Main Bearing (Standard) – Fits Yanmar 3TNE/3TNV/4TNE/4TNV Series (Replaces 129001-02931)
Main Bearing (Standard) – Fits Yanmar 3TNE/3TNV/4TNE/4TNV Series (Replaces 129001-02931) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Main Bearing (Standard) – Fits Yanmar 3TNE/3TNV/4TNE/4TNV Series (R...
Product Details
This is a standard main bearing for various Yanmar industrial and marine engines, including the 3TNE84, 3TNE88, 3TNV88, 4TNE84, 4TNE88, 4TNV84T, and 4TNV88 series. It also fits marine models such as the 3JH3E, 3JH4E, 3JH5E, 4JH4E, and 4JH5E, ensuring reliable performance for your engine's crankshaft assembly.
This part is a direct replacement for Yanmar part numbers 129001-02931 and 129001-02930.
- Installation Location: Engine Block Crankshaft Journal
- Size: Standard (STD)
- Warranty: Backed by a 6-month genuine Yanmar part warranty.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 129001-02931 |
| Yanmar | 129001-02930 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Yanmar | 3TNE84 | 4-Stroke | 129001-02931 | |
| Yanmar | 3TNE88 | 4-Stroke | 129001-02931 | |
| Yanmar | 3TNV88 | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNE84 | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNE88 | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV84T | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88 | 4-Stroke | 129001-02931 | |
| Yanmar | 3JH3E | 4-Stroke | 129001-02931 | |
| Yanmar | 3JH3E-YEU-E | 4-Stroke | 129001-02931 | |
| Yanmar | 3JH4E | 4-Stroke | 129001-02931 | |
| Yanmar | 3JH5AE | 4-Stroke | 129001-02931 | |
| Yanmar | 3JH5E | 4-Stroke | 129001-02931 | |
| Yanmar | 4JH4E | 4-Stroke | 129001-02931 | |
| Yanmar | 4JH4AE | 4-Stroke | 129001-02931 | |
| Yanmar | 4JH5E | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDHQ | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDHQ(T) | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDSA | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDSA(T) | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDSAC | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDSA2 | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDSA2T | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDWI | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BDYE | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BNYE883 | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BNYE883T | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-BPHB | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-GNP | 4-Stroke | 129001-02931 | |
| Yanmar | 4TNV88-XMS | 4-Stroke | 129001-02931 | |
| Komatsu | PC30MR-2, PC35MR-2, PC40MR-2 | 4-Stroke | 129001-02931 | Mini Excavators |
| Komatsu | PC45MR-3, PC50MR-2, PC55MR-3 | 4-Stroke | 129001-02931 | Mini Excavators |
| Komatsu | SK714, SK815, SK820 | 4-Stroke | 129001-02931 | Skid Steers |
| Gehl | 3640E, 4240E | 4-Stroke | 129001-02931 | Skid Steers |
| Takeuchi | TB135, TB145 | 4-Stroke | 129001-02931 | Compact Excavators |
| Kobelco | SK45SR-2, SK50UR-3 | 4-Stroke | 129001-02931 | Excavators |
Technical Specs
- Product Type
- Standard Main Bearing
- Installation
- Engine Block Crankshaft Journal
- Dimensions
- 5.5" L x 5.5" W x 2.0" H
- Weight
- 0.1 lbs (0.045 kg)
- Warranty
- 6 months (Genuine Yanmar part)
- Other Technical Attributes
- Standard Size (STD)
What’s in the Box
- 1 x Main Bearing (129001-02931)
Installation Notes
- Ensure the engine is turned off and has completely cooled. Disconnect the battery.
- Access the engine's crankshaft by removing the oil pan and any other necessary components.
- Carefully unbolt and remove the main bearing caps, keeping them in order.
- Remove the old main bearing halves from the engine block and caps.
- Thoroughly clean the crankshaft journals and bearing saddles. Inspect journals for any scoring or wear.
- Apply assembly lube to the new bearing halves and isntall them into the block and caps.
- Reinstall the bearing caps in their original positions and torque the bolts to the manufacturer's specifications.
- Ensure the crankshaft rotates smoothly by hand before reinstalling other components.
Troubleshooting & FAQ
How do I know if this is the correct size bearing for my engine?
This is a "Standard" (STD) size bearing. If your crankshaft has been machined or ground, you may need an undersize bearing. Always measure your crankshaft journals with a micrometer and consult your engine's service manual to confirm the required bearing size before ordering.
What are common signs of a failing main bearing?
Symptoms of main bearing failure include a deep, rhythmic knocking or rumbling sound from the engine that increases with RPM, low oil pressure readings, and the presence of metallic particles (bearing material) in the engine oil during an oil change.
Is this a single bearing or a complete engine set?
This listing is for a single main bearing. Depending on your engine, you will need multiple bearings to complete a full replacement. Please check your service manual for the exact quantity required.
Can I replace just one faulty main bearing?
While it is possible, it is highly recommended to replace all main bearings at the same time. If one bearing has failed, others are likely worn and may fail soon. Replacing them as a set ensures consistent clearances and long-term engine reliability.
What is the typical lifespan of a main bearing?
With proper lubrication and under normal operating conditions, main bearings can last the lifetime of the engine. Lifespan can be reduced by poor maintenance, oil contamination, low oil levels, or extreme operating conditions.
Does this bearing require special lubrication during installation?
Yes, it is critical to use a high-quality assembly lube on the bearing surface and crankshaft journal during installation. This protects the components from scoring during the initial engine startup before normal oil pressure is established.
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.
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