D348 INDUSTRIAL & MARINE ENGINES Caterpillar


Systems Operation

Usage:



Fuel System


FUEL SYSTEM SCHEMATIC
1. Fuel transfer pump inlet fuel line. 2. Fuel priming pump. 3. Fuel supply line from fuel tank. 4. Air-fuel bleed line from fuel control valve housing to fuel tank. 5. Fuel tank. 6. Fuel transfer pump outlet line to fuel filter housing. 7. Fuel transfer pump. 8. Fuel filters. 9. Fuel injection pump housing.


FUEL CONTROL VALVE CLOSED WITH ENGINE STOPPED
1. Fuel transfer pump inlet fuel line. 2. Fuel priming pump. 3. Fuel supply line from fuel supply tank. 6. Fuel transfer pump outlet line to fuel filter housing. 8. Fuel filters. 10. Air-fuel bleed line to fuel tank. 11. Fuel control valve. 12. Spring.


PRIMING PUMP SUCTION STROKE
1. Fuel transfer pump inlet fuel line. 2. Fuel priming pump. 3. Fuel supply line from fuel supply tank. 6. Fuel transfer pump outlet line to fuel filter housing. 8. Fuel filters. 10. Air-fuel bleed line to fuel tank. 11. Fuel control valve. 12 & 13. Springs.

The position of valve (11) controls the flow of fuel in this fuel system. With the engine stopped, spring (12) holds valve (11) in the closed position.

As the priming pump handle is pulled out (suction stroke) springs (12 and 13) expand and valve (11) moves, allowing fuel from supply line (3) to be drawn into fuel priming pump (2).

When the priming pump handle is pushed in (pressure stroke), the combination of fuel pressure and spring (12) force causes valve (11) to move, compressing spring (13). This action allows the required amount of fuel to flow through fuel filters (8) and on to the injection pumps. At the same time, excess fuel and any air that may be in the system flows through air-fuel bleed line (10) to return to the fuel supply tank.


PRIMING PUMP PRESSURE STROKE
1. Fuel transfer pump inlet fuel line. 2. Fuel priming pump. 3. Fuel supply line from fuel supply tank. 6. Fuel transfer pump outlet line to fuel filter housing. 8. Fuel filters. 10. Air-fuel bleed line to fuel tank. 11. Fuel control valve. 12. Spring. 13. Spring.

With the engine running, only the fuel required to maintain the desired engine speed is directed through the fuel filters and then to the fuel injection pump. Fuel not required by the engine is directed through passages, opened by the position of fuel control valve (11), and returns to the fuel transfer pump. At the same time, some fuel and any air that may be in the system returns to the fuel supply tank through air-fuel bleed line (10).


FUEL FLOW THROUGH FUEL CONTROL PISTON WITH ENGINE RUNNING
1. Fuel transfer pump inlet fuel line. 2. Fuel priming pump. 3. Fuel supply line from fuel supply tank. 6. Fuel transfer pump outlet line to fuel filter housing. 8. Fuel filters. 10. Air-fuel bleed line to fuel tank. 11. Fuel control valve.

Fuel Injection Pump

Fuel enters the fuel injection pump housing through passage (6) and enters the fuel injection pump body through the inlet port (2). The injection pump plungers (5) and the lifters (11) are lifted by the cam lobes (12) on the camshaft and always make a full stroke. The lifters are held against the cam lobes by the springs (3). Each pump measures the amount of fuel to be injected into its respective cylinder and forces it out the fuel injection nozzle.


FUEL INJECTION PUMP
1. Check valve. 2. Inlet port. 3. Spring. 4. Lubrication passage (fuel). 5. Pump plunger. 6. Fuel passage. 7. Bleed passage. 8. Fuel rack. 9. Lubrication passage (oil). 10. Gear segment. 11. Pump Lifter. 12. Camshaft lobe.

The amount of fuel pumped each stroke is varied by turning the plunger in the barrel. The plunger is turned by the governor action through the fuel rack (8) which turns the gear segment (10) on the bottom of the pump plunger. Passage (4) provides fuel to lubricate the pump plunger and passage (7) allows air to be bled from the system through the valve on top of the fuel filter case.

Fuel Injection Valve (Earlier)

Fuel, under high pressure from the injection pumps, is transferred through the injection lines to the injection valves. As high pressure fuel enters the nozzle assembly, the check valve within the nozzle opens and permits the fuel to enter the precombustion chamber. The injection valve provides the proper spray pattern.


FUEL INJECTION VALVE CROSS SECTION
1. Fuel line assembly. 2. Seal. 3. Body. 4. Nut. 5. Seal. 6. Nozzle assembly. 7. Glow plug. 8. Precombustion chamber.

Fuel Injection Valve (Later)

The operation is the same for the earlier and later fuel injection valves. A union (5) has been added to the later fuel injection valves. One end of the union is connected by a passage in precombustion chamber (9) to a chamber around nozzle assembly (7). The other end of the union is connected by a line to an opening in the cylinder head. A plug in the cylinder head opening can be removed to check for fuel leakage around the nozzle assembly.


FUEL INJECTION VALVE CROSS SECTION
1. Fuel line nut. 2. O-ring seal. 3. Nut. 4. Body. 5. Union. 6. O-ring seal. 7. Nozzle assembly. 8. Glow plug. 9. Precombustion chamber.

Glow Plugs

Glow plugs are an aid for cold weather starting. During cold weather starting, the pressure in the cylinders made by the compression stroke is not enough to start combustion of the fuel injection charge. Activating the glow plugs for the correct length of time heats the precombustion chambers to the temperature which is necessary for combustion when the engine is turned for starting. After combustion starts and the starting motor is no longer necessary to keep the engine running, more operation of the glow plugs heats the precombustion chambers until the engine is running smoothly.

Speed Sensing, Variable Timing Unit

The variable timing unit, couples the fuel injection pump camshaft to the engine rear timing gears. The variable timing unit advances the timing as engine rpm increases.

On engines with Serial Numbers 36J1-36J1035 and 38J1-38J255 the timing advances from 11° BTC at low idle to 19° BTC at high idle. On engines with Serial Numbers 36J1036-Up and 38J256-Up the timing advances from 8° BTC at low idle to 19° BTC at high idle.

During engine low rpm operation, the flyweight (8) force is not sufficient to overcome the force of control valve spring (3) and move control valve (7) to the closed position. Oil merely flows through the power piston cavity (2).


LOW RPM POSITION
1. Power piston. 2. Power piston cavity. 3. Control valve spring. 4. Power piston return spring. 5. Oil inlet passage. 6. Drain port. 7. Control valve. 8. Flyweights. 9. Shaft assembly.

As the engine rpm increases, flyweights (8) overcome the force of control valve spring (3) and move control valve (7) to the closed position, blocking the oil drain port (6). Pressurized oil, trapped in power piston cavity (2), overcomes the force of spring (4) and moves power piston (1) outward. This causes the fuel injection pump camshaft to index slightly ahead of the shaft portion (9) of the variable timing unit. Any outward movement of the power piston increases the force on the control valve spring. This tends to reopen the control valve, letting oil escape from the power piston cavity. As oil begins flowing from the cavity again, return spring (4) moves the power piston inward.

At any given rpm, a balance is reached between the flyweight force and the control valve spring force. The resultant position of control valve (7) will tend to maintain proper pressure behind the power piston. The greater the rpm, the smaller the drain port opening, and the further outward the power piston is forced.


HIGH RPM POSITION
1. Power piston. 2. Power piston cavity. 3. Control valve spring. 4. Power piston return spring. 5. Oil inlet passage. 6. Drain port. 7. Control valve. 8. Flyweights. 9. Shaft assembly.

As the power piston is moved outward, the angular relationship of the ends of the drive unit change. As the power piston moves forward in the internal helical spline, the fuel injection pump timing advances.

The gear teeth on shaft assembly (9) drive the governor drive pinion.

Hydra-Mechanical Governor

The governor controls engine speed by balancing governor spring force with governor weight centrifugal force. The compressed governor spring force is applied to increase the supply of fuel to the engine, while the centrifugal force of the engine driven governor weights is applied to decrease fuel to the engine.

Oil pump gear (15), driven by shaft (19), provides pressure oil for the servo portion of the governor. To operate correctly, the servo system requires a higher pressure oil than the engine oil system can maintain. A bypass valve in governor drive housing (16) maintains the correct oil pressure. A sump in the governor drive housing provides an immediate oil supply for governor operation during engine starting.

When the engine is operating, the balance between the centrifugal force of revolving weights (9) and the force of spring (7) controls valve (8). The valve directs pressure oil to either side of rack-positioning piston (13). Depending on the position of the valve (8), piston (13) will move the rack to increase or decrease fuel to the engine to compensate for load variation.

Pressurized lubrication oil, directed through passages in governor drive housing (16) and oil pump cover (17) enters a passage in governor cylinder (12). The oil encircles sleeve (14) within the cylinder. Oil is then directed through passage (11) in piston (13) where it contacts valve (8).

When engine load increases, engine rpm decreases and revolving weights (9) slow down. The weights move toward each other and allow governor spring (7) to move valve (8) down. As valve (8) moves, an oil passage around valve (8) opens to pressure oil. Oil then flows through passage (11) and fills the chamber behind piston (13). The pressure forces the piston and rack down, increasing the amount of fuel to the engine. Engine rpm increases until the revolving weights rotate fast enough to balance the force of the governor spring.


GOVERNOR
1. Shutoff shaft. 2. Collar. 3. Adjusting screw. 4. Stop bar. 5. Lever assembly. 6. Seat assembly. 7. Governor spring. 8. Valve. 9. Weight assembly. 10. Seat. 11. Oil passage. 12. Cylinder. 13. Piston. 14. Sleeve. 15. Oil pump gear. 16. Governor drive housing. 17. Oil pump cover. 18. Pin assembly. 19. Shaft assembly. 20. Lever. 21. Fuel rack. 22. Drive pinion.

When engine load decreases, engine rpm increases, revolving weights (9) speed-up, and the toes on the weights move valve (8) up, allowing the oil behind piston (13) to flow through a drain passage opened at the rear of the piston. At the same time, the pressure oil between sleeve (14) and piston (13) forces the piston and rack up, decreasing the amount of fuel to the engine. Engine rpm decreases until the revolving weights balance the force of the governor spring.

When the engine is started, a speed limiter plunger located in the governor housing, restricts the movement of the governor control linkage. When operating oil pressure is reached, the plunger in the speed limiter retracts and the governor control can be moved to the HIGH IDLE position.

Hydraulic Air-Fuel Ratio Control

The hydraulic air fuel ratio control works automatically. When the engine is starting, it lets the engine have the maximum amount of fuel for starting. After the engine is running, the control activates automatically as soon as the inlet manifold has enough pressure (boost). The engine must run under a load in order to get this amount of inlet manifold pressure.

After the control activates, it automatically controls how fast the rack can move to increase the fuel supply to the engine. The result of this action is that the engine gets enough fuel to increase the engine rpm, but not enough to cause black smoke in the exhaust. After the engine stops running, the control automatically goes back to the starting position.

Engine Starting


HYDRAULIC AIR-FUEL RATIO CONTROL (Engine Starting)
1. Adjustment cover. 2. Control valve. 3. Retainer for diaphragm. 4. Air inlet line. 5. Spring. 6. Diaphragm. 7. Spring. 8. Spring. 9. Land. 10. Piston end of valve (15). 11. Oil passage. 12. Oil outlet. 13. Oil outlet. 14. Oil passage. 15. Valve. 16. Oil inlet. 17. Rack stop collar.

When the engine is starting, the fuel ratio control lets the engine have full rack movement for easier starting. After the engine starts, oil from the engine lubrication system comes through passages in the governor housing into the control through oil inlet (16). This oil fills the chamber under the piston end (10) of valve (15). It then goes out through passage (11), around valve (2) in the bore of valve (15) and out of the control through oil outlet (13). At the same time, the air pressure in the inlet manifold is in the chamber above diaphragm (6). This air pressure comes through air inlet (4). It is not enough to activate the control unless the engine is running under a load.


CONTROL WITH ENGINE RUNNING (No Load)

Activating The Control

When the engine runs under a load, inlet manifold pressure (boost) gets higher. At about 3 psi (20 kPa), the force on diaphragm (6) with the force from spring (5) is enough to move valve (2) down into valve (15) against the forces of springs (7) and (8). When valve (2) is into valve (15) far enough for land (9) to close passage (11), the oil flow from the oil outlet (13) is stopped. Now the oil pressure in the chamber gets higher. At an oil pressure of about 10 psi (70 kPa) the force on the piston end (10) of valve (15) is enough to move valve (15) up in the bore of the housing against the force of spring (8). When valve (15) moves up enough, the oil in the chamber starts to go out between the edges of valve (2) and valve (15) as shown. At this point, the movement of valve (15) stops. Now the control is activated and operating.


CONTROL WITH ENGINE RUNNING (Load Applied)


CONTROL ACTIVATING

NOTE: The control must have both the minimum inlet manifold pressure and the minimum oil pressure, for approximately 3 seconds, to activate correctly. More of either pressure makes the control activate more quickly.

Control Operation

After the control activates, it can control how far and how fast the rack can move in the maximum fuel direction. When the operator moves the governor control for more engine rpm, the rack moves in the maximum fuel direction. The control is a restriction to this movement only if there is not enough inlet manifold pressure to make the combustion of the extra fuel complete, When the control is a restriction, the control releases the rack stop collar (17) at the same rate as the inlet manifold pressure increases. If the operator moves the governor control for less engine rpm, the control is not a restriction to the movement of the rack. The inlet manifold pressure will decrease when the engine rpm decreases. The diaphragm (6) and valve (2) then move into a new balance position between the springs. Valve (15) then follows valve (2) to put the force of the springs and the oil flow in balance. Now the control is ready to prevent black smoke in the exhaust during the next period of increasing engine rpm (acceleration).


CONTROL IN OPERATION

Fuel Ratio Control

The fuel ratio control coordinates the movement of the fuel rack with the amount of air available in the inlet manifold. The control keeps the air to fuel ratio more efficient, thus minimizing exhaust smoke.

A manually operated override lever (1) is provided to allow unrestricted rack movement during cold starts. After the engine starts, the override automatically resets in the RUN position.


FUEL RATIO CONTROL CROSS SECTION
1. Lever. 2. Housing. 3. Spring. 4. Spring. 5. Diaphragm. 6. Hook. 7. Bolt assembly. 8. Bolt and collar.

Bolt and collar (8) mechanically connect to the fuel rack. The head of bolt assembly (7) latches through a slot in hook (6) attached to bolt and collar (8). An air line joins the chamber above diaphragm (5), with the air in the engine inlet manifold.

When the operator moves the governor control to increase engine rpm, the fuel rack moves bolt and collar (8) down until hook (6) contacts the head of bolt assembly (7). The bolt assembly restricts the movement of the bolt and collar until a boost of air pressure in housing (2) forces diaphragm (5), spring (4) and bolt assembly (7) to relieve the restriction to bolt and collar (8). This allows the fuel rack to move to increase the fuel as turbocharger air pressure (boost) increases with the increase in engine rpm.

NOTE: Spring (3) holds the manual override plunger out of the way during normal operation.

Air Inlet And Exhaust System


AIR INLET AND EXHAUST SCHEMATIC
1. Left side exhaust manifold. 2. Aftercoolers. 3. Right side exhaust manifold. 4. Equalizer tube. 5. Left side air cleaner. 6. Turbocharger. 7. Exhaust outlet. 8. Turbocharger. 9. Right side air cleaner.

The air inlet and exhaust system includes two turbochargers (6 and 8) located at the rear of the engine.

Each turbocharger is driven from, and charges, its own cylinder bank. Balanced inlet manifold pressures between banks are assured through an equalizer tube (4) connecting the two aftercooler housings.

Exhaust manifolds (1 and 3) for the Industrial Engine have one section to a cylinder. These are interchangeable between banks. High-temperature studs and nuts are used to secure the manifold sections to the cylinder heads.

Exhaust manifolds (1 and 3) on the Marine Engine are one piece and water-cooled. The water-cooled, one piece manifold, for each cylinder bank helps to insure exhaust gas sealing.

The aftercooler housings (2) are located directly on top of the "V" side of the cylinder heads. The aftercooler housings contain the aftercooler cores, with provision for either engine coolant water or sea water as a cooling medium for the inlet air. The air inlet section of the aftercooler housing is connected to the turbochargers (6 and 8).

Inlet air for the engine is drawn through air cleaners (5 and 9) and directed to the turbochargers. From turbochargers (6 and 8), air is forced directly through the cores of aftercoolers (2) and into the combustion area.

There are four in-head valves (two intake and two exhaust) for each cylinder. The valves are actuated by overhead camshafts and forked rocker arm assemblies, located in the housing on top of the cylinder heads.

Exhaust gases leave each cylinder through two exhaust valve ports. After passing through the turbine side of the turbochargers, the exhaust exits through exhaust outlet (7) located between the turbochargers.

Turbochargers

The turbochargers are supported by brackets mounted to the engine cylinder block. All the exhaust gases from the diesel engine pass through the turbochargers.


TURBOCHARGER (Typical Illustration)
1. Air inlet. 2. Compressor housing. 3. Nut. 4. Compressor wheel. 5. Thrust plate. 6. Center housing. 7. Lubrication inlet port. 8. Shroud. 9. Turbine wheel and shaft. 10. Turbine housing. 11. Exhaust outlet. 12. Spacer. 13. Ring. 14. Seal. 15. Collar. 16. Lubrication outlet port. 17. Ring. 18. Bearing. 19. Ring.

The exhaust gases enter the turbine housing (10) and are directed through the blades of a turbine wheel (9), causing the turbine wheel and a compressor wheel (4) to rotate.

Filtered air from the air cleaners is drawn through the compressor housing air inlet (1) by the rotating compressor wheel. The air is compressed by action of the compressor wheel and forced to the inlet manifold of the engine.

When engine load increases, more fuel is injected into the engine cylinders. The volume of exhaust gas increases causing the turbocharger turbine wheel and compressor impeller to rotate faster. The increased rpm of the impeller increases the quantity of inlet air. As the turbocharger provides additional inlet air, more fuel can be burned; hence more horsepower derived from the engine.

Maximum rpm of the turbocharger is controlled by the rack setting, the high idle speed setting and the height above sea level at which the engine is operated.

------ WARNING! ------

If the high idle rpm or the rack setting is higher than given in the book RACK SETTING INFORMATION (for the height above sea level at which the engine is operated), there can be damage to engine or turbocharger parts.

--------WARNING!------

The bearings for the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (7) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the oil outlet port (16) in the bottom of the center section and goes back to the engine lubricating system.

The fuel rack adjustment is done at the factory for a specific engine application. The governor housing and turbocharger are sealed to prevent changes in the adjustment of the rack and the high idle speed setting.

Cylinder Heads, Valves And Camshafts

Cylinder Heads and Valves

This is a four stroke cycle engine; i.e., four separate piston strokes are required to complete the firing of one cylinder.

There are four in-head valves for each cylinder; two intake valves and two exhaust valves.

The in-head valves are perpendicular to the bottom face of the cylinder head. The exhaust valves and ports are located toward the outside of the engine. The intake valves are on the inside, toward the vee.

A primary feature of the cylinder head is parallel porting. This provides individual porting for each of the two exhaust valves and the two intake valves. This permits unrestricted flow of air and exhaust gasses; resulting in maximum breathing capability and efficiency.

Valves, valve seats, seating springs and rotators are all part of the cylinder head assembly. The valve seats are pressed into the cylinder head and are replaceable.

Valve rotators add much to valve life. Each valve is rotated approximately three degrees on every lift; thus minimizing pitting of the valve faces and valve seats. The rotation also causes a wiping action to remove carbon deposits from the valve seat.

Rocker Arms

Valve action is accomplished through a roller-rocker arm arrangement. The forked rocker arm (2), located in the camshaft housing, pivots on a shaft (4) at one end and depresses two valves at the other end through adjusting screws. A roller (5), supported by a pin near the center of the rocker arm, rides on the camshaft (1) lobe. Thus, one camshaft lobe actuates the forked rocker arm and opens two valves simultaneously.


ROCKER ARM
1. Camshaft. 2. Rocker arm. 3. Adjusting screw. 4. Pivot shaft. 5. Roller. 6. Spring. 7. Valve.

Valve adjustment can be quickly and accurately accomplished with a screwdriver. No thickness gauge is required. Turn the adjusting screw (3) down to remove all clearance, then back off to the required setting.

Camshafts

This engine uses two overhead camshafts in each cylinder bank. The inner camshaft in each bank actuates all the intake valves and the other camshaft actuates all the exhaust valves.

The camshafts are driven from both ends of the engine. The right bank camshafts are driven by the rear gear train. On the left bank, the inlet camshaft drives the exhaust camshaft. On the right bank, the exhaust camshaft (F) drives the inlet camshaft (E).


CYLINDER BLOCK
A. Flywheel end. B. Left side. C. Front end. D. Right side. E. Inlet camshaft. F. Exhaust camshaft.

The camshaft journals are supported in integrally cast webs of the camshaft housings. Pressure lubrication to the camshaft journals is supplied from the cylinder block through the cylinder head, and into drilled passages in the camshaft housing.

A crankcase breather is mounted on the front of the right bank camshaft cover. The element is removable for cleaning. A fumes disposal tube carries the crankcase fumes to a level below the engine.

Lubrication System


LUBRICATION SYSTEM
1. Turbochargers. 2. To valve train (left bank). 3. To governor and fuel injection pump housing. 4. Cylinder head. 5. Main oil manifold. 6. To valve train (right bank). 7. Oil filters. 8. To front timing gears. 9. Oil filter bypass valve. 10. Turbocharger lubrication valve. 11. Oil drain to pan. 12. Oil pump. 13. Oil pan. 14. Oil pump bypass valve. 15. To main bearings, rod bearings, and piston cooling tubes. 16. Oil cooler bypass valve. 17. Oil cooler.

Under normal operating conditions, oil flow is as follows: Oil from the sump is delivered by oil pump (12), through oil cooler (17) and oil filters (7), to the front mounted timing gears, rear mounted timing gears, crankshaft main bearings, connecting rod bearings, piston cooling jets, governor and fuel injection pump housing, right and left bank valve mechanisms, and the turbochargers.

Bypass valve (14), located in the body of oil pump (12), limits the maximum pressure of oil from the pump.

Turbocharger lubrication valve (10) is mounted on the top left portion of the flywheel housing. When the engine is started, the flow of oil through oil cooler (17) and oil filters (7) is momentarily restricted. Turbocharger lubrication valve (10) opens and oil flows directly to turbochargers (1). When pressure through oil cooler (17) and oil filters (7) is equalized, turbocharger lubrication valve (10) closes to provide filtered oil to turbochargers (1).

Oil filter bypass valve (9) is located in the right end cover of the oil filter housing at the front of the engine. Oil cooler bypass valve (16) is located in the lines above oil cooler (17) on the right side of the engine.

On cold starts, the oil cooler and filter bypass valves open, eliminating the oil cooler and filter restrictions. Oil from oil pump (12) is directed past the bypass valves and directly to the engine components.

As oil temperature increases, the bypass valves close. Oil is then forced to flow through the oil cooler and filter. Unless the oil filters are restricted, or oil viscosity is extremely high, only filtered oil is furnished to the engine components. If the oil filters become restricted, oil filter bypass valve (9) opens, and allows oil to flow directly to engine components.

Lubrication of Governor and Fuel Injection Pump

The governor lubrication system includes an oil pump within the governor. Governor oil collects at the bottom of the governor housing and overflows into the fuel pump housing through a standpipe. This reservoir supplies oil to the governor oil pump located in the plate assembly between the governor housing and the fuel pump housing. This pump supplies oil pressure to the servo mechanism to obtain quick response from the governor.

The fuel injection pump housing also contains an oil manifold which supplies oil to the camshaft bearings and the lifter rollers. The lifter rollers and camshaft lobes receive oil each time a lifter moves up and uncovers an oil hole. Oil drains from the fuel pump housing to the cylinder block.


FUEL INJECTION PUMP AND GOVERNOR LUBRICATION SYSTEM
1. Speed limiter. 2. Bypass valve. 3. Governor oil pump oil supply. 4. Oil supply from cylinder block. 5. Fuel injection pump oil manifold. 6. Oil supply to speed sensing - variable timing unit. 7. and 8. Oil return to cylinder block.

Cooling System

Engine Coolant


ENGINE COOLANT AFTERCOOLED
1. Left bank cylinder heads. 2. Left bank cylinders aftercooler. 3. Water temperature regulator housing. 4. Heat shield. 5. Right bank cylinders aftercooler. 6. Water pump. 7. Oil cooler. 8. Right bank cylinder heads. 9. Coolant bypass line. 10. Radiator.

Coolant is circulated by a water pump (6) located on the right front side of the flywheel housing. This pump is driven from the rear timing gear train.

Coolant from the radiator (10) or heat exchanger flows to the water pump. The entire pump flow is directed through the engine oil cooler (7) and the bypass tube on the right side of the engine. At the outlet of the oil cooler, part of the coolant is directed to the right bank cylinders (8), while the remaining flow continues to a lower chamber in the regulator housing (3), located at the front of the engine.

The lower portion of the regulator housing divides the flow equally between the left bank cylinders (1) and the aftercoolers (2 and 5) incorporated in the inlet manifolds. Flow exits from the rear of the aftercoolers into a heat shield (4). From here, the flow is divided to enter the cylinder block at the bottom rear of each cylinder bank. Coolant circulates up to the cylinder heads and exits to the regulator housing. Four water temperature regulators control the division of flow to the cooling unit (radiator, heat exhanger, or cooling tower) or back to the water pump inlet.

This engine has full coolant flow through the engine whether the regulators are closed, partly open or full open. This gives the engine more uniform temperatures. When the regulators are closed, all the coolant goes from the regulators through bypass line (9) to the water pump inlet. When the temperature of the coolant in the water temperature regulator housing (3) gets to approximately 25° F (14° C) less than the fully open temperature of the regulators, the regulators start to open. some of the coolant flow starts to go through the cooling unit. As the coolant temperature increases, more of the coolant goes through the cooling unit. When the coolant temperature gets to the fully open temperature of the regulators, most of the coolant goes through the cooling unit. If the cooling unit is of the correct size and is working correctly, the temperature of the coolant coming out of the cooling unit is approximately 15° F (8° C) less than the temperature of the coolant going in under full load conditions.

Marine Engine Equipped For Auxiliary Water Aftercooling


AUXILIARY WATER AFTERCOOLING
1. Turbocharger heat shield. 2. Left bank cylinder head. 3. Left bank cylinders aftercooler. 4. Water cooled exhaust manifold. 5. Heat exhanger. 6. Expansion tank. 7. Right bank cylinders aftercooler. 8. Marine gear oil cooler. 9. Auxiliary water pump. 10. Diesel engine water pump. 11. Right bank cylinder head. 12. Engine oil cooler. 13. Water cooled exhaust manifold.

Auxiliary water, from its source, is supplied to the auxiliary water pump (9). The auxiliary water pump is located at the right rear of the flywheel housing and is driven by the same gear that drives the diesel engine water pump (10). From the auxiliary water pump, part of the coolant flows to the marine gear oil cooler (8) (if so equipped), and then to the rear of the aftercoolers (3 and 7). Coolant flow through the aftercoolers is rear-to-front and then to a heat exhanger or to waste.

If an engine is equipped with water-cooled exhaust manifolds (4 and 13) and a turbocharger heat shield (1), these items are connected to the engine cooling system as illustrated.

Engine coolant temperature is controlled by the use of water temperature regulators. On cold starts, the regulators are closed, causing cold water from the engine to be circulated through the expansion tank (6) to the engine water pump inlet. Water from the heat exchanger (5) cannot enter the system because the regulators block the return flow.

As coolant temperature rises, the regulators open slightly to allow heat exhanger water to flow to the expansion tank where it mixes with heated water from the engine.

Basic Engine Components

Cylinder Block


CYLINDER BLOCK
A. Flywheel end. B. Left side. C. Front end. D. Right side.

The cylinder block is a 60° vee. One bank of cylinders is offset from the other bank of cylinders. This offset provides space at each end of the cylinder block for the camshaft drives. The offset also allows two connecting rods to be secured to each connecting rod journal of the crankshaft.

Cylinder Liners

On earlier engines a steel spacer plate is used between the cylinder heads and the cylinder block. The cylinder liners are supported in counterbores in the spacer plate.

On later engines the cylinder liner sits directly on the cylinder block. Engine coolant flows around the liners to cool them. Three O-ring seals at the bottom and a filler band at the top of each cylinder liner form a seal between the cylinder liner and the cylinder block.

Pistons, Rings And Connecting Rods

The piston has three rings; two compression and one oil ring. All rings are located above the piston pin bore. The two compression rings seat in an iron band which is cast into the piston. Pistons in earlier engines used compression rings with straight sides. Pistons in later engines use compression rings which are of the KEYSTONE type. KEYSTONE rings have a tapered shape and the movement of the rings in the piston groove (also of tapered shape) results in a constantly changing clearance (scrubbing action) between the ring and the groove. This action results in a reduction of carbon deposit and possible sticking of rings.

The oil ring is a standard (conventional) type and is spring loaded. Holes in the oil ring groove provide for the return of oil to the crankcase.

The full-floating piston pin is held in place by two snap rings which fit in grooves in the pin bore.

A steel heat plug in the top of the piston prevents erosion (wearing away) of the top of the piston at the point of highest heat.

Piston cooling jets, located on the cylinder block main bearing supports, throw oil to cool and give lubrication to the piston components and cylinder walls.

The connecting rods have diagonally cut serrated joints which allow removal of the piston and connecting rod assembly upward through the cylinder liner. Earlier engines use the same part number connecting rod for both odd and even numbered cylinders. This connecting rod uses a locating tab to position the connecting rod bearing.

Connecting rod bearings in later engines do not have locating tabs but are positioned by dowels in the connecting rods. The rods with dowel located bearings are marked " Even Cyl Only ..." or " Odd Cyl Only ...". These rods must be installed in the correct bank. They may be installed in earlier engines if the correct piston cooling jets are installed. Refer to Special Instruction Form No. GEG02495 for complete instructions.

Crankshaft

The crankshaft transforms the combustion forces in the cylinders into usable rotating torque which powers the machine. There is a timing gear at each end of the crankshaft which drives the respective timing gears.

Interconnecting drilled passages supply pressurized lubricating oil to all bearing surfaces on the crankshaft.

On later engines, wear sleeves and lip type seals were added to both ends of the crankshaft. If the wear sleeves become worn, the installation of new parts must be done with the correct tooling. Special Instructions are sent with the wear sleeves and seals for this operation. Make reference to the Tool Guide for tools to remove the seals and wear sleeves.

Air Starting System

The air starting motor is used to turn the engine flywheel fast enough to get the engine running.


AIR STARTING SYSTEM (TYPICAL EXAMPLE)
1. Starter control valve. 2. Oiler. 3. Relay valve. 4. Air starting motor.

The air starting motor can be mounted on either side of the engine. Air is normally contained in a storage tank and the volume of the tank will determine turning time of engine. The storage tank must hold this volume of air at 250 psi (1720 kPa) when filled.

For engines which do not have heavy loads when starting, the regulator setting is approximately 100 psi (690 kPa). This setting gives a good relationship between cranking speeds fast enough for easy starting and the length of time the air starting motor can turn the engine before the air supply is gone.

If the engine has a heavy load which can not be disconnected during starting, the setting of the air pressure regulating valve needs to be higher in order to get high enough speed for easy starting.

The air consumption is directly related to speed. The air pressure is related to the effort necessary to turn the engine flywheel. The setting of the air pressure regulator can be up to 150 psi (1030 kPa) if necessary to get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine as fast as it can turn a lightly loaded engine.

Other air supplies can be used if they have the correct pressure and volume. For good life of the air starting motor, the supply should be free of dirt and water. The maximum pressure for use in the air starting motor is 150 psi (1030 kPa). Higher pressures can cause safety problems.

The 1L5011 Regulating and Pressure Reducing Valve Group has the correct characteristics for use with the air starting motor. Most other types of regulators do not have the correct characteristics. Do not use a different style of valve in its place.


AIR STARTING MOTOR (Ingersoll-Rand Motor Shown)
5. Vanes. 6. Rotor. 7. Air inlet. 8. Pinion. 9. Gears. 10. Piston. 11. Piston spring.

The air from the supply goes to relay valve (3). The starter control valve (1) is connected to the line before the relay valve (3). The flow of air is stopped by the relay valve (3) until the starter control valve (1) is activated. Then air from the starter control valve (1) goes to the piston (10) behind the pinion (8) for the starter. The air pressure on the piston (10) puts the spring (11) in compression and puts the pinion (8) in engagement with the flywheel gear. When the pinion is in engagement, air can go out through another line to the relay valve (3). The air activates the relay valve (3) which opens the supply line to the air starting motor.

The flow of air goes through the oiler (2) where it picks up lubrication oil for the air starting motor.

The air with lubrication oil goes into the air motor. The pressure of the air pushes against the vanes (5) in the rotor (6). This turns the rotor which is connected by gears (9) to the starter pinion (8) which turns the engine flywheel.

When the engine starts running the flywheel will start to turn faster than the starter pinion (8). The pinion (8) retracts under this condition. This prevents damage to the motor, pinion (8) or flywheel gear.

When the starter control valve (1) is released, the air pressure and flow to the piston (10) behind the starter pinion (8) is stopped. The piston spring (11) pulls back the pinion (8). The relay valve (3) stops the flow of air to the air starting motor.

Hydraulic Starting System


HYDRAULIC STARTING SYSTEM DIAGRAM
1. Reservoir. 2. Hand pump. 3. Pressure gauge. 4. Hydraulic starting motor. 5. Starter control valve. 6. Hydraulic pump (driven by engine timing gears). 7. Unloading valve. 8. Filter. 9. Accumulator.

The hydraulic starting motor (4) is used to turn the engine flywheel fast enough to get the engine started. When the engine is running, the hydraulic pump (6) pushes oil through the filter (8) into the accumulator (9). The accumulator (9) is a thick wall cylinder. It has a piston which is free to move axially in the cylinder. A charge of nitrogen gas (N2) is sealed in one end of the cylinder by the piston. The other end of the cylinder is connected to the hydraulic pump (6) and the hydraulic starting motor (4). The oil from the hydraulic pump (6) pushes on the piston which puts more compression on the nitrogen gas (N2) in the cylinder. When the oil pressure gets to 3000 psi (20 700 kPa), the accumulator (9) has a full charge. At this point the piston is approximately in the middle of the cylinder.

The unloading valve (7) feels the pressure in the accumulator (9). When the pressure is 3000 psi (20 700 kPa) the unloading valve (7) sends the hydraulic pump (6) output back to the reservoir (1). At the same time it stops the flow of oil from the accumulator (9) back to hydraulic pump (6). At this time there is 3000 psi (20 700 kPa) pressure on the oil in the accumulator (9), in the line to the unloading valve (7), in the lines to the hand pump (2) and to the hydraulic starting motor (4).

Before starting the engine, the pressure on the pressure gauge (3) should be 3000 psi (20 700 kPa). When the starter control valve (5) is activated, the oil is pushed from the accumulator (9) by the nitrogen gas (N2). The oil flow is through the hydraulic starting motor (4), where the energy from the compression of the fluid is changed to mechanical energy for turning the engine flywheel.

Hydraulic Starting Motor


HYDRAULIC STARTING MOTOR
1. Rotor. 2. Piston. 3. Thrust bearing. 4. Starter pinion. A. Oil inlet. B. Oil outlet.

The hydraulic starting motor is an axial piston hydraulic motor. The lever for the starter control valve pushes the starter pinion (4) into engagement with the engine flywheel at the same time it opens the way for high pressure oil to get into the hydraulic starting motor.

When the high pressure oil goes into the hydraulic starting motor, it goes behind a series of pistons (2) in a rotor (1). The rotor (1) is a cylinder which is connected by splines to the drive shaft for the starter pinion (4). When the pistons (2) feel the force of the oil they move until they are against the thrust bearing (3). The thrust bearing (3) is at an angle to the axis of the rotor (1). This makes the pistons (2) slide around the thrust bearing (3). As they slide, they turn the rotor (1) which connects through the drive shaft and starter pinion (4) to the engine flywheel. The pressure of the oil makes the rotor (1) turn very fast. This turns the engine flywheel fast enough for quick starting.

Electrical System

The electrical system is a combination of three separate electric circuits: the charging circuit, the starting circuit and the lighting circuit. Each circuit is dependent on some of the same components. The battery (batteries), disconnect switch, circuit breaker, ammeter, cables and wires from the battery are common in each of the three circuits.


NOTICE

The disconnect switch must be ON to allow any part of the electrical system to function. Some charging circuit components will be damaged if the engine is operated with the disconnect switch OFF.


The charging circuit is in operation when the diesel engine is operating. The electricity producing (charging) unit is an alternator. A regulator in the circuit senses the state of charge in the battery and regulates the charging unit output to keep the battery fully charged.

The starting circuit operates only when the disconnect switch is ON and the start switch is actuated.

The direct electric starting circuit can have a glow plug for each diesel engine cylinder. Glow plugs are small heating elements in the precombustion chambers that promote fuel ignition when the engine is started in low temperatures.

The lighting and charging circuits are both connected on the same side of the ammeter while the starting circuit connects to the other side of the ammeter.

System Components

Alternator


ALTERNATOR
1. Regulator. 2. Fan. 3. Roller bearing. 4. Rotor. 5. Stator windings. 6. Ball bearing.

This alternator is a belt driven, three phase, self-rectifying, brushless unit.

The only moving part in the alternator is the rotor (4) which is mounted on a ball bearing (6) at the drive end, and a roller bearing (3) at the rectifier end.

On later alternators, the regulator is inside the alternator. It senses the charge condition of the battery and the electrical system power demands and controls the alternator output accordingly.

Earlier alternators have an alternator regulator which is installed separate from the alternator.


NOTICE

Do not operate alternator simultaneously with a D.C. generator to charge the same battery.



NOTICE

Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with a heavy load on the circuit will sometimes result in regulator damage.


Alternator Regulator

The regulator senses the charge condition of the battery as well as electrical system power demand and controls the alternator output accordingly by limiting the field current.


ALTERNATOR REGULATOR
1. Plug. 2. Connector.


NOTICE

The regulator has short life if the temperature of the air around it is above 170°F (77°C) in moving air or 140°F (60°C) in air which does not move.


Starting Motor


STARTING MOTOR
1. Field. 2. Solenoid. 3. Clutch. 4. Pinion. 5. Commutator. 6. Brush assembly. 7. Armature.

The starting motor used with direct electric start incorporates a solenoid. The action of the solenoid engages the pinion with the ring gear on the engine flywheel, when the solenoid is energized. The pinion always engages before the electric contacts in the solenoid close the circuit between the battery and the starting motor. An overrunning clutch protects the starting motor from being overspeeded. Releasing the start switch disengages the pinion from the ring gear on the flywheel.

Solenoid


SCHEMATIC OF A SOLENOID
1. Coil. 2. Switch terminal. 3. Battery terminal. 4. Contacts. 5. Spring. 6. Core. 7. Component terminal.

A solenoid is a magnetic switch that utilizes low current to close a high current circuit. The solenoid has an electromagnet with a movable core (6). There are contacts (4) on the end of the core. The contacts are held open by a spring (5) that pushes the core away from the magnetic center of the coil. Low current will energize the coil and form a magnetic field. The magnetic field draws the core to the center of the coil and the contacts close.

Circuit Breaker

The circuit breaker is a safety switch that opens the battery circuit whenever the current in the electrical system exceeds the rating of the circuit breaker.


SCHEMATIC OF A CIRCUIT BREAKER
1. Reset button. 2. Disc in open position. 3. Contacts. 4. Disc. 5. Battery circuit terminals.

A heat sensitive metal disc (4) with a contact point (3) completes the electric circuit through the circuit breaker. Excessive high current in the electric system promotes heat in the metal disc. Heat distorts the disc, causing the contacts to open. An open circuit breaker can be reset after it is allowed to cool. Push the reset button (1) to close the contacts.

Magnetic Switch

A magnetic switch (relay) is used sometimes for the starter solenoid or glow plug circuit. Its operation electrically, is the same as the solenoid. Its function is to reduce the low current load on the start switch and control low current to the starter solenoid or high current to the glow plugs. When more than one starter is used, a separate magnetic switch is used for each starter solenoid.

Pressure Switch

A pressure switch is installed in some systems to disconnect the voltage regulator and alternator from the battery when the engine is not running. This prevents damage to the alternator and regulator from the battery. It also prevents the battery from discharging through the voltage regulator and alternator.

Wiring Diagrams

Many types of electrical systems are available for these engines. Some charging systems use an alternator and a regulator in the wiring circuit. Others have the regulator inside the alternator. Some starting systems have one starting motor. Engines which must operate in bad starting conditions can have two starting motors. Other starting systems use air or hydraulic motors.

Glow plugs are provided for low temperature starting conditions. Systems without glow plugs are usually used where ideal starting conditions exist or where an Automatic Start-Stop system is used.

A fuel pressure switch is used in all systems with an external regulator. The switch prevents current discharge (field excitation) to alternator from the battery when the engine is not in operation. In systems where the regulator is part of the alternator, the transistor circuit prevents current discharge to the alternator and the fuel pressure switch is not required.

All wiring schematics are usable with 12, 24, 30 or 32 volts unless the title gives a specific description.

NOTE: Automatic Start-Stop systems use different wiring diagrams. Make reference to the Service Manual for the generator or to the modules for attachments for this information.

The chart gives the correct wire sizes and color codes. Make reference to the description in Systems Operation for the function of each of the components.

Grounded Electrical Systems

(Regulator Separate From Alternator)


CHARGING SYSTEM
1. Ammeter. 2. Regulator. 3. Battery. 4. Pressure switch. 5. Alternator.


CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Battery. 6. Pressure switch. 7. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Regulator. 4. Starting motor. 5. Battery. 6. Pressure switch. 7. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.


CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.


CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Battery. 5. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starting motor.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Battery. 5. Starting motor. 6. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Battery. 5. Starting motors. 6. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Magnetic switch. 2. Heat-Start switch. 3. Ammeter. 4. Glow plugs. 5. Battery. 6. Starting motors. 7. Alternator.

Insulated Electrical Systems

(Regulator Separate From Alternator)


CHARGING SYSTEM
1. Ammeter. 2. Regulator. 3. Battery. 4. Pressure switch. 5. Alternator.


CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Pressure switch. 8. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Regulator. 4. Starting motor. 5. Battery. 6. Pressure switch. 7. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Magnetic switch. 2. Heat-Start switch. 3. Ammeter. 4. Glow plugs. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.


CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.


CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Alternator.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starting motor.


CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starting motor. 7. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Battery. 5. Starting motors. 6. Alternator.


CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starting motors. 7. Alternator.

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