Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces 438592, 433548, 433549)

Water Pump Impeller Kit – Fits Johnson/Evinrude 40-50 HP (Replaces 438592, 433548, 433549)

This water pump impeller service kit is designed for Johnson/Evinrude 40-50 HP 2-Stroke (1989–2005) outboard engines, including 25-35 HP Jet Drive models from 1992 and up. It contains all the necessary components to service and rebuild the lower unit water pump.

This kit directly replaces Johnson/Evinrude OEM part numbers 438592, 0438592, 433548, 0433548, 433549, 0433549, 777805, 0777805 and aftermarket parts Sierra 18-3454, GLM 12245, and 18-3394.

• Complete Assembly: Includes the impeller, wear plate, cup, gaskets, o-rings, and housing for a full rebuild.
• Installation Location: Mounts on the lower unit.
• Fuel Compatibility: Designed for gasoline-powered engines.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson Serial Number Guide.

Technical Specifications

Package Contents

• 1 x Impeller (432941)
• 1 x Pump Cup/Insert Cup (340619)
• 1 x Wear Plate (341038)
• 1 x Water Pump Gasket (336530)
• 1 x Woodruff Key (334897)
• 1 x O-Ring (331188)
• 1 x O-Ring (310584)
• 1 x Seal (324981)
• 1 x Grommet (333758)
• 1 x Grommet/Adapter (331732)
• 1 x Pump Housing (438544)
• 4 x Bolt (302325)

Installation Guide

1. Safety First: Disconnect the battery and remove the ignition key. Shift the outboard into neutral.
2. Drain Gearcase Oil: Place a drain pan under the lower unit and remove the upper and lower oil drain screws to drain the gearcase lubricant.
3. Remove Lower Unit: Remove the bolts securing the lower unit (gearcase) to the upper leg of the outboard. Carefully lower the unit.
4. Access Water Pump: Unbolt and remove the old water pump housing to expose the impeller and wear plate.
5. Inspect and Clean: Remove the old impeller, plate, and gaskets. Clean all mating surfaces thoroughly, ensuring they are free of old gasket material and corrosion.
6. Install New Components: Place the new wear plate and gasket. Slide the new impeller into the pump cup with the vanes oriented correctly (typically clockwise). Install the Woodruff key before placing the impeller.
7. Reassemble Pump: Secure the new housing with the new bolts and o-rings, torquing to the manufacturer's specification.
8. Reinstall Lower Unit: Carefully guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure with bolts.
9. Refill and Test: Refill the gearcase with fresh lubricant. Reconnect the battery. Start the engine in a test tank or with a water flusher to confirm a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?
A: Verify your engine's model, horsepower, and year against the compatibility chart above. This kit is primarily a replacement for OEM part number 438592 for Johnson/Evinrude engines from 40-50 HP (1989-2005) and certain jet models. Comparing the parts in the product image to your old parts is also a reliable confirmation method.

Q: What is the difference between this kit and the original OEM part?
A: This aftermarket kit is engineered to meet or exceed original equipment manufacturer (OEM) standards. Notably, some versions feature an improved sealed bearing design that eliminates the need to align the grease hole found on older models, which can simplify the installation process.

Q: What are the symptoms of a failing water pump impeller?
A: The most common signs include the engine overheating, a weak or intermittent water stream from the engine's tell-tale outlet, or a complete lack of water flow. Upon inspection, a worn impeller may have cracked, brittle, or missing vanes.

Q: How often should I replace the water pump impeller?
A: For preventative maintenance, it is recommended to inspect and replace the water pump impeller every 1 to 2 years or every 100-200 hours of operation. Frequency should be increased if the engine is used in saltwater or in water with high levels of sand or silt.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.