Water Pump Impeller – Fits Johnson/Evinrude OMC 10-25 HP (Replaces 375638, 389646, 775518)

$13.99

Shipping calculated at checkout.

Water Pump Impeller – Fits Johnson/Evinrude OMC 10-25 HP (Replaces 375638, 389646, 775518) is backordered and will ship as soon as it is back in stock.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This is a direct replacement Water Pump Impeller – Fits Johnson/Evinrude OMC 10-25 HP (Replaces 375638, 389646, 775518) for 2-stroke outboard models produced between 1949 and 1978. It is engineered to meet or exceed original equipment specifications, ensuring reliable cooling performance for your marine engine.

It interchanges with Johnson/Evinrude numbers 375638, 389646, 775518, and 777829, as well as aftermarket equivalents from Sierra (18-3002), Mallory (9-45215), GLM (89650), and CEF (500351).

Designed for direct OEM replacement install.
Features a 6-blade flexible rubber impeller with a keyed driveshaft insert.
Engineered for durability in both freshwater and saltwater environments.

Part Number Matrix

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

Brand	Part Number
Johnson/Evinrude	375638
Johnson/Evinrude	389646
Johnson/Evinrude	775518
Johnson/Evinrude	777829
Sierra	18-3002
Mallory	9-45215
GLM	89650
CEF	500351

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Note: While this part is widely cross-referenced, always verify the specifications against your existing impeller, as some models within a year range may use a different part.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Johnson	Multiple	10 HP	2-Stroke	1949–1957	375638
Johnson/Evinrude	Multiple	15 HP	2-Stroke	1953–1965	375638
Johnson/Evinrude	Multiple	18 HP	2-Stroke	1953–1965, 1968–1970	375638
Johnson/Evinrude	Multiple	20 HP	2-Stroke	1966–1973	375638
Johnson/Evinrude	Multiple	25 HP	2-Stroke	1969–1978	375638
Johnson/Evinrude	Multiple	30 HP	2-Stroke	1970–1978	375638	Some sources include this HP rating
Johnson/Evinrude	Multiple	35 HP	2-Stroke	1970–1978	375638	Some sources include this HP rating

Technical Specs

Product Type: Water Pump Impeller
Installation: Direct OEM replacement
Connection: Driveshaft mounting
Dimensions: Outer Diameter: 69.2-69.37 mm; Inner Diameter: 12.7-12.8 mm; Depth/Height/Width: 12.8-12.9 mm
Weight: 41 g
Fitting Type: 6-blade rubber impeller
Warranty: Varies by manufacturer
Other Technical Attributes: 6 blades; internal shaft insert/hub diameter: 12.7mm

What’s in the Box

1 x Water Pump Impeller (375638/389646/775518)

Installation Notes

Disconnect the spark plug wires and shift the outboard into neutral.
Locate and remove the bolts securing the lower unit (gearcase) to the engine's midsection.
Carefully lower the gearcase away from the engine. The driveshaft will disengage from the powerhead.
Locate the water pump housing on top of the gearcase and remove its mounting bolts.
Lift the housing to expose the old impeller. Note the direction of the blades.
Remove the old impeller, key, and any gaskets or plates. Clean all mating surfaces thoroughly.
Install the new key and position the new impeller. Lightly lubricate the housing interior with marine grease.
To install the impeller, turn the driveshaft clockwise while pushing the housing down. This will correctly orient the blades.
Reinstall the housing bolts and torque to manufacturer specifications.
Raise the lower unit, align the driveshaft splines, and re-secure the gearcase bolts.
Reconnect spark plug wires and test the engine in a suitable water source, verifying strong water flow from the tell-tale outlet.

Troubleshooting & FAQ

How can I confirm this impeller fits my exact engine?

The most reliable method is to compare your old impeller's dimensions and blade count to the specs listed here. While the compatibility table is accurate for most models, manufacturers sometimes made mid-year changes. Always verify physically.

What are the signs of a failing water pump impeller?

Common symptoms include a weak or non-existent stream of water from the "tell-tale" cooling outlet, an engine overheating alarm, or steam from the exhaust. Do not run the engine if you suspect a cooling issue.

How often should this part be replaced?

For preventative maintenance, it is recommended to inspect impellers annually and replace them every 1 to 2 years. Replacement frequency depends on usage hours, water conditions (salt vs. fresh), and the amount of sand or silt in the water.

AIN

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

Payment methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.