Target Audience:
Sailboat and small craft owners, marine technicians, and DIY mechanics
Application:
Auxiliary propulsion for sailboats and small displacement powerboats
Design:
Compact, lightweight, and corrosion-resistant for marine use
Cooling:
Freshwater cooling with heat exchanger
Emissions:
Complies with EPA Tier 2 and EU RCD standards
Serviceability:
Easy access to maintenance points
Engine Models Covered:
Yanmar 3YM30, 3YM20, 2YM15
Engine Mechanical:
Cylinder head, block, pistons, crankshaft, bearings
Fuel System:
Fuel injection pump, injectors, fuel filter, lines
Cooling System:
Seawater pump, freshwater pump, heat exchanger, thermostat
Lubrication System:
Oil pump, oil filter, relief valve
Electrical System:
Alternator, starter motor, wiring, sensors
Exhaust System:
Exhaust manifold, mixing elbow
Diagnostics:
Troubleshooting charts and fault codes
Disassembly:
Step-by-step component removal
Inspection:
Measurement and wear limits
Assembly:
Reassembly with torque specifications
Adjustments:
Valve clearance, injection timing, belt tension
Testing:
Compression test, oil pressure test, cooling system test
Specifications:
Detailed torque values, clearances, and capacities
Exploded Views:
Illustrations for component identification
Wiring Diagrams:
Electrical schematics for all covered models
Special Tools:
Required tools and part numbers
Part Numbers:
OEM part numbers for service items
Interchange:
Compatibility across models
Ordering:
Guidance on sourcing replacement parts
File Format:
PDF (searchable, bookmarked, zoomable)
Compatibility:
Windows, macOS, Linux, iOS, and Android — any device with a PDF reader
Requirements:
A PDF reader application (e.g. Adobe Acrobat Reader, free)
Searchability:
Fully text searchable for fast lookup of any topic
Print Quality:
High-resolution digital pages, printable at full clarity
Binding Type:
N/A — digital download, no physical binding
Paper Type:
N/A — digital download, no physical paper
3YM30:
3-cylinder, 1.115 L, 29 hp (21.6 kW) at 3600 rpm
3YM20:
3-cylinder, 0.854 L, 20 hp (14.9 kW) at 3600 rpm
2YM15:
2-cylinder, 0.570 L, 14 hp (10.4 kW) at 3600 rpm
Configuration:
Inline, vertical
Bore x Stroke:
3YM30: 76 mm x 82 mm; 3YM20: 70 mm x 74 mm; 2YM15: 70 mm x 74 mm
Displacement:
3YM30: 1115 cc; 3YM20: 854 cc; 2YM15: 570 cc
Fuel System:
Mechanical fuel injection
Cooling:
Freshwater with heat exchanger
Aspiration:
Naturally aspirated
Emission Compliance:
EPA Tier 2, EU RCD
Standard:
Yanmar KM2P mechanical transmission
Optional:
Yanmar KM3P, KM4A, or other compatible marine gears
Reduction Ratio:
Varies by application; consult manual for specific ratios
Control:
Mechanical cable actuation
Lubrication:
Oil lubricated; uses same oil as engine
Maintenance:
Regular oil level checks and changes
Wheelbase:
N/A - engine, not vehicle
Length:
3YM30: 584 mm; 3YM20: 552 mm; 2YM15: 498 mm
Width:
3YM30: 468 mm; 3YM20: 468 mm; 2YM15: 468 mm
Height:
3YM30: 597 mm; 3YM20: 597 mm; 2YM15: 597 mm
Dry Weight:
3YM30: 159 kg; 3YM20: 139 kg; 2YM15: 115 kg
Oil Change:
Every 100 hours or annually
Oil Filter:
Every 200 hours or annually
Fuel Filter:
Every 200 hours or annually
Impeller:
Every 500 hours or annually
Valve Clearance:
Every 500 hours
Engine Oil:
API CD or better; SAE 10W-30 or 15W-40 depending on climate
Coolant:
Ethylene glycol-based antifreeze mixed 50/50 with water
Transmission Oil:
Same as engine oil
Common Wear Items:
Impeller, fuel filters, belts, hoses
Potential Issues:
Exhaust mixing elbow corrosion, raw water pump wear
