Water Pump Impeller – Fits Johnson/Evinrude 40-50 HP (Replaces 432941, 0437059, 18-3104)

$21.00

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Water Pump Impeller – Fits Johnson/Evinrude 40-50 HP (Replaces 432941, 0437059, 18-3104) is backordered and will ship as soon as it is back in stock.

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Product Details

This Water Pump Impeller – Fits Johnson/Evinrude 40-50 HP (Replaces 432941) provides a reliable solution for Johnson/Evinrude 2-stroke outboard motors, specifically 40-50 HP models manufactured between 1989 and 1994.

It serves as a direct interchange for Johnson/Evinrude parts 0432941 and 0437059, Sierra 18-3104, GLM 89790, CEF 500372NC, and Mercury 878838.

Installation: Direct OEM Replacement
Material: Durable Neoprene with a Brass Insert
Blades: Engineered with 6 blades for optimal water flow

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Johnson/Evinrude	0432941
Johnson/Evinrude	0437059
Sierra	18-3104
GLM	89790
CEF	500372NC
Mercury	878838

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Johnson/Evinrude owners, this table details compatible models and years. Cross-reference your engine's information to ensure a correct fit.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Johnson/Evinrude	40 HP	40	2-Stroke	1989–1994	432941
Johnson/Evinrude	48 HP	48	2-Stroke	1989–1996	432941
Johnson/Evinrude	50 HP	50	2-Stroke	1989–1994	432941
Johnson/Evinrude	35 HP Jet	35	2-Stroke	1992–1993	432941
Johnson/Evinrude	40-70 HP	40-70	2-Stroke	1989–2002	432941/437059	Based on JLM Marine data

Technical Specs

Product Type: Water Pump Impeller
Installation: Direct OEM Replacement
Blades: 6
Material: Neoprene with Brass Insert
Dimensions: Height: 19.13 mm (0.75 in), Diameter: 91.3 mm (3.59 in), Hub Diameter: 25.4 mm (1 in)
Fitting Type: Direct Fit

What’s in the Box

1 x Water Pump Impeller (432941)

Installation Notes

Disconnect the battery and remove the engine cowling.
Place a drain pan under the lower unit and remove the drain/fill plugs to drain the gearcase oil.
Remove the bolts securing the lower unit (gearcase) to the upper engine housing.
Carefully lower and separate the gearcase from the driveshaft housing.
Locate the water pump housing. Remove its mounting bolts and slide it up the driveshaft.
Remove the old impeller, noting the direction of the blades. You may need to remove a key or pin.
Clean the inside of the housing and the wear plate of any debris or corrosion.
Lightly lubricate the new impeller and the inside of the housing with marine grease or soapy water.
Install the new impeller onto the driveshaft, turning the shaft clockwise to bend the blades correctly as you slide the housing down over them.
Reinstall the water pump housing and torque its bolts to the manufacturer's specification.
Reassemble the lower unit to the engine, ensuring the driveshaft, shift shaft, and water tube align correctly.
Refill the gearcase with the correct type and amount of oil before starting the engine.

Troubleshooting & FAQ

How can I confirm this impeller fits my specific engine?

Always check the part numbers listed in the "Part Number Matrix" against your service manual or existing part. While the "Engine & Model Compatibility" table is a strong guide, part numbers are the most accurate way to guarantee fitment, accommodating for any mid-year production changes.

What are the signs of a worn or failing impeller?

Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent "tell-tale" water stream, or a visible decrease in water pressure on a gauge. A brittle, cracked, or deformed impeller upon inspection confirms the need for replacement.

How often should I replace the water pump impeller?

As a best practice, impellers should be inspected annually and replaced every 1–2 years, regardless of appearance. For boats used in saltwater or sandy/silty conditions, annual replacement is strongly recommended to prevent unexpected failure.

My engine still overheats after installing the new impeller. What else could be wrong?

If overheating persists, check for other blockages in the cooling system. Common culprits include clogged thermostats, debris in the water intake screens, blockages in the water passages within the engine block, or a worn-out water pump housing that prevents a proper seal.

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

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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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