Water Pump Impeller – Fits Johnson/Evinrude 3–7.5 HP 2-Stroke Outboards (Replaces 277181, 434424)
Water Pump Impeller – Fits Johnson/Evinrude 3–7.5 HP 2-Stroke Outboards (Replaces 277181, 434424) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Impeller – Fits Johnson/Evinrude 3–7.5 HP 2-Stroke Outbo...
Product Details
This Water Pump Impeller – Fits Johnson/Evinrude 3–7.5 HP 2-Stroke Outboards (Replaces 277181, 434424) is designed for a range of Johnson and Evinrude 2-stroke outboard engines, covering models from 3 HP to 7.5 HP manufactured between 1952 and 1983. It serves as a crucial component for maintaining proper engine cooling.
This part is a direct interchange for Sierra 18-3001 and Mallory 9-45216.
- For installation, please follow the guidance in your engine's service manual.
- Designed for gasoline-fueled outboard engines.
- Features a 6-blade design precision-machined for reduced vibration and noise.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 277181 |
| Johnson/Evinrude | 434424 |
| Sierra | 18-3001 |
| Mallory | 9-45216 |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Various | 3 | 2-Stroke | 1952–1978 | 277181/434424 | |
| Johnson/Evinrude | Various | 4 | 2-Stroke | 1969–1972 | 277181/434424 | |
| Johnson/Evinrude | Various | 4 | 2-Stroke | 1973–1983 | 277181/434424 | For water pumps using 1 water tube, 110 gearcase |
| Johnson/Evinrude | Various | 5 | 2-Stroke | 1965–1968 | 277181/434424 | |
| Johnson/Evinrude | Various | 5.5 | 2-Stroke | 1954–1964 | 277181/434424 | |
| Johnson/Evinrude | Various | 6 | 2-Stroke | 1952–1978 | 277181/434424 | |
| Johnson/Evinrude | Various | 7.5 | 2-Stroke | 1954–1958 | 277181/434424 |
Technical Specs
- Product Type
- Water Pump Impeller
- Material
- Neoprene rubber
- Number of Blades
- 6
- Dimensions
- Height: 6.0 in; Width: 7.13 in; Length: 0.5 in
- Weight
- 41 g (1.45 oz)
- Other Technical Attributes
- Water cooling system component; precision machined for reduced vibration and noise
- Warranty
- 1-year against manufacturing defects
What’s in the Box
- 1 x Water Pump Impeller (Replaces 277181/434424)
Installation Notes
- Disconnect the spark plug leads and battery cables for safety.
- Place the outboard motor in neutral and remove the lower unit (gearcase) bolts.
- Carefully lower and remove the gearcase assembly.
- Locate and unbolt the water pump housing cover.
- Inspect the housing, wear plate, and seals for damage, scoring, or corrosion.
- Slide the old impeller off the driveshaft, removing the drive key.
- Clean all mating surfaces and components thoroughly.
- Install the new drive key and lubricate the new impeller with a suitable marine lubricant.
- Slide the new impeller onto the driveshaft while turning the shaft clockwise to correctly orient the blades.
- Reassemble the pump with new gaskets and reinstall the housing.
- Reattach the lower unit to the outboard, ensuring all tubes and shafts align correctly.
- Once assembled, test the engine in water to confirm a steady stream from the cooling system outlet.
Troubleshooting & FAQ
How do I confirm this impeller fits my specific motor?
This impeller is made for Johnson/Evinrude 3 HP to 7.5 HP 2-stroke outboards from 1952–1983. To guarantee a match, check your original part number against 277181 or 434424. Also, review the compatibility table, paying special attention to the note for 4 HP models (1973–1983), which requires a specific gearcase configuration.
What are the signs of a worn or failed impeller?
Key indicators include the engine running hotter than normal, a weak or intermittent water stream from the tell-tale outlet, or finding brittle, cracked, or missing blades upon visual inspection of the water pump.
How often should this part be replaced?
As a best practice for preventative maintenance, we recommend replacing your water pump impeller every 100 operating hours or at least once per season, whichever comes first. More frequent changes may be needed if you operate in silty, sandy, or saltwater conditions.
My 4 HP Johnson is a 1976 model. Is this the right part?
It is likely correct, but you must verify your engine's configuration. For the 4 HP range from 1973–1983, this impeller fits water pumps that use a single water tube and are part of the '110' gearcase. Check your engine's service manual or existing setup to confirm before ordering.
Is there a correct way to install the impeller blades?
Yes. When inserting the new impeller into the pump housing, you must turn the driveshaft clockwise. This motion will naturally bend the impeller blades in the correct direction for proper water circulation when the engine is running.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and reliability.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
This part is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window for unused items in their original condition. See our 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 quality control.
Payment & Security
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