Alternator V-Belt – Fits Yanmar 4JH Series Marine Diesel Engines (Replaces 25132-004600)

Alternator V-Belt – Fits Yanmar 4JH Series Marine Diesel Engines (Replaces 25132-004600)

This high-quality alternator V-belt is designed for a wide range of Yanmar 4JH series 4-stroke marine diesel engines, including popular models like the 4JH2, 4JH3, 4JH-TE, and 4JH-HTE. It serves as a reliable replacement for belts on fresh water cooled engines, ensuring your alternator operates efficiently to keep your batteries charged.

This part is a direct replacement for several OEM and aftermarket part numbers, including Yanmar 25132-004600 and 25132-004600E, REMF 6460, and the Gates Green Stripe A46. It is engineered to meet or exceed original equipment specifications for a dependable fit and long-lasting performance.

• Installation Method: Engine-driven belt for the alternator.
• Belt Profile: Standard A46 V-belt profile with an approximate outside length of 48" (1220mm).
• Construction: Made from durable rubber with a reinforced core to resist stretching and wear.

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 V-Belt (Replaces 25132-004600)

Installation Guide

1. Safety First: Ensure the engine is completely cool and turned off. Disconnect the boat's battery terminals to prevent accidental starting.
2. Access the Belt: Open the engine compartment to gain clear access to the front of the engine where the alternator and pulleys are located.
3. Release Tension: Locate the alternator's pivot bolt and tensioning bolt. Loosen both bolts just enough to allow the alternator to pivot and release tension from the old belt.
4. Remove Old Belt: Carefully slip the old belt off the alternator pulley and the crankshaft pulley.
5. Inspect Pulleys: Before installing the new belt, check the pulleys for any signs of damage, rust, or misalignment. Clean the grooves if necessary.
6. Install New Belt: Route the new belt around the crankshaft pulley and the alternator pulley, making sure it is properly seated in the grooves.
7. Apply Tension: Using a pry bar or tensioning tool, carefully pivot the alternator outwards to apply tension to the new belt. Consult your engine's service manual for the correct belt tension specification (typically about 1/2 inch of deflection).
8. Tighten Bolts: While maintaining tension, tighten the alternator's adjustment and pivot bolts securely.
9. Final Check: Re-check the belt tension. Reconnect the battery, start the engine, and listen for any unusual noises. Ensure the belt runs smoothly without slipping.

Troubleshooting & FAQ

Q: How do I confirm this belt fits my Yanmar 4JH engine?
A: Verify that your engine model is listed in the compatibility table above. The most reliable method is to match the OEM part number 25132-004600 with your existing belt or service manual. Please note the specific year restriction for the 4JH4-TE model, as this belt only fits models built up to July 2006.

Q: Why is the new belt so tight to install?
A: A snug fit is normal for a new V-belt. Some users report a very tight installation, which can be due to variations in alternator mounting positions or slight differences in aftermarket belt manufacturing. Ensure the alternator tensioner is fully loosened before attempting installation. Do not force the belt on, as this can damage the belt or pulleys.

Q: What are the signs my alternator belt needs replacement?
A: Common indicators of a failing belt include loud squealing noises from the engine (especially on startup), visible cracks or fraying on the belt's surface, a glazed or shiny appearance, or a battery that is not charging properly (indicated by a warning light or low voltage reading).

Q: Is this belt the same as a Gates Green Stripe belt?
A: This belt is a direct cross-reference to the Gates Green Stripe A46, which is a well-regarded, high-quality aftermarket option that many boat owners use as a replacement for the original Yanmar belt.

Q: OEM vs. Aftermarket?
A: 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.

Q: How fast do you ship and how much does it cost?
A: 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.

Q: What is your warranty and return policy?
A: 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.