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)

This alternator V-belt is designed for reliable power transmission in Yanmar 2GM and 3GM series four-stroke marine diesel engines manufactured between 1980 and 2005. It ensures your alternator functions correctly to charge the battery and power your vessel's electrical systems.

This is a direct replacement for Yanmar part numbers 25132-003000 and 25132-00300.

• Installation Location: Engine alternator/generator drive
• Belt Dimensions: 790 mm (Length) x 13 mm (Width)
• Type: Smooth (non-toothed) V-belt for diesel engines

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 x Alternator V-Belt (Replaces 25132-003000)

Installation Guide

1. Disconnect the negative terminal of the battery to ensure safety.
2. Locate the alternator on the engine and identify the tensioner assembly and pivot bolts.
3. Loosen the alternator's tensioning bolt to release the tension on the old V-belt.
4. Once slack, carefully slip the old belt off the alternator and crankshaft pulleys.
5. Inspect the pulleys for any signs of damage, rust, or misalignment before proceeding.
6. Route the new V-belt around the pulleys, ensuring it is seated correctly in the grooves.
7. Apply tension to the new belt by adjusting the alternator. The belt should have approximately 1/2 inch (13mm) of deflection when pressed firmly.
8. Securely tighten the tensioning and pivot bolts to lock the alternator in place.
9. Reconnect the battery, start the engine, and listen for abnormal noises while checking that the belt is running smoothly.

Troubleshooting & FAQ

How do I confirm this V-belt fits my Yanmar engine?
This belt is specifically designed for Yanmar 2GM and 3GM series engines, including popular models like the 2GM20, 3GM30, 2GMF, and 3GM30F. The best way to ensure compatibility is to verify your engine model is listed in our "Compatible Engine Models" table and that it replaces OEM part number 25132-003000.

What are the signs my alternator belt needs replacement?
Common signs of a failing V-belt include visible cracks, fraying, glazing on the surface, or splitting. You may also hear a persistent high-pitched squealing from the engine bay, or notice dimming lights and battery charging issues, which indicate the alternator is not being driven effectively.

What are the dimensions of this belt?
This V-belt has a length of 790 mm and a width of 13 mm. It is a smooth (non-cogged) V-belt, as specified for these Yanmar engine applications.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.