a stable metal contact surface for the drive shaft.
Useful for Preventive Maintenance
Impeller replacement is commonly included in seasonal lower-unit service. Replacing a suspect impeller before failure can help reduce the risk of poor tell-tale flow and heat-related troubleshooting.
Clear Cross-Reference Identification
The page lists Mercury Marine and Sierra Marine reference numbers so buyers can compare the part against manuals, exploded diagrams, previous orders, and the markings on existing components.
Part Number Cross Reference
The following numbers are provided to help identify compatible applications. Brand names and part numbers are used only as fitment references for this aftermarket replacement impeller.
| Reference Brand | Part Number | How to Use This Number |
|---|---|---|
| Mercury Marine | 47-89980 | Match against your parts diagram, previous impeller listing, or original service information. |
| Mercury Marine | 47-68988 | Alternative Mercury reference number associated with this impeller family. |
| Sierra Marine | 18-3054 | Aftermarket cross-reference number used for compatibility identification. |
Technical Specifications
Use the dimensions below as a practical confirmation checklist. The internal shaft diameter is especially important because this part is made for a 0.438 inch shaft application, not the 0.456 inch version used on some other small outboards.
| Specification | Value | Fitment Note |
|---|---|---|
| Product Type | Outboard water pump impeller | Cooling-system replacement component for compatible lower-unit water pumps. |
| Blade Count | 6 blades | Compare with the impeller removed from your pump housing. |
| Impeller Height | 14.20 mm | Measure the old impeller height before ordering if fitment is uncertain. |
| Overall Diameter | 31.91 mm | Compare outside diameter against the original part. |
| Internal Shaft Diameter | 11.13 mm / 0.438 inches | Not suitable for 0.456 inch shaft applications. |
| Material | Neoprene with brass hub | Flexible impeller body with metal center hub. |
| Net Weight | 11 g | Approximate part weight. |
| Package Contents | 1 × outboard water pump impeller | No additional gaskets, keys, plates, or housings are listed as included. |
Compatible Engine Models
This compatibility information is organized by engine group to help buyers quickly evaluate whether the impeller may match their Mercury or Mariner outboard. The final decision should always be based on the part number, official diagram, shaft diameter, and old impeller measurements.
| Engine Group / Horsepower | Year Range | Application Context | Verification Note |
|---|---|---|---|
| Mercury 3.5HP | 1983–1985 | Selected small outboard applications. | Confirm 47-89980 / 47-68988 and 0.438 inch I.D. |
| Mercury 3.6HP | 1980–1982 | Selected small outboard applications. | Confirm old impeller dimensions before ordering. |
| Mercury 40 / 4HP 2-cylinder | Various 1979–1985 | Certain Mercury 40 / 4HP 2-cylinder listings in this impeller family. | Use the parts diagram because naming can vary by market and model year. |
| Mercury 4HP 1-cylinder | Various 1979–1985 | Selected 1-cylinder applications. | Verify the shaft bore is 0.438 inch / 11.13 mm. |
| Mercury / Mariner 4.5HP | Various 1979–1985 | Selected Mercury and Mariner small outboards. | Match OEM number and measure the old component. |
| Mercury / Mariner 7.5HP | Various 1979–1985 | Selected Mercury and Mariner small outboards. | Confirm parts diagram before purchase. |
| Mercury / Mariner 9.8HP | Various 1979–1985 | Selected Mercury and Mariner small outboards. | Confirm part number and dimensions. |
Important shaft warning: This impeller is for a 0.438 inch internal shaft diameter. It is not compatible with 0.456 inch shaft applications, including some 5HP models. If your old impeller measures differently, do not assume fitment based only on horsepower.
Installation and Inspection Notes
The following notes are general maintenance guidance and are not a replacement for the official service manual for your engine. If you are unsure about lower-unit disassembly or water pump service, consult a qualified marine technician.
- Inspect related pump parts. Before installing the new impeller, check the pump housing, wear plate, gaskets, key, and cup for scoring, corrosion, or deformation.
- Lubricate for assembly. A light coating of water-compatible lubricant or soapy water can help the neoprene blades seat into the pump housing during installation.
- Install the blades in the correct rotation. Follow the rotation direction used by your pump and service literature so the impeller vanes are folded correctly.
- Do not dry run the engine. Never start the outboard without an adequate water supply. Dry running can quickly damage a new neoprene impeller.
- Check cooling flow after service. After installation, run the engine only with proper water supply and verify a steady tell-tale water stream. Shut the engine off promptly if the stream is weak or absent.
Frequently Asked Questions
How do I know if this impeller fits my Mercury or Mariner outboard?
Confirm that your engine parts diagram or old impeller calls for Mercury Marine 47-89980, Mercury Marine 47-68988, or Sierra Marine 18-3054. Then verify that the original impeller uses a 0.438 inch / 11.13 mm internal shaft diameter and matches the listed height and outside diameter.
Is this an OEM Mercury or Mariner part?
No. This Quickmarine product is an aftermarket replacement part. Mercury, Mariner, and Sierra names and part numbers are used only to identify compatible applications and are not intended to imply original equipment origin, endorsement, or affiliation.
What comes in the package?
The package includes one outboard water pump impeller made from neoprene with a brass hub. Additional water pump kit components, such as gaskets, drive keys, wear plates, cups, or housings, are not listed as included.
What are signs that an outboard impeller may need replacement?
Common warning signs include a weak or missing tell-tale stream, overheating alarms or high temperature, visible cracks or missing blade material on the old impeller, and reduced cooling flow after storage. Other cooling-system faults can cause similar symptoms, so inspect the complete pump assembly during service.
How often should a water pump impeller be replaced?
Replacement intervals vary by engine, use pattern, water conditions, storage time, and service recommendations. Many owners inspect or replace impellers during seasonal maintenance, but the safest approach is to follow your engine service manual and inspect the part whenever cooling flow appears abnormal.
Will this fit a Mercury 5HP outboard?
Do not assume fitment for a 5HP model. This impeller is specifically for 0.438 inch shaft applications and is not compatible with 0.456 inch shafts, which are found on some 5HP models. Measure the shaft bore and verify the OEM part number before ordering.
Important Compatibility and Trademark Disclaimer
This product is an aftermarket replacement water pump impeller supplied under the Quickmarine brand. It is not an OEM Mercury, Mariner, or Sierra part.
Mercury, Mariner, Sierra, and all related part numbers, model names, and trademarks are the property of their respective owners. They are referenced only to help buyers identify replacement compatibility. Quickmarine is not affiliated with, sponsored by, or endorsed by those manufacturers.
Before ordering, verify your old part, OEM number, shaft diameter, engine model, model year, and official parts diagram. Fitment can vary across similar horsepower ratings and production years.
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