Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces Sierra 18-3454, Johnson/Evinrude 438592, 433548, 433549, 777805)
Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces Sierra 18-3454, Johnson/Evinrude 438592, 433548, 433549, 777805) 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 Kit – Fits Johnson/Evinrude 40-50 HP (Replaces ...
Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces Sierra 18-3454, Johnson/Evinrude 438592, 433548, 433549, 777805) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces 438597) is engineered for Johnson/Evinrude 2-stroke outboard motors, including 40, 45, 48, and 50 HP models manufactured between 1989 and 1998. It is designed as a direct replacement for engines equipped with the small housing variant, ensuring proper cooling system function.
It serves as a direct interchange for Sierra 18-3454, and Johnson/Evinrude part numbers 438592, 433548, 433549, and 777805.
- Installation Method: Direct OEM Replacement
- Key Components: Includes housing, impeller, wear plate, and gaskets
- Impeller Design: Features a durable 3-vane impeller
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Sierra | 18-3454 |
| Johnson/Evinrude | 438597 |
| Johnson/Evinrude | 438592 |
| Johnson/Evinrude | 433548 |
| Johnson/Evinrude | 433549 |
| Johnson/Evinrude | 777805 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Outboard | 40 | 2-Stroke | 1989–1998 | 438592 | Small Housing |
| Johnson/Evinrude | Outboard | 48 | 2-Stroke | 1986–1989 | 438592 | |
| Johnson/Evinrude | Outboard | 50 | 2-Stroke | 1989–1998 | 438592 | Small Housing |
| Johnson/Evinrude | Outboard | 25 Jet | 2-Stroke | 1995-Up | 438592 | |
| Johnson/Evinrude | Outboard | 30 Jet | 2-Stroke | 1995-Up | 438592 |
Technical Specs
- Product Type
- Water Pump Impeller Kit with Housing
- Installation
- Direct OEM Replacement
- Housing Material
- Plastic/Nylon
- Housing Color
- Black
- Fitting Type
- Direct OEM Fitment
- Other Technical Attributes
- 3-Vane Impeller Design
What’s in the Box
- 1 x Impeller (18-3104-1)
- 1 x Housing (OEM equivalent)
- 1 x O-Ring
- 1 x Gasket
- 1 x Wear Plate
- 1 x Insert Cartridge
- 1 x Water Seal/Grommet
Installation Notes
- Disconnect the battery and spark plug wires for safety.
- Place the outboard gear selector in the neutral position.
- Remove the lower unit (gearcase) from the outboard by unbolting it.
- Unbolt and remove the old water pump housing assembly from the driveshaft.
- Clean all mating surfaces, removing any old gasket material or sealant.
- Slide the new impeller onto the driveshaft, ensuring the key is properly aligned.
- Install the new gasket, wear plate, housing, and seals from the kit.
- Torque the housing bolts to the manufacturer's specifications.
- Reinstall the lower unit, ensuring the driveshaft and shift shaft are correctly aligned.
- Once assembled, test the engine with a water supply to verify proper pump operation.
Troubleshooting & FAQ
How do I know if this kit fits my engine?
Verify your outboard's model, horsepower, and year against the compatibility chart. This kit is specifically for the "small housing" variants of 40 HP and 50 HP engines from 1989–1998. Always check your existing parts to confirm the housing size.
What are the signs of a failing water pump impeller?
Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "telltale" outlet, and a dry, brittle, or cracked impeller with missing vanes upon visual inspection.
How often should I replace my impeller?
For preventative maintenance, it is recommended to replace the impeller every 1-2 years or 100-200 hours of use, whichever comes first. Frequency should increase if operating in sandy, silty, or saltwater conditions.
Is the housing included in this kit?
Yes, this is a complete water pump rebuild kit that includes the impeller, housing, wear plate, gaskets, o-rings, and other components required for a full replacement.
What tools are needed for installation?
You will typically need a basic socket/wrench set, screwdrivers, a gasket scraper or plastic blade, and marine-grade grease. A torque wrench is recommended to ensure bolts are tightened to the correct specification.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
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 (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs 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 QC.
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