853811T10 Regulator Rectifier for Mercury Tohatsu F25 F30 MFS25 MFS25B MFS30 MFS30B | JLM Marine

Regulator Rectifier for Mercury Tohatsu F25 F30 MFS25 MFS25B MFS30 MFS30B

This aftermarket regulator rectifier is designed to fit Mercury and Tohatsu 4-stroke outboard engines rated at 25–30 HP. It ensures stable voltage regulation for reliable electrical system performance on MFS25, MFS25B, MFS30, and MFS30B models from 2005 to 2014, as well as Mercury F25 and F30 engines.

This unit directly replaces OEM part numbers 853811T10 and 898103T14 for Mercury, and 3AC-76065-0, 3AC-76065-1, and 3AC-76065-2 for Tohatsu. It provides a cost-effective solution for maintaining your outboard's charging system.

• 100% brand-new aftermarket replacement
• Fits 4-stroke Mercury and Tohatsu outboards
• Replaces multiple OEM part numbers for broad compatibility

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

• 1 × Voltage Regulator Rectifier

The package contains all the parts shown in the picture.

Installation Guide

1. Disconnect the battery's negative terminal to prevent electrical shock or short circuits.
2. Locate the existing regulator rectifier on your outboard engine, typically mounted near the powerhead or electrical components.
3. Disconnect all electrical connectors from the old regulator rectifier, noting their positions for reassembly.
4. Remove the mounting bolts securing the old unit to the engine. Keep hardware if reusable.
5. Clean the mounting surface to ensure proper heat dissipation and electrical grounding.
6. Position the new regulator rectifier in place and secure it with the mounting bolts. Torque to manufacturer specifications.
7. Reconnect all electrical connectors to the new unit, matching colors and positions from the original configuration.
8. Ensure all connections are tight and secure to prevent voltage drops or electrical failures.
9. Reconnect the battery's negative terminal.
10. Start the engine and verify proper charging system operation using a multimeter (voltage should read 13.5–14.5V at idle).
11. Check for any unusual heat buildup on the regulator rectifier after 10–15 minutes of operation.
12. If voltage readings are abnormal or the unit overheats, shut down immediately and recheck all connections.

Troubleshooting & FAQ

Q: How do I confirm this regulator rectifier fits my engine?
A: Cross-reference your original part number with the OEM numbers listed (853811T10, 898103T14 for Mercury; 3AC-76065-0/1/2 for Tohatsu). Also verify your engine model and year against the compatibility table above.

Q: What are the symptoms of a failing regulator rectifier?
A: Common signs include battery not charging, dim or flickering lights, battery overcharging (boiling), or electrical components failing intermittently. Use a multimeter to check voltage output while the engine is running.

Q: How often should I replace the regulator rectifier?
A: Regulator rectifiers typically last several years under normal conditions. Replace immediately if you experience charging system failures, overheating, or electrical issues. Regular inspection during annual maintenance is recommended.

Q: Can I install this myself or do I need a professional?
A: Installation is straightforward for those with basic mechanical and electrical skills. However, professional installation is recommended to ensure proper connections and prevent electrical system damage.

Q: Will this work if my engine model is listed but the year is different?
A: Only proceed if your original part number matches one of the OEM numbers listed. Even if your model appears compatible, year variations may have different electrical specifications.

Q: What's the difference between OEM and aftermarket regulator rectifiers?
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.