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 140 to 280 kPa (20 to 40 psi). 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 34 liters (9 gal.) 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 the fuel increases. At approximately 690 kPa (100 psi), 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 0.31 mm (.012 in.) 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.

Air Inlet And Exhaust System

Air Inlet And Exhaust System (Engines With Turbochargers)

AIR INLET AND EXHAUST SYSTEM FOR ENGINES WITH A TURBOCHARGER
1. Exhaust manifold. 2. Inlet manifold. 3. Engine cylinder. 4. Turbocharger compressor wheel. 5. Turbocharger turbine wheel. 6. Air inlet. 7. Exhaust outlet.

The air inlet and exhaust system components are: air cleaner, inlet manifold, cylinder head, valves and valve system components, exhaust manifold, and turbocharger.

Clean inlet air from the air cleaner is pulled through the air inlet (6) of the turbocharger by the turning compressor wheel (4). The compressor wheel causes a compression of the air. The air then goes to the inlet manifold (2) of the engine. When the intake valves open, the air goes into the engine cylinder (3) and is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinder and into the exhaust manifold (1). From the exhaust manifold, the exhaust gases go through the blades of the turbine wheel (5). This causes the turbine wheel and compressor wheel to turn. The exhaust gases then go out the exhaust outlet (7) of turbocharger (8).

AIR INLET AND EXHAUST SYSTEM (TYPICAL EXAMPLE)
8. Turbocharger.

Turbocharger

The turbocharger is installed on the exhaust manifold. All the exhaust gases from the engine go through the turbocharger.

The exhaust gases go through the blades of the turbine wheel (9). This causes the turbine wheel (9) and compressor wheel (4) to turn which causes a compression of the inlet air.

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. Ring. 13. Collar. 14. Seal. 15. Lubrication outlet port. 16. Ring. 17. Bearing. 18. Ring.

When the load on the engine goes up more fuel is put into the engine. This makes more exhaust gases and will cause turbine wheel (9) and compressor wheel (4) of the turbocharger to turn faster. As the turbocharger turns faster, it gives more inlet air and makes it possible for the engine to burn more fuel and will give the engine more power.

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.

The bearings (17) 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 (17). Oil from the turbocharger goes out through the oil outlet port (15) in the bottom of the center section and goes back to the engine lubricating system.

The fuel system 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.

Air Inlet And Exhaust System (Engines Without Turbochargers)

AIR INLET AND EXHAUST SYSTEM FOR ENGINES WITHOUT A TURBOCHARGER
1. Exhaust manifold. 2. Inlet manifold. 3. Engine cylinder.

The air inlet and exhaust system components are: air cleaner, inlet manifold, cylinder head, valves and valve system components and exhaust manifold.

When the engine is running each time a piston moves through the inlet stroke, it pulls air into the cylinder. The air flow is through the air filter, inlet manifold, passages in the cylinder head and past the open intake valve into the cylinder. Too much restriction in the inlet air system makes the efficiency of the engine less.

When the engine is running, each time a piston moves through the exhaust stroke, it pushes hot exhaust gases from the cylinder. The exhaust gas flow is out of the cylinder between the open exhaust valve and the exhaust valve seat. Then it goes through passages in the cylinder head, through the exhaust manifold and out through the exhaust pipe. Too much restriction in the exhaust system makes the efficiency of the engine less.

Valves And Valve System Components

The valve system components control the flow of inlet air into and exhaust gases out of the cylinder 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) causes 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 without Turbocharger)

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 s 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 slall 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.

Lubrication System (Engines with Turbocharger)

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. Oil return line from turbocharger to oil pan. 11. Turbocharger. 12. Oil supply to turbocharger for lubrication. 13. Bypass valve for oil filter. 14. Oil passage from oil cooler to oil filter. 15. Oil passage from oil pump to oil cooler. 16. Oil passage in shaft for idler gear. 17. Bypass valve for oil pump. 18. Oil filter. 19. Oil cooler. 20. Bypass valve for oil cooler. 21. Suction pipe for oil pump. 22. 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 (22) to an oil passage (15) at the right front of the cylinder block. Oil from this passage goes through oil cooler (19), from front to rear. From the oil cooler, the oil goes through oil filter (18) 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 (16) 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 an oil supply line (12) connected from the main oil passage (9) to the top of the turbocharger for lubrication of the bearings. After the oil has lubricated the turbocharger bearings, it will return through the bottom of the turbocharger through oil return line (10) to the engine oil pan.

There is a bypass valve (17) in the cover of the oil pump (22). This bypass valve controls the pressure of the oil from the oil pump (22). 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 (17) 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 (22).

With the engine cold (starting conditions), bypass valves (13 and 20) 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 (19) and oil filter (18). Oil pump (22) 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.

Cooling System

SCHEMATIC OF THE COOLING SYSTEM (Typical)
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 two V-type belts. 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 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 coolant 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 through the passage in the front cover to the water pump. This will cause the engine to get too hot in hot weather. In cold weather the small amount of coolant that does flow to the radiator will be too much. The engine will not get to normal temperature for operation.

Basic Block

Crankshaft

The action of the crankshaft changes the combustion forces in the cylinders into usable power to operate the machine. The crankshaft is forged steel. A gear that is a tight fit on the front of the crankshaft drives the front gear train. Lip type seals are used on the front and rear of the crankshaft. The front seal is pressed in the front cover and rides on the hub of the crankshaft pulley. The rear seal is pressed in the flywheel housing and rides on a wear sleeve pressed onto the crankshaft. The crankshaft is supported by five main bearings. Two thrust plates, one on either side of the center main bearing, prevent too much linear (line) movement of the crankshaft.

Front Gear Train

FRONT GEAR TRAIN

Camshaft

This engine uses a single forged camshaft that is driven at the front. It is supported by four bearings. The front journal is supported by two bearings. This extra support at the front is necessary because the camshaft gear drives the hydraulic pump gear. The camshaft has eight cam lobes. It is held in position by a thrust bearing plate that goes into a groove in the camshaft and is fastened to the front face of the cylinder block.

Each lobe on the camshaft moves a valve lifter, which in turn moves a push rod, rocker arm and a valve (either intake or exhaust).

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

Connecting Rods

The 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.

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.

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 a disconnect switch is used, 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 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 (Delco-Remy)

The alternator is an electrical and mechanical component driven by a belt from engine rotation. It is used to charge the storage battery during the engine operation. The alternator is cooled by fan (5) that is part of the alternator.

A solid state regulator is installed inside the back frame of the alternator. Two brushes send current through two slip rings to the field coil on the rotor. A rectifier bridge connected to the stator windings contains six diodes, and electrically changes the stator AC voltages to a DC voltage. The DC voltage goes to the alternator output terminal. Alternator field current comes through a diode trio which also is connected to the stator windings. A capacitor, or condenser, installed in the end frame gives protection to the rectifier bridge and diode trio from high voltages.

Alternator Operation

When the ignition switch is turned ON, current from the battery flows to brush (1) and slip-ring (6) through rotor field coil (3) to another slip-ring (7) and brush (2) to ground which is called field current. As rotor field coil (3) is mechanically rotated inside stator windings (4), AC current is made. Connected to stator windings (4) are the six diodes which electrically change the stator AC current to DC current. The DC current from the rectifier bridge goes to the alternator output terminal.

When the alternator is in operation, AC voltage is generated in the stator windings. The stator gives DC field current through the diode trio, the field, TR1 and then to ground. The six diodes in the rectifier bridge change the stator AC voltage to a DC voltage which is between ground and the alternator "BAT" terminal. As alternator speed increases, current is available for charging the battery and operation of electrical accessories.

ALTERNATOR OPERATION
1. Brush. 2. Brush. 3. Rotor field coil. 4. Stator windings. 5. Fan. 6. Slip-ring. 7. Slip-ring.

Starting System 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.

TYPICAL SOLENOID SCHEMATIC

The solenoid switch is made of an electromagnet (one or 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 the start switch is closed and electricity is sent through 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.

When the start switch is opened, current no longer flows through the 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.

When two sets of windings in the solenoid are used, they are called the hold-in windings and the pull-in windings. Both have the same number of turns around the cylinder, but the pull-in windings 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 through the hold-in windings to motor terminal, then through the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off through 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.

Starter Motor

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

The starter motor has a solenoid. When the start switch is activated, the solenoid will move the starter pinion to engage it 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 circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine can not turn the starter motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.

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

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.

A heat activated metal disc with a contact point makes complete 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 (an adjustment to make the circuit complete again) after it becomes cool. 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.