Idler Pulley – Fits Volvo Penta D4/D6 Marine Diesel Engines (Replaces 21280913, 3848896)

Idler Pulley – Fits Volvo Penta D4/D6 Marine Diesel Engines (Replaces 21280913, 3848896)

This aftermarket idler pulley is designed for Volvo Penta D4 and D6 Series marine diesel engines. It ensures proper tension on the engine compressor belt for reliable performance.

This component is a direct replacement for multiple Volvo Penta part numbers, including 21280913, 3848896, 3809465, 3883786, and 21172053.

• Application: Mounts on the engine compressor belt system.
• Engine Fuel Type: Diesel
• Quality: Manufactured to meet or exceed OEM specifications.

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 Idler Pulley (Replaces 21280913)

Installation Guide

1. Safety First: Ensure the engine is off and cool, and disconnect the battery terminals before starting work.
2. Locate the Belt System: Identify the compressor belt and the idler pulley on your Volvo Penta engine.
3. Release Tension: Use the appropriate tool to release the tension from the belt tensioner, allowing you to slacken and remove the belt from the idler pulley.
4. Remove the Old Pulley: Unbolt and remove the old idler pulley from its mounting point. Note the orientation of any washers or spacers.
5. Install the New Pulley: Mount the new idler pulley, ensuring it is correctly aligned. Tighten the mounting bolt to the manufacturer's specified torque.
6. Reinstall the Belt: Route the compressor belt back over all the pulleys according to the engine diagram.
7. Apply Tension: Re-engage the tensioner to apply the correct tension to the belt.
8. Final Check: Reconnect the battery. Start the engine and listen for any unusual noises, and visually confirm the pulley and belt are operating smoothly.

Troubleshooting & FAQ

How do I confirm this pulley fits my D4 or D6 engine?

A: Check your engine model and, most importantly, its serial number. This pulley is specifically for D4 models up to serial number 2004017297 and D6 models up to serial number 2006032252. If your serial number is higher, this part will not fit.

What are the signs that my idler pulley is failing?

A: Common signs of a failing idler pulley include a persistent squeaking, chirping, or grinding noise from the engine compartment, visible wobble or physical damage (cracks, chips) on the pulley itself, or a loose or damaged compressor belt.

Is this a genuine Volvo Penta part?

A: This is a high-quality aftermarket replacement part that is engineered to be a direct replacement for Volvo Penta part number 21280913 and other cross-referenced numbers. It is not an OEM component but is built to meet or exceed original equipment standards.

OEM vs. Aftermarket?

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.

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.

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.