Yanmar 3GM30FC Specifications
| Engine Model: Yanmar 3GM30FC |
| Engine Type: 4-stroke inline 3-cylinder water-cooled diesel |
| Total Displacement: 58.2 cu.in (0.95 L) |
| Rated Engine Power: 27 Hp (20.1 kW) at 3600 rpm |
| Fuel System Type: Indirect injection |
____________________________________________________________________________________
The Yanmar 3GM30FC is a 3-cylinder,
freshwater-cooled diesel engine from the GM series, specifically
configured with a "C" designation for use with a saildrive unit, most
commonly the SD20. This engine was produced from approximately 1984
onwards and became a popular auxiliary powerplant for sailing yachts in
the 28 to 35 foot (8.5 to 10.7 meter) range. The FC variant
distinguishes itself from the raw-water cooled 3GM30 through the
inclusion of a heat exchanger, which circulates fresh coolant through
the engine block while using seawater only in a closed loop, reducing
internal corrosion.
The engine features an indirect injection system with a swirl
pre-combustion chamber, a design that promotes smoother and quieter
operation than direct injection alternatives of its era. Natural
aspiration keeps the design mechanically simple. The Yanmar 3GM30FC is
commonly paired with a folding or fixed 2-blade propeller through the
SD20 saildrive, which provides a 2.64:1 reduction ratio in both forward
and reverse. Applications include sailing yachts from manufacturers such
as Beneteau, Jeanneau, and Hunter, as well as small motor cruisers and
light commercial vessels.
The Yanmar 3GM30FC is a vertical, 4-stroke, water-cooled, naturally
aspirated, inline 3-cylinder diesel engine. The 3-cylinder configuration
provides a compact footprint while maintaining acceptable balance
through the use of a counterweighted crankshaft.
Engine Type: Vertical, inline 3-cylinder, 4-stroke, water-cooled diesel.
Displacement: 0.954 L (954 cc, 58.21 cu.in).
Bore x Stroke: 75 mm x 72 mm (2.95 in x 2.83 in).
Combustion System: Indirect injection with a swirl pre-combustion
chamber.
Aspiration: Naturally aspirated.
Maximum Output: 20.1 kW (27 hp) at 3600 rpm.
Continuous Output: 17.9 kW (24 hp) at 3400 rpm.
Firing Order: 1-2-3.
Compression Ratio: 23:1.
Idling Speed: 750 to 800 rpm (in neutral).
The cylinder block is constructed from cast iron, a material choice
providing rigidity and acoustic damping. The block is a single casting
incorporating the three cylinder bores. Replaceable dry-type cylinder
liners are pressed into the block. The liners are made of centrifugally
cast alloy iron with a hardened internal bore surface.
The block incorporates a side-mounted oil filter housing, a water pump
mounting face at the front of the timing gear housing, and a rear face
drilled for the flywheel housing. A pressed steel oil pan bolts to the
lower flange. The crankshaft is supported by four main bearings.
The cylinder head is a single-piece, cast-iron cross-flow unit covering
all three cylinders. The overhead valve (OHV) configuration places the
camshaft within the cylinder block. Pushrods and rocker arms actuate the
valves. Two valves per cylinder (one intake, one exhaust) produce a
total of six valves. The intake ports are designed to generate swirl
within the pre-combustion chamber for efficient mixing. Valve seats are
pressed-in.
The valvetrain uses mechanical lash adjusters (screw and locknut type).
Valve Clearance (cold engine): Intake: 0.2 mm (0.008 in). Exhaust: 0.2
mm (0.008 in).
The cylinder head gasket is a composite construction with steel fire
rings.
The fuel system is a mechanical indirect injection design utilizing a
swirl pre-combustion chamber in the cylinder head. An in-line injection
pump (Bosch-style) is mounted on the side of the cylinder block and
driven by the engine gear train. The pump incorporates a mechanical
centrifugal governor.
A gear-type feed pump draws fuel from the tank through a primary fuel
strainer. High-pressure steel lines route fuel to three mechanical
injectors. Each injector delivers fuel into the swirl chamber, where
initial combustion occurs before the flame front propagates into the
main combustion chamber. The engine is equipped with a mechanical stop
device for shutdown.
The lubrication system is a fully pressurized, forced-feed circuit using
a trochoid-type oil pump. The pump is mounted on the front of the
crankshaft and draws oil through a strainer from a pressed steel sump.
Oil passes through a spin-on full-flow canister filter mounted on the
side of the block. A pressure regulating valve maintains system
pressure. Pressurized oil then travels to the main bearings, connecting
rod bearings, camshaft bearings, and rocker shaft.
Oil Capacity (total): 2.7 L (2.85 qt).
Oil Grade: SAE 15W-40 or SAE 30, meeting API CD or higher.
The 3GM30FC employs an indirect freshwater cooling system with a heat
exchanger. A belt-driven centrifugal fresh water pump circulates coolant
through the cylinder block, cylinder head, and a plate-type heat
exchanger. Within the heat exchanger, raw seawater pumped by a separate
flexible-impeller pump absorbs heat from the freshwater circuit before
exiting through the exhaust mixing elbow. A thermostatically controlled
bypass circuit permits coolant circulation within the engine during
warm-up. An expansion tank communicates with the heat exchanger.
Coolant Capacity: 2.5 L (2.6 qt), engine and heat exchanger only.
Thermostat Start Opening Temperature: 82°C (180°F).
Thermostat Fully Open Temperature: 95°C (203°F).
Electrical System: 12-volt negative ground. A gear-reduction starter
motor rated at 1.0 kW is standard. A 55-amp alternator (LR155-20)
charges a single 12-volt battery.
Control Device: A mechanical cable-actuated remote control system
operates the fuel injection pump throttle and the sail drive clutch
(forward/neutral/reverse).
Air Intake System: A dry-type paper air cleaner element mounted on the
intake manifold.
Exhaust System: A water-cooled mixing elbow mixes seawater from the heat
exchanger with exhaust gases before routing through a flexible hose to
the gooseneck and overboard exhaust outlet.
Governor: Mechanical, centrifugal-type governor integrated into the
injection pump. Maintains engine speed from idle to maximum rated load.
Length (excluding control lever): 740 mm (29.1 in).
Width: 455 mm (17.9 in).
Height: 545 mm (21.5 in).
Dry Weight (engine only, without saildrive): 130 kg (287 lb).
Dry Weight (with SD20 Saildrive): 165 kg (364 lb).
Oil Change Interval: 100 hours or annually, whichever occurs first.
Oil Filter Replacement: At every oil change.
Fuel Filter Replacement (primary strainer): Clean element at 100 hours.
Fuel Filter Replacement (primary strainer): Replace element at 500
hours.
Valve Clearance Inspection: 500 hours.
Injector Service Interval: Test spray pattern and crack pressure at 1000
hours.
Timing Chain/Belt: The GM series uses a gear train for camshaft drive.
Coolant Replacement: 1000 hours or 2 years. Use ethylene glycol
antifreeze.
Seawater Pump Impeller Replacement: 200 hours or annually. Inspect at
each oil change.
Heat exchanger (Freshwater Cooler): Inspect and clean zinc anodes at 200
hours.
Drive Belt (alternator/seawater pump): Inspect at 100 hours. Replace at
200 hours.
Engine Mount Inspection: Inspect for rubber deterioration at 500 hours.
Cylinder Head Bolts (Stage 1): 30 Nm (22 lb-ft).
Cylinder Head Bolts (Stage 2): 54 Nm (40 lb-ft).
Cylinder Head Bolts (Stage 3): 80 Nm (59 lb-ft).
Connecting Rod Bolts: 35 Nm (26 lb-ft).
Main Bearing Cap Bolts: 70 Nm (52 lb-ft).
Flywheel Bolts (to crankshaft flange): 44 Nm (33 lb-ft).
Flywheel Housing Bolts: 35 Nm (26 lb-ft).
Crankshaft Pulley Bolt: 60 Nm (44 lb-ft).
Camshaft Thrust Plate Bolts: 18 Nm (13 lb-ft).
Rocker Arm Shaft Bracket Bolts: 22 Nm (16 lb-ft).
Injector Hold-Down Clamp Bolts: 20 Nm (15 lb-ft).
Injection Pump Mounting Nuts: 15 Nm (11 lb-ft).
High-Pressure Fuel Line Nuts: 25 Nm (18 lb-ft).
Oil Pump Mounting Bolts: 15 Nm (11 lb-ft).
Water Pump Mounting Bolts (fresh water): 15 Nm (11 lb-ft).
Seawater Pump Mounting Bolts: 15 Nm (11 lb-ft).
Thermostat Housing Bolts: 15 Nm (11 lb-ft).
Starter Motor Mounting Bolts: 25 Nm (18 lb-ft).
Alternator Pivot Bolt: 30 Nm (22 lb-ft).
The Yanmar 3GM30FC is used almost exclusively in marine applications,
predominantly as auxiliary power for sailing yachts and for small
powered vessels.
Sailing Yachts (28 to 35 feet / 8.5 to 10.7
meters):
Beneteau First 32, First 305, Oceanis 321.
Jeanneau Sun Odyssey 32, Sun Odyssey 32.1, Sun Odyssey 32.2.
Hunter 33, Hunter 34, Hunter 35.5.
Catalina 32, Catalina 34.
Bavaria 32, Bavaria 34.
Hallberg-Rassy 31, Rasmus 35.
Najad 331, Najad 343.
Moody 31, Moody 33.
Motor Cruisers (Small Planing and
Displacement Hulls):
Small trawler yachts up to 10 meters (e.g., Ranger Tugs R-27).
Semi-displacement cruisers requiring a compact, lightweight diesel.
Light Commercial Vessels:
Small fishing skiffs (up to 8 meters) used in inshore waters.
Dive boats and passenger tenders.
____________________________________________________________________________________
| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
