Belt Tensioner Pulley for Mercruiser 4.3- 8.1 L 8M6500024

Belt Tensioner Pulley – Fits MerCruiser 4.3-8.1L Engines (Replaces 8M6500024, 865598)

This belt tensioner pulley is designed for a range of MerCruiser inboard and stern drive engines, including 4.3L, 5.0L, 5.7L, 5.8L, 6.2L, and 8.1L V6/V8 models. It is also compatible with General Motors 262 CID V6 (4.3L) and GM V8 small block 5.0L & 5.7L engine blocks.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 8M6500024, 818382, and 865598, as well as Sierra 710-8M6500024.

• Installation: Direct replacement for a straightforward installation.
• Material: Constructed from durable black thermal resin.
• Key Feature: Features a smooth, flat pulley surface with a bearing molded directly into the pulley for reliability.

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.

Confirm your engine model/year in the table below.

MerCruiser/Mercury

General Motors

Technical Specifications

Package Contents

• 1 x Belt Tensioner Pulley (Replaces 8M6500024, 865598, 818382)

Explosion Diagram

Installation Guide

1. Disconnect the negative battery terminal to ensure safety.
2. Use a breaker bar or tensioner tool to release the tension on the serpentine belt and carefully slide it off the tensioner pulley.
3. Unbolt and remove the old tensioner pulley from its mounting bracket. Note its orientation.
4. Clean the mounting surface before installing the new pulley.
5. Mount the new tensioner pulley, ensuring it is securely fastened to the manufacturer's recommended torque specifications.
6. Route the serpentine belt back into its correct position over all pulleys, referring to your engine's belt diagram if needed.
7. Slowly release the tensioner to apply pressure to the newly installed belt. Double-check alignment.
8. Reconnect the battery terminal, start the engine, and check for proper belt alignment and operation.

Troubleshooting & FAQ

Q: How do I confirm this pulley fits my MerCruiser engine?

A: This pulley fits a wide range of MerCruiser V6 and V8 engines, including 4.3L, 5.0L, 5.7L, 6.2L, and 8.1L models. The best way to confirm is by matching your original part number to our cross-reference list, which includes Mercury 8M6500024, 865598, and 818382. Also, check the compatible engine models table on this page.

Q: What are the signs of a failing tensioner pulley?

A: Common symptoms of a worn or failing tensioner pulley include a squealing or rattling noise from the engine bay, visible wear or wobbling of the pulley itself, and premature wear or damage to the serpentine belt.

Q: What is this pulley made of, and is the bearing replaceable?

A: The pulley is constructed from a durable, high-strength thermal resin, similar to the OEM part. For a solid, integrated design, the bearing is molded directly into the pulley and is not separately replaceable. The entire unit should be replaced if the bearing fails.

Q: 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.

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.