Serpentine Belt – Fits MerCruiser 4.3L, 5.0L, 5.7L V6/V8 Alpha Engines (Replaces 57-861758Q)

Serpentine Belt – Fits MerCruiser 4.3L, 5.0L, 5.7L V6/V8 Alpha Engines (Replaces 57-861758Q)

This replacement serpentine belt is designed for specific MerCruiser V6 and V8 Alpha sterndrive engines manufactured between 1996 and 1999. It is engineered to fit models equipped with standard cooling and a 5-3/4" power steering pulley, ensuring reliable performance of engine accessories.

This part is a direct replacement for Mercury/MerCruiser part numbers 57-861758, 57-861758Q, 861758, and 861758Q. It also replaces Sierra 18-15116 and Recmar RM57-861758Q.

• Precise Fit: Engineered for MerCruiser 4.3L, 5.0L, and 5.7L Alpha sterndrives within the specified serial number range.
• Durable Construction: Made from a superior, tension-resistant rubber compound with a strengthened main structure for longevity.
• Application Specific: Designed for engines with standard cooling systems and a 5-3/4" power steering pulley.

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 Serpentine Belt (Replaces 57-861758Q)

Installation Guide

1. Safety First: Disconnect the boat's battery to prevent accidental starting.
2. Locate Components: Identify the serpentine belt, tensioner pulley, and all accessory pulleys (alternator, power steering pump, etc.).
3. Document the Route: Before removing the old belt, take a clear photo or draw a diagram of its routing path. This is critical for correct installation.
4. Release Tension: Use a properly sized socket or wrench on the automatic tensioner pulley to release the belt's tension.
5. Remove Old Belt: Carefully slide the old belt off all the pulleys.
6. Verify the Part: Compare the new belt with the old one to confirm the length and number of ribs are identical.
7. Route New Belt: Following your diagram, carefully route the new belt around the pulleys, saving the smoothest, most accessible pulley (like the idler or water pump) for last.
8. Apply Tension: Release the tensioner again and slide the belt over the final pulley. Double-check that all ribs are properly seated in the pulley grooves.
9. Final Check: Slowly release the tensioner, allowing it to apply pressure to the new belt. Visually inspect the entire belt path one more time.
10. Test: Reconnect the battery, start the engine, and listen for any unusual noises. Let it run for a minute to ensure the belt tracks correctly.

Troubleshooting & FAQ

How do I confirm this belt fits my MerCruiser engine?
Verify your engine details against the "Compatible Engine Models" table. This belt is specifically for MerCruiser 4.3L, 5.0L, and 5.7L Alpha engines from 1996-1999 falling within serial numbers OF803000-OL618999. It is also critical to confirm your engine uses a standard cooling system and a 5-3/4" power steering pulley, as other configurations will use a different belt.

What are common signs that my serpentine belt needs replacement?
Indicators of a failing belt include visible cracks, fraying, missing ribs, or a glazed, shiny appearance. You may also hear persistent squealing or chirping noises from the engine bay, especially on startup or when turning the steering wheel. Failure of accessories like the alternator or power steering can also point to a broken belt.

How often should I inspect or replace my serpentine belt?
Regular inspection during routine maintenance is recommended. A general guideline for replacement is every 3-5 years or upon visible signs of wear and tear. Always consult your engine's service manual for the manufacturer's specific maintenance schedule.

OEM vs. Aftermarket?
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?
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?
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.