Systems Operation

Usage:

Introduction

NOTE: For Specifications with illustrations, make reference to SPECIFICATIONS for 3204 VEHICULAR ENGINE, Form No. REG01254. If the Specifications in Form REG01254 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

DI ENGINE

PC ENGINE CYLINDER AND VALVE LOCATION

Bore ... 4.50 in.(114.3 mm)

Stroke ... 5.00 in.(127.0 mm)

Number and Arrangement of Cylinders ... 4, in line

Firing Order (Injection Sequence) ... 1, 3, 4, 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 engine.

Fuel System

Fuel Flow

FUEL SYSTEM SCHEMATIC
1. Fuel tank. 2. Fuel return line. 3. Fuel injection nozzle. 4. Fuel injection line. 5. Fuel injection pump. 6. Primary fuel filter. 7. Fuel transfer pump. 8. Secondary fuel filter. 9. Constant bleed valve. 10. Fuel injection pump housing.

Fuel is pulled from fuel tank (1) through primary fuel filter (6) by fuel transfer pump (7). From the fuel transfer pump the fuel is pushed through secondary fuel filter (8) and to the fuel manifold in fuel injection pump housing (10). A bypass valve in the fuel transfer pump keeps the fuel pressure in the system at 20 to 40 psi (140 to 280 kPa). Constant bleed valve (9) lets a constant flow of fuel go through fuel return line (2) back to fuel tank (1). The constant bleed valve returns approximately 9 gal. (34 liters) per hour of fuel and air to the fuel tank. This helps keep the fuel cool and free of air.

Fuel injection pump (5) gets fuel from the fuel manifold and pushes fuel at very high pressure through fuel line (4) to fuel injection nozzle (3). The fuel injection nozzle has very small holes in the tip that change the flow of fuel to a very fine spray that gives good fuel combustion in the cylinder.

Fuel Injection Pump

The fuel injection pump increases the pressure of the fuel and sends an exact amount of fuel to the fuel injection nozzle. There is one fuel injection pump for each cylinder in the engine.

The fuel injection pump is moved by cam (14) of the fuel pump camshaft. When the camshaft turns, the cam raises lifter (11) and pump plunger (6) to the top of the stroke. The pump plunger always makes a full stroke. As the camshaft turns farther, spring (8) returns the pump plunger and lifter to the bottom of the stroke.

When the pump plunger is at the bottom of the stroke, fuel at transfer pump pressure goes into inlet passage (2), around pump barrel (4) and to bypass closed port (5). Fuel fills the area above the pump plunger.

After the pump plunger begins the up stroke, fuel will be pushed out the bypass closed port until the top of the pump plunger closes the port. As the pump plunger travels farther up, the pressure of fuel increases. At approximately 100 psi (690 kPa), check valve (1) opens and lets fuel flow into the fuel injection line to the fuel injection nozzle. When the pump plunger travels farther up, scroll (9) uncovers spill port (10). The fuel above the pump plunger goes through slot (7), along the edge of scroll (9) and out spill port (10) back to fuel manifold (3). This is the end of the injection stroke. The pump plunger can have more travel up, but no more fuel will be sent to the fuel injection nozzle.

FUEL INJECTION PUMP
1. Check valve. 2. Inlet passage. 3. Fuel manifold. 4. Pump barrel. 5. Bypass closed port. 6. Pump plunger. 7. Slot. 8. Spring. 9. Scroll. 10. Spill port. 11. Lifter. 12. Fuel rack. 13. Gear. 14. Cam.

When the pump plunger travels down and uncovers bypass closed port (5), fuel begins to fill the area above the pump plunger again, and the pump is ready to begin another stroke.

The amount of fuel the injection pump sends to the injection nozzle is changed by the rotation of the pump plunger. Gear (13) is attached to the pump plunger and is in mesh with fuel rack (12). The governor moves the fuel rack according to the fuel needs of the engine. When the governor moves the fuel rack, and the fuel rack turns the pump plunger, scroll (9) changes the distance the pump plunger pushes fuel between bypass closed port (5) and spill port (10) opening. The longer the distance from the top of the pump plunger to the point where scroll (9) uncovers spill port (10), the more fuel will be injected.

To stop the engine, the pump plunger is rotated so that slot (7) on the pump plunger is in line with spill port (10). The fuel will now go out the spill port and not to the injection nozzle.

Fuel Injection Nozzle

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. Spring. 4. Passage. 5. Inlet passage. 6. Orifice. 7. Valve. 8. Diameter.

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

Fuel with high pressure from the fuel injection pump goes into inlet passage (5). Fuel then goes into passage (4) 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 (3), valve (7) lifts up. When valve (7) lifts, the tip of the valve comes off of the nozzle seat and the fuel will go through the four .012 in. (0.31 mm) 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 (3). With less pressure against diameter (8), spring (3) pushes valve (7) against the nozzle seat and stops the flow of fuel to the combustion chamber.

Fuel Transfer Pump

The fuel transfer pump is a single piston pump that is moved by a cam lobe on the camshaft for the fuel injection pump.

When the camshaft turns, the cam lobe moves tappet (1) into the pump body. The tappet pushes piston (3) against the force of pumping spring (6). Outlet check valve (2) closes and inlet check valve (4) in the piston opens. Fuel in fuel inlet chamber (5) flows through the inlet check valve to the outlet side of the piston.

As the camshaft continues to turn, the cam lobe lets the tappet move out of the pump body. Pumping spring (6) pushes piston (3) towards the tappet. Inlet check valve (4) in the piston closes and outlet check valve (2) opens. The force of the pumping spring pushes fuel through the outlet check valve and into the fuel system.

The force of pumping spring (6) limits the pressure of the fuel in the system so that a bypass valve is not needed.

FUEL TRANSFER PUMP
1. Tappet. 2. Outlet check valve. 3. Piston. 4. Inlet check valve. 5. Fuel inlet chamber. 6. Pumping spring.

Governor

The governor controls the amount of fuel needed by the engine to maintain a desired rpm.

The governor flyweights (8) are driven directly by the fuel pump camshaft. Riser (10) is moved by flyweights (8) and governor spring (1). Lever (7) connects the riser with sleeve (2) which is fastened to valve (3). Valve (3) is a part of governor servo (5) and moves piston (4) and fuel rack (6). The fuel rack moves toward the front of the fuel pump housing (to the right in the illustration) when moved in the FUEL OFF direction.

GOVERNOR
1. Governor spring. 2. Sleeve. 3. Valve. 4. Piston. 5. Governor servo. 6. Fuel rack. 7. Lever. 8. Flyweights. 9. Over fueling spring. 10. Riser. 11. Spring seat. 12. Stop bolt. 13. Torque spring. 14. Power setting screw. 15. Torque rise setting screw. 16. Stop collar. 17. Stop bar.

The force of governor spring (1) always pushes to give more fuel to the engine. The centrifugal (rotating) force of flyweights (8) always push to get a reduction of fuel to the engine. When these two forces are in balance (equal), the engine runs at a constant rpm.

When the engine is started and the governor is at the low idle position, over fueling spring (9) moves the riser forward and gives an extra amount of fuel to the engine. When the engine has started and begins to run, the flyweight force becomes greater than the force of the over fueling spring. The riser moves to the rear and reduces the amount of fuel to the low idle requirement of the engine.

When the governor control lever is moved to the high idle position, governor spring (1) is put in compression and pushes riser (10) toward the flyweights. When the riser moves forward, lever (7) moves sleeve (2) and valve (3) toward the rear. Valve (3) stops oil flow through governor servo (5) and the oil pressure moves piston (4) and the fuel rack to the rear. This increases the amount of fuel to the engine. As engine speed increases, the flyweight force increases and moves the riser toward the governor spring. When the riser moves to the rear, lever (7) moves sleeve (2) and valve (3) forward. Valve (3) now directs oil pressure to the rear of piston (4) and moves the piston and fuel rack forward. This decreases the amount of fuel to the engine.

When the flyweight force and the governor spring force become equal, the engine speed is constant and the engine runs at high idle rpm. High idle rpm is adjusted by the high idle adjustment screw. The adjustment screw limits the amount of compression of the governor spring.

With the engine at high idle, when the load is increased, engine speed will decrease. Flyweights (8) move in and governor spring (1) pushes riser (10) forward and increases the amount of fuel to the engine. As the load is increased more, governor spring (1) pushes riser (10) farther forward. Spring seat (11) pulls on stop bolt (12). Stop collar (16) on the opposite end has power setting screw (14) and torque rise setting screw (15) that control the maximum amount of fuel rack travel. The power setting screw moves forward and makes contact with torque spring (13). This is the set point (balance point). If more load is added to the engine, engine speed will decrease and push riser (10) forward more. This will cause power setting screw (14) to bend (deflect) torque spring (13) until torque rise setting screw (15) makes contact with stop bar (17). This is the point of maximum fuel to the engine.

Governor Servo

The governor servo gives hydraulic assistance to the mechanical governor force to move the fuel rack. The governor servo has cylinder (3), cylinder sleeve (4), piston (2) and valve (1).

GOVERNOR SERVO (Fuel on position)
1. Valve. 2. Piston. 3. Cylinder. 4. Cylinder sleeve. 5. Fuel rack. A. Oil inlet. B. Oil outlet. C. Oil passage. D. Oil passage.

When the governor moves in the FUEL ON direction, valve (1) moves to the left. The valve opens oil outlet (B) and closes oil passage (D). Pressure oil from oil inlet (A) pushes piston (2) and fuel rack (5) to the left. Oil behind the piston goes through oil passage (C), along valve (1) and out oil outlet (B).

GOVERNOR SERVO (Balanced position)
1. Valve. 2. Piston. 3. Cylinder. 4. Cylinder sleeve. 5. Fuel rack. A. Oil inlet. B. Oil outlet. C. Oil passage. D. Oil passage.

When the governor spring and flyweight forces are balanced and the engine speed is constant, valve (1) stops moving. Pressure oil from oil inlet (A) pushes piston (2) until oil passages (C and D) are opened. Oil now flows through oil passage (D) along valve (1) and out through oil outlet (B). With no oil pressure on the piston, the piston and fuel rack (5) stop moving.

GOVERNOR SERVO (Fuel Off Position)
1. Valve. 2. Piston. 3. Cylinder. 4. Cylinder sleeve. 5. Fuel rack. A. Oil inlet. B. Oil outlet. C. Oil passage. D. Oil passage.

When the governor moves in the FUEL OFF direction, valve (1) moves to the right. The valve closes oil outlet (B) and opens oil passage (D). Pressure oil from oil inlet (A) is now on both sides of piston (2). The area of the piston is greater on the left side than on the right side of the piston. The force of the oil is also greater on the left side of the piston and moves the piston and fuel rack (5) to the right.

Dashpot

The dashpot helps give the governor better speed control when there are sudden speed and load changes. The dashpot has cylinder (1), piston (2), dashpot spring (3), needle valve (5) and check valve (6). Piston (2) and spring seat (4) are fastened to dashpot spring (3).

DASHPOT (Governor Moving to Fuel On)
1. Cylinder. 2. Piston. 3. Dashpot spring. 4. Spring seat. 5. Needle valve. 6. Check valve. 7. Oil reservoir.

When the governor moves toward FUEL ON, spring seat (4) and piston (2) move to the right. This movement pulls oil from oil reservoir (7) through check valve (6) and into cylinder (1).

DASHPOT (Governor Moving to Fuel Off)
1. Cylinder. 2. Piston. 3. Dashpot spring. 4. Spring seat. 5. Needle valve. 6. Check valve. 7. Oil reservoir.

When the governor moves toward FUEL OFF, spring seat (4) and piston (2) move to the left. This movement pushes oil out of cylinder (1), through needle valve (5) and into oil reservoir (7).

If the governor movement is slow, the oil gives no restriction to the movement of the piston and spring seat. If the governor movement is fast in the FUEL OFF direction, the needle valve gives a restriction to the oil and the piston and spring seat will move slowly.

Oil Flow For Fuel Pump And Governor

Oil from the side of the cylinder block goes to support (9) and into the bottom of front governor housing (4). The flow of oil now goes in three different directions.

A part of the oil goes to the rear camshaft bearing in fuel pump housing (5). The bearing has a groove around the inside diameter. Oil goes through the groove and into the oil passage in the bearing surface (journal) of camshaft (7). A drilled passage through the center of the camshaft gives oil to the front camshaft bearing and to the thrust face of the camshaft drive gear. Drain hole (6) in the front of fuel pump housing (5) keeps the level of the oil in the housing even with the center of the camshaft. The oil returns to the oil pan through the timing gear housing.

Oil also goes from the bottom of the front governor housing through a passage to the fuel pump housing and to governor servo (2). The governor servo gives hydraulic assistance to move the fuel rack.

The remainder of the oil goes through passages to the rear of rear governor housing (3), through cover (1) and back into another passage in the rear governor housing. Now the oil goes into the compartment for the governor controls. Drain hole (8) keeps the oil at the correct level. The oil in this compartment is used for lubrication of the governor control components and the oil is the supply for the dashpot.

The internal parts of the governor are lubricated by oil leakage from the servo and the oil is thrown by parts in rotation. The flyweight carrier thrust bearing gets oil from the passage at the rear of the camshaft.

Oil from the governor returns to the oil pan through a hole in the bottom of the front governor housing and through passages in the support and cylinder block.

FUEL PUMP AND GOVERNOR
1. Cover. 2. Servo. 3. Rear governor housing. 4. Front governor housing. 5. Fuel pump housing. 6. Drain hole. 7. Camshaft. 8. Drain hole. 9. Support.

Fuel System

Schematic Of The Fuel System
1. Fuel injection line (under valve cover). 2. Fuel injection line. 3. Housing for fuel injection pumps. 4. Glow plug. 5. Fuel injection valve (PC) or nozzle (DI). 6. Governor. 7. Precombustion chamber. 8. Fuel filter. 9. Fuel priming pump. 10. Fuel transfer pump. 11. Fuel tank.

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 (3) on the top of the engine. The injection valves for the PC engine are in the precombustion chambers (7). For the DI engine, the injection valves go through the cylinder head directly into the cylinder. Both types are found under the valve covers.

Fuel is pulled from fuel tank (11) through a filter screen in the inlet valve of fuel transfer pump (10). The fuel transfer pump sends fuel through fuel filter (8) to fuel manifold in injection pump housing. Fuel in the manifold of the injection pump housing is the supply for the injection pumps.

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

Fuel transfer pump (10) has a pressure relief spring that controls the maximum fuel pressure output of the pump. As the fuel pressure increases, the pump piston will not return to its former position since the force of the spring on one side and the fuel pressure on the other side are equal. In this position the cam of the pump continues to move but can not reach the piston. Without piston movement, no more fuel can be pumped. When the pressure decreases, the spring rate again pushes the piston back toward the cam and the piston starts to pump fuel again.

When there is air on the inlet side of the fuel system, fuel priming pump (9) is used. Operation of the priming pump fills the system with fuel. This forces the air back into the tank, or to the point where a fuel line has been loosened.

Fuel Injection Pump

Injection pump plungers (4) and lifters (8) are lifted by cams on camshaft (9) and always make a full stroke. The force of springs (5) hold the lifters (8) against the cams of the camshaft.

When the pump plunger is down, fuel from fuel manifold (1) goes through inlet passage (2) and fills the chamber above pump plunger (4). 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 in plunger (4). The pressure in the chamber then decreases and check valve (3) closes.

CROSS SECTION OF THE HOUSING FOR THE FUEL INJECTION PUMPS
1. Fuel manifold. 2. Inlet passage in pump barrel. 3. Check valve. 4. Pump plunger. 5. Spring. 6. Gear. 7. Fuel rack. 8. Lifter. 9. Camshaft.

The longer period that 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 rack (7), it moves gears (6) that are fastened to plungers (4). This causes a rotation of the plungers.

Fuel Injection Valves

Direct Injection Nozzle

Fuel inlet (6) and nozzle tip (13) are parts of nozzle body (11). Valve (8) is held in position by spring force. The force of the spring is controlled by pressure adjustment screw (3). Locknut (4) holds pressure adjustment screw (3) in position. The lift of valve (8) is controlled by lift adjustment screw (2). Locknut (10) holds lift adjustment screw (2) in position. Compression seal (7) goes on nozzle body (11).

The compression seal goes against fuel inlet (6) and prevents the leakage of compression from the cylinder. Carbon dam (12), at the lower end of nozzle body (11) prevents the deposit of carbon in the bore in the cylinder head.

FUEL INJECTION NOZZLE
1. Cap. 2. Lift adjustment screw. 3. Pressure adjustment screw. 4. Locknut for pressure adjustment screw. 5. O-ring seal. 6. Fuel inlet. 7. Compression seal. 8. Valve. 9. Orifices (four). 10. Locknut for lift adjustment screw. 11. Nozzle body. 12. Carbon dam. 13. Nozzle tip.

Fuel, under high pressure from the fuel injection pump goes through the hole in fuel inlet (6). The fuel then goes around valve (8), fills the inside of nozzle body (11) and pushes against the valve guide. When the force made by the pressure of the fuel is more than the force of the spring, valve (8) will lift. When valve (8) lifts, fuel under high pressure will go through the four .0128 in. (0.325 mm) orifices (9) into the cylinder. When the fuel is sent to the cylinder, the force made by the pressure of the fuel in the nozzle body will become less. The force of the spring will then be more than the force of the pressure of the fuel in the nozzle body. Valve (8) will move to the closed position.

Valve (8) is a close fit with the inside of nozzle tip (13), and this makes a positive seal for the valve.

When the fuel is sent to the cylinder, a very small quantity of fuel will leak by the valve guide. This fuel gives lubrication to the moving parts of the fuel injection nozzle.

PC Type Nozzle

Fuel, under high pressure from the injection pumps, is sent through the injection valves into the precombustion chambers. One precombustion chamber is located above each cylinder.

The injection valves have a large single orifice. The action of the fuel flowing through this orifice causes the fuel to atomize (change to very small drops). This makes it possible for the fuel to burn with a high level of efficiency.

Hydra-Mechanical Governor

The accelerator pedal, or 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 has governor weights (12), driven by the engine, governor spring (5), valve (14) and piston (15). The valve and piston are connected to fuel rack (18). The pressure oil for the governor comes from the engine oil pump. Pressure oil goes through oil passage (17) and around sleeve (16). The accelerator pedal, or governor control, controls only the compression of governor spring (5). Compression of the spring pushes to give more fuel to the engine. The centrifugal force (rotation) of governor weights (12) pulls 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).

HYDRA-MECHANICAL GOVERNOR (Typical Example)
1. Collar. 2. Speed limiter plunger. 3. Lever assembly. 4. Seat. 5. Governor spring. 6. Thrust bearing. 7. Oil passage. 8. Drive gear (weight assembly). 9. Cylinder. 10. Bolt. 11. Spring seat. 12. Governor weights. 13. Spring. 14. Valve. 15. Piston. 16. Sleeve. 17. Oil passage. 18. Fuel rack.

Valve (14) is shown in the position when the force of the governor weights and the force of the governor spring are in balance.

When there is an increase in engine load, there will be a decrease in engine rpm and the rotation of governor weights (12) will get slower. (The governor weights will move toward each other.) Governor spring (5) moves valve (14) forward (toward the right in picture shown). When valve (14) moves forward, an oil passage around valve (14) opens to pressure oil. Oil now flows through oil passage (7) and fills the chamber behind piston (15) (the rear end of the valve stops oil flow through the rear of the cylinder, around the valve). This pressure oil pushes the piston and rack forward to give more fuel to the engine. Engine rpm goes up until the rotation of the governor weights is fast enough to be in balance with the force of governor spring (5).

When there is a reduction in engine load, there will be an increase in engine rpm and the rotation of governor weights (12) will get faster. This will move valve (14) backwards (toward the left in picture shown). This movement stops oil flow from the forward passage through piston (15) and allows the oil behind the piston to go out through a passage at the rear of the piston, around valve (14). Now, the pressure oil between sleeve (16) and piston (15) pushes the piston and fuel rack backwards. There is now 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).

When engine rpm is at LOW IDLE, a spring-loaded plunger in lever assembly (3) comes in contact with a shoulder on the adjustment screw for low idle. To stop the engine, pull back on the governor control. This will let the spring-loaded plunger move over the shoulder on the low idle adjustment screw and move the fuel rack to the fuel closed position. With no fuel to the engine cylinders, the engine will stop.

After the engine has stopped, spring (13) moves valve (14) and piston (15) to the full load position. This moves the rack to full travel position and gives full fuel flow through the fuel injection pump to start the engine.

Oil from the engine gives lubrication to the governor weight bearing. The other parts of the governor get lubrication from "splash-lubrication" (oil thrown by other parts). Oil from the governor runs back into the housing for the fuel injection pumps.

In earlier engines, when the governor control is moved to fuel-on position to start the engine, plunger (2) of the speed limiter puts a restriction on the movement of lever assembly (3). After oil pressure of the engine gets to a safe level, plunger (2) of the speed limiter moves back (out of the way) and the governor control can be moved to increase engine rpm. Later engines do not have a speed limiter.

A small force from spring (13) moves fuel rack (18) to give a little more fuel for engine start. With the engine running, the rotation of governor weights (12) will put spring (13) in compression and cause fuel rack (18) to move back. (Spring (13) is extended only when the engine is stopped or at start.) When the engine is running, spring (13) is in compression.

Air Inlet And Exhaust System

AIR FLOW SCHEMATIC OF THE AIR INLET AND EXHAUST SYSTEM (PC TYPE SHOWN)
1. Inlet manifold. 2. Cylinder head. 3. Air inlet passage. 4. Exhaust valve location. 5. Intake valve location. 6. Exhaust manifold.

The air inlet and exhaust system components are: air precleaner, air cleaner, intake manifold, cylinder head, valve mechanism, exhaust manifold and muffler.

The precleaner and air cleaner filter the air before it gets into the inlet manifold and the passage in the cylinder head. This clean air passes through the inlet manifold and fills the inlet ports in the cylinder heads. Air flow from the inlet port into the cylinder is controlled by the intake valves.

There is one intake and one exhaust valve for each cylinder. Make reference to Valves And Valve System Components. Intake valve (5) will open when the piston moves down on the inlet stroke. When the intake valve opens, air from the inlet port is pulled into the cylinder. The intake valve closes and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the precombustion chamber above the cylinder on the PC engine, and directly into the cylinder on the DI engine. 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. Exhaust valve (4) opens, and the exhaust gases are pushed through the exhaust port into exhaust manifold (5). Exhaust gases then pass through the exhaust outlet pipe, the muffler and the exhaust stack. After the piston makes the exhaust stroke, the exhaust valve closes and the cycle (inlet, compression, power, exhaust) starts again.

Valves And Valve System Components

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

The crankshaft gear drives the camshaft gear. The camshaft gear must be timed to the crankshaft gear to get the correct relation between piston and valve movement.

The camshaft has two cams for each cylinder. One cam controls the exhaust valve the other controls the intake valve.

As the camshaft turns, the lobes of camshaft (6) cause lifters (5) to go up and down. This movement makes push rods (3) move rocker arms (2). Movement of the rocker arms open and close valves (4) (intake or exhaust) according to the firing order (injection sequence) of the engine. There is one intake and one exhaust valve for each cylinder, and one rocker arm for each valve.

Valve springs (1) cause the valves to close when the lifters move down.

VALVE SYSTEM COMPONENTS
1. Valve spring. 2. Rocker arm. 3. Push rod. 4. Valve. 5. Lifter. 6. Camshaft.

Lubrication System

Lubrication System (Engines With New Scroll Fuel System)

SCHEMATIC OF THE LUBRICATION SYSTEM
1. Vertical oil passage at rear of cylinder block. 2. Oil passage in cylinder head. 3. Rocker arms. 4. Shaft for the rocker arms. 5. Oil supply passage for camshaft bearings. 6. Oil supply passage for bearings of the crankshaft and connecting rods. 7. Shaft for the idler gear. 8. Piston cooling jets. 9. Main oil passage. 10. Bypass valve for oil filter. 11. Oil passage from oil cooler to oil filter. 12. Oil passage from oil pump to oil cooler. 13. Oil passage in shaft for idler gear. 14. Bypass valve for oil pump. 15. Oil filter. 16. Oil cooler. 17. Bypass valve for oil cooler. 18. Suction pipe for oil pump. 19. Oil pump.

The lubrication system of this engine has the parts that follow: oil pan, oil pump, oil cooler, oil filter, bypass valve for oil cooler and oil filter and oil passages in the cylinder block.

Oil from the oil pan is sent by oil pump (19) to an oil passage (12) at the right front of the cylinder block. Oil from this passage goes through oil cooler (16) from front to rear. From the oil cooler, the oil goes through oil filter (15) and then into main oil passage (9). The main oil passage is located in the right side of the cylinder block, just above the oil passage for the oil cooler.

From main oil passage (9), oil goes through oil passages (5 and 6) to camshaft bearings and crankshaft bearings and through oil passage (13) to idler gear shaft (7). Oil in passages (6) also goes to piston cooling jets (8) in numbers 2 and 4 main bearing supports. Piston cooling jets (8) are pressed into drilled holes in the supports for the main bearings.

Oil for the rocker arms (3) comes from passage (1) at the left rear of the cylinder block. It then goes into the cylinder head through a hollow dowel in the top, left side of the cylinder block. Passage (2) in the cylinder head sends oil into an oil hole in the bottom of the rear bracket that holds shaft (4) for the rocker arms. The oil then goes into the center of the shaft for the rocker arms, where it is pushed out through small holes for lubrication of each rocker arm. Some of the oil is also sent for lubrication of the valves, push rods and valve lifters (camshaft followers).

There is an oil line connected from main oil passage (9) to an elbow on the bottom of the fuel injection pump. Oil is sent from this elbow for operation and lubrication of the governor, and also for lubrication of the parts in the fuel injection pump housing. Some of the oil also gives lubrication to the bearing on the shaft of the fuel pump drive gear. After the oil has done its work, it will return to the engine oil pan.

There is a bypass valve (14) in the cover of the oil pump (19). This bypass valve controls the pressure of the oil from the oil pump (19). The oil pump output capacity is normally larger than the system will need. When there is more oil available than needed, the oil pressure will increase and bypass valve (14) will open. The oil that goes through the bypass valve is not needed, and this extra oil is returned to the inlet oil passage of oil pump (19).

With the engine cold (starting conditions), bypass valves (10 and 17) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil cooler (16) and oil filter (15). Oil pump (19) sends the cold oil through the bypass valves around the oil cooler and oil filter to oil manifold (9) in the cylinder block.

When the oil gets warm, the pressure difference in the bypass valves decreases and the bypass valves close. Now there is a normal flow of oil through the oil cooler and oil filter.

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

Engines with Serial Numbers 45V1 through 45V32893

SCHEMATIC OF THE LUBRICATION SYSTEM
1. Vertical oil passage at rear of cylinder block. 2. Oil passage in cylinder head. 3. Rocker arms. 4. Shaft for the rocker arms. 5. Oil supply passage for camshaft bearings. 6. Oil supply passage for bearings of the crankshaft and connecting rods. 7. Shaft for the idler gear. 8. Main oil passage. 9. Oil passage in shaft for idler gear. 10. Oil passage from oil cooler to oil filter. 11. Oil passage from oil pump to oil cooler. 12. Bypass valve for the oil pump. 13. Oil filter. 14. Oil cooler. 15. Suction pipe for the oil pump. 16. Oil pump.

The lubrication system of this engine has the parts that follow: oil pan, oil pump, oil cooler, oil filter and oil passages in the cylinder block.

Oil from the oil pan is sent by oil pump (16) to an oil passage (11) at the right front of the cylinder block. Oil from this passage goes through oil cooler (14), from front to rear. From the oil cooler, the oil goes through oil filter (13) and then into main oil passage (8). The main oil passage is located in the right side of the cylinder block, just above the oil passage for the oil cooler.

From the main oil passage, oil is sent through passages (5), (6) and (9) to the main bearings, connecting rods, camshaft bearings and the idler gear of the accessory drive.

Oil for rocker arms (3) comes from passage (1) at the left rear of the cylinder block. It then goes into the cylinder head through a hollow dowel pin in the top, left side of the cylinder block. Passage (2) in the cylinder head sends oil into an oil hole in the bottom of the rear bracket that holds shaft (4) for the rocker arms. The oil then goes into the center of the shaft for the rocker arms, where it is pushed out through small holes for lubrication of each rocker arm. Some of the oil is also sent for lubrication of the valves, push rods, and valve lifters (camshaft followers).

There is an oil line connected from main oil passage (8) to an elbow on the bottom of the fuel injection pump. Oil is sent from this elbow for operation and lubrication of the governor, and also for lubrication of the parts in the fuel injection pump housing. Some of the oil also gives lubrication to the bearing on the shaft of the accessory drive gear. After the oil has done its work, it will return to the engine oil pan.

There is a bypass valve in the cover of the oil pump. This bypass valve controls the pressure of the oil from the oil pump. The oil pump output capacity is normally larger than the system will need. When there is more oil available than needed, the oil pressure will increase and the bypass valve will open. The oil that goes through the bypass valve is not needed, and this extra oil is returned to the inlet oil passage of the oil pump.

This system permits a constant controlled oil pressure for engine operation.

Engines with Serial Numbers 45V32894-Up

SCHEMATIC OF THE LUBRICATION SYSTEM
1. Vertical oil passage at rear of cylinder block. 2. Oil passage in cylinder head. 3. Rocker arms. 4. Shaft for the rocker arms. 5. Oil supply passage for camshaft bearings. 6. Oil supply passage for bearings of the crankshaft and connecting rods. 7. Shaft for the idler gear. 8. Main oil passage. 9. Oil passage in shaft for idler gear. 10. Bypass valve for oil filter. 11. Oil passage from oil cooler to oil filter. 12. Oil passage from oil pump to oil cooler. 13. Bypass valve for the oil pump. 14. Oil filter. 15. Oil cooler. 16. Suction pipe for the oil pump. 17. Oil pump.

The lubrication system of this engine has the parts that follow: oil pan, oil pump, oil cooler, oil filter and oil passages in the cylinder block.

Oil from the oil pan is sent by oil pump (17) to an oil passage (12) at the right front of the cylinder block. Oil from this passage goes through oil cooler (15), from front to rear. From the oil cooler, the oil goes through oil filter (14) and then into main oil passage (8). The main oil passage is located in the right side of the cylinder block, just above the oil passage for the oil cooler.

From the main oil passage, oil is sent through passages (5), (6) and (9) to the main bearings, connecting rods, camshaft bearings and the idler gear of the accessory drive.

Oil for rocker arms (3) comes from passage (1) at the left rear of the cylinder block. It then goes into the cylinder head through a hollow dowel pin in the top, left side of the cylinder block. Passage (2) in the cylinder head sends oil into an oil hole in the bottom of the rear bracket that holds shaft (4) for the rocker arms. The oil then goes into the center of the shaft for the rocker arms, where it is pushed out through small holes for lubrication of each rocker arm. Some of the oil is sent for lubrication of the valves, push rods, and valve lifters (camshaft followers).

There is a bypass valve (13) in the cover of the oil pump (17). This bypass valve controls the pressure of the oil from the oil pump (17). The oil pump output capacity is normally larger than the system will need. When there is more oil available than needed, the oil pressure will increase and bypass valve (13) will open. The oil that goes through the bypass valve is not needed, and this extra oil is returned to the inlet oil passage of oil pump (17).

With the engine cold (starting conditions), bypass valve (10) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil filter (14). Oil pump (17) sends the cold oil through the bypass valve around the oil filter to main oil passage (8) in the cylinder block.

When the oil gets warm, the pressure difference in the bypass valve decreases and the bypass valve closes. Now there is a normal flow of oil through the oil filter.

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

Oil Filter Base

FLOW OF OIL (Bypass Valve (10) Closed)

FLOW OF OIL (Bypass Valve (10) Open)

Cooling System

SCHEMATIC OF THE COOLING SYSTEM
1. Cylinder head. 2. Elbow. 3. Radiator cap. 4. Coolant line. 5. Cylinder block. 6. Water pump. 7. Coolant line. 8. Engine oil cooler. 9. Coolant line. 10. Radiator.

Water pump (6) is driven from the crankshaft pulley by a V type belt. The water pump gets coolant from the bottom of radiator (10) and sends it into water passages of cylinder block (5). These passages send coolant around the cylinders to take away the heat of combustion.

Some of the coolant in the cylinder block is sent through coolant line (7) into oil cooler (8) to cool the oil for lubrication of the engine. The coolant then goes through line (9) to the inlet side of the water pump. The remainder of the coolant in cylinder block (5) goes up into cylinder head (1).

Coolant moves through the cylinder head to a thermostat under elbow (2) at the front of the engine. If the coolant is cold (cool), the thermostat will be closed. The coolant will go through a passage in the front cover to the water pump. If the coolant is warm, the thermostat will be open and coolant will go through line (4) and into the top tank of radiator (10). Coolant then goes through the core of the radiator to the bottom tank, where it is again sent through the cooling system.

Radiator cap (3) is used to keep the correct pressure in the cooling system. This pressure keeps a constant supply of coolant to the water pump. If this pressure goes too high, a valve in the radiator cap moves (opens) to get a reduction of pressure. When the correct pressure is in the cooling system, the valve in the radiator cap moves down (closed).

NOTE: The thermostat is an important part of the cooling system. If the thermostat is not installed in the system most of the coolant from the cylinder head will go to the radiator. This will result in high flow through the radiator, reducing the amount of heat rejection from the coolant, causing boiling to take place at the water pump inlet. This results in water pump cavitation which reduces the flow of coolant to the engine. Both conditions results in overheating. In cold weather the coolant that flows to the radiator will also be too much. The engine will not get to normal temperature for operation.

Basic Block

Crankshaft

The crankshaft rotation changes the combustion forces in the cylinder into usable torque that powers the machine. There is a gear at the front of the crankshaft to drive the accessory drive gear, camshaft gear and the oil pump gear.

The crankshaft is supported by five main bearings. Pressure oil is supplied to all connecting rod bearing surfaces through drilled holes in the crankshaft.

Lip seals are used at both ends and a wear sleeve is used at the rear of the crankshaft for easy replacement and a reduction of maintenance cost.

Camshaft

This engine uses a single, forged camshaft that is driven at the front end and is supported by four bearings. Each lobe on the camshaft moves a valve lifter, which in turn moves a push rod, rocker arm, and a valve (either exhaust or intake). There are two lobes for each cylinder.

Pistons And Rings

The cast aluminum piston has two rings; one compression ring and one oil ring. The rings are located above the piston pin bore. The compression ring is a standard (conventional) type.

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 direct injection piston has a special shape (cardioid design) of the top surface to help combustion efficiency. This piston also has a tapered pin bearing design. This provides a larger surface area at the top of the pin bearing to take the load of the power stroke more evenly.

The prechamber piston has a steel heat plug assembled in the pocket (crater) on top of the piston. This plug protects the top of the piston from erosion (distortion by heat).

The piston pin is retained by two snap rings which fit in grooves in the pin bore.

Connecting Rods

The DI connecting rod eye end has the tapered design with the larger bearing surface at the bottom of the eye. This provides more surface area for the increased load of the power stroke.

The PC connecting rod eye has the standard (conventional) type bearing.

Electrical System

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

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NOTICE

The disconnect switch, if so equipped, must be in the ON position to let the electrical system function. There will be damage to some of the charging circuit components if the engine is running with the disconnect switch in the OFF position.

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.

If the machine has a disconnect switch, the starting circuit can operate only after the disconnect switch is put in the ON position.

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

The starting circuit of a "PC" engine can have a glow plug for each cylinder. 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 through the ammeter. The starting circuit is not connected through the ammeter.

Charging System Components

Alternator

The alternator is driven by a V-type belt from the crankshaft pulley. It is a 12 volt, 40 ampere unit with a regulator which has no moving parts (solid state). The only part in the alternator which has movement is rotor assembly (9). Rotor assembly (9) is held in position by a ball bearing at each end of rotor shaft (8).

The alternator is made up of a frame (3) on the drive end, rotor assembly (9), stator assembly (5), rectifier assembly (11), brushes (7) and holder assembly, slip rings (13), rear end frame (12) and regulator (6). Drive pulley (1) has a fan (2) for heat removal by the movement of air thru the alternator.

ALTERNATOR SCHEMATIC (WITH REGULATOR ATTACHED)
1. Pulley. 2. Fan. 3. Drive end frame. 4. Stator coils. 5. Stator assembly. 6. Regulator. 7. Brushes. 8. Rotor shaft. 9. Rotor assembly. 10. Field windings. 11. Rectifier assembly. 12. Rear end frame. 13. Slip rings.

Rotor assembly (9) has field windings (10) (wires around an iron core) which make magnetic lines of force when direct current (DC) flows through them. As the rotor turns, the magnetic lines of force are broken by stator assembly (5). This makes an alternating current (AC) in the stator. Rectifier assembly (11) has diodes which change the alternating current (AC) from the stator to direct current (DC). Most of the direct current (DC) goes to charge the battery and make a supply of direct current (DC) for the low amperage circuit. The remainder of the direct current (DC) is sent to field windings (10) through brushes (7).

Alternator Regulator

The regulator is fastened to the alternator by two different methods. One method fastens the regulator to the top, rear of alternator. With the other method the regulator is fastened separately by use of a wire and a connector that goes into the alternator.

The voltage regulator is a solid state (transistor, no moving parts) electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second. There is no voltage adjustment for this regulator.

Starting Circuit Components

Solenoid

A solenoid is a magnetic switch that does two basic operations:

a. Closes the high current starter motor circuit with a low current start switch circuit.

b. Engages the starter motor pinion with the ring gear.

SOLENOID SCHEMATIC

The solenoid switch is made of an electromagnet (two sets of windings) around a hollow cylinder. There is a plunger (core) with a spring load inside the cylinder that can move forward and backward. When electricity is sent thru the windings, a magnetic field is made that pulls the plunger forward in the cylinder. This moves the shift lever (connected to the rear of the plunger) to engage the pinion drive gear with the ring gear. The front end of the plunger then makes contact across the battery and motor terminals of the solenoid, and the starter motor begins to turn the flywheel of the engine.

The two windings in the solenoid are the hold-in winding and the pull-in winding. Both have the same number of turns around the cylinder, but the pull-in winding uses a larger diameter wire to produce a greater magnetic field. When the start switch is closed, part of the current flows from the battery thru the hold-in winding, and the rest flows thru the pull-in windings to motor terminal, then thru the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off thru the pull-in windings. Now only the smaller hold-in windings are in operation for the extended period of time it takes to start the engine. The solenoid will now take less current from the battery, and heat made by the solenoid will be kept at an acceptable level.

When the start switch is opened, current no longer flows thru hold-in windings. The spring now pushes the plunger back to the original position, and, at the same time, moves the pinion gear away from the flywheel.

Other Components

Circuit Breaker

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

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

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.