21103642 Starter Motor | Genuine Volvo Penta Part

🔧 Product Description

A genuine Volvo Penta 12-volt reduction starter motor for D9 and selected D11 marine diesel installations. It supersedes starter 3801284 and combines the solenoid, reduction gearing, armature and overrunning drive into a high-torque unit capable of cranking the large-displacement diesel at starting speed. Mounting pattern, pinion geometry and electrical system voltage must match the original starter.

🚤 Compatibility

Typically suits:

• Volvo Penta D9A2L MH
• Volvo Penta D9A2M MP

• Engine Family: D
• HP Range: Approximately 575 HP
• Year Range: Approximately 2004-2010 D9A2 production; verify starter mounting and original unit by engine serial number

⚙️ Key Features

• 12-volt heavy-duty reduction starter for D9/D11 diesel engines
• Integrated solenoid engages the pinion and switches cranking current
• Reduction gearing produces high cranking torque with controlled current draw
• Current service replacement for Volvo Penta 3801284
• Pinion, mounting flange and cable-terminal positions must match the original unit
• Engine type: 9.4-litre inline-six marine diesel, 12-volt starting system

🔌 Function

Converts battery power into high-torque rotation of the flywheel so the diesel reaches the cranking speed required for compression ignition.

⚠️ Common Signs of Failure

• Solenoid clicks but the engine does not crank
• Slow cranking with correctly charged batteries and sound cables
• Pinion spins without engaging the flywheel
• Intermittent no-crank caused by worn solenoid contacts or brushes
• Grinding, excessive current draw or heat at the starter terminals

🛠️ Service Notes

• Disconnect the batteries before touching starter cables, and label the main and control connections as they come off
• Inspect the ring gear teeth before fitting a new motor; a chipped or worn ring gear will ruin the new pinion
• Mount the motor square on clean faces with whatever shims the installation uses, so pinion engagement matches what the workshop manual for your engine specifies — never leave shims out to make it fit
• Clean the main and earth terminals back to bright metal, tighten to the specified figure and refit the insulating boots; a great many failed starters are really voltage drop in the cables and earth path
• Crank with the engine unable to start first, listening for clean engagement and release, then feel the terminals for heat after several attempts

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 21103642 → Supersedes 3801284 → Supersedes 3803873 → Supersedes 3803842

OEM / Related Numbers

• 3801284 earlier number superseded by this part
• 3803873 earlier number superseded by this part
• 3803842 earlier number superseded by this part
• 3849004 - 12-volt starter relay
• 21308514 - insulating bushing
• 21780397 - associated wiring harness
• 21546674 - cable kit

Other-Brand OEM Numbers

• Mitsubishi M009T72779 / M9T72779

Aftermarket / Verified Equivalents

• API Marine / Sterndrive Engineering: 1506914
• Rareelectrical: replacement starter for 21103642 / 3801284
• AS-PL: S5313S

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging