Alternator V-Belt – Fits Yanmar 4JH4 Series Marine Diesel Engines (Replaces 129671-42280E, 129671-42280)

Alternator V-Belt – Fits Yanmar 4JH4 Series Marine Diesel Engines

This high-quality alternator V-belt is engineered to fit Yanmar 4JH4 series marine diesel engines, including models ranging from 75 to 110 HP manufactured since 2006. It ensures reliable power transmission from the crankshaft to the alternator, which is critical for maintaining your boat's electrical systems.

Designed as a direct replacement for OEM parts, this belt meets or exceeds original equipment specifications for fit, form, and function. It serves as a direct cross for Yanmar part numbers 129671-42280E and 129671-42280, as well as Mitsuboshi RECMF-6455.

• Compatible with Yanmar 4JH4-E, 4JH4-TE, 4JH4-HTE, and 4JH4-HTE1 marine engines.
• Engineered for durability in demanding marine environments.
• Includes one (1) replacement alternator V-belt.

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 129671-42280E, 129671-42280)

Installation Guide

1. Safety First: Disconnect the engine's battery terminals to prevent accidental starting.
2. Locate the Belt: Identify the alternator and the V-belt connecting it to the engine's crankshaft pulley.
3. Release Tension: Loosen the alternator's pivot bolt and the tensioning bolt or adjusting bracket. This will allow you to move the alternator and slacken the belt.
4. Remove Old Belt: Carefully slip the old belt off the pulleys. Take this opportunity to inspect the pulleys for damage, rust, or misalignment.
5. Route New Belt: Install the new belt, ensuring it sits correctly in the grooves of all pulleys as per the engine diagram.
6. Apply Tension: Pry the alternator away from the engine to apply tension to the belt. A rule of thumb is about 1/2 inch (13mm) of deflection when pressed firmly at the longest span.
7. Tighten Bolts: While maintaining tension, tighten the tensioning bolt and then the main pivot bolt to secure the alternator in place.
8. Final Check: Reconnect the battery, start the engine, and observe the belt. Ensure it runs smoothly without squealing or wobbling.

Troubleshooting & FAQ

How do I confirm this V-belt is the right one for my Yanmar 4JH4 engine?
This belt replaces Yanmar part numbers 129671-42280E and 129671-42280. To ensure a perfect fit, please cross-reference your existing part number and check the "Compatible Engine Models" table above, paying close attention to your specific model (e.g., 4JH4-E, 4JH4-TE) and any serial number restrictions noted.

What are the signs that my alternator belt needs replacing?
Common signs of a failing belt include visible cracks, fraying, or a glazed, shiny appearance on the belt surface. You might also hear a high-pitched squealing sound from the engine, especially on startup or when under load. Dimming lights or a battery warning indicator can also point to a slipping belt that is preventing the alternator from charging properly.

How often should I replace my engine's alternator belt?
Replacement intervals depend on engine hours and operating conditions. We recommend inspecting the belt during every routine engine service and replacing it every few hundred hours or as soon as signs of wear appear. Always consult your Yanmar engine's service manual for specific maintenance schedules.

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.