128670-77350 V Belt for Yanmar 2GM 3GM 2GMLP 3HM | JLM Marine

V Belt for Yanmar 2GM 3GM 2GMLP 3HM Marine Inboard Engines – OEM 128670-77350

This high-quality V Belt is engineered to fit a wide range of Yanmar marine inboard engines, including the 2GM, 3GM, and 3HM series. Designed as a direct replacement for OEM part number 128670-77350, this belt ensures reliable performance and proper power transmission in your marine engine's accessory drive system.

Whether you're maintaining a 2GM20, 3GM30, or 3HM engine, this V Belt delivers the durability and precision fit required for marine applications. Built to meet OEM specifications, it provides consistent performance in demanding marine environments.

• Direct replacement for Yanmar OEM part number 128670-77350
• Fits multiple Yanmar 2GM, 3GM, and 3HM series marine engines
• Includes 1 V Belt per package

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

This package contains the following components:

• 1 × V Belt

Installation Guide

1. Ensure the engine is completely shut off and cooled down before beginning any maintenance work.
2. Locate the existing V Belt on your Yanmar engine and identify the routing path around all pulleys.
3. Release tension on the belt by loosening the tensioner bolt or adjusting the alternator position, depending on your engine configuration.
4. Carefully remove the old V Belt from all pulleys, inspecting each pulley for wear or damage.
5. Route the new V Belt around all pulleys following the same path as the original belt.
6. Adjust the tensioner or alternator position to apply proper tension to the new belt. The belt should deflect approximately ½ inch when pressed firmly at its midpoint.
7. Tighten all adjustment bolts securely once proper tension is achieved.
8. Rotate the engine crankshaft manually (by hand) through two complete revolutions to ensure the belt is seated properly on all pulleys.
9. Recheck belt tension and adjust if necessary after the initial rotation.
10. Start the engine and listen for any unusual noises such as squealing or slapping, which may indicate improper tension.
11. Allow the engine to run for several minutes, then shut it off and perform a final tension check.
12. Re-inspect belt tension after the first few hours of operation and adjust as needed.

Troubleshooting & FAQ

Q: How do I confirm this V Belt fits my specific Yanmar engine model?
A: Check the compatibility table above to verify your engine model is listed. Additionally, compare your original belt with the OEM part number 128670-77350 to ensure an exact match.

Q: How often should I replace the V Belt on my Yanmar marine engine?
A: Inspect the V Belt every 100 operating hours or annually, whichever comes first. Replace the belt if you notice cracks, glazing, fraying, or excessive wear. Most marine V Belts should be replaced every 2–3 years under normal operating conditions.

Q: What are the signs that my V Belt is failing or needs replacement?
A: Common symptoms include squealing noises during engine operation, visible cracks or fraying on the belt surface, loss of alternator charging, overheating due to water pump failure, or belt slippage. If you observe any of these signs, replace the belt immediately.

Q: How do I ensure proper belt tension after installation?
A: Proper tension allows approximately ½ inch of deflection when you press firmly on the belt's longest span between pulleys. Too loose and the belt will slip; too tight and it will cause excessive wear on bearings and pulleys.

Q: What is the difference between OEM and aftermarket V Belts?
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.