Alternator V-Belt – Fits Yanmar 6LY3-Series Marine Engines (Replaces 119578-42360)

$19.99 $31.00

Shipping calculated at checkout.

Alternator V-Belt – Fits Yanmar 6LY3-Series Marine Engines (Replaces 119578-42360) is backordered and will ship as soon as it is back in stock.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This high-quality Alternator V-Belt is engineered as a direct-fit replacement for Yanmar 6LY3-series marine diesel engines, including the STC, STP, UTC, UTP, and ETP models. It ensures your alternator functions correctly to power your vessel's electrical systems.

This part is a direct cross-reference for Yanmar part number 119578-42360.

Installs as a direct OEM-spec replacement.
Crafted from durable, fiber-reinforced rubber for reliable performance.
Package includes one new alternator belt.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.

Brand	Part Number
Yanmar	119578-42360

Engine & Model Compatibility

Confirm your engine model in the table below. This belt is specifically for the Yanmar 6LY3 engine series.

Brand	Model	Stroke	OEM Part No.
Yanmar	6LY3-UTC	4-Stroke	119578-42360
Yanmar	6LY3-STP	4-Stroke	119578-42360
Yanmar	6LY3-UTP	4-Stroke	119578-42360
Yanmar	6LY3-STC	4-Stroke	119578-42360
Yanmar	6LY3-ETP	4-Stroke	119578-42360

Technical Specs

Product Type: Alternator V-Belt
Installation: Direct OEM replacement
Fuel Type Compatibility: Diesel
Material: Rubber with fiber reinforcement
Belt Profile: V-belt

What’s in the Box

1 x Alternator Belt (119578-42360)

Installation Notes

Disconnect the negative battery terminal to prevent electrical hazards.
Locate the alternator and loosen its pivot and tensioning bolts.
Pivot the alternator to release tension from the old belt.
Remove the old belt and inspect the pulleys for wear or damage.
Route the new belt over the pulleys in the correct orientation.
Apply tension to the belt according to your engine's service manual (a general rule is about 1/2 inch of deflection under firm thumb pressure).
Securely tighten the tensioning and pivot bolts.
Reconnect the battery, start the engine, and listen for any unusual noises while checking for proper belt operation.

Troubleshooting & FAQ

How do I know if this belt fits my engine?

This belt is specifically designed for the Yanmar 6LY3-series. You can confirm fitment by matching your engine model to the compatibility table or by verifying this part replaces OEM number 119578-42360.

How many belts do I need for my engine?

Most Yanmar 6LY3 engines require a single alternator belt. However, some sources suggest certain configurations may need two. Always check your service manual or inspect your current setup to confirm the required quantity.

What are the signs of a failing alternator belt?

Common signs include a loud squealing noise from the engine, a battery warning light on your console, or visible damage to the belt, such as cracks, fraying, glazing, or missing chunks of rubber.

How often should this V-belt be replaced?

Replacement intervals depend on engine hours and operating conditions. It is best practice to inspect the belt during routine maintenance and replace it at the first sign of wear or damage, or as recommended in your engine's service manual.

Is this an OEM part?

This listing is for an aftermarket replacement, not an OEM part. It is built to meet or exceed OEM-level specifications with comparable materials, manufactured in an ISO 9002 facility, and batch-inspected for quality and consistency.

What are the shipping speed and cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and expedited options are shown at checkout where available.

What is the warranty and return policy?

This part is covered by a 1-year warranty against manufacturing defects under normal use. If an issue arises, contact our support team with your order details. Returns are accepted within our standard window for unused items in original condition.

razor

Safety & Important Info

Verify images and specifications against your original part before purchasing. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
Professional installation is recommended for safety and optimal 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 quality control.

Payment & Security

Payment methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.