Oil Pump Gasket – Fits Yanmar 3JH3 Series Marine Engines (Replaces 129120-35121)
Oil Pump Gasket – Fits Yanmar 3JH3 Series Marine Engines (Replaces 129120-35121) is backordered and will ship as soon as it is back in stock.
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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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Oil Pump Gasket – Fits Yanmar 3JH3 Series Marine Engines (Replaces ...
Product Details
This high-quality Oil Pump Gasket is designed for a precise fit on Yanmar 3JH3 series marine diesel engines, including models 3JH3, 3JH3E, and 3JH3E-YEU from the mid-2000s.
It serves as a direct replacement for Yanmar part number 129120-35121 and aftermarket equivalents.
- Installation: Direct replacement for a secure, leak-free seal.
- Material: Made from a durable, heat and oil-resistant composite material.
- Included: Essential gasket for oil pump service or replacement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 129120-35121 |
| Aftermarket | REC129120-35121 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yanmar Marine engines, this part is confirmed to fit the 3JH3 series.
| Brand | Model | Stroke | OEM Part No. |
|---|---|---|---|
| Yanmar | 3JH3 | 4-Stroke | 129120-35121 |
| Yanmar | 3JH3E | 4-Stroke | 129120-35121 |
| Yanmar | 3JH3E-YEU | 4-Stroke | 129120-35121 |
Technical Specs
- Product Type
- Oil Pump Gasket
- Installation
- Direct replacement
- Material
- Heat and oil-resistant composition
- Dimensions
- 10.0" L x 7.0" W x 0.1" H
- Operating Temperature
- Designed for marine diesel engine operating temperatures
- Other Technical Attributes
- Precision-cut for exact OEM fit
What’s in the Box
- 1 x Oil Pump Gasket (Replaces 129120-35121)
Installation Notes
- Ensure the engine is off, cool, and the battery is disconnected. Drain the engine oil.
- Locate and remove the oil pump from the engine block, noting the position of all fasteners.
- Carefully remove the old gasket. Thoroughly clean both the pump and engine mating surfaces, ensuring they are free of old gasket material, oil, and debris.
- Place the new gasket into position. Do not use any sealant unless specified by the engine manufacturer.
- Reinstall the oil pump and tighten the fasteners to the manufacturer's recommended torque specifications in the correct sequence.
- Refill the engine with new oil, reconnect the battery, and check for leaks after starting the engine.
Troubleshooting & FAQ
How do I know if this gasket will fit my engine?
This gasket is specifically for Yanmar 3JH3, 3JH3E, and 3JH3E-YEU marine engines. Cross-reference your engine model and original part number (129120-35121) to confirm compatibility.
What are the signs of a failing oil pump gasket?
Common signs include visible oil leaks around the oil pump, a low oil pressure warning, or an engine that is overheating due to poor lubrication.
Do I need to use sealant with this gasket?
Generally, no. This gasket is designed to create a seal on its own. Always follow the specific instructions in your Yanmar service manual, but applying sealant is not typically required.
What is the difference between this aftermarket gasket and the OEM part?
This is an aftermarket replacement part, not an OEM component. It has been engineered to meet or exceed OEM specifications for fit, material composition, and performance, offering a reliable alternative at a better value.
How often should the oil pump gasket be replaced?
The gasket should be replaced any time the oil pump is removed for service or inspection. There is no fixed replacement interval otherwise, but it should be inspected for leaks during routine maintenance.
Can I install this gasket myself?
While installation is possible for those with mechanical experience, we recommend professional installation to ensure a proper seal and prevent potential engine damage.
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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