21407026 Serpentine Belt for Volvo Penta D4-260 D6-350 D6-370 | JLM Marine

21407026 Serpentine Belt for Volvo Penta D4-260 D6-350 D6-370 | JLM Marine

This high-quality serpentine belt is engineered to fit Volvo Penta D4 and D6 diesel engines, including the D4-260 and D6-350/D6-370 series. Designed for marine compressor and alternator drive applications, this belt ensures reliable power transmission in demanding marine environments.

This belt directly replaces OEM part numbers 21407026 and 3583963, offering a precise fit and dependable performance for your Volvo Penta inboard diesel engine.

• Direct replacement for Volvo Penta compressor/alternator serpentine belt
• Compatible with D4-260 and D6-350/D6-370 engine families
• Engineered for marine-grade durability and performance

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 × Serpentine Belt (Replaces 21407026 / 3583963)

Installation Guide

1. Disconnect the battery negative terminal to ensure safety during installation.
2. Locate the serpentine belt routing diagram on your engine or consult your service manual.
3. Release tension on the belt tensioner using the appropriate tool (typically a wrench or socket on the tensioner bolt).
4. Remove the old serpentine belt from all pulleys, noting the routing path.
5. Inspect all pulleys and the tensioner for wear, damage, or excessive play; replace if necessary.
6. Route the new serpentine belt around all pulleys following the correct path as per the diagram.
7. Ensure the belt is properly seated in all pulley grooves with no twists or misalignment.
8. Release the tensioner slowly to apply proper tension to the new belt.
9. Verify that the belt is correctly positioned on all pulleys and moves freely.
10. Reconnect the battery negative terminal.
11. Start the engine and observe the belt operation, listening for any unusual noises or slippage.
12. Re-check belt alignment and tension after the first few hours of operation.

Troubleshooting & FAQ

Q: How do I confirm this serpentine belt fits my Volvo Penta engine?
A: Check the compatible engine models table above to verify your specific D4 or D6 engine variant is listed. Also confirm that your original belt has the OEM part number 21407026 or 3583963 stamped on it.

Q: How often should I replace the serpentine belt on my Volvo Penta diesel?
A: Volvo Penta typically recommends inspecting serpentine belts every 200 operating hours and replacing them every 800–1,000 hours or sooner if signs of wear, cracking, or fraying appear. Always consult your engine's service manual for specific intervals.

Q: What are the signs that my serpentine belt needs replacement?
A: Common indicators include squealing or chirping noises during engine operation, visible cracks or glazing on the belt surface, fraying edges, loss of accessory function (alternator, compressor), or visible belt slippage on pulleys.

Q: Can I install this belt myself or do I need a mechanic?
A: If you have basic mechanical skills and the correct tools to release the belt tensioner, installation can be done yourself following the routing diagram. However, professional installation is recommended to ensure proper tension and alignment.

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.