# 889956 8M0033842 Mercury Alternator | Genuine Used Part

🔧 Product Description

  

Genuine Mercury 12V 50A OptiMax Alternator - Part Number: 8M0033842

  

A genuine used Mercury Marine Delco 5SI alternator for selected Mercury and Mariner OptiMax, DFI, EFI, Pro Max and Sport Jet engines.

  

The alternator uses an internally regulated, internal-fan design with a multi-groove serpentine pulley. It supplies up to 50 amps to recharge the starting battery and operate the engine-management and onboard electrical systems.

  

⚙️ Key Features

  

• Genuine used Mercury Marine alternator

• 12-volt, 50-amp charging output

• Delco 5SI internally regulated design

• SAE J1171 marine ignition protection

• Used on selected 1.5L, 2.5L and 3.0L Mercury outboard and Sport Jet engines

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 8M6000803 → Supersedes 8M0064020

• 8M0064020 → Supersedes 8M0033842

• 8M0033842 → Supersedes 889956

• 889956 → Supersedes 881247A1

• 881247A1 → Supersedes 875286A1

• 875286A1 earlier OEM alternator assembly

  

OEM / Related Numbers:

  

• 8M6000803

• 8M0064020

• 8M0033842

• 889956

• 881247

• 881247A1

• 875286

• 875286A1

• 875286T

• 828506

• Delco Remy: 19020704

• Delco Remy: 19020707

• Prestolite: 20115011TBA

• Lester: 8471

  

Aftermarket / Verified Equivalents:

  

• ARCO Marine: 20850

• Sierra: 18-6455

• DB Electrical: 400-12303

• API Marine: 20117-AM

• OEG Parts: ADR0318

• WAI: 8471N

• ComponentsPlus: 400-12155

  

🚤 Compatibility

  

Commonly used on:

  

• Mercury and Mariner OptiMax / DFI outboard charging systems

• Mercury EFI, XB, Pro Max and Sport Jet applications using a Delco 5SI alternator

  

Typically suits:

  

• Engine models:

• Mercury / Mariner 75HP 1.5L OptiMax - approximately 2005-2006

• Mercury / Mariner 90HP 1.5L OptiMax - approximately 2004-2006

• Mercury / Mariner 115HP 1.5L OptiMax - approximately 2004-2006 and selected 2009 applications

• Mercury 200HP 3.0L OptiMax - approximately 2001-2004

• Mercury 200HP 3.0L EFI - approximately 2005-2006

• Mercury 225HP OptiMax applications using the 889956 alternator family

• Mercury 250HP 3.0L XB - approximately 2002-2003

• Mercury 250HP Sport Jet 2.5L - approximately 2002-2006

• Mercury 250HP and 300HP Pro Max / Racing applications using alternator 881247A1 or 889956

• Mercury OptiMax serial families using part numbers 875286A1, 881247A1, 889956 or 8M0033842

  

• HP Range: 75HP - 300HP

• Engine Type: Mercury / Mariner OptiMax, DFI, EFI, Sport Jet and Racing outboard

• Year Range: Approximately 1998-2009

  

🔌 Function

  

The alternator maintains battery charge and provides electrical power to the engine control module, electric fuel pumps, injectors, instrumentation, trim system and boat accessories.

  

Common signs of failure:

  

• Battery discharges while the engine is operating

• Low charging-voltage alarm

• Engine-management voltage faults

• Electric fuel pump or trim system operates slowly

• Alternator produces a whining, grinding or rumbling noise

• Serpentine pulley or bearing develops excessive play

• Charging voltage fluctuates as engine speed changes

  

📦 Condition

  

• Genuine used part

• Removed from running engine where applicable

• In good working condition unless otherwise stated

## Details

- **Price:** 75.0 AUD
- **Vendor:** Sawley's Auto and Marine
- **Tags:** Sawley’s AAM Used Parts – Alternators | Marine Charging Systems & Alternators

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 75.00 AUD | In stock |

## Images

- 889956 8M0033842 Mercury Alternator | Genuine Used Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/889956-8m0033842-mercury-alternator-genuine-used-part)
> Updated: 2026-07-18