Water Pump Impeller – Fits Johnson/Evinrude OMC 40 HP (Replaces 390286, 18-3366)

Water Pump Impeller – Fits Johnson/Evinrude OMC 40 HP

This water pump impeller is designed to fit Johnson/Evinrude 40 HP 2-Stroke outboard motors from model years 1974–1976 and 1981–1987.

It serves as a direct replacement for OEM and aftermarket part numbers, including OMC 390286, Sierra 18-3366, CEF 500353, Mallory 9-45212, and RCS 18-3366/183366.

• Engineered for a direct, drop-in replacement of the original part.
• Constructed from durable neoprene rubber for reliable cooling performance.
• Restores cooling system efficiency to prevent engine overheating.

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 Water Pump Impeller (390286)

Explosion Diagram

Installation Guide

Follow these steps for proper installation. Always consult your service manual for model-specific instructions.

1. Disconnect the negative battery cable before starting work.
2. Place a drain pan under the lower unit and remove the gearcase lubricant drain screw to drain the oil.
3. Remove the bolts that secure the lower unit (gearcase) to the engine's midsection.
4. Carefully slide the lower unit down and away from the engine to expose the driveshaft.
5. Unbolt and remove the water pump housing cover to access the impeller.
6. Note the rotational direction of the old impeller's vanes before removing it.
7. Remove the old impeller, gaskets, and wear plate. Clean all surfaces thoroughly.
8. Install the new gaskets and components. Lightly lubricate the interior of the housing and the new impeller with grease.
9. Insert the drive key into the shaft and slide the new impeller on, turning the driveshaft clockwise to correctly flex the vanes.
10. Reinstall the water pump housing and torque its bolts to the manufacturer's specification.
11. Reattach the lower unit to the engine, ensuring the driveshaft and water tube align correctly.
12. Refill the gearcase with the recommended lubricant and reinstall the battery cable. Test the engine in water to verify proper water flow.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my 40 HP Johnson/Evinrude engine?

A: This impeller is designed for the 40 HP 2-Stroke models from 1974-1976 and 1981-1987. Please verify your engine's model year and check the part number against the cross-reference table to ensure an exact match.

Q: What are the common signs that my water pump impeller needs replacing?

A: Key signs include engine overheating, a weak or inconsistent water stream from the "telltale" outlet, or visible cracks, stiffness, or damage to the impeller vanes during inspection.

Q: How often should I replace my water pump impeller?

A: For preventative maintenance, it is recommended to inspect your impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions (e.g., saltwater vs. freshwater).

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.