Yanmar 1GM - Service Manual
Chapter 1 - BASIC ENGINE

1. Exterior Views

Exterior View  - Stern/Port   Exterior view bow / stbd side
1GM - Intake side viewed from stern / port side   1GM - Exhaust side viewed from bow / stbd side

2. Specifications

Vertical 4-cycle water cooled diesel engine
Combustion chamber
Swirl pre-combustion chamber
Number of cylinders
Bore x stroke
72 x 72
Continuous rating output (DIN6270A) Output/Crankshaft speed
Brake mean effective pressure
Piston Speed
One hour rating output (DIN6270B) Output/Crankshaft speed
7.5 /3600
Brake mean effective pressure
Piston Speed
Compression Ratio
Fuel injection timing (FID)
Fuel injection Pressure

Main power take off

at Flywheel side
Front power take off
at Crankshaft V-pulley side
Direction of Rotation Crankshaft
Counter-clockwise viewed from stern
Propeller shaft (A head)
Clockwise viewed from stern
Cooling system
Direct sea water cooling (rubber impeller water pump)
Lubricating system
Completed enclosed forced lubrication
Starting system
Electric and/or manual
Clutch Model
Mechanical cone clutch with single stage for both ahead and astern
Reduction ratio (Ahead/Astern)
Propeller speed DINA rating (Ahead/Astern)
Lubricating oil capacity
Clutch weight
Dimensions Overall length
Overall width
Overall height
Lubricating oil capacity (rake angel 8 degrees) Total
Engine weight with clutch (dry)

3. Principal Construction

Engine model
Engine block Cylinder block Integrally-cast water jacket and crankcase
Cylinder Liner Sleeveless
Main bearing Metal housing type
Oil sump Oil pan
Intake and exhaust systems and valve mechanism Cylinder head Integrated type cylinder
Intake and exhaust valves Poppet type, seat angle 90 degrees
Exhaust silencer Water-cooled mixing elbow type
Valve mechanism Overhead valve push rod, rocker arm system
Intake silencer Round polyurethane sound absorbing type
Main moving elements Crankshaft Stamp forging
Flywheel Attached to crankshaft by flange, with ring gear
Piston Oval type
Piston pin Floating type
Piston rings 2 compression rings, 1 oil ring
Lubrication system Oil pump Trochoid pump
Oil filter Full-flow cartridge type, paper element
Oil level gauge Dipstick
Cooling system Water pump Rubber impeller type S
Thermostat Wax pellet type
Fuel system Fuel injection pump YPFR-0707-1
Fuel injection valve 530 semi-throttle valve
Fuel strainer Filter paper
Governor Governor Centrifugal all-speed mechanical type
Starting system Electric Pinion ring gear type starter motor
Manual Camshaft starting
Electrical system Charger Alternator (with built-in IC regulator)
Reduction reversing Reduction gear Helical gear constant-mesh system
Clutch system Clutch Servo-cone type

4. Performance Curves

1GM - Performance Curves   1GM10 - Torque   1GM10 - Fuel Consumption   1GM10 - Power Out
1GM - Performance Curves   1GM10 - Torque   1GM10 - Fuel Consumption   1GM10 - Power Out

5. Features

5-1 Superior combustion performance

The unique Yanmar swirl precombustion chamber and new cooling system display superior combustion performance in all types of operation. Low-speed, low-load combustion performance, especially demanded for marine applications, is also superb, and stable performance is maintained over a wide range of speeds. Since starting characteristics are also excellent and warm-up speed is fast, full engine performance can be obtained within a short time.

5-2 Low operating costs

Excellent combustion and low friction reduce fuel costs, while the optimized piston shape and ring configuration and improved cooling system reduce oil consumption. Continuous operating time have been extended and operating costs reduced throughout improved durability.

5-3 Compact, lightweight

The cylinder head is the integrally-cast type, and the crankshaft is the housing type. Minimum weight has been pursued for each engine part, and a reduction revering gear employing a special new mechanism has been incorporated to obtain revolutionary engine lightness.

5-4 Long term continuous operation

Improved durability has been achieved by adopting special construction and materials for main moving paths and the valve mechanism, which are the areas most subject to trouble in high-speed engines. Moreover, a bypass system with a thermostat maintains the cooling water at a table high temperature, resulting in reduced cylinder liner and piston ring wear, reduced thermal load around the combustion chamber, and substantially improved durability. Long-term continuous operation is possible by correct operation and proper attention to fuel and lubricating oil.

5-5 Low vibration

Vibration has been reduced by minimizing the weights of the pistons, connecting rods, and other sources of vibration, stringent weight management at assembly, and balancing of the flywheel, V-pulley, etc. Vibration has also been suppressed through the adoption of a special cylinder block rib construction and improved rigidity. Rubber shock mounts are available when the engine is to be used which may lead to severe vibration.

5-6 Quiet operation

Intake and exhaust noises have been lowered by adopting an intake silencer, water-cooled exhaust manifold, and water mixing elbow type exhaust system.

The precombustion chamber system and semi-throttle type injection valve suppress combustion noise substantially.

Moreover, gear noise has been reduced by the use of helical gears around the gear train and clutch gear, and by the buffering effect of a damper disc.

In addition, noise prevention measures have also been taken at the control valve mechanism and other parts.

5-7 Superior matching to the hull

(1) Four-point support engine installation feet make installation easy.
(2) Mist intake system prevents contamination of the engine room.
(3) Since the fuel pump is mounted on the engine, the fuel tank can be installed anywhere.
(4) Water-cooled manifold prevents a rise in the engine room temperature.
(5) Independent type instrument panel can be installed wherever it is easiest to see.
(6) Speed, clutch forward and reverse, and engine stop can all be remotely controlled.
(7) The use of rubber and vinyl hoses for ship interior piping not only facilitates piping work, but also eliminates brazing faults caused by vibration.
(8) Electric type bilge pump is available as an option.

5-8 Easy to operate

(1) Cooling water temperature switch and lubricating oil pressure switch are provided, and alarm lamps and buzzer are mounted on the instrument panel.
(2) Manual starting handle permits manual starting.
(3) Positive clutch engagement and disengagement; propeller shaft does not rotate when clutch is placed in neutral position.

6. Engine Cross-Section

1GM - Engine Cross-Section - front   1GM - Engine Cross-Section - side
1GM - Engine Cross-Section - front   1GM - Engine Cross-Section - side

7. Dimensions

1GM - Plan   1GM - Body (stern)   1GM - Profile   1GM - Body (bow)
1GM - Plan View   1GM - Body (stern) View   1GM - Profile View   1GM - Body (bow) View
1GM10 - Profile   1GM10 Back   1GM10 - Top   Shaft Coupling
1GM10 - Profile   1GM10 - Back   1GM10 - Top   Shaft Coupling

8. Piping Diagram

1GM Piping Diagram
1GM Piping Diagram

9. System Diagrams

1GM Cooling System   1GM Lubrication System   1GM Fuel System   1GM Electrical System
1GM Cooling System   1GM Lubrication System   1GM Fuel System   1GM Electrical System

10. Standard Accessories

10-1 Parts packed with engine

The parts packed with the listed below.

Part name
Instrument panel with wiring harness, 3m
Starting handle
Tool box
Operating manual
Fexible mount

10-2 Parts mounted on engine

The parts mounted on the engine are listed below.

Part name
Intake silencer  
Mixing elbow  
Cooling water pump  
Fuel feed pump  
Fuel oil filter  
Lubricating oil filter  
Oil pressure switch  
Cooling water temperature switch  
Starter motor  
Alternator (with ICR)  
Electric wiring harness  
Speed remote control bracket with cable clamp
Engine stop remote control bracket  
Engine stop device  
Clutch remote control bracket with clutch cable
Clevis or spring joint Fitted to clutch lever

11. Optional Accessories

11-1 Parts mounted on engine

The parts mounted on the engine are listed below.

Part name
Tachometer sender Hex plug M18 unnecessary

11-2 Parts packed with the engine

The parts mounted on the engine are listed below.

Part name
Stop remote control cable ass'y 3m x 1
Morse one handle control Model MT2 top mounted type
Morse one handle control Model MV side mounted type
Push-pull cable 33-C, 4m x 2
Battery switch  
Oil evacuation pump ass'y  
Kingston cock and cooling water pipe Cooling water pipe, 2m x 1
Propeller shaft coupling Taper shaft
Propeller shaft coupling Slit type
Fuel oil tank and fuel oil pipe Fuel oil tank, 30l, pipe, 2m
Spare parts kit  
Packing Kit  
Special disassembly tools  
Instrument panel (large, with tachometer)  
Instrument panel (small)  
Extension wiring harness, 3m To be selected according to order specification. One harness is fitted as a Standerd accessory. However, longer parts are optionally available should the standard accessory prove too short.