Yanmar 3YM20 Three-Cylinder Marine Diesel Engine, 21 HP

The Yanmar 3YM20 is a compact three-cylinder, vertical four-stroke marine diesel producing 15.3 kW (21 hp) at 3600 RPM from 0.854 L. It is naturally aspirated, fresh-water cooled through a heat exchanger, and uses indirect injection with a swirl pre-combustion chamber.

A redesigned cylinder block and combustion system are tuned for quiet, low-vibration running, and the engine complies with EPA Tier 2 and BSO/SAV Stage 2 emission rules. A compact control panel, injection pump, electric stop solenoid and 60-amp alternator are standard; an 80-amp alternator is optional. The water pump, fuel filter, oil change point and dipstick are grouped at the front on one side for easier maintenance.

The 3YM20 is offered as a standard inboard or with Yanmar's double-seal saildrive. The inboard version uses a servo-cone clutch with 2.21:1, 2.62:1 or 3.22:1 forward ratios and 3.06:1 in reverse. The saildrive version, designated 3YM20C, has a constant-mesh dog clutch geared 2.64:1 forward and reverse.

Highlights

• 15.3 kW (21 hp) at 3600 RPM

• Three cylinders, 0.854 L displacement

• Fresh-water cooling with heat exchanger

• 60 A alternator standard, 80 A optional

• Control panel and electric stop solenoid standard

• Inboard or 3YM20C saildrive versions offered

Specifications

Good to know

• Installation, rigging and commissioning by a qualified marine technician are recommended; follow the manufacturer's pre-delivery and break-in procedures.