Water Pump Impeller – Fits Johnson/Evinrude OMC 40 HP (Replaces 390286, 18-3366)
Water Pump Impeller – Fits Johnson/Evinrude OMC 40 HP (Replaces 390286, 18-3366) 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 – Fits Johnson/Evinrude OMC 40 HP (Replaces 390...
Water Pump Impeller – Fits Johnson/Evinrude OMC 40 HP (Replaces 390286, 18-3366) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Water Pump Impeller is a direct-fit replacement for Johnson/Evinrude 40 HP 2-Stroke outboard engines from model years 1974–1976 and 1981–1987. It is engineered to meet original equipment specifications for reliable cooling performance.
This part interchanges with several OEM and aftermarket part numbers, including OMC 390286, Sierra 18-3366, CEF 500353, and Mallory 9-45212.
- Designed for simple, drop-in installation.
- Made from durable neoprene rubber for a long service life in marine environments.
- Includes one impeller as pictured.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| OMC | 390286 |
| Sierra | 18-3366 |
| CEF | 500353 |
| Mallory | 9-45212 |
| RCS | 18-3366/183366 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Johnson/Evinrude/OMC models, see details below to ensure this part fits your specific outboard.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Outboard | 40 | 2-Stroke | 1974–1976 | 390286 | |
| Johnson/Evinrude | Outboard | 40 | 2-Stroke | 1981–1987 | 390286 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Drop-in replacement
- Material
- Neoprene Rubber
- Compatibility
- Johnson/Evinrude/OMC Outboards
- Dimensions
- Same as OEM
- Other Technical Attributes
- Standard impeller design
What’s in the Box
- 1 x Water Pump Impeller (390286)
Installation Notes
- Disconnect the battery and shift linkage.
- Unbolt and remove the lower unit (gearcase).
- Remove the water pump housing bolts and slide the housing up.
- Remove the old impeller, noting the vane direction if applicable.
- Clean the housing interior and inspect for wear or damage.
- Lightly lubricate the new impeller and housing with marine grease.
- Install the new impeller into the housing, turning the driveshaft clockwise to bend the vanes correctly.
- Reinstall the housing, gaskets, and keyway.
- Reattach the lower unit, ensuring the water tube and driveshaft align.
- Securely tighten all bolts and reconnect the shift linkage.
Troubleshooting & FAQ
How can I be sure this impeller fits my 40 HP engine?
This impeller is designed for Johnson/Evinrude 40 HP 2-stroke outboards from 1974–1976 and 1981–1987. Please verify your engine's model and year against the compatibility chart. It replaces OEM part 390286.
How often should a water pump impeller be replaced?
For preventative maintenance, it is recommended to inspect and/or replace your impeller every 1-2 years or every 100-200 hours of use, especially if operating in saltwater or sandy/silty conditions.
What are the signs of a failing impeller?
Common signs include an engine that is overheating, a weak or non-existent water stream from the "tell-tale" port, or finding damaged impeller fragments in the cooling system.
Do the vanes need to be bent in a certain direction during installation?
Yes. When installing the impeller into the pump housing, turn the driveshaft clockwise to ensure the vanes bend in the correct direction for proper water flow.
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.
Payment & Security
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