Water Pump Impeller – Fits Johnson Evinrude OMC BRP 10-30 HP Outboard Motors
This aftermarket water pump impeller is designed to fit Johnson, Evinrude, OMC, and BRP outboard motors ranging from 10 HP to 30 HP. It provides reliable cooling system performance for engines manufactured between 1949 and 1978, ensuring your outboard operates at optimal temperatures.
This impeller directly replaces OEM part numbers 375638, 389646, 775518, and Sierra 18-3002. It is manufactured to OEM specifications and offers dependable water flow for a wide range of vintage Johnson and Evinrude outboard models.
- Features 6 durable rubber blades for efficient water pumping
- Includes drive key/pin for complete installation
- Precision-molded to exact OEM dimensions for proper fit and seal
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Johnson / Evinrude |
375638 |
| Johnson / Evinrude |
389646 |
| Johnson / Evinrude |
775518 |
| OMC / BRP |
389642 |
| Sierra |
18-3002 |
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.
| Brand |
Rated HP |
Years |
| Johnson / Evinrude |
10 HP |
1949-1957 |
| Johnson / Evinrude |
15 HP |
1953-1965 |
| Johnson / Evinrude |
18 HP |
1953-1965, 1968-1970 |
| Johnson / Evinrude |
20 HP |
1966-1973 |
| Johnson / Evinrude |
25 HP |
1969-1978 |
| Johnson / Evinrude |
30 HP |
1970-1978 |
Technical Specifications
| Specification |
Value |
| Number of Blades |
6 |
| Depth / Height / Width |
13.08 mm |
| Outer / External Impeller Overall Diameter |
69.37 mm |
| Internal Shaft Insert / Hub Diameter |
12.68 mm |
| Net Weight |
42 g |
Package Contents
- 1 × Outboard Rubber Impeller with Key / Pin
Installation Guide
- Disconnect the fuel line and remove the engine cover to access the lower unit. Ensure the engine is off and cool before starting.
- Remove the propeller and drain gear oil from the lower unit according to your engine's service manual.
- Unbolt and carefully separate the lower unit from the mid-section housing. Mark alignment points for reassembly.
- Locate the water pump housing on top of the lower unit and remove the retaining bolts.
- Carefully remove the old impeller from the pump housing, noting the direction of the blades. Inspect the housing and plate for wear or damage.
- Lubricate the new impeller with water pump grease or glycerin to prevent dry-start damage.
- Install the drive key/pin into the impeller hub, ensuring it is properly seated.
- Insert the new impeller into the pump housing, aligning the key with the drive shaft slot. Rotate blades in the correct direction during installation.
- Reinstall the pump housing cover and base plate, ensuring all gaskets are properly positioned and seal surfaces are clean.
- Reattach the lower unit to the mid-section, aligning previously marked points. Torque all bolts to manufacturer specifications.
- Refill the lower unit with the correct grade and amount of gear oil. Reinstall the propeller and torque the prop nut properly.
- Test the cooling system by running the engine in a test tank or on muffs, verifying strong water flow from the telltale outlet.
Troubleshooting & FAQ
Q: How do I confirm this impeller fits my specific Johnson or Evinrude engine?
A: Cross-reference your engine's horsepower and year with the compatibility table above. Verify your original impeller matches the OEM part numbers 375638, 389646, or 775518, and confirm the physical dimensions match your current impeller before ordering.
Q: How often should I replace my water pump impeller?
A: Most manufacturers recommend replacing the impeller every 2-3 years or every 200-300 hours of operation, whichever comes first. If you frequently operate in sandy or silty water, inspect and replace more often.
Q: What are the signs that my impeller is failing?
A: Common symptoms include weak or no water flow from the telltale outlet, engine overheating, steam from the engine, reduced cooling performance, or visible damage such as missing or cracked blades when inspected.
Q: Can I install this impeller myself or do I need a mechanic?
A: If you have basic mechanical skills and the proper tools, you can install this yourself following your engine's service manual. However, proper torque specifications and gasket sealing are critical, so professional installation is recommended if you're unsure.
Q: What's the difference between this aftermarket impeller and the original OEM part?
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?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.