Major Rebuild Kit – Fits Yanmar 2GM, 3GM Series (Replaces 128377-42500, 128397-42500)

Major Rebuild Kit – Fits Yanmar 2GM, 3GM Series (Replaces 128377-42500, 128397-42500)

This high-quality sea water pump major rebuild kit is designed for specific Yanmar marine diesel engines. It is engineered to fit the GM-YEU European-built series manufactured between 1996 and 2004, which are identifiable by an E-prefix serial number.

This kit serves as a direct replacement for several Yanmar and Johnson part numbers, ensuring a precise fit and reliable performance for compatible sea water pumps.

• Installation: Direct OEM-style replacement for a straightforward installation.
• Compatibility: Designed specifically for pumps with a 6-bolt cover measuring 76mm (3") in diameter.
• Complete Kit: Includes all necessary components for a major overhaul, such as the impeller, bearings, seals, O-rings, and end cover.

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 Water Pump Impeller (128991-42200/128990-42200)
• 1 x Pump End Cover O-ring (X02173476)
• 1 x Slinger O-ring (X02173432)
• 1 x Retaining Ring (X00370012)
• 1 x Retaining Ring (X00371732)
• 1 x Spacer Plate (X0145050)
• 1 x Bearing (X03431760)
• 1 x Bearing (X03431748)
• 1 x SS Screws Set (X0504163)
• 1 x Lip Seal (X02233010)
• 1 x End Cover (X0142398/128990-42540)

Installation Guide

1. Safety First: Before starting, ensure the engine is off and cool. Close the sea cock to prevent water from entering the boat.
2. Access the Pump: Locate the sea water pump on the engine and remove any guards or hoses blocking access. Place a rag underneath to catch any spilled coolant.
3. Remove the Old Pump Cover: Unscrew the six bolts holding the end cover in place. Carefully pry off the cover.
4. Extract the Old Impeller: Using pliers or an impeller puller tool, remove the old impeller from the pump housing.
5. Disassemble the Pump: Remove the retaining rings, bearings, and seals from the pump housing. Note their orientation for reassembly.
6. Clean and Inspect: Thoroughly clean the pump housing, cover, and all contact surfaces. Inspect for any cracks, scoring, or excessive wear.
7. Install New Components: Install the new bearings, lip seal, and retaining rings from the kit in the reverse order of disassembly.
8. Install the New Impeller: Lightly lubricate the new impeller and housing interior with a suitable marine lubricant. Insert the new impeller, bending the blades in the correct rotational direction.
9. Install the New Cover: Place the new gaskets/O-rings and install the new end cover. Secure it with the new stainless steel screws, tightening them in a star pattern to ensure an even seal.
10. Final Checks: Reconnect all hoses. Open the sea cock. Start the engine and immediately check for any leaks around the pump.

Troubleshooting & FAQ

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

A: This kit is specifically for the European-built Yanmar 2GM-YEU and 3GM-YEU series engines manufactured between 1996 and 2004. A key identifier is an "E" prefix on your engine's serial number. The pump this kit services has a 6-bolt cover with a 76mm (3") diameter. Please verify these details against your engine and existing pump.

Q: Is this kit compatible with Japanese-built Yanmar GM engines?

A: No, this kit is designed exclusively for the European-built models (-YEU). The pumps on Japanese-built models are different. Please double-check your engine's model and serial number before ordering.

Q: What are common signs that my sea water pump needs a rebuild?

A: Common signs of failure include the engine overheating at idle or low speeds, visible water leaks from the pump itself (weep holes), reduced water flow from the exhaust, or a damaged or brittle impeller found during routine inspection. It is recommended to inspect your impeller annually and replace it as a preventative measure.

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?

• 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.