Sea Water Pump for Yanmar 2GMF, 3GMF, 2YM & 3YM Engines – Replaces 128397-42500, 128990-42500, 128397-42501 & 128377-42500
Sea Water Pump for Yanmar 2GMF, 3GMF, 2YM & 3YM Engines – Replaces 128397-42500, 128990-42500, 128397-42501 & 128377-42500 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Sea Water Pump for Yanmar 2GMF, 3GMF, 2YM & 3YM Engines – Repla...
Sea Water Pump for Yanmar 2GMF, 3GMF, 2YM & 3YM Engines – Replaces 128397-42500, 128990-42500, 128397-42501 & 128377-42500 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Sea Water Pump, also called a raw water pump, is intended for the seawater cooling systems used on selected Yanmar marine diesel engines. It is listed for Yanmar 2GMF, 3GMF, 2YM and 3YM high-speed engine applications.
The pump is identified as an aftermarket replacement associated with JMP part number JPR-YM08IH and is also listed with SPX Flow Johnson Pumps references F4B-903, 10-24509-01 and 10-13337-01. Yanmar reference numbers listed for this pump include 128397-42500, 128990-42500, 128397-42501 and 128377-42500.
- Replacement sea water pump for selected Yanmar marine diesel engines.
- Designed for raw-water circulation in the engine cooling system.
- Sold as one pump assembly; this listing does not specify an included impeller or separate installation kit.
Part Number Matrix
Use the following manufacturer and aftermarket references to compare the pump with your existing part before ordering. Part-number listings should be confirmed against the engine model and the original pump.
| Brand or source | Part Number | Reference type |
|---|---|---|
| Yanmar | 128397-42500 | OEM reference |
| Yanmar | 128990-42500 | OEM reference |
| Yanmar | 128397-42501 | OEM reference |
| Yanmar | 128377-42500 | OEM reference |
| JMP | JPR-YM08IH | Aftermarket reference |
| SPX Flow Johnson Pumps | F4B-903 | Manufacturer reference |
| SPX Flow Johnson Pumps | 10-24509-01 | Manufacturer reference |
| SPX Flow Johnson Pumps | 10-13337-01 | Manufacturer reference |
Engine Compatibility
The company catalog identifies this pump for the following Yanmar high-speed engine applications. Verify the complete engine model and the pump mounting pattern against your original part before installation.
| Brand | Engine model | Application | Stroke | OEM references |
|---|---|---|---|---|
| Yanmar | 2GMF | Sea raw water pump | Not specified | 128397-42500, 128990-42500, 128397-42501, 128377-42500 |
| Yanmar | 3GMF | Sea raw water pump | Not specified | 128397-42500, 128990-42500, 128397-42501, 128377-42500 |
| Yanmar | 2YM | Sea raw water pump | Not specified | 128397-42500, 128990-42500, 128397-42501, 128377-42500 |
| Yanmar | 3YM | Sea raw water pump | Not specified | 128397-42500, 128990-42500, 128397-42501, 128377-42500 |
Technical Specifications
- Product type
- Sea water pump / raw water pump
- Product configuration
- Single pump assembly, not specified as a kit
- Application
- Marine diesel engine seawater cooling system
- Aftermarket reference
- JPR-YM08IH
- Manufacturer references
- F4B-903, 10-24509-01 and 10-13337-01
- Included impeller
- Not specified; inspect the product received and confirm the contents before installation
What's in the Box
- 1 x Sea Water Pump assembly
An impeller, key, gasket, bracket or other separate installation parts are not specified as included in the company product record. Confirm the package contents before beginning installation.
Installation Notes
- Close the raw-water seacock and allow the engine to cool completely.
- Place a container below the pump to catch residual water.
- Label and remove the inlet and outlet hoses, then inspect the hoses and clamps for wear.
- Remove the mounting fasteners securing the pump to the engine.
- Remove the old pump and clean the mounting surface.
- Compare the replacement pump with the original pump, including the mounting points, shaft orientation and hose connections.
- Install the replacement pump with the correct seal or gasket for the application. Do not reuse damaged sealing components.
- Tighten the mounting fasteners according to the engine manufacturer's specifications.
- Reconnect the hoses and secure the clamps.
- Open the raw-water seacock before starting the engine.
- Start the engine and immediately check for leaks and visible raw-water discharge. Stop the engine if the pump does not prime or if leakage occurs.
Troubleshooting & FAQ
How do I confirm that this pump fits my Yanmar engine?
Confirm that your engine is one of the listed Yanmar models: 2GMF, 3GMF, 2YM or 3YM. Also compare the original pump, mounting arrangement, hose connections and one or more of the listed reference numbers before ordering.
Does this pump fit 2GM20 or 3GM30 engines?
The company record for this product identifies 2GMF, 3GMF, 2YM and 3YM applications. It does not specifically confirm 2GM20, 2GM20C, 3GM30 or 3GM30C fitment, so those models should not be treated as confirmed applications from this listing alone.
Is an impeller included?
The company record identifies this product as a single sea water pump and does not state that an impeller is included. Do not assume that an impeller, key or gasket is supplied; verify the package contents before installation.
What are common signs of a failing sea water pump?
Common symptoms can include reduced raw-water flow, engine overheating, visible leakage around the pump or weep area, abnormal noise and impeller damage. Inspect the complete raw-water circuit before replacing the pump.
How often should the impeller be replaced?
Inspect and service the impeller according to the engine manufacturer's maintenance schedule. Replace it sooner if it is cracked, hardened, damaged or missing vanes, and verify that the pump is properly primed after service.
Is this an OEM pump?
This listing is for an aftermarket replacement pump, not a Yanmar-branded OEM component. The listed Yanmar and pump-manufacturer numbers are reference numbers used to help compare the application.
What should I check before ordering?
Confirm the complete engine model, compare the original pump and mounting arrangement, and check the reference numbers. If the original part differs in mounting, shaft or connection details, contact the seller before ordering.
Safety & Important Information
- Close the raw-water seacock before removing the pump and reopen it before operating the engine.
- Never operate the engine without confirming that the raw-water system is open, connected and supplying water.
- Verify the engine model, original pump and reference numbers before purchase.
- This is an aftermarket replacement, not a Yanmar OEM component.
- Professional installation is recommended when the pump, cooling system or engine fitment is uncertain.
About Sea Sierra
- Marine replacement parts — Practical replacement components for marine cooling and engine systems.
- Application-focused listings — Product references and engine applications are provided to help you compare the replacement with your original part.
- Support before installation — Contact support if you need help comparing the engine model, pump references or package contents.
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