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 comprehensive water pump impeller kit is designed for Johnson/Evinrude 2-Stroke outboard engines from 40-50 HP (1989–2005), including specific jet drive models. It contains all necessary components to perform a complete service or rebuild of the lower unit water pump assembly, restoring cooling performance and reliability.

This kit is a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for the specified engine range. It addresses common wear and failure points in the cooling system.

• Installation Location: Lower Unit
• Included Components: Full kit with impeller, housing, plate, gaskets, seals, and hardware.
• Primary Material: Housing is constructed from durable plastic with brass inserts for longevity.

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/Evinrude Serial Number Guide.

Technical Specifications

Package Contents

• 1 x Pump Housing (438544)
• 1 x Impeller (432941)
• 1 x Wear Plate (341038)
• 1 x Pump Cup/Insert Cup (340619)
• 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)
• 4 x Bolt (302325)

Installation Guide

1. Disconnect the battery and shift linkage. Unbolt and remove the lower unit from the engine assembly.
2. Locate the water pump housing on the top of the lower unit. Note the orientation of the bolts for reassembly.
3. Unscrew the four bolts securing the water pump housing and carefully lift the housing off the driveshaft.
4. Slide the old impeller off the driveshaft. Remove the Woodruff key, old wear plate, gaskets, and seals.
5. Thoroughly clean all mating surfaces, ensuring they are free of old gasket material, salt deposits, and corrosion.
6. Install the new seals, gaskets, and wear plate from the kit onto the lower unit.
7. Apply a light coat of marine grease or dish soap to the inside of the new impeller housing cup for lubrication.
8. Slide the new Woodruff key into its slot on the driveshaft.
9. Align the new impeller with the key and slide it down. Rotate the driveshaft clockwise while lowering the housing to seat the impeller blades correctly inside the cup.
10. Re-install the pump housing, making sure all components are correctly aligned. Tighten the bolts to the manufacturer's specified torque.
11. Re-attach the lower unit to the engine, reconnect the shift linkage, and secure all bolts.
12. Reconnect the battery. Test the engine in a suitable water source to verify proper water flow from the tell-tale port.

Troubleshooting & FAQ

How do I confirm this kit fits my specific Johnson/Evinrude engine?
Check the "Compatible Engine Models" table on this page. Match your engine's brand, model, horsepower, and year range. This kit is for 40-50 HP 2-stroke models from 1989-2005 and replaces OEM part number 438592. Note that it is the "small housing" design.

What are the signs that my water pump impeller needs replacing?
Common signs include the engine overheating at idle or low speeds, a weak or inconsistent stream of water from the "tell-tale" port, or if the impeller has not been replaced in over a year or 100 hours of use.

My engine is listed, but what does "Small Housing" mean?
For certain model years, Johnson/Evinrude used different water pump housing sizes. This kit is specifically for the "small housing" design. Please verify against your existing part or an engine diagram if you are unsure which version your outboard uses.

Can I install just the impeller instead of the whole kit?
While the impeller is a primary wear item, it is highly recommended to replace the entire assembly, including the housing, wear plate, cup, and gaskets. This prevents leaks from old seals and ensures all components wear evenly, prolonging the life of the repair.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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.