Alternator V-Belt – Fits Yanmar 2GM, 3GM Marine Diesel Engines (Replaces 25132-003000)
Alternator V-Belt – Fits Yanmar 2GM, 3GM Marine Diesel Engines (Replaces 25132-003000) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Alternator V-Belt – Fits Yanmar 2GM, 3GM Marine Diesel Engines (Rep...
Alternator V-Belt – Fits Yanmar 2GM, 3GM Marine Diesel Engines (Replaces 25132-003000) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Alternator V-Belt – Fits Yanmar 2GM, 3GM Marine Diesel Engines (Replaces 25132-003000) is designed for reliable power transmission on various Yanmar marine diesel engines. It fits the 2GM, 2GM20, 3GM, and 3GM30 series four-stroke models manufactured between 1980 and 2005.
It serves as a direct replacement for Yanmar part numbers 25132-003000 and 25132-00300.
- Installation: Mounts on the engine's alternator/generator drive.
- Dimensions: 790 mm (Length) x 13 mm (Width).
- Included: One smooth (non-toothed) alternator V-belt.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 25132-003000 |
| Yanmar | 25132-00300 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This belt is confirmed to fit the following Yanmar marine diesel engines.
| Brand | Model | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Yanmar | 2GM | 4-Stroke | 1980–1983 | 25132-003000 | |
| Yanmar | 2GM20 | 4-Stroke | 1983–2005 | 25132-003000 | |
| Yanmar | 2GM20-YEU | 4-Stroke | 1997-present | 25132-003000 | |
| Yanmar | 2GMF | 4-Stroke | 1980–1983 | 25132-003000 | Fresh Water Cooled |
| Yanmar | 2GM20F | 4-Stroke | 1983–2005 | 25132-003000 | Fresh Water Cooled |
| Yanmar | 3GM | 4-Stroke | 1980–1983 | 25132-003000 | |
| Yanmar | 3GM30 | 4-Stroke | 1983–2005 | 25132-003000 | Serial numbers beginning with "E" |
| Yanmar | 3GMF | 4-Stroke | 1980–1983 | 25132-003000 | Fresh Water Cooled |
| Yanmar | 3GM30F | 4-Stroke | 1983–2005 | 25132-003000 | Fresh Water Cooled |
Technical Specs
- Product Type
- V-Belt (Alternator)
- Installation
- Engine alternator/generator drive
- Fuel Type
- Diesel
- Dimensions
- 790 mm (Length); 13 mm (Width)
- Housing Color
- Black
- Other Technical Attributes
- No tooth system (smooth V-belt)
What’s in the Box
- 1 x Alternator V-Belt (Replaces 25132-003000)
Installation Notes
- Ensure the engine is off and the battery is disconnected.
- Loosen the alternator's pivot and tensioning bolts to create slack.
- Carefully remove the old, worn V-belt from the pulleys.
- Install the new V-belt, ensuring it is properly seated in the pulley grooves.
- Apply tension to the belt. A general rule is allowing about 1/2 inch (13 mm) of deflection with firm thumb pressure at the longest span.
- Tighten the alternator's tensioning and pivot bolts securely.
- Reconnect the battery and start the engine to check for proper operation and listen for abnormal noises.
Troubleshooting & FAQ
How do I know if this V-belt is correct for my engine?
This belt fits a specific range of Yanmar 2GM and 3GM series engines. The most reliable method is to check your engine's model and serial number against the compatibility table above. If your original part is a Yanmar 25132-003000 or 25132-00300, this is a direct cross-reference.
What are the signs of a failing alternator belt?
Common signs include a loud squealing sound from the engine bay (especially on startup or under load), visible cracks or fraying on the belt, a glazed or shiny appearance on the belt’s surfaces, or a loss of charging capability from the alternator.
How often should an alternator belt be replaced?
There is no fixed interval, as it depends on engine hours, operating conditions, and belt tension. We recommend inspecting the belt during every routine service for signs of wear. Consult your Yanmar service manual for specific guidance.
Is this belt toothed or smooth?
This is a smooth (non-toothed) V-belt, as specified for the listed Yanmar applications.
How can I ensure the correct belt tension during installation?
Proper tension is crucial. If too loose, it will slip and squeal. If too tight, it will put excessive strain on the alternator and water pump bearings. A common guideline is allowing for approximately 1/2 inch (13 mm) of flex when you press firmly on the longest span of the belt. Always refer to your engine's service manual for official specifications.
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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