Sea Water Pump – Fits Yanmar 2GM20/3GM30 Series (Replaces 128377-42500, 128397-42500)

Sea Water Pump – Fits Yanmar 2GM20/3GM30 Series

This high-quality sea water pump assembly is a direct replacement for Yanmar GM-YEU series marine diesel engines, specifically the European-built models manufactured between 1996 and 2004, which are identifiable by an "E" prefix on the engine serial number.

It is engineered to directly replace Yanmar part numbers 128377-42500, 128397-42500, and 128990-42510, as well as multiple Johnson Pump references. This component ensures reliable raw water circulation for proper engine cooling.

• Installation: Mounts directly to the engine block as a complete assembly for a straightforward OEM replacement.
• Fuel Type: Designed for use with diesel engines.
• Ready to Install: Comes with a pre-installed impeller for your convenience.

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.

Technical Specifications

Package Contents

• 1 x Sea Water Pump with Bracket
• 1 x Impeller (653-0001) pre-installed inside the pump.

Installation Guide

1. Safety First: Disconnect the vessel's battery and close the raw water intake seacock.
2. Access the Pump: Locate the sea water pump on the engine block.
3. Disconnect Hoses: Loosen the hose clamps and carefully detach the intake and outlet hoses from the pump.
4. Remove Old Pump: Unfasten the mounting bolts securing the pump to the engine. Gently remove the old pump assembly.
5. Prepare Surface: Clean the engine mounting surface and inspect it for any damage or old gasket material.
6. Install New Pump: Position the new sea water pump, ensuring it aligns correctly with the mounting holes.
7. Secure Pump: Hand-tighten the mounting bolts first, then torque them to the manufacturer's recommended specification.
8. Reconnect Hoses: Attach the raw water hoses to the new pump and secure them firmly with the hose clamps.
9. Final Checks: Open the raw water seacock and reconnect the battery.
10. Test for Leaks: Start the engine and immediately check the pump and hose connections for any signs of water leaks. Confirm water is exiting the exhaust.

Troubleshooting & FAQ

Q: How do I confirm this pump fits my engine?

A: This pump is specifically for Yanmar GM-YEU series engines (2GM20 & 3GM30) built in Europe from 1996-2004. You can verify this by checking if your engine's serial number starts with an "E". Please compare the part numbers and photos to your existing pump before ordering.

Q: What are the symptoms of a failing sea water pump?

A: Common signs include the engine overheating, a noticeable reduction in water flow from the exhaust, or visible water leaks around the pump housing or weep holes. A damaged impeller is a frequent cause of failure.

Q: How often should the impeller be replaced?

A: The included impeller (653-0001) should be inspected at least once a year and replaced every 1-2 years as part of regular maintenance, or as recommended in your Yanmar service manual. Operating in sandy or debris-heavy water may require more frequent changes.

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. Brand names and part numbers are used for reference purposes only.
• 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.