Water Pump Impeller – Fits Evinrude Johnson 2–6 HP (Replaces 387361, 763735)
This water pump impeller is designed for specific Evinrude Johnson outboard engines, including 2 HP (1985–1990), 4 HP (1976–1980) models with a 90-degree gearcase, and 6 HP (1979) models. It provides a reliable direct replacement fit to restore your engine's cooling system performance.
This part directly replaces Johnson/Evinrude part numbers 387361, 763735, and 777831; Sierra 18-3090; and Mallory 9-45210.
- Features six durable rubber blades with a brass insert for longevity.
- Designed for direct OEM replacement for a straightforward installation.
- Engineered to provide reliable cooling system operation and prevent overheating.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
Brand |
Part Number |
Johnson/Evinrude |
387361 |
Johnson/Evinrude |
763735 |
Johnson/Evinrude |
777831 |
Sierra |
18-3090 |
Mallory |
9-45210 |
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.
Brand |
Model |
Rated HP |
Stroke |
Years |
OEM Part No. |
Notes |
Johnson/Evinrude |
2 Jr, Colt |
2 HP |
2-Stroke |
1985-1990 |
387361, 763735 |
|
Johnson/Evinrude |
Outboard |
4 HP |
2-Stroke |
1976-1980 |
387361, 763735 |
90 degree gearcase only |
Johnson/Evinrude |
Outboard |
6 HP |
2-Stroke |
1979 |
387361, 763735 |
|
Technical Specifications
Specification |
Value |
Product Type |
Water Pump Impeller |
Installation |
Direct OEM replacement |
Housing Material |
Rubber with brass insert |
Dimensions |
38.27–38.8 mm external diameter × 17.82–18.6 mm height (1.5 inch diameter) |
Weight |
33–40 g |
Number of Blades |
6 |
Internal Shaft Insert Diameter |
11.2–11.23 mm |
Other Technical Attributes |
Brass center insert for durability |
Package Contents
- 1 x Water Pump Impeller (Replaces 387361/763735)
- 1 x Impeller Key (Please note: The key is included in most packages but is not guaranteed. Please verify if your application requires a new key.)
Installation Guide
Professional installation is recommended. The general steps are outlined below:
-
Disconnect the spark plug leads and shift the outboard into neutral.
-
Remove the lower unit (gearcase) by undoing the mounting bolts. Be prepared for it to drop.
- Locate the water pump assembly on top of the gearcase. Unbolt and remove the pump housing cover.
- Slide the old impeller off the driveshaft. If it's stuck, you may need to carefully cut it off.
- Clean any debris or corrosion from the housing interior and pump plates.
-
Lightly grease the new impeller with marine grease and slide it onto the driveshaft, turning the shaft clockwise to bend the vanes correctly.
- Install the new impeller key if required for your model.
- Reinstall the water pump housing and torque the bolts to the manufacturer's specification.
- Re-attach the lower unit to the engine, ensuring the driveshaft and water tube align correctly.
- Reconnect spark plug leads, start the engine in water, and confirm a steady stream of water from the tell-tale port.
Troubleshooting & FAQ
Q: How do I confirm this impeller fits my engine?
A: First, check your original part number against our "Part Number Cross-Reference" table. This part replaces OEM numbers 387361, 763735, and 777831. Second, consult the "Compatible Engine Models" table to verify your exact model and year range. For the 4 HP model, ensure you have the 90-degree gearcase.
Q: What are the common signs that my impeller needs replacing?
A: The most common sign of a failing impeller is your engine overheating. Other indicators include a weak or intermittent water stream from the "tell-tale" outlet port. During a visual inspection, a worn impeller may have cracked, brittle, or missing vanes.
Q: How often should I replace my water pump impeller?
A: As a general rule, we recommend inspecting your impeller annually and replacing it every 1-2 years or every 100-200 hours of use, whichever comes first. If you frequently operate in saltwater or sandy/murky water, you should replace it more often.
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?
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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.