Introduction

NOTE: For Specifications with illustrations, make reference to Specifications for 3208 Industrial & Marine Engines, SENR4606. If the Specifications in SENR4606 are not the same as in the Systems Operation and the Testing & Adjusting, look at the printing date on the front cover of each book. Use the Specifications given in the book with the latest date.

Fuel System

Engines With Serial Numbers 90N1-90N6120

Schematic Of Fuel System
(1) Return line for fuel injection nozzles. (2) Fuel priming pump. (3) Return line for constant purge valve. (4) Constant purge valve. (5) Manual purge valve. (6) Fuel injection nozzle. (7) Fuel tank. (8) Fuel inlet line. (9) Fuel filter. (10) Bypass valve (for fuel priming pump). (11) Fuel transfer pump. (12) Fuel bypass valve. (13) Camshaft. (14) Fuel injection pump housing. (A) Check valve. (B) Check valve. (C) Check valve. (D) Check valve.

The sleeve metering fuel system is a pressure type fuel system. The name for the fuel system is from the method used to control the amount of fuel sent to the cylinders. This fuel system has an fuel injection pump for each cylinder of the engine. It also has a fuel transfer pump on the front of the fuel injection pump housing. The governor is on the rear of the fuel injection pump housing.

The drive gear for the fuel transfer pump is on the front of the camshaft for the fuel injection pumps. The carrier for the governor weights is bolted to the rear of the camshaft for the fuel injection pumps. The fuel injection pump housing has a bearing at each end to support the camshaft. The camshaft for the sleeve metering fuel system is driven by the timing gears at the front of the engine.

The fuel injection pumps, lifters and rollers, and the camshaft are all inside of the fuel injection pump housing. The fuel injection pump housing and the governor housing are full of fuel at transfer pump pressure (fuel system pressure).

This fuel system has governor weights, a thrust collar and two governor springs. One governor spring is for high idle and the other governor spring is for low idle. Rotation of the shaft for governor control, compression of the governor springs, movement of connecting linkage in the governor and fuel injection pump housing controls the amount of fuel sent to the engine cylinders.

Cross Section Of Fuel System
(11) Fuel transfer pump. (13) Camshaft. (14) Fuel injection pump housing. (15) Lever. (16) Governor housing. (17) Load stop pin. (18) Cover. (19) Sleeve control shafts (two). (20) Inside fuel passage. (21) Drive gear for fuel transfer pump. (22) Lever on governor shaft. (23) Governor springs (inner spring is for low idle: outer spring is for high idle). (24) Spring seat. (25) Thrust collar. (26) Overfuel spring. (27) Load stop lever. (28) Carrier and governor weights. (29) Sleeve levers.

Fuel System Components
(14) Fuel injection pump housing. (19) Sleeve control shafts. (29) Sleeve levers. (30) Sleeves.

Fuel from fuel tank (7) is pulled by fuel transfer pump (11) through fuel filter (9). From fuel filter (9) the fuel goes to the fuel injection pump housing (14). The fuel goes in fuel injection pump housing (14) at the top and goes through inside passage (20) to fuel transfer pump (11).

From fuel transfer pump (11), fuel under pressure, fills the fuel injection pump housing (14). Pressure of the fuel in the fuel injection pump housing (14) is controlled by bypass valve (12). Pressure of the fuel at Full Load is 205 ± 35 kPa (30 ± 5 psi). If the pressure of fuel in the fuel injection pump housing (14) gets too high, bypass valve (12) will move (open) to let some of the fuel return to the inlet of fuel transfer pump (11).

Lever (15) for the governor is connected by linkage and governor springs (23) to the sleeve control shafts (19). Any movement of lever (22) will cause a change in the position of sleeve control shafts (19).

When lever (15) is moved to give more fuel to the engine, lever (22) will put governor springs (23) in compression and move thrust collar (25) forward. As thrust collar (25) moves forward, the connecting linkage will cause sleeve control shafts (19) to turn. With this movement of the sleeve control shafts, levers (29) will lift sleeves (30) to make an increase in the amount of fuel sent to the engine cylinders.

When starting the engine, the force of overfuel spring (26) is enough to push thrust collar (25) to the full fuel position. This lets the engine have the maximum amount of fuel for injection when starting. At approximately 400 rpm, carrier and governor weights (28) make enough force to push overfuel spring (26) together. Thrust collar (25) and spring seat (24) come into contact. From this time on, the governor works to control the speed of the engine.

When governor springs (23) are put in compression, the spring seat at the front of the governor springs will make contact with load stop lever (27). Rotation of the load stop lever moves load stop pin (17) up until the load stop pin comes in contact with the stop bar or stop screw. This stops the movement of thrust collar (25), the connecting levers, and sleeve control shafts (19). At this position, the maximum amount of fuel per stroke is being injected by each fuel injection pump.

The carrier and governor weights (28) is held on the rear of camshaft (13) by bolts. When engine rpm goes up, fuel injection pump camshaft (13) turns faster. Any change of camshaft rpm will change the rpm and position of carrier and governor weights (28). Any change of governor weight position will cause thrust collar (25) to move. As carrier and governor weights (28) turn faster, thrust collar (25) is pushed toward governor springs (23). When the force of governor springs (23) is balanced by the centrifugal force of the governor weights, sleeves (30) of the fuel injection pumps are held at a specific position to send a specific amount of fuel to the engine cylinders.

When the governor control lever is turned toward the Fuel-Off position with the engine running, there is a reduction of force on governor springs (23). The movement of the linkage in the governor will cause fuel control shafts (19) to move sleeves (30) down, and less fuel will be injected in the engine cylinders.

To stop the engine, turn the ignition switch to the "OFF" position. This will cause the shut-off solenoid to move linkage in the fuel injection pump housing. Movement of the linkage will cause sleeve levers (29) to move sleeves (30) down, and no fuel is sent to the engine cylinders. With no fuel going to the engine cylinders, the engine will stop.

Flow Of Fuel Using The Priming Pump

when the handle of priming pump (2) is pulled out, negative air pressure in priming pump (2) opens check valve (A) and pulls fuel from fuel tank (7). Pushing the handle in closes check valve (A) and opens check valve (B). This pushes air and/or fuel into the fuel injection pump housing (14) through the fuel passages and check valve (C). More operation of priming pump (2) will pull fuel from fuel tank (7) until the fuel lines, fuel filter (9) and fuel injection pump housing (14) are full of fuel. Do this until the flow of fuel from manual purge valve (5) is free of air bubbles. Bypass Valve (10) will open and let the fuel go to the inlet for fuel priming pump (2) if the pressure gets higher than 20 kPa (140 psi) when using priming pump (2).

Constant Purge Valve

Constant Purge Valve
(4) Constant purge valve. (D) Check valve.

Constant purge valve (4) lets approximately nine gallons of fuel per hour go back to fuel tank (7). This fuel goes back to fuel tank (7) through return line for constant purge valve (3). This flow of fuel removes air from the fuel injection pump housing (14) and also helps to cool the fuel injection pump. Check valve (D) makes a restriction in this flow of fuel until the pressure in fuel injection pump housing (14) is at 55 ± 20 kPa (8 ± 3 psi).

Operation Of Fuel Injection Pumps

Fuel Injection Sequence
(1), (2), (3) Injection stroke (positions) of a fuel injection pump. (4) Fuel injection pump camshaft. (A) Barrel. (B) Plunger. (C) Fuel inlet. (D) Sleeve. (E) Fuel outlet. (F) Lifter.

The main components of a fuel injection pump in the sleeve metering fuel system are barrel (A), plunger (B), and sleeve (D). Plunger (B) moves up and down inside barrel (A) and sleeve (D). Barrel (A) is stationary while sleeve (D) is moved up and down on plunger (B) to make a change in the amount of fuel for injection.

When the engine is running, fuel under pressure from the fuel transfer pump goes in the center of plunger (B) through fuel inlet (C) during the down stroke of plunger (B). Fuel cannot go through fuel outlet (E) at this time because it is stopped by sleeve (D), (see position 1).

Fuel injection starts (see position 2) when plunger (B) is lifted up in barrel (A) enough to close fuel inlet (C). There is an increase in fuel pressure above plunger (B), when the plunger is lifted by camshaft (4). The fuel above plunger (B) is injected into the engine cylinder.

Injection will stop (see position 3) when fuel outlet (E) is lifted above the top edge of sleeve (D) by camshaft (4). This movement lets the fuel that is above, and in, plunger (B) go through fuel outlet (E) and return to the fuel injection pump housing.

When sleeve (D) is raised on plunger (B), fuel outlet (E) is covered for a longer time, causing more fuel to be injected in the engine cylinders. If sleeve (D) is low on plunger (B) fuel outlet (E) is covered for a shorter time, causing less fuel to be injected.

Operation Of 9L7883 Fuel Injection Nozzle

Fuel Injection Nozzle
(1) Lift adjusting screw. (2) Locknut. (3) Pressure screw. (4) Spring. (5) Spring seat. (6) Valve guide. (7) Fuel inlet. (8) Compression seal. (9) Valve. (10) Orfices (four). (11) Shims. (12) Nozzle body. (13) Carbon dam. (14) Nozzle tip.

The fuel inlet (7) and nozzle tip (14) are parts of the nozzle body (12). Valve (9) is held in position by force of spring (4). Force of spring (4) is controlled by shims (11). The lift of valve (9) is controlled by lift adjusting screw (1). Locknut (2) holds lift adjusting screw (1) in position. Compression seal (8) goes on nozzle body (12).

The compression seal goes against fuel inlet (7) and prevents the leakage of compression from the cylinder. Carbon dam (13), at the lower end of nozzle body (12), prevents the deposit of carbon in the bore in the cylinder head.

Fuel, under high pressure from the fuel injection pump goes through the hole in fuel inlet (7). The fuel then goes around valve (9), fills the inside of nozzle body (12) and pushes against valve guide (6). When the force made by the pressure of the fuel is more than the force of spring (4), valve (9) will lift. When valve (9) lifts, fuel under high pressure will go through the four 0.325 mm (.0128 in) orifices (10) 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 spring (4) will then be more than the force of the pressure of the fuel in the nozzle body. Valve (9) will move to the closed position.

Valve (9) is a close fit with the inside of nozzle tip (14), this makes a positive seal for the valve.

When the fuel is sent to the cylinder, a small quantity of fuel will leak by valve guide (6). This fuel gives lubrication to the moving parts of the fuel injection nozzle. This fuel then goes through a leak off boot at the top of nozzle body (12) and is returned to the fuel tank.

Function Of Fuel Junction Block

Connection For Fuel Lines At The Fuel Junction Block
(1) Connection for constant purge line to fuel tank. (2) Connection for fuel supply line to fuel tank. (3) Connection for fuel supply line to fuel filter. (4) Fuel junction block. (5) Connection for purge line for fuel injection nozzles to fuel tank. (6) Connection for constant purge line to fuel injection pump housing. (7) Connection for purge line for fuel injection nozzles on right side of engine. (8) Connection for purge line for fuel injection nozzles on left side of engine. (9) Tee.

The location of the fuel junction block (4) is at the right rear of the engine. The fuel lines from the fuel tank and the engine connect at fuel junction block.

Connections For Fuel Lines At The Fuel Junction Block
(1) Connection for constant purge line to fuel tank. (2) Connection for fuel supply line to fuel tank. (3) Connection for fuel supply line to fuel filter. (4) Fuel junction block. (5) Connection for purge line for fuel injection nozzles to fuel tank. (7) Connection for purge line for fuel injection nozzles on right side of engine. (8) Connection for purge line for fuel injection nozzles on left side of engine. (9) Tee.

Automatic Timing Advance Unit

Automatic Timing Advance Unit
(1) Gear on camshaft for fuel injection pump. (2) Automatic timing advance unit. (3) Camshaft for the engine.

Automatic Timing Advance Unit
(4) Weights. (5) Springs. (6) Slides.

The automatic timing advance unit (2) is installed on the front of the camshaft (3) for the engine. The automatic timing advance unit (2) drives the gear (1) on the camshaft for the fuel injection pump. This gear is the drive for the camshaft for the fuel injection pump.

The weights (4) in the timing advance are driven by two slides (6) that fit into notches made on an angle in the weights. The slides (6) are driven by two dowels which are in the drive gear for the engine camshaft. As centrifugal force (rotation) moves weights (4) outward against the force of springs (5), the movement of the notches in weights (4) will cause the slides to make a change in the angle between the timing advance gear and the two drive dowels in the drive gear for the engine camshaft. Since the timing advance unit drives gear (1) on the camshaft for the fuel injection pump, the fuel injection timing is also changed.

The automatic timing advance unit will change the timing 8 degrees. This change starts at approximately low idle rpm and is operating up through the rated speed of the engine. No adjustment can be made to the automatic timing advance unit.

Lubrication oil for the timing advance unit comes from drilled holes that connect with the front bearing for the engine camshaft.

Fuel System

Engines With Serial Numbers 75V1-UP, 90N6121-UP

Schematic Of Fuel System
(1) Fuel priming pump (closed position). (2) Fuel priming pump (open position). (3) Return line for constant purge valve. (4) Constant purge valve. (5) Manual purge valve. (6) Fuel injection nozzle. (7) Fuel tank. (8) Fuel inlet line. (9) Fuel filter. (10) Fuel line to fuel injection pump. (11) Fuel transfer pump. (12) Fuel bypass valve. (13) Camshaft. (14) Fuel injection pump housing. (A) Check valve. (B) Check valve. (C) Check valve. (D) Check valve. (F) Water Separator.

The sleeve metering fuel system is a pressure type fuel system. The name for the fuel system is from the method used to control the amount of fuel sent to the cylinders. This fuel system has a fuel injection pump for each cylinder of the engine. It also has a fuel transfer pump on the front of the fuel injection pump housing. The governor is on the rear of the fuel injection pump housing.

The drive gear for the fuel transfer pump is on the front of the camshaft for the fuel injection pumps. The carrier for the governor weights is bolted to the rear of the camshaft for the fuel injection pumps. The fuel injection pump housing has a bearing at each end to support the camshaft. The camshaft for the sleeve metering fuel system is driven by the timing gears at the front of the engine.

The fuel injection pumps, lifters and rollers, and the camshaft are all inside of the fuel injection pump housing. The fuel injection pump housing and the governor housing are full of fuel at transfer pump pressure (fuel system pressure).

This fuel system has governor weights, a thrust collar and two governor springs. Rotation of the shaft for governor control, compression of the governor springs, movement of connecting linkage in the governor and fuel injection pump housing controls the amount of fuel sent to the engine cylinders.

Cross Section Of Fuel System With Dashpot Governor
(11) Fuel transfer pump. (13) Camshaft. (14) Fuel injection pump housing. (15) Lever. (16) Governor housing. (17) Load stop pin. (18) Cover. (19) Sleeve control shafts (two). (20) Inside fuel passage. (21) Drive gear for fuel transfer pump. (22) Lever (on governor shaft). (23) Dashpot governor piston. (24) Dashpot governor spring. (25) Governor springs (inner spring is for low idle: outer spring is for high idle). (26) Spring seat. (27) Overfuel spring. (28) Thrust collar. (29) Load stop lever. (30) Carrier and governor weights. (31) Sleeve levers. (E) Orifice for dashpot.

Fuel from fuel tank (7) is pulled by fuel transfer pump (11) through water separator (F) (if so equipped) and fuel filter (9). From fuel filter (9) the fuel goes to fuel injection pump housing (14). The fuel goes in the fuel injection pump housing (14) at the top and goes through inside passage (20) to fuel transfer pump (11).

From fuel transfer pump (11), fuel under pressure, fills the fuel injection pump housing (14). Pressure of the fuel in fuel injection pump housing (14) is controlled by fuel bypass valve (12). Pressure of the fuel at Full Load is 205 ± 35 kPa (30 ± 5 psi). If the pressure of fuel in fuel injection pump housing (14) gets too high, fuel bypass valve (12) will move (open) to let some of the fuel return to the inlet of fuel transfer pump (11).

Lever (15) for the governor is connected by linkage and governor springs (25) to the sleeve control shafts (19). Any movement of lever (22) will cause a change in the position of sleeve control shafts (19).

Governor Parts
(23) Dashpot governor piston. (24) Dashpot governor spring. (26) Spring seat. (27) Overfuel spring. (28) Thrust collar.

Fuel System Components
(14) Fuel injection pump housing. (19) Sleeve control shafts. (31) Sleeve levers. (32) Sleeves.

When lever (15) is moved to give more fuel to the engine, lever (22) will put governor springs (25) in compression and move thrust collar (28) forward. As thrust collar (28) moves forward, the connecting linkage will cause sleeve control shafts (19) to turn. With this movement of the sleeve control shafts, sleeve levers (31) will lift sleeves (32) to make an increase in the amount of fuel sent to the engine cylinders.

When starting the engine, the force of overfuel spring (27) is enough to push thrust collar (28) to the full fuel position. This lets the engine have the maximum amount of fuel for injection when starting. At approximately 400 rpm, carrier and governor weights (30) make enough force to push overfuel spring (27) together. Thrust collar (28) and spring seat (26) come into contact. From this time on, the governor works to control the speed of the engine.

When governor springs (25) are put in compression, the spring seat at the front of the governor springs will make contact with load stop lever (29). Rotation of the load stop lever moves load stop pin (17) up until the load stop pin comes in contact with the stop bar or stop screw. This stops the movement of thrust collar (28), the connecting levers, and sleeve control shafts (19). At this position, the maximum amount of fuel per stroke is being injected by each fuel injection pump.

The carrier and governor weights (30) are held on the rear of camshaft (13) by bolts. When engine rpm goes up, fuel injection pump camshaft (13) turns faster. Any change of camshaft rpm will change the rpm and position of carrier and governor weights (30). Any change of governor weight position will cause thrust collar (28) to move. As carrier and governor weights (30) turn faster, thrust collar (28) is pushed toward governor springs (25). When the force of governor springs (25) is balanced by the centrifugal force of the governor weights, sleeves (32) of the fuel injection pumps are held at a specific position to send a specific amount of fuel to the engine cylinders.

The parts of the dashpot work together to make the rpm of the engine steady. The dashpot works as dashpot governor piston (23) moves in the cylinder which is filled with fuel. The movement of dashpot governor piston (23) in the cylinder either pulls fuel into the cylinder or pushes it out. In either direction the flow of fuel is through orifice for the dashpot (E). The restriction to the flow of fuel by orifice for the dashpot (E) gives the governor its function.

When the load on the engine decreases, the engine starts to run faster and governor weights put force against governor springs (25). This added force puts more compression on governor springs (25) and starts to put dashpot governor spring (24) in compression. Dashpot governor spring (24) is in compression because the fuel in the cylinder behind dashpot governor piston (23) can only go out through orifice for the dashpot (E). The rate of flow through orifice for the dashpot (E) controls how fast dashpot governor piston (23) moves. As the fuel is pushed out of the cylinder by dashpot governor piston (23), the compression of dashpot governor piston (23), the compression of dashpot governor spring (24) becomes gradually less. When governor springs (25) and dashpot governor spring (24) are both in compression, their forces work together against the force of weights. This gives the effect of having a governor spring with a high spring rate. A governor spring with a high spring rate keeps the engine speed from having oscillations during load changes.

When the load on the engine increases, the engine starts to run slower. Governor weights puts less force against governor springs (25). Governor springs (25) starts to push spring seat (26) to give more fuel to the engine. Spring seat (26) is connected to dashpot governor piston (23) by dashpot governor spring (24). When spring seat (26) starts to move, the action puts dashpot governor spring (24) in tension. As dashpot governor piston (23) starts to move, a vacuum is made inside the cylinder. The vacuum will pull fuel into the cylinder through orifice for the dashpot (E). The rate of fuel flow through orifice for the dashpot (E) again controls how fast dashpot governor piston (23) moves. During this condition, dashpot governor spring (24) is pulling against governor springs (25). This makes the movement of spring seat (26) and governor springs (25) more gradual. This again gives the effect of a governor spring with a high spring rate.

When the governor control lever is turned toward the Fuel-Off position with the engine running, there is a reduction of force on governor springs (25). The movement of the linkage in the governor will cause fuel control shafts (19) to move sleeves (32) down, and less fuel will be injected in the engine cylinders.

To stop the engine, turn the ignition switch to the "OFF" position. This will cause the shut-off solenoid to move linkage in the fuel injection pump housing. Movement of the linkage will cause sleeve levers (31) to move sleeves (32) down, and no fuel is sent to the engine cylinders. With no fuel going to the engine cylinders, the engine will stop.

Flow Of Fuel Using The Priming Pump

When the handle of priming pump (2) is pulled out, negative air pressure in priming pump (2) opens check valve (A) and pulls fuel from fuel tank (7). Pushing the handle in closes check valve (A) and opens check valve (B). This pushes air and/or fuel into fuel injection pump housing (14) through the fuel passages and check valve (C). More operation of priming pump (2) will pull fuel from fuel tank (7) until the fuel lines, fuel filter (9) and fuel injection pump housing (14) are full of fuel. Do this until the flow of fuel from manual purge valve (5) is free of air bubbles.

Constant Purge Valve

Constant Purge Valve
(4) Constant purge valve. (D) Check valve.

Constant purge valve (4) lets approximately nine gallons of fuel per hour go back to fuel tank (7). This fuel goes back to fuel tank (7) through return line for constant purge valve (3). This flow of fuel removes air from fuel injection pump housing (14) and also helps to cool the fuel injection pump. Check valve (D) makes a restriction in this flow of fuel until the pressure in fuel injection pump housing (14) is at 55 ± 20 kPa (8 ± 3 psi).

Fuel Temperature Compensated Torque Control Groups

Fuel systems on the 3208 Engines use four types of torque control groups; the stop bar, the torque spring (leaf), the fuel temperature compensator, and the Low Emission System (LES).

Governor and fuel injection pump groups with rigid torque control stops limit the performance of the engine to its natural torque rise. Fuel injection pump and governor groups with torque springs allow the engine to perform above its natural torque rise.

Torque control groups used in earlier fuel systems are fastened to the governor housing with two bolts. Later torque control groups, are fastened with a bolt and a stud. Use only the later method to fasten the torque control group to the governor housing when rebuilding a fuel system. The temperature compensating torque control group uses shorter bolts with special heads.

Stop Bar Torque Spring Group
(1) Adjustable stop.

The stop bar torque control is the most common. It uses a threaded adjustable stop (1) to adjust the fuel setting.

Torque Spring Control Group
(1) Shims. (2) Stop bar. (3) Leaf spring.

The torque spring control group uses a leaf spring (3) and a rigid stop bar (2) that is adjusted by inserting shims (1), of appropriate thickness, between the stop bar (2) and the leaf spring (3), and lower insulator.

Fuel Temperature Compensated Torque Control Group
(1) Bellows. (2) Spring. (3) Rocker arm. (4) Fuel setting screw.

The fuel temperature compensator torque control group is used in mobile agricultural engine arrangements where the fuel temperature can get very hot. When the temperature of the fuel increases, the performance of the engine decreases. The fuel temperature compensating torque conntrol group increases the fuel setting when the fuel temperature increases to help keep engine performance normal. The space under the cover for the torque control group is completely filled with fuel when the engine is in operation. Bellows (1) senses (feels) the temperature of the fuel.

As the temperature of the fuel increases, the bellows expands (gets longer) and pushes down on the end of rocker arm (3). This will cause the opposite end of the rocker arm to move up against the force of spring (2). This will also move fuel setting screw (4) up and increase the fuel setting. The increase in the fuel setting will keep engine performance the same when the fuel temperature increases.

When the temperature of the fuel decreases to the normal fuel temperature, the bellows contracts (gets shorter) and spring (2) pushes down on rocker arm (3) and fuel setting screw (4). The fuel setting will return to the normal fuel setting.

Low Emission System (LES)/Exhaust Gas Recirculation (EGR) Switch Torque Control Group
(1) Load stop pin.

The Low Emission System (LES) torque control group uses a threaded adjustable stop and a series of electrical switches to control solenoids that position the Exhaust Gas Recirculation (EGR) valve. The standard load stop pin is replace with a load stop pin (1) with an extended arm. As the load stop pin (1) moves towards full load point, the arm actuates the switches.

Fuel Injection Pumps

A. Fuel Injection Pump uses a reverse flow check valve (RFC).

B. Fuel Injection Pump uses an orificed delivery valve (ODV).

C. Fuel Injection Pump also has an orificed delivery valve (ODV).

D. Fuel Injection Pump uses an orificed reverse flow check (ORFC).

Operation Of Fuel Injection Pumps

Fuel Injection Sequence
(1,2,3) Injection stroke (positions) of a fuel injection pump. (4) Injection pump camshaft. (A) Barrel. (B) Plunger. (C) Fuel inlet. (D) Sleeve. (E) Fuel outlet. (F) Lifter.

The main components of a fuel injection pump in the sleeve metering fuel system are barrel (A), plunger (B), and sleeve (D). Plunger (B) moves up and down inside the barrel (A) and sleeve (D). Barrel (A) is stationary while sleeve (D) is moved up and down on plunger (B) to make a change in the amount of fuel for injection.

When the engine is running, fuel under pressure from the fuel transfer pump goes in the center of plunger (B) through fuel inlet (C) during the down stroke of plunger (B). Fuel can not go through fuel outlet (E) at this time because it is stopped by sleeve (D), (see position 1).

Fuel injection starts (see position 2) when plunger (B) is lifted up in barrel (A) enough to close fuel inlet (C). There is an increase in fuel pressure above plunger (B), when the plunger is lifted by camshaft (4). The fuel above plunger (B) is injected into the engine cylinder.

Injection will stop (see position 3) when fuel outlet (E) is lifted above the top edge of sleeve (D) by camshaft (4). This movement lets the fuel that is above, and in, plunger (B) go through fuel outlet (E) and return to the fuel injection pump housing.

When the sleeve (D) is raised on plunger (B), fuel outlet (E) is covered for a longer time, causing more fuel to be injected in the engine cylinders. If sleeve (D) is low on plunger (B), fuel outlet (E) is covered for a shorter time, causing less fuel to be injected.

Operation Of Fuel Injection Nozzle (7000 Series)

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 fuel injection 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 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.

Operation Of Fuel Injection Nozzle (Pencil Type)

Pencil Type Fuel Injection Nozzle
(1) Cap. (2) Lift adjustment screw. (3) Pressure adjustment screw. (4) Locknut (for adjustment screw). (5) O-ring seal. (6) Fuel inlet. (7) Compression seal. (8) Valve. (9) Nozzle orifices. (10) Locknut (for lift adjustment screw). (11) Nozzle body. (12) Carbon dam. (13) Nozzle tip.

The fuel inlet (6) and nozzle tip (13) are parts of the nozzle body (11). Valve (8) is held in position by spring force. 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 the nozzle body (11).

Compression seal (7) goes against the fitting of fuel inlet (6) and prevents the leakage of compression from the cylinder. Carbon dam (12), at the lower end of the nozzle body (11), prevents the deposit of carbon in the bore of the cylinder head.

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 the 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 nozzle 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), 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.

Automatic Timing Advance Unit

Automatic Timing Advance Unit
(1) Gear. (2) Automatic timing advance unit. (3) Camshaft (engine).

Automatic Timing Advance Unit
(4) Weights. (5) Springs. (6) Slides.

The automatic timing advance unit (2) is installed on the front of the camshaft (3). The automatic timing advance unit (2) drives gear (1). This gear is the drive for the camshaft for the fuel injection pump.

The weights (4) in the timing advance are driven by two slides (6) that fit into notches made on an angle in the weights. The slides (6) are driven by two dowels which are in the drive gear for the engine camshaft. As centrifugal force (rotation) moves weights (4) outward against the force of springs (5), the movement of the notches in weights (4) will cause the slides to make a change in the angle between the timing advance gear and the two drive dowels in the drive gear for the engine camshaft. Since the timing advance unit drives the gear (1), the fuel injection timing is also changed.

The automatic timing advance unit will change the timing 5 degrees. This change starts at approximately low idle rpm and is operating up through the rated speed of the engine. No adjustment can be made to the automatic timing advance unit.

Lubrication oil for the timing advance unit comes from drilled holes that connect with the front bearing for the engine camshaft.

Function Of Fuel Junction Block

Connection For Fuel Lines At The Fuel Junction Block
(1) Connection for constant purge line to fuel injection pump housing. (2) Connection for constant purge line to fuel tank. (3) Connection for fuel tank. (4) Fuel junction block. (5) Connection for fuel supply line to fuel tank.

The location of the fuel junction block (4) is at the right rear of the engine. The fuel lines from the fuel tank and the engine connect at fuel junction block (4).

Water Separator

Water Separator
(1) Vent valve. (2) Drain valve.

Some engines have a water separator. The water separator is installed between the fuel tank and the rest of the fuel system. For efficiency in the action of the water separator the fuel flow must come directly from the fuel tank and through the water separator. This is because the action of going through a pump or valves before the water separator lowers the efficiency of the water separator.

The water separator can remove 95 percent of the water in a fuel flow of up to 125 liter/hr (33 gph) if the concentration of the water in the fuel is 10 percent or less. It is important to check the water level in the water separator frequently. The maximum amount of water which the water separator can hold is 0.4 liter (0.8 pt). At this point the water fills the glass to 3/4 full. Do not let the water separator exceed this water volume before draining

Drain the water from the water separator every day or when the water level gets to 1/2 full. This gives the system protection from water in the fuel. If the fuel has a high concentration of water, or if the flow rate of fuel through the water separator is high, the water separator fills with water faster and must be drained more often. To drain the water separator, open drain valve (2) in the drain line and vent valve (1) at the top of the water separator. Let the water drain until it is all out of the water separator. Close both valves.

Sleeve Control Levers (All Serial Numbers)

4N1763 Sleeve Control Lever
(A) Dimension A.

Two sleeve control levers are used for the Sleeve Metering Fuel System (SMFS). They are two different styles and are not interchangeable.

The 4N1763 Sleeve Control Lever is used on all fuel systems with 8.0 mm (.31 in) fuel pump assemblies (most Naturally Aspirated engines). Dimension A of 4N1763 Sleeve Control Lever is 6.25 ± 0.13 mm (.246 ± .005 in). This sleeve control lever should NOT be used in fuel systems with 8.5 mm (.33 in) fuel injection pump assemblies. The sleeve control lever could interfere with the sleeve and result in sticking or binding of the sleeve, or damage to the fuel injection pump.

9N5820 Sleeve Control Lever
(B) Dimension B. (1) Chamfer.

The 9N5820 Sleeve Control Lever is used on all fuel systems with 8.5 mm (.33 in) fuel injection pump assemblies (most turbocharged engines). Dimension B of 9N5820 Sleeve Control Lever is 6.11 ± 0.07 mm (.241 ± .003 in). This sleeve control lever is also identified by a chamfer (1) on one side of the lever. This lever may be used in fuel systems with EITHER 8.0 mm (.31 in) or 8.5 mm (.33 in) fuel injection pump assemblies.

Fuel Injection Pump Lifters (All Serial Numbers)

Fuel Injection Pump Lifters Dimensions
(1) Crown. (2) Guide slot.

The generations of 3208 Engines have used a variety of fuel injection pump lifters. When rebuilding or replacing components be sure to use the correct piece parts. The following chart and illustration offers the correct usage for the different fuel injection pump lifters.

NA-1 fuel injection pump lifters can be identified by the smaller diameter 9.1 mm (.36 in) crown and are separated into two categories: narrow 3.43 mm (.135 in) guide slot fuel injection pump lifters and wide 3.96 mm (.156 in) guide slot fuel injection pump lifters.

The narrow slot NA-1 fuel injection pump lifters must only be use in NA-1 fuel injection pump housings with the 2.39 mm (.094 in) diameter lifter guide pins and only with NA-1 camshafts. The side slot NA-1 fuel injection pump lifters must only be used in NA-1 housing with 3.18 mm (.125 in) diameter guide pins and NA-1 camshafts.

The NA-2, 3, 4 fuel injection pump lifters have the same outside diameter 17.462 mm (.6875 in) as the NA-1 fuel injection pump lifters and have a wide 3.96 mm (.156 in) guide slot, but the crown diameter is larger 9.8 mm (.39 in). They can be used in NA-2, 3, 4 housing and in the NA-1 housing with 3.18 mm (.125 in) diameter guide pins, but only with NA-2, 3, 4 camshafts when rebuilding NA-2, 3, 4 fuel systems.

The T-1, 2, 3 fuel injection pump lifters have a wide 3.96 mm (.156 in) guide slot and a larger 9.8 mm (.39 in) diameter crown. The outside diameter of the turbocharged fuel injection pump lifters has a larger diameter than that of the NA. The dimension is 19.480 mm (.7669 in). The T fuel injection pump lifters must be used only in T housing and with T camshafts.

Air Inlet And Exhaust System (Engines Without Turbocharger)

Air Inlet And Exhaust System (Industrial Engine)
(1) Air inlet pipe. (2) Pipe plug. (3) Mounting flange for the air cleaner. (4) Fitting. (5) Positive crankcase ventilation valve. (6) Inlet manifolds. (7) Valve cover. (8) Exhaust manifolds.

The air inlet system is on the top side of the engine. The air cleaner goes on air inlet pipe (1). The inlet pipe can not be turned end for end because the mounting flange for the air cleaner (3) has a small angle toward the front of the engine.

The air inlet manifolds (6) are made as part of the cylinder heads. The air inlet openings and the design of the combustion chamber give the air needed for complete combustion.

The exhaust system is on each side of the engine. The exhaust manifolds (8) are along the outside of the cylinder heads. The exhaust manifold for the right side of the engine will not go on the left side of the engine. The exhaust manifold for the left side of the engine will not go on the right side of the engine.

Air Inlet And Exhaust System (Marine Engine)
(1) Air inlet pipe. (2) Pipe plug. (3) Mounting flange for the air cleaner. (4) Fitting. (5) Positive crankcase ventilation valve. (6) Inlet manifolds. (7) Valve cover. (8) Exhaust manifolds.

A positive crankcase ventilation valve (5) goes on valve cover (7). Valve (5) will return crankcase fumes to the engine through air inlet pipe (1).

Valve cover (7) can also be put on the other cylinder head. When valve cover (7) is put on the other cylinder head, fitting (4) must be exchanged with pipe plug (2) in the air inlet pipe (1).

Air Inlet And Exhaust System (Marine Engines With Turbocharger)

Air Inlet And Exhaust System (Marine Engines With Turbocharger)
(1) Air inlet pipe. (2) Positive crankcase ventilation valves. (3) Air cleaner adapter. (4) Turbocharger. (5) Valve cover. (6) Air inlet pipe. (7) Inlet manifold. (8) Turbocharger support. (9) Water cooled exhaust manifold.

The 3208 Turbocharged Marine Engine has a watercooled turbocharger located at the rear of the engine. The exhaust gases from all of the cylinders are used to turn the turbocharger. Air is pulled through the air cleaner and adapter by the turbocharger compressor wheel. The air goes from the turbocharger through air inlet pipes (1 and 6) to the inlet manifold in each cylinder head. The air enters the cylinders when the inlet valves open.

The exhaust gases go out of the cylinders and into the exhaust ports when the exhaust valves open. The exhaust then goes through the watercooled exhaust manifolds to the turbocharger support. From the turbocharger support, the exhaust gases enter the turbocharger turbine housing and cause the turbine wheel to turn. The exhaust gases leave the turbocharger through the exhaust outlet.

There is a positive crankcase ventilation valve on each valve cover. The ventilation valves are connected to the air cleaner adapter on the air inlet side of the turbocharger.

Turbocharger (Marine Engine)

Turbocharger
(1) Compressor wheel. (2) Compressor housing. (3) Lubrication inlet passage (4) Turbine housing. (5) Coolant outlet passage. (6) Turbine wheel. (7) Lubrication outlet passage. (8) Coolant inlet passage.

The watercooled turbocharger is supported by the mount at the rear of the engine. All the exhaust gases from the diesel engine go through the turbocharger.

The exhaust gases enter the turbine housing (4) and go through the blades of turbine wheel (6) causing the turbine wheel and compressor wheel (1) to turn.

When compressor wheel (1) turns, it pulls filtered air from the air cleaner through compressor housing (2) air inlet. The air is put in compression by action of compressor wheel (1) and is pushed to the inlet manifold of the engine.

When the engine load increases, more fuel is injected into the engine cylinders. The volume of exhaust gas increases which causes the turbocharger turbine wheel and compressor impeller to turn faster. The increased rpm of the impeller increases the quantity of inlet air. As the turbocharger provides additional inlet air, more fuel can be burned. This results in more horsepower from the engine.

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

The bearings for the turbocharger use engine oil for lubrication. The oil comes in through the lubrication inlet passage (3) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the lubrication outlet passage (7) in the bottom of the center section and goes back to the engine lubrication system.

Cylinder Head And Valves

Engines With Serial Numbers 75V1-75V1446, 90N1-90N6120

Cylinder Head And Valves
(1) Push rod. (2) Lifter. (3) Guide support. (4) Rocker arm shaft. (5) Rocker arm. (6) Exhaust valve. (7) Valve seat insert. (8) Inlet valve. (9) Inner valve spring. (10) Outer valve spring.

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 inlet and exhaust valves are opened and closed by movement of these components; crankshaft, camshaft, lifters, push rods, rocker arms, and valve springs.

Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is driven by, and timed to, a gear on the front of the crankshaft. When the camshaft turns, the lobes on the camshaft also turn and cause the lifters to go up and down. This movement makes the push rods move the rocker arms.

The movement of the rocker arms will make the inlet and exhaust valves in the cylinder head open and close according to the firing order (injection sequence) of the engine. Two valve springs for each valve hold the valves in the closed position.

There is one inlet and one exhaust valve for each cylinder. The valve seat insert for the exhaust valves can have replacement. The valve seat for the inlet valve is machined in and is a part of the cylinder head. When the seat for the inlet valve has been machined to the limits given in Specifications, it can be bored (machined) for a valve seat insert. The valve guide bore is machined in and is a part of the cylinder head.

Engines With Serial Numbers 75V1447-UP, 90N6121-UP

Cylinder Head And Valves
(1) Push rod. (2) Lifter. (3) Guide support. (4) Rocker arm shaft. (5) Rocker arm. (6) Exhaust valve. (7) Valve seat insert. (8) Inlet valve. (9) Valve spring.

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 inlet and exhaust valves are opened and closed by movement of these components; crankshaft, camshaft, lifters, push rods, rocker arms, and valve springs.

Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is driven by, and timed to, a gear on the front of the crankshaft. When the camshaft turns, the lobes on the camshaft also turn and cause the lifters to go up and down. This movement makes the push rods move the rocker arms.

The movement of the rocker arms will make the inlet and exhaust valves in the cylinder head open and close according to the firing order (injection sequence) of the engine. One valve spring for each valve holds the valves in the closed position.

There is one inlet and one exhaust valve for each cylinder. The valve seat insert for the exhaust valves can have replacement. The valve seat for the inlet valve may or may not use an insert replacement, dependent on application. Engines that do not have inlet valve seat inserts, can be bored (machined) for a insert when the seat has been machined to the limits given in Specifications. The valve guide bore is machined in and is a part of the cylinder head.

Lubrication System

(Engines With Oil Filter Bypass In Oil Filter)

Schematic Of Lubrication System
(1) Vacuum pump or air compressor. (2) Cylinder head. (3) Front cover for the engine. (4) Oil manifold. (5) Base for the oil cooler. (6) Oil pump bypass valve. (7) Oil cooler. (8) Oil pump. (9) Oil pump cover. (10) Suction bell for oil pump. (11) Oil cooler bypass valve. (12) Oil filter bypass valve. (13) Oil filters.

Schematic Of Oil Passages In Crankshaft

The lubrication system uses a six lobe, rotor type oil pump (8). Bolts hold the oil pump cover (9) on the front cover for the engine (3). The gear on the crankshaft drives the outer rotor. The outer rotor has rotation in a bearing in the front cover for the engine. The inner rotor goes on a short shaft in the front cover for the engine. The inner rotor is driven by the outer rotor.

Oil pump bypass valve (6), in the cover for the oil pump (9) controls the pressure of the oil coming from oil pump (8). The oil pump can put more oil into the system than needed. When the pressure of the oil going into the engine is more than 520 to 590 kPa (75 to 85 psi) the bypass valve (6) will open. This permits the oil that is not needed to bypass the system.

Oil from the oil pan is pulled through the suction bell for the oil pump (10) by oil pump (8). The oil is sent by the oil pump to an oil passage in the front cover for the engine (3). Oil from this passage goes to the cylinder block and on to the base for the oil cooler (5). The base for the oil cooler is on the left side of the engine, near the front of the engine. Oil cooler bypass valve (11) in the base for the oil cooler, will let the oil go around the oil cooler (7) when the oil is cold or if the restriction in the oil cooler is more than the other parts of the system. A difference in pressure of 85 to 105 kPa (12 to 15 psi) between the oil inlet and the oil outlet will open the bypass valve.

Oil from the oil cooler goes to the oil filters. Oil filter bypass valve (12) in the base for the oil cooler will let the oil go around the oil filters (13) if there is a restriction in the filters.

There are two pressure outlets in the base for the oil cooler. The pressure outlets are on the outlet side of the oil cooler and oil filters. The pressure outlets are for the sending unit and switch for the oil pressure.

Oil from the oil filters (13) goes through a passage in the cylinder block to oil manifold (4). The oil manifold is in the center of the cylinder block, above the camshaft, and goes the full length of the cylinder block. Oil goes from the oil manifold to the bearings for the camshaft. There are grooves in the bores in the cylinder block around the bearings for the camshaft. The bearing surfaces (journals) on the camshaft get lubrication from these grooves through a hole in the bearings for the camshaft. Some of the oil goes around the grooves and down through passages to the main bearing bores. The oil goes through a hole in the upper main bearing and into a groove in the bearing. This oil gives lubrication to the bearing surfaces (journals) of the crankshaft for the main bearings.

Oil gets into the crankshaft through holes in the bearing surfaces (journals) for the main bearings. Passages connect the bearing surface (journal) for the main bearing with the bearing surface (journal) for the connecting rod. The piston pins get lubrication from oil thrown by other parts.

Oil for the rocker arms comes from the oil manifold (4) through passages in the cylinder block. The passages in the cylinder block are in alignment with a passage in each cylinder head. The passage to the cylinder head on the left side is near the front of the cylinder block. The passage to the cylinder head on the right side is near the rear of the cylinder block.

The passage in each cylinder head sends the oil into an oil hole in the bottom of the mounting surface of the bracket that holds the shaft for the rocker arms. The oil hole is in the front bracket on the left side and in the rear bracket on the right side. The oil then goes up through the bracket and into the center of the shaft for the rocker arms. Oil goes along the center of the shaft to the bearings for the rocker arms. From the rocker arms, the oil is pushed through small holes to give lubrication to the valves, push rods, lifters, and camshaft lobes.

After the lubrication oil has done its work, it will return to the engine oil pan.

(Engines With Oil Filter Bypass Valve In Oil Cooler Base)

Schematic Of Lubrication System
(1) Vacuum pump or air compressor. (2) Cylinder head. (3) Front cover for the engine. (4) Oil manifold. (5) Base for the oil cooler. (6) Oil pump bypass valve. (7) Oil cooler. (8) Oil pump. (9) Oil pump cover. (10) Suction bell for oil pump. (11) Oil cooler bypass valve. (12) Oil filter bypass valve. (13) Oil filters.

Schematic Of Oil Passages In Crankshaft

The lubrication system uses a six lobe, rotor type oil pump (8). Bolts hold the oil pump cover (9) on the front cover for the engine (3). The gear on the crankshaft drives the outer rotor. The outer rotor has rotation in a bearing in the front cover for the engine. The inner rotor goes on a short shaft in the front cover for the engine. The inner rotor is driven by the outer rotor.

Oil pump bypass valve (6), in the cover for the oil pump (9), controls the pressure of the oil coming from oil pump (8). The oil pump can put more oil into the system than needed. When the pressure of the oil going into the engine is more than 520 to 590 kPa (75 to 85 psi), the bypass valve (6) will open. This permits the oil that is not needed to bypass the system.

Oil from the oil pan is pulled through the suction bell for the oil pump (10) by oil pump (8). The oil is sent by the oil pump to an oil passage in the front cover for the engine (3). Oil from this passage goes to the cylinder block and on to the base for the oil cooler (5). The base for the oil cooler is on the left side of the engine, near the front of the engine. Oil cooler bypass valve (11), in the base for the oil cooler, will let the oil go around the oil cooler (7) when the oil is cold or if the restriction in the oil cooler is more than the other parts of the system. A difference in pressure of 85 to 105 kPa (12 to 15 psi) between the oil inlet and the oil outlet will open the bypass valve.

Oil from the oil cooler goes to the oil filters. Oil filter bypass valve (12), in the base for the oil cooler will let oil go around oil filters (13) if there is a restriction in the oil filters.

There are two pressure outlets in the base for the oil cooler. The pressure outlets are on the outlet side of the oil cooler and oil filters. The pressure outlets are for the sending unit and switch for the oil pressure.

Oil from the oil filters (13) goes through a passage in the cylinder block to oil manifold (4). The oil manifold is in the center of the cylinder block, above the camshaft, and goes the full length of the cylinder block. Oil goes from the oil manifold to the bearings for the camshaft. There are grooves in the bore in the cylinder block around the bearings for the camshaft. The bearing surfaces (journals) on the camshaft get lubrication from these grooves through a hole in the bearings for the camshaft. Some of the oil goes around the grooves and down through a passage to a hole and groove in the top half of the main bearing. Oil from the hole and groove gives lubrication to the bearing surfaces (journals) of the crankshaft for the main bearings.

Oil gets into the crankshaft through holes in the bearing surfaces (journals) for the main bearings. Passages connect the bearing surface (journal) for the main bearing with the bearing surface (journal) for the connecting rod. The piston pins get lubrication from oil thrown by other parts.

Oil for the rocker arms comes from the oil manifold (4) through passages in the cylinder block. The passages in the cylinder block are in alignment with a passage in each cylinder head. The passage to the cylinder head on the left side is near the front of the cylinder block. The passage to the cylinder head on the right side is near the rear of the cylinder block.

The passage in each cylinder head sends the oil into an oil hole in the bottom of the mounting surface of the bracket that holds the shaft for the rocker arms. The oil hole is in the front bracket on the left side and in the rear bracket on the right side. The oil then goes up through the bracket and into the center of the shaft for the rocker arms. Oil goes along the center of the shaft to the bearings for the rocker arms. From the rocker arms, the oil is pushed through small holes to give lubrication to the valves, push rods, lifters, and camshaft lobes.

After the lubrication oil has done its work, it will return to the engine oil pan.

Cooling System

(Industrial Engines)

Cooling System With Standard Vertical Radiator
(1) Radiator cap. (2) Radiator top tank. (3) Radiator top hose. (4) Shunt line. (5) Housing (for water temperature regulators). (6) Return to water temperature regulator housing. (7) Cylinder heads (two). (8) Vent tube. (9) Surge tank. (10) Inside bypass. (11) Radiator bottom tank. (12) Radiator bottom hose. (13) Water pump. (14) Outlet line (for oil cooler). (15) Oil cooler. (16) Inlet line (for oil cooler). (17) Cylinder block. (A) Orifices between cylinder heads and front cover. (B) Orifice in oil cooler inlet.

Cooling System With Cross Flow Radiator
(1) Radiator cap. (2) Radiator left side tank. (3) Radiator top hose. (4) Shunt line. (5) Housing (for water temperature regulators). (6) Return to housing for water temperature regulators. (7) Cylinder heads (two). (8) Vent tube. (9) Surge tank. (10) Inside bypass. (11) Radiator right side tank. (12) Radiator bottom hose. (13) Water pump. (14) Outlet line (for oil cooler). (15) Oil cooler. (16) Inlet line (for oil cooler). (17) Cylinder block. (A) Orifices between cylinder heads and front cover for the engine. (B) Orifice in oil cooler inlet.

Cooling System With Vertical Radiator And Separate Surge Tank
(1) Radiator cap. (2) Radiator top tank. (3) Radiator top hose. (4) Shunt line. (5) Housing (for water temperature regulators). (6) Return to housing for water temperature regulators. (7) Cylinder heads (two). (8) Vent tube. (9) Surge tank. (10) Inside bypass. (11) Radiator bottom tank. (12) Radiator bottom hose. (13) Water pump. (14) Outlet line (for oil cooler). (15) Oil cooler. (16) Inlet line (for oil cooler). (17) Cylinder block. (A) Orifices between cylinder heads and front cover. (B) Orifice in oil cooler inlet.

Flow Of Coolant
(3) Radiator top hose. (5) Housing (water temperature regulators). (6) Return to housing for water temperature regulators. (10) Inside bypass. (18) Water temperature regulators (two). (C) Flow with warm coolant. (D) Flow with cold coolant.

Water pump (13) is installed on the front face of the front cover for the engine and is driven by belts from the crankshaft pulley. The inlet opening of water pump (13) is connected to radiator bottom hose (12). The outlet flow of coolant from water pump (13) goes through inside passages in the front cover for the engine.

As the coolant goes from the water pump, it divides and goes through the inside passages in the front cover for the engine to cylinder block (17). Most of the coolant goes through cylinder block (17) and up to cylinder heads (7). From cylinder heads (7) the coolant goes forward through orifices (A) to the front cover for the engine.

Part of the coolant going to the left side (when viewed from the flywheel) of cylinder block (17) goes through orifice (B) to inlet line (16) and on to oil cooler (15), to cool the oil for lubrication of the engine, and back to the front cover for the engine through outlet line (14).

From the front cover for the engine, the coolant either goes to the inlet for water pump (13) or to the radiator.

If the coolant is cold (cool), the water temperature regulators (18) will be closed. The coolant will go through inside bypass (10) to water pump (13). If the coolant is warm, the water temperature regulators (18) will be open. When the water temperature regulators (18) are open, they make a restriction in the inside bypass (10) and the coolant goes through radiator top hose (3) and into radiator top tank (2) or left side tank (2). Coolant then goes through the core of the radiator to the radiator bottom tank (11) or radiator right side tank (11), where it is again sent through the cooling system. A small amount of coolant goes through inside bypass (10) when temperature regulators (18) are open.

NOTE: The water temperature regulators (18) are an important part of the cooling system. They divide coolant flow between radiator (2) and inside bypass (10) as necessary to maintain the correct temperature. If the water temperature regulators are not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

Cooling System With Cross Flow Radiator And Separate Surge Tank
(1) Radiator cap. (2) Radiator left side tank. (3) Radiator top hose. (4) Shunt line. (5) Housing (for water temperature regulators). (6) Return to housing for water temperature regulators. (7) Cylinder heads (two). (8) Vent tube. (9) Surge tank. (10) Inside bypass. (11) Radiator right side tank. (12) Radiator bottom hose. (13) Water pump. (14) Outlet line (for oil cooler). (15) Oil cooler. (16) Inlet line (for oil cooler). (17) Cylinder block. (A) Orifices between cylinder heads and front cover. (B) Orifice in oil cooler inlet.

Location Of Water Temperature Regulators

The vertical radiator is made with a top tank (2) above the core and a surge tank (9) either above or separate from the top tank. Vent tube (8) connects radiator top tank (2) and surge tank (9). The cross flow radiator is made with a left side tank (2) and a right side tank (11).

The surge tank (9) is either a part of right side tank (11), separated by an inside baffle, or a tank separate from the radiator. Vent tube (8) connects the surge tank (9) to the radiator.

Surge tank (9) has a shunt line (4) that connects to the inlet of water pump (13). This shunt type system keeps a positive pressure on the inlet of water pump (13) at all times. When putting coolant in the cooling system, coolant from surge tank (9) goes through shunt line (4) to the inlet of water pump (13) and fills cylinder block (17) from the bottom. By filling the system from the bottom, any air in the system is pushed out through radiator top tank (2), through vent tube (8) into surge tank (9).

Radiator cap (1) is used to keep the correct pressure in the cooling system. This pressure keeps a constant supply of coolant to water pump (13). If this pressure goes too high, a valve in radiator cap (1) moves (opens) to get a reduction of pressure. When the correct pressure is in the cooling system, the valve in radiator cap (1) moves down (to the closed position).

Location Of Vent Valve

The vent valve is located in the front housing next to the temperature regulators. The vent valve is used to let the air out of the cooling system when the cooling system is filled. When the engine is in operation, the vent valve will close and not let coolant go through. This will help increase the temperature of the coolant at low engine loads.

Locations Of Heater Connections

The front housing has several plugs that give access to water passages inside the housing. For the correct access points to install heater hoses, see the preceding photo.

(Marine Engine Without Turbocharger)

Cooling System Schematic
(1) Sea water pump. (2) Expansion tank. (3) Exhaust risers. (4) Shunt line. (5) Heat exchanger. (6) Inside bypass. (7) Outlet for sea water. (8) Housing (for water temperature regulators). (9) Water pump. (10) Water cooled exhaust manifolds. (11) Orifices (between cylinder heads and front cover for the engine). (12) Cylinder block. (13) Engine oil cooler. (14) Marine gear oil cooler.

Water pump (9) is installed on the front face of the front cover for the engine and is driven by belts from the crankshaft pulley. As the coolant goes from the water pump, it divides and goes through inside passages in the front cover for the engine to cylinder block (12) and up to the cylinder heads. From the cylinder heads the coolant goes forward through orifices (11) to the front cover for the engine.

Part of the coolant going to the left side (when viewed seen from the flywheel) of cylinder block (12) goes to engine oil cooler (13) and on to the marine gear oil cooler (14).

After the coolant goes through the marine gear oil cooler, it divides and goes to the rear of water cooled exhaust manifolds (10). After going through the water cooled exhaust manifolds, the coolant goes to the front cover for the engine.

From the front cover for the engine, the coolant either goes to the inlet for water pump (9) or to expansion tank (2).

Flow Of Coolant
(6) Inside bypass. (8) Housing for water temperature regulators. (15) Passage to lower part of expansion tank. (16) Return to housing for water temperature regulators. (17) Water temperature regulators (two). (A) Flow with warm coolant. (B) Flow with cold coolant.

If the coolant is cold (cool), the water temperature regulators (17) will be closed. The coolant will go through inside bypass (6) to water pump (9). If the coolant is warm, the water temperature regulators (17) will be open. When the water temperature regulators (17) are open, they make a restriction in the inside bypass (6) and the coolant goes to the lower part of expansion tank (2). Expansion tank (2) is divided into an upper and lower compartment by a baffle.) From the lower compartment of expansion tank (2), most of the coolant goes through heat exchanger (5) and the inlet for water pump (9).

A small part of the coolant from the lower compartment of expansion tank (2) goes through a small vent tube into the upper compartment of expansion tank (2). This coolant goes through shunt line (4) to the inlet of water pump (9). This shunt type system keeps a positive pressure on the inlet of water pump (9) at all times.

Location Of Water Temperature Regulators

NOTE: The water temperature regulators (17) are an important part of the cooling system. They divide coolant flow between radiator and inside bypass (6) as necessary to maintain the correct temperature. If the water temperature regulators are not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

Sea water pump (1) is installed on the left side of the front cover for the engine, and is driven by a belt from the crankshaft pulley.

Sea water is sent by sea water pump (1) to heat exchanger (5). From the heat exchanger, the sea water goes to exhaust risers (3) After going through exhaust risers (3), the sea water mixes with the exhaust gases, and goes through outlet for sea water (7).

(Marine Engine With Turbocharger)

Cooling System Schematic
(1) Sea water pump. (2) Expansion tank. (3) Exhaust outlet elbow. (4) Shunt line. (5) Heat exchanger. (6) Inside bypass. (7) Outlet for sea water. (8) Housing (for water temperature regulators). (9) Water pump. (10) Water cooled exhaust manifolds. (11) Orfices (between cylinder heads and front cover for the engine). (12) Water cooled exhaust elbows. (13) Water cooled turbocharger support. (14) Cylinder block. (15) Engine oil cooler. (16) Marine gear oil cooler. (17) Water cooled turbocharger.

Water pump (9) is installed on the front face of the front cover for the engine and is driven by belts from the crankshaft pulley. As the coolant goes from the water pump, it divides and goes through inside passages in the front cover for the engine to cylinder block (14) and up to the cylinder heads. From the cylinder heads the coolant goes forward through orifices (11) to the front cover for the engine.

Part of the coolant going to the left side of cylinder block (14) goes to cooler for engine oil (15). Then a part of the coolant goes to the cooler for marine gear oil (16) and the remainder goes to the bottom left opening in water cooled turbocharger (17). Coolant from the cooler for the marine gear oil goes to the bottom right opening in the water cooled turbocharger.

Coolant leaves the turbocharger from two lines at the top and goes to water cooled turbocharger support (13). Coolant then goes to the right side and left side water cooled exhaust elbows (12) and then on to water cooled exhaust manifolds (10). The coolant then goes to the front cover for the engine.

From the front cover for the engine, the coolant either goes to the inlet for water pump (9) or to expansion tank (2).

Flow Of Coolant
(6) Inside bypass. (8) Housing for water temperature regulators. (18) Passage to lower part of expansion tank. (19) Return to housing for water temperature regulators. (20) Water temperature regulators (two). (A) Flow with warm coolant. (B) Flow with cold coolant.

If the coolant is cold (cool), the water temperature regulators (20) will be closed. The coolant will go through inside bypass (6) to water pump (9). If the coolant is warm, the water temperature regulators (20) will be open. When the water temperature regulators (20) are open, they make a restriction in the inside bypass (6) and the coolant goes to the lower part of expansion tank (2). (Expansion tank (2) is divided into an upper and lower compartment by a baffle.) From the lower compartment of expansion tank (2), most of the coolant goes through heat exchanger (5) and the inlet for water pump (9).

A small part of the coolant from the lower compartment of expansion tank (2) goes through a small vent tube into the upper compartment of expansion tank (2). This coolant goes through shunt line (4) to the inlet of water pump (9). This shunt type system keeps a positive pressure on the inlet of water pump (9) at all times.

Location Of Water Temperature Regulators

NOTE: The water temperature regulators (20) are an important part of the cooling system. They divide coolant flow between radiator and inside bypass (6) as necessary to maintain the correct temperature. If the water temperature regulators are not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

Sea water pump (1) is installed on the left side of the front cover for the engine, and is driven by a belt from the crankshaft pulley.

Sea water is sent by sea water pump (1) to heat exchanger (5). From the heat exchanger, the sea water goes to exhaust risers (3) After going through exhaust risers (3), the sea water mixes with the exhaust gases, and goes through outlet for sea water (7).

Basic Block

Cylinder Block

The cylinders are a part of the cylinder block. There are no replaceable cylinder liners. The cylinders can be machined (bored) up to 1.02 mm (.040 in) oversize for reconditioning. The cylinders in the block are at a 90 degree angle to each other. There are five main bearings in the block to support the crankshaft.

Cylinder Head

There is one cylinder head for each side (bank) of the engine. One inlet and one exhaust valve is used for each cylinder. The valve guides are a part of the cylinder head and can not be replaced. Valve seat insert are used for the exhaust valves and can be replaced. Valve seat inserts are used for some inlet valves and can be replaced. On other engines the inlet valve seat can be machined and an insert installed.

Pistons, Rings And Connecting Rods

The pistons have two rings which are located above the piston pin bore. There is one compression ring and one oil control ring. The oil ring is made in one piece and has an expansion spring behind it. The compression ring is also one piece and goes into an iron band that is cast into the piston.

The piston pin is held in the piston by two snap rings which go into the piston pin bore.

The piston pin end of the connecting rod is tapered to give more bearing surface at the area of highest load. The rod is installed on the piston with the boss on the connecting rod on the same side as the crater in the piston. The connecting rod bearings are held in location with a tab that goes into a groove in the connecting rod.

Crankshaft

The force of combustion in the cylinders is changed to usable rotating power by the crankshaft. The crankshaft can have either six or eight counterweights. A gear on the front of the crankshaft turns the engine camshaft gear and the engine oil pump. The end play of the crankshaft is controlled by the thrust bearing on No.4 main bearing.

Vibration Damper

The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. The 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.

The damper is made of a flywheel ring (1) connected to an inner hub (3) by a rubber ring (2). The rubber makes a flexible coupling between the flywheel ring and the inner hub.

Cross Section Of A Vibration Damper
(1) Flywheel ring. (2) Rubber ring. (3) Inner hub.

Electrical System

Grounding Practices

Proper grounding of the engine electrical systems is necessary for proper engine performance and reliability. Improper grounding will result in uncontrolled and unreliable electrical circuit paths.

Uncontrolled engine electrical circuit paths can result in damage to main bearings, crankshaft journal surfaces, and aluminum components.

Uncontrolled electrical circuit paths can cause electrical noise which may degrade engine performance.

To insure proper functioning of the engine electrical systems, an engine-to-frame ground strap with a direct path to the battery must be used. This may be provided by way of a starting motor ground, a frame to starting motor ground, or a direct frame to engine ground.

Ground wires/straps should be combined at ground studs dedicated for ground use only. All grounds should be tight and free of corrosion.

All ground paths must be capable of carrying any conceivable fault currents, and an awg #0 or larger wire is recommended for the cylinder head grounding strap.

The engine alternator should be battery negative (-) grounded with a wire size adequate to handle full alternator charging current.

Engine 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 activated.

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

Alternators (7G7889 And 3T6352)

7G7889 And 3T6352 Alternators
(1) Regulator. (2) Roller bearing. (3) Stator winding. (4) Ball bearing (5) Rectifier bridge. (6) Field winding. (7) Rotor assembly. (8) Fan.

The alternator is driven by belts from the crankshaft pulley. This alternator is a three phase, self-rectifying charging unit, and the regulator is part of the alternator.

This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are the field winding, stator windings, six rectifying diodes and the regulator circuit components.

The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of this current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent on to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.

The voltage regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

Alternators (7N9720, 9W3043 And 100-5046)

7N9720, 9W3043 And 100-5046 Alternators
(1) Fan. (2) Stator winding. (3) Field winding. (4) Regulator. (5) Ball bearing. (6) Roller bearing. (7) Rotor. (8) Rectifier assembly.

The alternator is driven by belts from the crankshaft pulley. This alternator is a three phrase, self-rectifying charging unit, and the regulator is part of the alternator.

This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are: the field winding, stator windings, six rectifying diodes, and the regulator circuit components.

The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of this current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force.

These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.

The voltage regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

The voltage regulator is an 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.

Alternators (6T1395, 6T1396, 7T2095, 7T2096, 107-2519, And 112-8032)

7T2095 And 7T2096 Alternators
(1) Slip rings. (2) Fan. (3) Stator assembly. (4) Rotor assembly. (5) Brush and holder assembly.

The alternator is a three phase, self-rectifying charging unit that is driven by belts. The only part of the alternator that has movement is the rotor assembly. Rotor assembly (4) is held in position by a ball bearing at each end of the rotor shaft.

The alternator is made up of a front frame at the drive end, rotor assembly (4) stator assembly (3), rectifier assembly, brushes and holder assembly (5), slip rings (1) and rear end frame. Fan (2) provides heat removal by the movement of air through the alternator.

Rotor assembly (4) has field windings (wires around an iron core) that make magnetic lines of force when direct current (DC) flows through them. As the rotor assembly turns, the magnetic lines of force are broken by stator assembly (3). This makes alternating current (AC) in the stator. The rectifier assembly diodes that change the alternating current (AC) from the stator to direct current (DC). Most of the DC current goes to charge the battery and make a supply for the low amperage circuit. The remainder of the DC current is sent to the field windings through the brushes.

The voltage regulator is not fastened to the alternator, but is mounted separately and is connected to the alternator with wires. The regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output. There is a voltage adjustment for this regulator to change the alternator output.

Alternator (9G4574, 8T9700 And 100-5045)

9G4574, 8T9700 And 100-5045) Alternator
(1) Fan. (2) Front frame assembly. (3) Stator assembly. (4) Rotor assembly. (5) Field winding (coil) assembly. (6) Regulator assembly. (7) Condenser (suppression capacitor). (8) Rectifier assembly. (9) Rear frame assembly.

The alternator has three-phase, full-wave rectified output. It is brushless. The rotor and bearings are the only moving parts.

When the engine is started and the rotor turns inside the stator windings, three-phase alternating current (AC) and rapidly rising voltage is generated.

A small amount of alternating current (AC) is changed (rectified) to pulsating direct current (DC) by the exciter diodes on the rectifier assembly. Output current from these diodes adds to the initial current which flows through the rotor field windings from residual magnetism. This will make the rotor a stronger magnet and cause the alternator to become activated automatically. As rotor speed, current and voltages increase, the rotor field current increases enough until the alternator becomes fully activated.

The main battery charging current is charged (rectified) from AC to DC by the other positive and negative diodes in the rectifier and pack (main output diodes) which operate in a full wave linkage rectifier circuit.

The voltage regulator is a solid state 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.

Alternator (2P1204)

2P1204 Alternator
(1) Brush assembly. (2) Stator. (3) Rotor. (4) Roller bearing. (5) Slip rings. (6) Ball bearing.

The alternator is driven by two belts from the fan pulley. It is a 24 volt, 19 ampere unit with a regulator which has no moving parts (solid state) installed on the side opposite the pulley. The alternator is made up of a head assembly on the drive end, rotor assembly, stator assembly, rectifier and heat removal assemblies, brush and holder assembly, head assembly on the ring end and regulator.

The rotor assembly has the field windings (wires around an iron core) which make magnet like lines of force when direct current (DC) flows through them. As the rotor turns, the magnet like lines of force are broken by the stator. This makes an alternating current (AC) in the stator. The rectifier 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 the field windings through the brushes.

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.

Starting System Components

Solenoid

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

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

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

Typical Solenoid Schematic

The solenoid switch is made of an electromagnetic (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 starting 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 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 through the hold-in windings, and the rest flows through the pull-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.

Starting Motor

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

Starting Motor
(1) Field. (2) Solenoid. (3) Clutch. (4) Pinion. (5) Commutator. (6) Brush assembly. (7) Armature.

The starting motor has a solenoid. When the start switch is turned to the START position, the solenoid will be activated electrically. The solenoid core will now move to push the starting motor pinion, by a mechanical linkage, to engage with the ring gear on the flywheel of the engine. The starting motor pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starting motor. When the circuit between the battery and the starting motor is complete, the starting motor pinion will turn the engine flywheel. A clutch gives protection for the starting motor so that the engine, when it starts to run, cannot turn the starting motor too fast. When the start switch is released, the starting motor pinion will move away from the flywheel ring gear.

Magnetic Switch

A magnetic switch (relay) is used sometimes for the starting motor solenoid circuit. Its operation electrically is the same as the starting motor solenoid. Its function is to reduce the current load on the start switch and control current to the starting motor solenoid.

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 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.