Introduction

NOTE: For Specifications with illustrations, make reference to SPECIFICATIONS for 3408 VEHICULAR ENGINE, Form No. SENR7804. If the Specifications in Form SENR7804 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Engine Design

CYLINDER, VALVE AND INJECTION PUMP LOCATION

Bore ... 5.40 in.(137.2 mm)

Stroke ... 6.00 in.(152.4 mm)

Number and Arrangement of Cylinders ... V-8

Firing Order (Injection Sequence) ... 1, 8, 4, 3, 6, 5, 7, 2

Rotation of Crankshaft (when seen from flywheel end) ... counterclockwise

Rotation of Fuel Pump Camshaft (when seen from pump drive end) ... counterclockwise

NOTE: Front end of engine is opposite to flywheel end. Left side and right side of engine are as seen from flywheel end. No. 1 cylinder is the front cylinder on the left side. No. 2 cylinder is the front cylinder on the right side.

Fuel System

This engine has a pressure type fuel system. There is one injection pump and one injection valve for each cylinder. The injection pumps are in injection pump housing (5) on the top of the engine. Injection valves (6) are in the precombustion chambers or adapters (for engines with direct injection) under the valve covers.

Fuel is pulled from fuel tank (11) through primary fuel filter (10) by fuel transfer pump (9). The transfer pump sends fuel through secondary fuel filter (8) to the manifold of the fuel injection pump housing.

Fuel in the manifold of the injection pump housing is the supply for the injection pumps. Some of the fuel in the manifold is constantly sent through an orifice in the fitting that connects the return line to the manifold. The orifice controls the pressure in the manifold and the amount of fuel that returns to the tank. The constant flow of fuel back to the tank removes air from the system.

FUEL SYSTEM SCHEMATIC
1. Inlet line. 2. Adapter with orifice. 3. Return line. 4. Location for pressure measurement. 5. Injection pump housing. 6. Injection valve. 7. Priming pump. 8. Secondary fuel filter. 9. Fuel transfer pump. 10. Primary fuel filter. 11. Fuel tank.

The injection pumps are in time with the engine. They send fuel to the injection valves under high pressure. When the fuel pressure at the injection valve is high enough the valve opens and sends fuel into the precombustion chamber or directly into the cylinder on direct injection engines.

LOCATION OF FUEL SYSTEM COMPONENTS
1. Inlet line. 2. Adapter with orifice. 3. Return line. 4. Location for pressure measurement. 5. Injection pump housing. 9. Fuel transfer pump.

Fuel transfer pump (9) has a bypass valve and a pressure relief valve. The bypass valve makes it possible for the priming pump to send fuel through the transfer pump. The pressure relief valve controls the maximum pressure of the fuel. When the pressure gets too high the valve opens and some of the fuel goes back to the inlet side of the pump.

When there is air on the inlet side of the fuel system use priming pump (7). Operation of the priming pump fills the system with fuel. This forces the air back into the tank.

Air can be removed from the fuel injection lines by loosening a fuel injection line nut (one at a time) at the valve cover base adapter. On PC Engines use the priming pump to remove the air. On DI Engines use the starter motor to turn the engine until fuel without air flows from the loosen nut. Tighten the nuts after air has been removed.

NOTE: Because of the check assemblies in the injection pump outlets for the DI engine, the priming pump will not give enough pressure to remove air from the fuel injection lines.

Fuel Injection Pump

The rotation of the cams on the camshaft (12) cause lifters (9) and pump plungers (5) to move up and down. The stroke of each pump plunger is always the same. The force of springs (6) hold lifters (9) against the cams of the camshaft.

The pump housing is a "V" shape (similar to the engine cylinder block), with four pumps on each side.

When the pump plunger is down, fuel from fuel manifold (1) goes through inlet passage (2) and fills the chamber above pump plunger (5). As the plunger moves up it closes the inlet passage.

The pressure of the fuel in the chamber above the plunger increases until it is high enough to cause check valve (3) to open. Fuel under high pressure flows out of the check valve through the fuel line to the injection valve until the inlet passage opens into pressure relief passage (4) in the plunger. The pressure in the chamber decreases and check valve (3) closes.

The longer the inlet passage is closed the larger the amount of fuel which will be forced through check valve (3). The period for which the inlet passage is closed is controlled by the pressure relief passage. The design of the passage makes it possible to change the inlet passage closed time by rotation of the plunger. When the governor moves fuel racks (8) they move gears (7) that are fastened to plungers (5). This causes a rotation of the plungers.

The governor is connected to the left rack. The spring load on lever (11) removes the play between the racks and link (10). The fuel racks are connected by link (10). They move in opposite directions (when one rack moves in, the other rack moves out).

CROSS SECTION OF THE FUEL INJECTION PUMP HOUSING (Pumps Illustrated for DI Engines)
1. Fuel manifold. 2. Inlet passage. 3. Check valve. 4. Pressure relief passage. 5. Pump plunger. 6. Spring. 7. Gear. 8. Fuel rack (left). 9. Lifter. 10. Link. 11. Lever. 12. Camshaft.

Fuel Injection Valves - (On Earlier Engines)

Fuel, under high pressure from the injection pumps, is sent through the injection valves. The injection valves change the fuel to the correct fuel characteristic (spray pattern) for good combustion in the cylinders.

The fuel injection valves are installed in the precombustion chambers in engines equipped with precombustion chambers. An adapter takes the place of the precombustion chamber in engines equipped with direct injection. The precombustion chambers or adapters are installed in the cylinder heads.

Fuel Injection Nozzles - (On Later Engines)

The fuel injection nozzle goes through the cylinder head into the combustion chamber. The fuel injection pump sends fuel with high pressure to the fuel injection nozzle where the fuel is made into a fine spray for good combustion.

FUEL INJECTION NOZZLE
1. Carbon dam. 2. Seal. 3. Passage. 4. Filter screen. 5. Inlet passage. 6. Orifice. 7. Valve. 8. Diameter. 9. Spring.

Seal (2) goes against the nozzle adapter and prevents leakage of compression from the cylinder. Carbon dam (1) keeps carbon out of the bore in the nozzle adapter.

Fuel with high pressure from the fuel injection pump goes into inlet passage (5). Fuel then goes through filter screen (4) and into passage (3) to the area below diameter (8) of valve (7). When the pressure of the fuel that pushes against diameter (8) becomes greater than the force of spring (9), valve (7) lifts up. This occurs when the fuel pressure goes above the Valve Opening Pressure of the fuel injection nozzle. When valve (7) lifts, the tip of the valve comes off of the nozzle seat and the fuel will go through the six small orifices (6) into the combustion chamber.

The injection of fuel continues until the pressure of fuel against diameter (8) becomes less than the force of spring (9). With less pressure against diameter (8), spring (9) pushes valve (7) against the nozzle seat and stops the flow of fuel to the combustion chamber.

The fuel injection nozzle can not be disassembled and no adjustments can be made.

Hydra-Mechanical Governor

HYDRA-MECHANICAL GOVERNOR (PC ENGINE)
1. Collar. 2. Bolt. 3. Lever assembly. 4. Upper spring seat. 5. Weights. 6. Governor spring. 7. Lower spring seat. 8. Thrust bearing. 9. Valve. 10. Upper oil passage in piston. 11. Piston. 12. Lower oil passage in piston. 13. Sleeve. 14. Oil passage in cylinder. 15. Drive assembly. 16. Cylinder. 17. Pin. 18. Lever.

The operation of the governor for the DI Engine is the same as the PC Engine governor except for the governor drive. This governor uses a "damped" drive system to remove any quick movement (forward and backward) of gear assembly (20). This can be caused by torsional (twisting) vibration through the engine drive lines which are passed on (sometimes increased) by drive assembly (15).

The top end of drive assembly (15) is between two rings (19) that are spring loaded. This creates enough friction to dampen out the small frequencies but allows movement when a real need is necessary. Since governor weights (5) will now sense only true load changes, the engine will not go into a "hunt condition" (increase and decrease engine speed constantly).

HYDRA-MECHANICAL GOVERNOR (DI ENGINE)
15. Drive assembly. 19. Rings. 20. Gear assembly. 21. Dowels (two).

The governor control is connected to the control lever on the engine governor. The governor controls the amount of fuel needed to keep the desired engine rpm.

The governor, driven by the engine through drive assembly (15), has governor weights (5), governor spring (6), valve (9) and piston (11). The valve and piston are connected to one fuel rack through pin (17) and lever (18). The pressure oil for the governor comes from the governor oil pump, on top of the injection pump housing. The oil used is from the engine lubrication system. Pressure oil goes through passage (14) and around sleeve (13). The governor controls only the compression of governor spring (6). Compression of the springs always pushes down to give more fuel to the engine. The centrifugal force (rotation) of governor weights (5) always pulls up to get a reduction of fuel to the engine. When these two forces are in balance, the engine runs at the desired rpm (governed rpm).

When the engine load increases, the engine rpm decreases and the rotation of governor weights (5) will get slower. The governor weights will move toward each other. Governor spring (6) moves valve (9) down. This lets the oil flow from lower passage (12), around valve (9), and through upper passage (10) to fill the chamber behind piston (11). This pressure oil pushes piston (11) and pin (17) down to give more fuel to the engine. The upper end of the valve stops the oil flow through the top of the piston around the valve. Engine rpm goes up until the rotation of the governor weights is fast enough to be in balance with the force of the governor spring.

When there is a reduction in engine load, there will be an increase in engine rpm and the rotation of governor weights (5) will get faster. This will move valve (9) up. This stops oil flow from lower passage (12), and oil pressure above piston (11) goes out through the top, around valve (9). Now, the pressure between sleeve (13) and piston (11) pushes the piston and pin (17) up. This causes a reduction in the amount of fuel to the engine. Engine rpm goes down until the centrifugal force (rotation) of the governor weights is in balance with the force of the governor spring. When these two forces are in balance, the engine will run at the desired rpm (governed rpm).

Oil from the governor pump gives lubrication to the governor weight support (with gear), thrust bearing (8), and drive gear bearing. The other parts of the governor get lubrication from "splash-lubrication" (oil thrown by other parts). Oil from the governor runs down into the housing for the fuel injection pumps.

Shutoff Solenoid

The governor can not be moved to the shutoff position by the governor control. To stop the engine, push and hold the stop button in the cab. This will activate shutoff solenoid (23). The solenoid will pull lever (22) down causing the governor to move the fuel racks to the shutoff position.

SHUTOFF SOLENOID
22. Lever. 23. Solenoid.

Automatic Timing Advance Unit

The automatic timing advance unit is installed on the front of camshaft (6) for the fuel injection pump and is gear driven through the timing gears. Drive gear (5) for the fuel injection pump is connected to camshaft (6) through a system of weights (2), springs (3), slides (4) and a flange (1). Each one of the two slides (4) is held on gear (5) by a pin. The two weights (2) can move in guides inside flange (1) and over slides (4), but the notch for the slide in each weight is at an angle with the guides for the weight in the flange. As centrifugal force (rotation) moves the weights away from the center, against springs (3), the guides in the flange and the slides on the gear make the flange turn a little in relation to the gear. Since the flange is connected to the camshaft for the fuel injection pump, the fuel injection timing is also changed.

There is no adjustment for the timing advance unit.

AUTOMATIC TIMING ADVANCE UNIT
1. Flange. 2. Weight. 3. Springs. 4. Slide. 5. Drive gear. 6. Camshaft.

Fuel Ratio Control

FUEL RATIO CONTROL (Engine Stopped)
1. Inlet air chamber. 2. Valve. 3. Diaphragm assembly. 4. Oil drains. 5. Pressure oil chamber. 6. Large oil passages. 7. Oil inlet. 8. Small oil passages. 9. Oil outlet. 10. Fuel rack linkage. 11. Valve.

With the engine stopped, valve (11) is in the fully extended position. The movement of fuel rack linkage (10) is not limited by valve (11).

When the engine is started oil flows through oil inlet (7) into pressure oil chamber (5). From chamber (5) the oil flows through large oil passages (6), inside valve (11), and out small oil passages (8) to oil outlet (9).

FUEL RATIO CONTROL (Ready for operation)
1. Inlet air chamber. 2. Valve. 5. Pressure oil chamber. 6. Large oil passages. 8. Small oil passages. 11. Valve.

A hose assembly connects inlet air chamber (1) to the inlet air system. As the inlet air pressure increases it causes diaphragm assembly (3) to move down. Valve (2), that is part of the diaphragm assembly, closes large and small oil passages (6 and 8). When these passages are closed oil pressure increases in chamber (5). This increase in oil pressure moves valve (11) up. The control is now ready for operation.

When the governor control is moved to increase fuel to the engine, valve (11) limits the movement of fuel rack linkage (10) in the "Fuel On" direction. The oil in chamber (5) acts as a restriction to the movement of valve (11) until inlet air pressure increases.

FUEL RATIO CONTROL (Increase in inlet air pressure)
2. Valve. 4. Oil drains. 5. Pressure oil chamber. 10. Fuel rack linkage. 11. Valve.

As the inlet air pressure increases valve (2) moves down and lets oil from chamber (5) drain through large oil passages (6) and out through oil drains (4). This lets valve (11) move down so fuel rack linkage (10) can move gradually to increase fuel to the engine. The control is designed not to let the fuel increase until the air pressure in the inlet manifold is high enough for complete combustion. It prevents large amounts of exhaust smoke caused by an air-fuel mixture with too much fuel.

The control movements take a very short time. No change in engine acceleration (rate at which speed increases) can be felt.

Air Inlet And Exhaust System

The components of the air inlet and exhaust system control the quality and amount of air available for combustion.

AIR INLET AND EXHAUST SYSTEM
1. Exhaust manifold. 2. Aftercooler. 3. Engine cylinder. 4. Air inlet. 5. Compressor wheel. 6. Turbine wheel. 7. Exhaust outlet.

Clean inlet air from the air cleaners is pulled through air inlet (4) by compressor wheel (5). The rotation of the compressor wheel causes compression of the air and forces it through a tube to aftercooler (2). The aftercooler lowers the temperature of the compressed air before it goes into the inlet manifold (passages in cylinder block). This cooled compressed air goes through the inlet manifold and fills the inlet chambers in the cylinder heads. Air flow from the inlet chamber into the cylinder is controlled by the intake valves.

AIR FLOW SCHEMATIC
1. Exhaust manifold. 2. Aftercooler. 8. Turbocharger.

There are two intake and two exhaust valves for each cylinder. Make reference to Valve System Components. The intake valves open when the piston moves down on the inlet stroke. Cooled compressed air from the inlet chamber is pulled into the cylinder. The intake valves closed and the piston starts to move up on the compression stroke. When the piston is near the top of the compression stroke fuel is injected into the precombustion chamber above the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again it is on the exhaust stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the piston makes the exhaust stroke the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again.

AIR INLET AND EXHAUST SYSTEM
1. Exhaust manifold. 2. Aftercooler. 8. Turbocharger. 9. Air cleaners.

Exhaust gases from the exhaust manifold go into the turbine side of turbocharger (8) and cause turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives compressor wheel (5). The exhaust gases then go out the exhaust outlet (7) and to the muffler.

Aftercooler

Aftercooler (2) is located at the rear of the engine between the cylinder heads. Coolant from the water pump flows through pipe (1) into the aftercooler. It flows through the core assembly, then out of the aftercooler through a different pipe into the rear of the cylinder block. Inlet air from the compressor side of the turbocharger flows into the aftercooler. The air passes over the core assembly. This lowers the temperature of the air to approximately 200°F (93°C). The cooler air goes out the bottom of the aftercooler into the inlet manifold. The advantage of cooler air is better combustion efficiency.

AFTERCOOLER
1. Pipe. 2. Aftercooler.

Turbocharger

The turbocharger is installed at the rear of the engine on a cross pipe between the two exhaust manifolds. All the exhaust gases from the engine go through the turbocharger.

TURBOCHARGER
1. Turbine housing. 2. Cross pipe. 3. Exhaust manifolds.

The exhaust gases go into the turbine housing (1) and push the blades of the turbine wheel. This causes the turbine wheel and compressor wheel to turn.

Clean air from the air cleaners is pulled through compressor housing air inlet (6) by the rotation of compressor wheel (4). The action of the compressor wheel blades causes compression of the inlet air. This gives the engine more power because it makes it possible for the engine to burn more air and fuel during combustion.

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.

TURBOCHARGER
1. Turbine housing. 4. Compressor wheel. 5. Oil inlet port. 6. Air inlet. 7. Bearings.

The bearings (7) in the turbocharger use engine oil under pressure for lubrication. The oil comes in through oil inlet port (5) and goes through passages in the housing to the bearings. Then the oil goes out the oil outlet port at the bottom of the turbocharger and back to the oil pan.

Valves And Valve System Components

VALVE SYSTEM COMPONENTS
1. Intake bridge. 2. Intake rocker arm. 3. Push rod. 4. Rotocoil assemblies. 5. Valve spring. 6. Valve guide. 7. Intake valves. 8. Lifter. 9. Camshaft.

The valves and valve system components control the flow of inlet air and exhaust gases into and out of the cylinder during engine operation.

The intake and exhaust valves are opened and closed by movement of these components: crankshaft, camshaft, lifters, push rods, rocker arms, bridges, and valve springs. Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is timed to, and driven by, a gear on the front of the crankshaft. As camshaft (9) turns, the cams of the camshaft also turn and cause lifters (8) to go up and down. This movement makes push rods (3) move rocker arms (2). Movement of the rocker arms will make intake and exhaust bridges (1 and 11) move up and down on dowels mounted in the cylinder head.

These bridges let one rocker arm operate two valves (intake or exhaust) for each cylinder. There are two intake and two exhaust valves in each cylinder. Movement of the bridges will make the intake and exhaust valves in the cylinder head open and close according to the firing order (injection sequence) of the engine. One valve spring (5) for each valve helps to hold the valves in the closed position.

VALVE SYSTEM COMPONENTS
1. Intake bridge. 2. Intake rocker arm. 7. Intake valves. 10. Exhaust rocker arm. 11. Exhaust bridge. 12. Exhaust valves.

Rotocoil assemblies (4) cause the valves to have rotation while the engine is running. This rotation of the valves keeps the deposit of carbon on the valves to a minimum and gives the valves longer service life.

Lubrication System

Oil Flow Through The Oil Cooler And Oil Filter

With the engine warm (normal operation), oil is pulled from oil pan (6) through a bell assembly and pipe to oil pump (5). The oil pump sends oil through a pipe to a passage in the cylinder block. Flange (8) of the bypass valve body is at the other end of the passage. Oil flows through a chamber in the valve body into oil cooler (3). The oil goes out of the cooler and through hose assembly (10) to the filters. The clean oil goes through hose assembly (9) back to another chamber in the bypass valve body, then into the oil manifold on the right side of the cylinder block.

SCHEMATIC OF OIL FLOW
1. To oil manifold. 2. Filter bypass valve. 3. Engine oil cooler. 4. Cooler bypass valve. 5. Oil pump. 6. Oil pan. 7. Oil filters.

OIL LINES AND FILTERS
2. Filter bypass valve. 3. Oil cooler. 4. Cooler bypass valve. 7. Oil filters. 8. Flange. 9. Hose assembly. 10. Hose assembly.

When the engine is cold (starting condition), bypass valves (2 and 4) open because cold oil with high viscosity causes a restriction to the oil flow through oil cooler (3) and filters (7). When the bypass valves are open oil flows directly through passages in the valve body to the oil manifold.

When the oil gets warm, the pressure difference at the bypass valves decreases and the bypass valves close. This gives normal oil flow through oil cooler (3) and oil filters (7).

The bypass valves will also open when there is a restriction in the oil cooler or oil filters. This action does not let an oil cooler or oil filter with a restriction prevent the lubrication of the engine.

There is also a bypass valve in engine oil pump (5). This bypass valve controls the pressure of the oil from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure goes up and the bypass valve will open. This lets the oil that is not needed to go back to the inlet oil passage of the oil pump.

Oil Flow In The Engine

The oil manifolds are cast into the sides of the cylinder block. Oil goes into manifold (16) from the bypass valve body. From manifold (16) oil is sent to manifold (12) through drilled passages in the cylinder block that connect main bearing bores (17) and camshaft bearing bores (9). Oil goes through holes in the bearings and gives them lubrication. Oil from the main bearings goes through holes drilled in the crankshaft to give lubrication to the connecting rod bearings. A small amount of oil from the oil manifolds goes through tubes (10) to make the pistons cooler.

Oil goes through grooves in the outside of the front and rear camshaft bearings to passages (7 and 8). The oil in these passages gives lubrication to the valve lifters and rocker arm shafts. Holes in the rocker arm shafts let the oil give lubrication to the valve system components in the cylinder head.

The fuel injection pumps, governor and air/fuel ratio control get oil from passage (5) in the cylinder block. Oil for the air/fuel ratio control flows through passages in the injection pump and governor housings. Oil for the hydraulic operation of the hydra/mechanical governor comes from a small gear pump between the injection pump housing and the governor. The automatic timing advance unit gets oil from the injection pump housing through passages in the injection pump camshaft.

SCHEMATIC OF OIL FLOW
1. To air compressor. 2. To rear idler gear. 3. To rocker arm shaft. 4. To power take/off. 5. To fuel injection pump housing. 6. Rocker arm shaft. 7. To rocker arm shaft and valve lifters. 8. To valve lifters. 9. Bore for camshaft. 10. Tube. 11. To turbocharger. 12. Oil manifold (left side). 13. To timing gear housing. 14. To front idler gear. 15. From bypass valve. 16. Oil manifold (right side). 17. Main bearing bore.

The bearing of the idler gear on the front of the engine gets oil through a passage in the idler gear shaft that is connected to passage (14).

The bearing for the balancer gear at the rear of the engine gets oil through a passage in the balancer gear shaft that is connected to passage (2).

The bearings of the power take/off idler gear and drive gear get oil from the oil manifold on the left side of the cylinder block through a tube assembly connected to passages in the flywheel housing.

Tube assembly (18) gives oil to the trubocharger impeller shaft bearings. The oil goes out of the turbocharger through tube assembly (19) to the flywheel housing.

On Earlier Engines the oil for lubrication of the fan drive bearing flows from the left oil manifold through the timing gear housing to tube assembly (20). The fan drive lubrication oil returns to the oil pan through hose assembly (21).

TURBOCHARGER LUBRICATION
18. Tube assembly (supply). 19. Tube assembly (return).

FAN DRIVE LUBRICATION ON EARLIER ENGINES
20. Tube assembly (supply). 21. Hose assembly (return).

Oil that gives pressure lubrication to gear shafts and bearings then flows free to give lubrication to the gear teeth. After the oil for lubrication has done its work it flows free back to the oil pan.

Cooling System

SCHEMATIC OF COOLING SYSTEM
1. Air compressor. 2. Aftercooler. 3. Pipe. 4. Outlet pipes. 5. Radiator. 6. Pressure relief valve. 7. Bypass lines. 8. Bonnet. 9. Engine oil cooler. 10. Torque converter oil cooler. 11. Coolant pump inlet. 12. Coolant pump. 13. Drain.

When the coolant temperature regulators are fully closed, no coolant goes through outlet pipes (4) to radiator (5). All of the coolant from the cylinder block flows directly to coolant pump (12) through bypass lines (7).

When the coolant temperature regulators are fully open, a small amount of coolant from the cylinder block flows through bypass lines (7) to the coolant pump (12). Most of the coolant flows through outlet pipes (4) to radiator (5). The coolant flows out of the radiator through a hose to coolant pump inlet (11).

The coolant pump forces coolant out in three directions. Part of it flows through pipe (3) to aftercooler (2) then goes into the cylinder block at the top rear. Part of it flows through engine oil cooler (9) and goes into the side of the cylinder block. Part of it flows through torque converter oil cooler (10), bonnet (8), and then goes in the side of the cylinder block with the flow from the engine oil cooler.

Coolant for air compressor (1) comes from the aftercooler through tube assembly (15). It returns to the engine cylinder head through tube assembly (14).

The coolant flows through passages in the cylinder heads and block to the regulator housings (16) on the front of the cylinder heads.

AIR COMPRESSOR COOLANT LINES
14. Tube assembly (return). 15. Tube assembly (supply).

The cooling system has a drain (13) to drain the cylinder block, radiator, and coolers. The drain is located at the bottom of the radiator outlet elbow.

The cooling system is equipped with a pressure relief valve (6), in the top of the radiator. Its purpose is to prevent damage to the system from high coolant pressure.

NOTE: High coolant pressure is the result of coolant temperature that is higher than normal. See Cooling System in Testing and Adjusting.

Coolant Conditioner

Some conditions of operation have been found to cause pitting (small holes in the metal surface) from corrosion or cavitation erosion (wear caused by air bubbles in the coolant) on the outer surface of the cylinders liners and the inner surface of the cylinder block next to the liners. The addition of a corrosion inhibitor (a chemical that gives a reduction of pitting) can keep this type of damage to a minimum.

The "spin-on" coolant conditioner elements, similar to the fuel filter and oil filter elements, fasten to a base that is mounted on the engine or is remote mounted. Coolant flows through lines from the water pump to the base and back to the air compressor. There is a constant flow of coolant through the element.

The element has a specific amount of inhibitor for acceptable cooling system protection. As coolant flows through the element, the corrosion inhibitor, which is a dry material, dissolves (goes into solution) and mixes to the correct concentration. Two basic types of elements are used for the cooling system, and they are called the "PRECHARGE" and the "MAINTENANCE" elements. Each type of element has a specific use and must be used correctly to get the necessary concentration for cooling system protection. The elements also contain a filter and should be left in the system so coolant flows through it after the conditioner materials is disolved.

The "PRECHARGE" element has more than the normal amount of inhibitor, and is used when a system is first filled with new coolant (unless Dowtherm 209 Antifreeze is used). This element has to add enough inhibitor to bring the complete cooling system up to the correct concentration.

The "MAINTENANCE" elements have a normal amount of inhibitor and are installed at the first change interval and provide enough inhibitor to keep the corrosion protection at an acceptable level. After the first change period, only "MAINTENANCE" elements are installed at specified intervals to give protection to the cooling system.

Basic Block

Cylinder Block, Liners And Heads

The cylinders in the left side of the block make an angle of 65° with the cylinders in the right side of the block. The main bearing caps are fastened to the block with two bolts per cap.

The cylinder liners can be removed for replacement. The top surface of the block is the seat for the cylinder liner flange. Engine coolant flows around the liners to keep them cool. Three O-ring seals around the bottom of the liner make a seal between the liner and the block. A filler band at the top of each liner forms a seal between the liner and the cylinder block.

A steel spacer plate is used between the cylinder head and block. A thin gasket with a rubber coating is used between the plate and the block to seal water and oil. A thick gasket of metal and asbestos is used between the plate and the head to seal combustion gases, water and oil.

The engine has a single, cast head on each side. Four vertical valves (two intake and two exhaust), controlled by a pushrod valve system, are used per each cylinder. The opening for the direct injection adapter or prechamber is located between the four valves. Series ports (passages) are used for both intake and exhaust valves.

The size of the pushrod openings through the head permits the removal of the valve lifters with the head installed.

Valve guides without shoulders are pressed into the cylinder head.

Pistons, Rings And Connecting Rods

The aluminum pistons have three rings; two compression rings and one oil ring. All rings are located above the piston pin bore. The two compression rings are of the KEYSTONE type, which have a tapered shape. The seat for the rings is an iron band that is cast into the piston. The action of the rings in the piston groove, which is also tapered, helps prevent seizure of the rings caused by too much carbon deposit. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove.

The piston for the direct injection engine has a cardioid design (special shape) on the top surface to help combustion efficiency. The piston pin is held in place by two snap rings that fit in grooves in the pin bore of the piston.

The piston for precombustion engines has a steel heat plug fastened to the top of the piston at the center.

The connecting rod has a taper on the pin bore end. This gives the rod and piston more strength in the areas with the most load.

Oil spray tubes, located on the cylinder block main webs, direct oil to cool and give lubrication to the piston components and cylinder walls.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. Vibration, caused by combustion impacts along the crankshaft, is kept small by a vibration damper on the front of the crankshaft.

There is a gear at the front of the crankshaft to drive the timing gears and the oil pump. Lip seals and wear sleeves are used at both ends of the crankshaft for easy replacement and a reduction of maintenance cost. Pressure oil is supplied to all bearing surfaces through drilled holes in the crankshaft. The crankshaft is supported by five main bearings. A thrust plate at either side of the center main bearing controls the end play of the crankshaft.

Camshaft

The engine has a single camshaft that is driven at the front end. Five bearings support the camshaft. As the camshaft turns, each cam (lobe) (through the action of valve systems components) moves either two exhaust valves or two intake valves for each cylinder. The camshaft gear must be timed to the crankshaft gear. The relation of the cams (lobes) to the camshaft gear cause the valves in each cylinder to open and close at the correct time.

A gear on the rear of the camshaft is used to drive the balancer gear. Vibration, caused by the balance of the crankshaft, is kept small by the balance gear.

Vibration Damper

The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. The fluid type vibration damper is installed on the front end of the crankshaft. It is used for reduction of torsional vibrations and stops the vibration from building up to amounts that cause damage.

Electrical System

The electrical system has three separate circuits: the charging circuit, the starting circuit and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits.

The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.

The starting circuit is in operation only when the start switch is acivated.

On precombustion engines, the starting circuit has a glow plug for each cylinder of the diesel engine. Glow plugs are small heating units in the precombustion chambers. Glow plugs make ignition of the fuel easier when the engine is started in cold temperature.

The low amperage circuit and the charging circuit are both connected to the same side of the ammeter. The starting circuit connects to the opposite side of the ammeter.

Charging System Components

Alternator (Delco-Remy)

The alternator is a three phase, self rectifying charging unit. The regulator for the alternator is part of the alternator. The alternator is driven by a V type belt from the crankshaft pulley.

5S9088 ALTERNATOR
1. Regulator. 2. Fan. 3. Roller bearing. 4. Rotor. 5. Stator windings. 6. Ball bearing.

The only part in the alternator which has movement is the rotor. The rotor is held in position by a ball bearing at the drive end and a roller bearing at the rectifier end.

The compartment for the regulator is sealed. The regulator controls the alternator output according to the needs of the battery and the other components in the electrical system.

Starting System Components

Starter Motor

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

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

The starter motor has a solenoid. When the start switch is activated, electricity from the electrical system will cause the solenoid to move the starter pinion to engage with the ring gear on the flywheel of the engine. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the start switch is released, the starter pinion will move away from the ring gear of 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 uses low current to close a high current circuit. The solenoid has an electromagnet with a core (6) which moves.

There are contacts (4) on the end of core (6). The contacts are held in the open position by spring (5) that pushes core (6) from the magnetic center of coil (1). Low current will energize coil (1) and make a magnetic field. The magnetic field pulls core (6) to the center of coil (1) and the contacts close.

Other Components

Circuit Breaker

The circuit breaker is a safety switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker.

A heat activated metal disc with a contact point completes the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset after it cools. Push the reset button to close the contacts and reset the circuit breaker.

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