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

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.

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.