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Alternator – Fits Mercury Outboards V-6 DFI/Optimax (Replaces 8M0064020, 881247A1, 875286A1)

Regular price $580.00

Worry-free returns

Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.


If the return is due to our error or a defective item, we’ll make it right.


Please contact us before returning any item.

Delivery and Shipping

Orders are typically processed within 1–2 business days.


U.S. orders usually arrive within 6–15 days, depending on stock location and destination.


International delivery times may vary due to customs processing.


Tracking information will be provided once your order ships.

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This high-quality replacement Alternator fits Mercury Outboards with V-6 DFI/Optimax technology. It is specifically designed for use on 200-225 HP 3.0L models, providing reliable charging performance.

This unit serves as a direct interchange for Mercury part numbers 8M0064020, 8M6013461, 881247A1, 875286A1, 828506, and 875286T.

  • Installs as a direct replacement for the original OEM part.
  • Features a connection compatible with the factory OEM wiring harness.
  • Covered by a 1-year warranty when purchased new.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand Part Number Superseded By
Mercury 8M0064020 8M6013461
Mercury 881247A1
Mercury 875286A1
Mercury 828506
Mercury 875286T

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury engines, please ensure your model is a V-6 3.0L with DFI/Optimax technology.

Brand Model Rated HP Stroke OEM Part No. Notes
Mercury Optimax/DFI V-6 3.0L 200-225 2-Stroke 8M0064020 Superseded by 8M6013461

Technical Specs

Product Type
Alternator
Installation
Direct Replacement OEM
Connection
OEM Wiring Harness Compatible
Housing Color
Black
Product Dimensions (L x W x H)
19.0 x 19.0 x 20.5 cm
Warranty
1 Year (when purchased new)
Other Technical Attributes
12V System, Delco/Remy Design

What’s in the Box

  • 1 x Alternator (8M0064020/8M6013461)

Installation Notes

  1. Disconnect the negative terminal from your boat's battery to prevent electrical shorts.
  2. Loosen the belt tensioner and carefully remove the serpentine belt from the alternator pulley.
  3. Unplug the main wiring harness and disconnect the battery cable from the back of the old alternator.
  4. Remove the mounting bolts securing the alternator to the engine block.
  5. Carefully lift the old alternator out of the engine bay.
  6. Position the new alternator and loosely tighten the mounting bolts.
  7. Reconnect the electrical connectors and battery cable.
  8. Reinstall the serpentine belt and apply the correct tension using the tensioner.
  9. Tighten all mounting bolts to the manufacturer's specified torque.
  10. Reconnect the battery terminal, start the engine, and verify the charging system is operating correctly.

Troubleshooting & FAQ

How do I know if my alternator is failing?

Common signs of a faulty alternator include dimming or flickering lights, a battery warning light on your dashboard, a weak or dead battery, frequent battery jumps, or a whining/grinding noise coming from the engine area.

Will this alternator fit my Optimax engine?

This unit is specifically designed as a replacement for alternators on Mercury V-6 DFI/Optimax 3.0L (200-225 HP) engines. To guarantee fitment, always compare your original part number to the references listed in our Part Number Matrix.

Do I need to modify my boat's wiring?

No. This alternator is engineered to be compatible with the factory OEM wiring harness, allowing for a direct, plug-and-play installation without any modifications.

What is the output amperage of this alternator?

While a specific amperage rating is not provided, this alternator is manufactured to meet or exceed the electrical demands and specifications of the original factory part for all listed compatible models.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

  • Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
  • This is an aftermarket replacement, not an OEM component.
  • Professional installation is recommended for safety and performance.

About Sea Sierra

  • Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
  • Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
  • Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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