864625T Serpentine Belt Idler Pulley for Mercruiser V6 V8 4.3L 5.0L 5.7L 6.2L 8.2L | JLM Marine

864625T Serpentine Belt Idler Pulley for Mercruiser V6 V8 4.3L 5.0L 5.7L 6.2L 8.2L

This 4-1/4" Serpentine Belt Idler Pulley is engineered for 1999 and newer Mercruiser Stern Drive engines, including 4.3L, 5.0L, 5.7L, 6.2L, and 8.2L V6/V8 configurations with Alpha and Bravo stern drives. It ensures proper belt tension and reliable performance in demanding marine environments.

This aftermarket replacement directly cross-references OEM 864625T, 849296T, and multiple industry part numbers including 57-8638764, 57-862086, 57-862086A1, 57-865615004, 57-865615Q04, and 18-15101, providing broad compatibility across Mercruiser engine platforms.

• Pulley Size: 4-1/4 inches diameter
• Application: Engine idler pulley for serpentine belt systems
• Fitment: Race stern drive and standard Mercruiser V6/V8 engines

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. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

Your package includes the following component:

• 1 × Serpentine Belt Idler Pulley (4-1/4") – Same as picture shown

Installation Guide

1. Disconnect the battery to prevent electrical hazards during installation.
2. Locate the existing serpentine belt idler pulley on your Mercruiser engine. Refer to your engine manual if needed.
3. Release tension on the serpentine belt using the tensioner tool or appropriate wrench to loosen the belt.
4. Remove the serpentine belt from the idler pulley and other pulleys, noting the belt routing for reinstallation.
5. Unbolt the old idler pulley from its mounting bracket using the appropriate socket or wrench.
6. Inspect the mounting surface and bracket for wear, damage, or debris; clean if necessary.
7. Position the new 4-1/4" idler pulley onto the mounting bracket, aligning the bolt holes.
8. Secure the pulley with the mounting bolt, tightening to manufacturer's torque specifications.
9. Re-route the serpentine belt according to the original path, ensuring it sits properly on all pulleys including the new idler.
10. Apply tension to the belt using the tensioner, ensuring proper belt alignment and tension.
11. Reconnect the battery and start the engine briefly to verify smooth belt operation without slipping or noise.
12. Perform a final visual inspection to confirm the belt is running true on all pulleys and the idler is functioning correctly.

Troubleshooting & FAQ

Q: How do I confirm this idler pulley fits my Mercruiser engine?
A: Verify your engine is a 1999 or newer Mercruiser 4.3L, 5.0L, 5.7L, 6.2L, or 8.2L V6/V8 with Alpha, Bravo, or Race stern drive. Cross-reference your current pulley's OEM number (864625T, 849296T, or equivalents listed) and confirm the 4-1/4" diameter matches your original part.

Q: What are the signs that my idler pulley needs replacement?
A: Common symptoms include squealing or chirping noises from the belt area, visible wobbling or play in the pulley, excessive belt wear or fraying, and rough or grinding bearing feel when spinning the pulley by hand with the belt removed.

Q: How often should I replace the serpentine belt idler pulley?
A: Inspect the idler pulley during routine maintenance or whenever replacing the serpentine belt (typically every 3–5 years or per your engine's service schedule). Replace immediately if you notice noise, wobble, rough bearing rotation, or any visible damage.

Q: Is this an OEM part or 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.