57-34359 V-Belt for MerCruiser 3.7L 4.3L 5.0L 5.7L Sterndrive Engines | JLM Marine

57-34359 V-Belt for MerCruiser 3.7L 4.3L 5.0L 5.7L Sterndrive Engines | JLM Marine

This high-quality alternator drive V-belt is engineered for MerCruiser 3.7L, 4.3L, 5.0L, and 5.7L sterndrive engines manufactured between 1973 and 1995. Designed to deliver reliable performance in demanding marine environments, this belt ensures consistent power delivery from your alternator and water pump.

This aftermarket replacement directly cross-references OEM part numbers 57-33170, 57-33170Q, 57-37619T, and 57-34359, as well as Sierra 18-15520, providing broad compatibility across multiple MerCruiser sterndrive applications.

• 51-inch V-belt designed specifically for water pump and alternator drive applications
• Direct fit for MerCruiser 3.7L, 4.3L, 5.0L, and 5.7L sterndrive engines
• Replaces multiple OEM part numbers for simplified sourcing

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

This package includes:

• 1 × 51" V-Belt

Installation Guide

1. Disconnect the battery to ensure safety before beginning any work on your engine.
2. Access the belt area by removing any engine covers or components obstructing the alternator and water pump pulleys.
3. Release tension on the old belt by loosening the alternator mounting bolts or adjusting the tensioner mechanism.
4. Remove the old belt from the pulleys, noting the routing path for proper reinstallation.
5. Inspect all pulleys for wear, damage, or debris, and clean if necessary.
6. Route the new 51" V-belt around the water pump, crankshaft, and alternator pulleys following the original path.
7. Adjust the alternator position to achieve proper belt tension—typically 1/2 inch deflection with moderate thumb pressure at the belt's midpoint.
8. Tighten all mounting bolts securely once proper tension is achieved.
9. Rotate the pulleys by hand to confirm the belt is seated correctly and running smoothly.
10. Reinstall any covers or components removed during access.
11. Reconnect the battery and start the engine to verify proper operation.
12. Check belt tension after initial run-in and re-adjust if necessary.

Troubleshooting & FAQ

Q: How do I confirm this V-belt fits my MerCruiser engine?
A: Cross-reference your engine model and year with the compatibility table above. Also verify that your current belt matches OEM part numbers 57-33170, 57-33170Q, 57-37619T, or 57-34359. If your engine is listed but the belt length differs, do not purchase.

Q: How often should I replace my alternator drive belt?
A: Inspect your V-belt every 100 hours of operation or annually. Replace immediately if you notice cracking, fraying, glazing, or slippage. Most marine belts should be replaced every 2-3 years or 300-500 hours under normal conditions.

Q: What are the signs that my V-belt is failing?
A: Common symptoms include squealing noise during acceleration, dimming electrical accessories, battery not charging, overheating engine, or visible belt damage such as cracks and glazing.

Q: How tight should the belt be after installation?
A: Proper tension allows approximately 1/2 inch (12-13mm) of deflection when moderate thumb pressure is applied at the belt's longest span. Over-tightening can damage bearings; under-tightening causes slippage.

Q: Is this an OEM belt or 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.