SKU: 21957716756

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

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Description

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

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.

Brand Part Number Superseded By Notes
Volvo Penta 3848896 21280913
Volvo Penta 3809465
Volvo Penta 3883786
Volvo Penta 21172053
Volvo Penta 21280913 Current Part Number

Compatible Engine Models

Confirm your engine model/year in the table below.

Brand Model Rated HP Stroke OEM Part No. Notes
Volvo Penta D4-260 260 4-Stroke 21280913 Up to SN 2004017297
Volvo Penta D4-300 300 4-Stroke 21280913 Up to SN 2004017297
Volvo Penta D6-350 350 4-Stroke 21280913 Up to SN 2006032252
Volvo Penta D6-370 370 4-Stroke 21280913 Up to SN 2006032252
Volvo Penta D6-400 400 4-Stroke 21280913 Up to SN 2006032252
Volvo Penta D6-435 435 4-Stroke 21280913 Up to SN 2006032252

Technical Specifications

Specification Value
Product Type Idler Pulley / Tensioner Pulley
Installation Engine Compressor Belt System
Fuel Type Diesel
Warranty 1 Year (Aftermarket)
Other Technical Attributes For compressor belt tensioning in marine diesel engines

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.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 21957716756

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Todd Wahl
Charlottesville, US
★★★★★ 4
Almost Perfect But With Workaround it Rocks
Style: Dash+Screen+Qi2 Charger, Style: Dash+Screen+Qi2 Charger
This works almost perfectly in my Tesla, with one small tweak for hot summer conditions. It holds my phone very well overall—I position it slightly off-center at about the 10 o’clock position. However, with a larger phone like the Galaxy S25 Ultra, the combination of weight and summer heat can cause the mount to slowly rotate as the suction cup loses some grip. I found a simple fix that works extremely well: applying a small amount of rosin (the same kind used for violin bows) to the friction point where the rotating arm meets the suction base. That added grip completely solved the issue. Now the mount stays exactly where I position it, even in the heat. Solid product, and with that minor adjustment, it performs exactly how I need it to.
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Kady
Natrona Heights, US
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This worked perfectly in my vehicle making hands free driving easy. Installation was very simple, easy to charge my phone in this mount. Very stable, my phone never fell out or off.
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Reviewed in the United States on April 25, 2026
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Leah
Lowell, US
★★★★★ 5
Almost perfect
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Solid mount. I’ve tried other ones but they don’t sit as nicely as this one. It also has a lot of adjustments to allow for using it any way you need it to so it is very versatile. The magnet strength is really good and holds my phone really well. Sometimes it feels too strong which I guess is a good thing. The charging works well but I wish the cable was a little longer
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