119578-42360 Alternator Belt for Yanmar 6LY3-UTC 6LY3-STP 6LY3-UTP 6LY3-STC 6LY3-ETP | JLM Marine

119578-42360 Alternator Belt for Yanmar 6LY3-UTC 6LY3-STP 6LY3-UTP 6LY3-STC 6LY3-ETP

This alternator belt is designed specifically for Yanmar 6LY3 series marine diesel engines, including the UTC, STP, UTP, STC, and ETP variants. Engineered to deliver reliable power transmission from the engine to the alternator, this belt ensures consistent charging performance for your marine electrical system.

This component serves as a direct replacement for OEM part number 119578-42360, providing dependable compatibility with your Yanmar inboard engine.

• Precise fit for Yanmar 6LY3 engine family
• Ensures reliable alternator drive and battery charging
• Direct OEM specification replacement

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

Your package includes the following components:

• 1 × V Belt (Alternator Belt 119578-42360)

Installation Guide

1. Ensure the engine is off and cool before beginning work. Disconnect the battery to prevent accidental startup.
2. Locate the alternator and identify the belt routing path around the pulleys. Take a photo for reference if needed.
3. Release tension on the old belt by loosening the alternator adjustment bolt and pivot bolt. Slide the alternator toward the engine block to create slack.
4. Remove the old belt from the pulleys and inspect all pulleys for wear, damage, or debris.
5. Route the new belt around the crankshaft pulley and alternator pulley following the correct path. Ensure the belt seats properly in each groove.
6. Move the alternator outward to apply proper tension to the belt. The belt should deflect approximately ½ inch (13 mm) when pressed firmly midway between pulleys.
7. Tighten the alternator adjustment bolt first, then secure the pivot bolt to lock the alternator in position.
8. Rotate the crankshaft by hand two full revolutions to confirm the belt tracks correctly and does not slip off.
9. Reconnect the battery and start the engine. Listen for any unusual noises and verify the alternator is charging properly.
10. Re-check belt tension after the first hour of operation and adjust if necessary.

Troubleshooting & FAQ

Q: How do I confirm this belt fits my Yanmar 6LY3 engine?
A: Verify your engine model matches one of the following: 6LY3-UTC, 6LY3-STP, 6LY3-UTP, 6LY3-STC, or 6LY3-ETP. Cross-reference the OEM part number 119578-42360 with your engine manual or existing belt.

Q: How often should I replace the alternator belt?
A: Inspect the belt every 200 hours of operation or annually. Replace immediately if you notice cracking, fraying, glazing, or excessive wear. Preventive replacement every 2–3 years or 500–800 hours is recommended.

Q: What are signs that my alternator belt is failing?
A: Common symptoms include squealing noises during startup or acceleration, battery warning light illumination, electrical system malfunctions, visible cracks or shiny glazed surfaces on the belt, and poor battery charging performance.

Q: How tight should the alternator belt be?
A: The belt should have approximately ½ inch (13 mm) of deflection when pressed firmly at the midpoint between pulleys. Over-tightening can damage bearings; under-tightening causes slippage and poor charging.

Q: Is this an OEM belt or an aftermarket replacement?
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.