Optimizing the 3.0L Mercury & Mariner 200 Optimax: Premium OEM
Replacement Parts Guide
When it comes to raw, fuel-efficient low-end torque on the water, few powerheads have established a legacy
quite like the 3.0-Liter V6 Mercury and Mariner Optimax DFI (Direct Fuel Injection) series. Engineered to
deliver high-output performance while meeting strict emissions baselines, these systems require precise
timing, high air-to-fuel integration, and heavy-duty structural components. Over time, salt-water exposure,
thermal cycles, and general operational stress demand targeted component refreshes to preserve factory
performance specifications.
Finding direct, high-quality replacements can be challenging—especially given that aftermarket components
often fail to mirror the precise tolerances mandated by Mercury’s Direct Fuel Injection systems. At
DobsonParts.com, we specialize in supplying original, hard-to-find OEM Mercury and Mariner Optimax
components. Below is a comprehensive breakdown of our current premium inventory designed to keep your
200HP, 225HP, or high-horsepower 3.0L DFI configuration performing at its peak.
Essential Structural, Powerhead, & Internal Engine Components
Maintaining structural integrity and robust internal dynamics within the powerhead block prevents catastrophic
failures down the line. Our current inventory features vital, factory-tolerance engine components:

Mercury 1997 – 2002 Crankshaft Assembly w/ Bearings (200 / 225 / 250 HP)
Application: 3.0L V6 DFI Block | Condition: OEM Inspected & Certified
The structural centerpiece of your powerhead. This genuine factory crankshaft assembly retains pristine bearing
surfaces and journal dimensions. It delivers zero-deflection rotational balance required to handle the rigorous
compression profiles of early-generation 200–250 HP Optimax blocks without risking premature rod-journal scarring.

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Mercury 200 DFI STBD Cylinder Head Assembly (PN: 850275A2)
Fits: 1998 – 1999 Models | Orientation: Starboard Side Only
Engineered precisely for the unique direct-injection combustion chambers of 1998 and 1999 200HP DFI blocks. This
OEM Starboard Cylinder Head assembly ensures a flawless mating surface to minimize combustion leak risks while
maximizing thermal dissipation in critical high-heat operating zones.

Flywheel Assembly (PN: 283-850293-C / 850293A1)
Fits: Mercury Marine Optimax 200-225 HP Outboards
Critical for sustaining correct rotational inertia and charging alternator efficiency. This genuine flywheel assembly
features clean, uncompromised starter-ring gear teeth and strong interior charging magnets, guaranteeing smooth
starter engagement and consistent crank position sensing.

High-Performance DFI Air & Fuel Management Systems
The signature of the Optimax platform is its dual-stage direct injection system, which demands flawless
synchronized airflow and fuel atomization. If your air compressor or injectors lose pressure consistency, the
entire motor risks leaning out or experiencing severe power hesitation.

Mercury Optimax DFI Air Compressor (PN: 828123 A26)
Fits: 2003 – 2010 Models | Horsepower Range: 200, 225, 250, 300+ HP (3.0L)

The critical secondary heart of the DFI platform. This premium factory air compressor maintains stable, high-
pressure output to drive atomized fuel directly into the combustion cylinders. Free from interior chamber wall scoring

or rod play, it is ready to replace failing or locked compressors on multi-horsepower V6 fleets.

OEM Mercury Optimax Black Air Injector (PN: 85000653 / 850065-2)
Color Designation: Black Band | Application: Direct Injection Rails
Avoid the inconsistent flow rates associated with cheap aftermarket imitations. These authentic OEM “Black Band”
air injectors supply crisp, ultra-fine mist atomization profiles to ensure optimal combustion efficiency, pristine throttle
response, and maximum fuel economy.

Electrical, Ignition, & Charging System Integrity
A weak spark or a dropping voltage rail can rapidly disrupt direct injection calculations within the engine
control unit. Keep your electrical infrastructure in factory specification with these OEM components:

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Mercury Outboard Optimax 200HP DFI ECU (PN: 85649612)
Application: 200HP Engine Control Unit | System Type: SmartCraft Compatible
The central nervous system of your engine. This genuine Mercury ECU controls ignition mapping, fuel scheduling,
and diagnostic telemetry for 200HP DFI motors. Fully tested and free of hardware faults, it provides reliable data
logging and safe parameter enforcement.

Mercury Optimax 200-225 HP Ignition Coil Plate Assembly (OEM 6 COILS – 850227)
Configuration: 6-Coil Complete Cluster | Compatibility: V6 Blocks
Eliminate dropouts and multi-cylinder misfires under load. This complete, bracketed 6-coil plate assembly arrives
populated with genuine OEM ignition coils, providing uniform high-voltage delivery to every spark plug across the
entire RPM range.

Mercury Mariner Optimax DFI Alternator Assembly (PN: 828506)
Fits: 200-225 HP Configurations | Output: Heavy-Duty Amperage Capacity
Keeps onboard batteries charged and ensures the massive current demands of the DFI injectors and fuel pumps
are met without voltage sags. Features smooth internal bearings and a clean internal stator winding field.

Mercury 135 / 150 / 200 / 225 HP Starter Motor (PN: 50-833153-5 / PH130-0030)
Voltage/Rotation: 12V, Counter-Clockwise (CCW) | Fitment: V6 Outboards
A heavy-duty 12V starter motor delivering reliable cranking torque to fire over high-compression 2.5L and 3.0L
Mercury V6 outboards instantly, even under challenging cold-start conditions.

Midsection, Transom Brackets, & Lower Units
Power is nothing without structural support and efficient transfer to the prop shaft. Secure your transom and
power transmission with these heavy-duty components:

Mercury Optimax 225hp 2-Stroke Outboard 20″ Lower Unit
Fits Production Years: 1998 – 2006 | Shaft Length: 20-Inch Standard
A complete, fully inspected 20-inch standard shaft lower unit gearcase. It features factory gear ratios, straight
splines, and pressure-tested seals to protect internal gearing from water intrusion, ensuring proper power transfer to
the propeller.

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Mercury Transom Bracket Starboard Side (PN: 3425-828333-C)
Fits: Wide Compatibility across 75 HP & 115-300 HP Engines
Constructed from heavy marine alloy to withstand extreme torsional stress and hydrodynamic force. This starboard
side transom bracket replacement provides solid, reliable clamp-and-tilt structural integration for your midsection
layout.

Exterior Cosmetics & Accessibility Components
Protect your mechanical investments from harsh, corrosive marine environments while ensuring easy
accessibility during scheduled service calls:

1998 Mariner 200 Optimax Outboard Cowling Hood 200HP (PN: 850299A2) – Silver
Colorway: Vintage Mariner Silver | Material: Marine-Grade Composite
Keep your engine dry and protected. This rare, original silver Mariner 200HP cowling hood provides robust
environmental sealing with sound-dampening insulation intact, presenting an excellent opportunity to restore a
vintage look.

Mercury Cowl Handle 200 225 250 300 HP 3.0L DFI (PN: 852361-C1)
Fits Production Years: 1998 – 2009 | Application: Rear Hatch Lift / Latches
A direct, heavy-duty replacement cowl rear handle. Restores solid leverage and reliable, positive latch engagement
to prevent cover play and vibration noise at high speeds.

Why Choose OEM Parts from DobsonParts.com?
Unlike generic, unverified aftermarket replicas that often lead to inaccurate ignition firing or irregular fuel ratios, our
original equipment manufacturer (OEM) inventory guarantees full compatibility and long-term durability. We inspect
every block, sensor, and bracket to ensure it meets strict marine tolerances before adding it to our live catalog.

Ready to Restore Your Mercury or Mariner Outboard?

Don’t let an out-of-stock component ground your boat. Discover our complete, up-to-date catalog of
3.0L V6 mechanical components today at DobsonParts.com. Find your part, confirm your serial

number, and get back out on the water!