Engine Cooling Pump – Fits Yanmar 3JH4/5 & 4JH4/5 Series (Replaces 129271-42502)
Engine Cooling Pump – Fits Yanmar 3JH4/5 & 4JH4/5 Series (Replaces 129271-42502) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Engine Cooling Pump – Fits Yanmar 3JH4/5 & 4JH4/5 Series (Repla...
Product Details
This is a direct replacement Engine Cooling Pump for Yanmar 3JH4, 3JH5, 4JH4, and 4JH5 series marine diesel engines, including models 4JH5E, 3JH4E, 4JH4E, 4JH4AE, 3JH5E, 4JH45, 4JH57, 4JH80, and 4JH110. It is engineered with a bronze housing for reliable performance in raw water/seawater environments.
It serves as a direct interchange for Yanmar part 129271-42502 and aftermarket references from Johnson Pump (10-13328-01, 10-13328-03) and JMP Marine (JPR-YM04JHB).
- Designed for direct OEM replacement installation.
- Features a self-priming, flexible impeller design for high flow capacity.
- Includes pump, neoprene impeller, drive gear, and mounting gasket.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| Yanmar | 129271-42502 | Current Part | |
| Yanmar | 129271-42501 | 129271-42502 | |
| Yanmar | 129271-42500 | 129271-42502 | |
| Johnson Pump | 10-13328-01 | Aftermarket Interchange | |
| Johnson Pump | 10-13328-03 | Aftermarket Interchange | |
| JMP Marine | JPR-YM04JHB | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model in the table below.
This pump is designed for the following Yanmar marine diesel engines.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Yanmar | 3JH4E | 4-Stroke | 129271-42502 | |
| Yanmar | 3JH5E | 4-Stroke | 129271-42502 | |
| Yanmar | 4JH4E | 4-Stroke | 129271-42502 | |
| Yanmar | 4JH4AE | 4-Stroke | 129271-42502 | |
| Yanmar | 4JH5E | 4-Stroke | 129271-42502 | |
| Yanmar | 4JH45 | 45 | 4-Stroke | 129271-42502 |
| Yanmar | 4JH57 | 57 | 4-Stroke | 129271-42502 |
| Yanmar | 4JH80 | 80 | 4-Stroke | 129271-42502 |
| Yanmar | 4JH110 | 110 | 4-Stroke | 129271-42502 |
Technical Specs
- Product Type
- Raw Water / Seawater Engine Cooling Pump
- Installation
- Direct OEM replacement
- Connection
- Hose ports
- Housing Material
- Bronze
- Housing Color
- Bronze (natural)
- Dimensions
- 20.0cm x 16.0cm x 15.0cm (L x W x H)
- Weight
- 2.50 kg (5.5 lbs)
- Fitting Type
- Hose ports
- Warranty
- 90 days (varies by manufacturer/seller)
- Other Technical Attributes
- Self-priming, flexible impeller pump with high volume flow capacity
What’s in the Box
- 1 x Engine Cooling Pump (129271-42502)
- 1 x Neoprene Impeller (129670-42530/129670-42531)
- 1 x Drive Gear
- 1 x Mounting Gasket
Installation Notes
- Close the engine's raw water intake seacock.
- Place a suitable container under the pump to catch any drained coolant.
- Loosen the hose clamps and carefully remove the intake and outlet hoses from the pump.
- Remove the mounting bolts securing the pump to the engine block.
- Gently detach the old pump. You may need to lightly tap it to break the gasket seal.
- Thoroughly clean the engine mounting surface to remove all old gasket material and corrosion.
- Position the new gasket on the engine block, aligning it with the mounting holes.
- Install the new pump, ensuring the drive gear meshes correctly. Tighten the mounting bolts to the manufacturer's specified torque.
- Reconnect the hoses and tighten the clamps securely.
- Open the raw water seacock.
- Start the engine and immediately check for any leaks around the pump body, gasket, and hoses.
- Monitor the engine temperature to ensure the cooling system is functioning correctly.
Troubleshooting & FAQ
How do I know if this pump will fit my specific engine?
This pump fits Yanmar JH series engines as listed in the compatibility table. The most reliable way to confirm fitment is to match your existing pump's part number to one of the references in our Part Number Matrix. If you are unsure, please contact us with your engine's model and serial number before ordering.
What are the signs of a failing raw water pump?
Common signs include the engine overheating at normal operating speeds, reduced water flow from the exhaust outlet, visible water leaks from the pump body (especially the weep holes), or a damaged or missing impeller upon inspection.
How often should the impeller be replaced?
For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years, or sooner depending on usage hours and water conditions. Always replace an impeller that shows signs of cracking, brittleness, or worn blades.
Is this pump difficult to install?
For those with mechanical experience, installation is straightforward. It involves draining the system, removing the old pump, cleaning the mounting surface, and installing the new unit with the provided gasket. However, we recommend professional installation if you are not familiar with marine engine maintenance.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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