Introduction

NOTE: For Specifications with illustrations, make reference to Specifications for 3208 Marine Engine, SENR2131. If the Specifications in SENR2131 are not the same as in the Systems Operation, 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

Schematic Of Fuel System
(1) Fuel priming pump (closed position). (2) Fuel priming pump (open position). (3) Return line for constant bleed valve. (4) Constant bleed valve. (5) Manual bleed valve. (6) Fuel injection nozzle. (7) Fuel tank. (8) Fuel inlet line. (9) Fuel filter. (10) Fuel line to 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 an injection pump for each cylinder of the engine. It also has a fuel transfer pump on the front of the injection pump housing. The governor is on the rear of the injection pump housing.

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

The injection pumps, lifters and rollers, and the camshaft are all inside of the pump housing. The 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 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 piston. (24) Dashpot spring. (25) Governor springs (inner spring is for low idle: outer spring is for high idle). (26) Spring seat. (27) Overfueling spring. (28) Thrust collar. (29) Load stop lever. (30) Carrier and governor weights. (31) Sleeve levers. (E) Dashpot orifice.

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 the fuel injection pump housing (14). The fuel goes in the fuel injection pump housing (14) at the top and goes through the inside fuel 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 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 the 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).

Fuel System Components
(14) Fuel injection pump housing. (19) Sleeve control shafts (two). (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 overfueling 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 compress overfuel spring (27). Thrust collar (28) and spring seat (26) come into contact. From this time on, the governor works to control the speed of the engine.

Governor Parts
(23) Piston for dashpot governor. (24) Spring for dashpot governor. (26) Spring seat. (27) Overfueling spring. (28) Thrust collar.

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 injection pump.

The carrier and governor weights (30) is held on the rear of camshaft (13) by bolts. When engine rpm goes up, camshaft (13) turns faster. Any change of camshaft rpm will change the rpm and position of the carrier and governor weights (30). Any change of the carriera and governor weight position will cause thrust collar (28) to move. As the 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 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 piston (23) moves in the cylinder which is filled with fuel. The movement of dashpot piston (23) in the cylinder either pulls fuel into the cylinder or pushes it out. In either direction the flow of fuel is through dashpot orifice (E). The restriction to the flow of fuel by dashpot orifice (E) gives the governor its function.

When the load on the engine decreases, the engine starts to run faster and carrier and governor weights (30) put force against governor springs (25). This added force puts more compression on governor springs (25) and starts to put dashpot spring (24) in compression. Dashpot spring (24) is in compression because the fuel in the cylinder behind dashpot piston (23) can only go out through dashpot orifice (E).

The rate of flow through dashpot orifice (E) controls how fast dashpot piston (23) moves. As the fuel is pushed out of the cylinder by dashpot piston (23), the compression of dashpot spring (24) becomes gradually less. When governor springs (25) and dashpot spring (24) are both in compression, their forces work together against the force of carrier and governor weights (30). 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. Carrier and governor weights (30) 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 piston (23) by dashpot spring (24). When spring seat (26) starts to move, the action puts dashpot spring (24) in tension. As dashpot piston (23) starts to move, a vacuum is made inside the cylinder. The vacuum will pull fuel into the cylinder through dashpot orifice (E). The rate of fuel flow through dashpot orifice (E) again controls how fast dashpot piston (23) moves. During this condition, dashpot 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 shutoff solenoid to move linkage in the fuel 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 fuel priming pump (2) is pulled out, negative air pressure in fuel 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 fuel 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 bleed valve (5) is free of air bubbles.

Constant Bleed Valve

Constant Bleed Valve
(4) Constant bleed valve. (D) Check valve.

Constant bleed valve (4) lets approximately 9 gallons of fuel per hour go back to fuel tank (7). This fuel goes back to fuel tank (7) through return line for constant bleed 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 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 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 injection pump 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 injection pump 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 7E3969, 9N3979, 1W5829, 4W1819, 4W8483 And 115-3354 Fuel Injection Nozzles

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

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 in 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 four 0.325 mm (.0128 in) 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.

Operation Of 7000 Series 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 the nozzle seat and the fuel will go through the four 0.29 mm (.011 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 the fuel to the combustion chamber.

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).

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.

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

The weights (4) in the timing advance are drive 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) on the camshaft for the fuel injection pump, the fuel injection timing is also changed.

The automatic timing advance unit will change the timing 3.5 or 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.

Fuel Ratio Control

(1) Air Chamber. (2) Diaphragm. (3) Bolt.

The fuel ratio control limits the amount of fuel to the cylinders during an increase of engine speed (acceleration) to reduce exhaust smoke.

Bolt (3) in the fuel ratio control limits the travel of the fuel control shaft in the FUEL ON direction only. As the engine accelerates, bolt (3) will not let the fuel control shaft go to full fuel position. When the turbocharger gives enough air pressure to give good combustion in the cylinders, the inlet manifold pressure goes through a line into air chamber (1). The air pressure in air chamber (1) pushes on diaphragm (2) which moves bolt (3) down. When bolt (3) moves down, the fuel control shaft can move to the full fuel position.

Air Inlet And Exhaust System

Air Flow (Engines Without Aftercooler)

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 watercold 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

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 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.

Air Flow (235 To 375 HP Aftercooled Engines)

Air Inlet And Exhaust System
(1) Oil separator. (2) Positive crankcase ventilation valve. (3) Air cleaner adapter. (4) Air cleaner. (5) Turbocharger support. (6) Turbocharger. (7) Pipe. (8) Air inlet pipe. (9) Aftercooler. (10) Watercooled exhaust manifold.

This 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 pipe (7) to aftercooler (9). From the aftercooler, air goes through air inlet pipe (8) 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 cylinder 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 oil separator (1). The oil separator removes the oil from the crankcase fumes and returns the oil to the engine oil pan. The fumes then go to the air cleaner adapter (3) on the inlet side of the turbocharger.

Aftercooler

The aftercooler cools the air coming out of the turbocharger before it goes into the inlet manifold. The purpose of this is to make the air going into the combustion chambers more dense. The more dense the air is, the more fuel the engine can burn efficiently. This gives the engine more power.

Turbocharger

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.

Air Flow (425 And 435 HP Aftercooled Engines)

Air Inlet And Exhaust System
(1) Air Cleaner Adapter. (2) Air Cleaner. (3) Aftercooler. (4) Turbocharger. (5) Turbocharger support. (6) Air inlet pipe. (7) Watercooled exhaust manifold.

This 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 to aftercooler (3). From the aftercooler, air goes through air inlet pipe (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 cylinder 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.

Aftercooler

The aftercooler cools the air coming out of the turbocharger before it goes into the inlet manifold. The purpose of this is to make the air going into the combustion chambers more dense. The more dense the air is, the more fuel the engine can burn efficiently. This gives the engine more power.

Turbocharger

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.

Aftercooler Condensate Drain Valve

Typical Example
(1) Condensate drain valve. (2) Inlet/aftercooler housing.

An aftercooler condensate drain system is provided with this engine. Under certain conditions: cold sea water, warm, humid air, engine stopped, moisture can collect in the air inlet/aftercooler housing (2) and pool in the bottom of the housing, it can run down the inlet ports into the cylinders. Trying to start the engine would result in a hydraulic lock.

A condensate drain valve (1) is installed in a lower part of the inlet/aftercooler housing (2) to allow the moisture to drain. The condensate drain valve (1) is open when the engine is stopped to allow for drainage. When boost is present, the condensate drain valve (1) closes.

Most engines will not normally see conditions that will cause condensation. The condensate drain valve (1) should be regularly inspected to insure proper operation in the event that it is needed. The volume of water that may drain from the inlet/aftercooler housing (2) will be small. When installing the drain hose be sure the end of the hose is not submergered in any water or allowed to collect debris.

The condensate drain valve (1) is typically installed at the rear of the inlet/aftercooler housing (2). This is the correct location for an engine rear down application. If the engine installation is front down the condensate drain valve (1) must be relocated to the front of the inlet/aftercooler housing (2).

During engine operation the boost pressure forces the condensate drain valve plunger down to close the orifice. The plunger must close against the seat at pressure of 27.5 kPa (4 psi). When the engine is stopped the absence of boost pressure allows the plunger to raise to the open position which allows condensation from the inlet/aftercooler housing (2) to drain out. It is important that the plunger move freely to close off the system when the engine is running and to allow the moisture to escape from the inlet/aftercooler when the engine is stopped. Remove the condensate drain valve (1) from the adapter and inspect to determine if the plunger moves freely. Residue from normal engine operation could cause the condensate drain valve (1) to become sticky. If the condensate drain valve (1) does not move easily, use solvent to clean the it.

Remove the drain lines and check for plugging in the drain lines. Pressure air or a small diameter flexible rod can be use to clean the drain lines.

Crankcase Ventilation And Fumes Disposal

Air Cleaner Group-Top View
(1) Air cleaner. (2) Turbocharger. (3) Aftercooler. (4) Breather hose.

Air Cleaner Group-Right Side View
(5) Drain line.

All turbocharged and aftercooled engines may utilize the closed crankcase breathing system incorporated within the air cleaner group. This system provides an efficient method of separating oil from crankcase blowby fumes.

A vacuum is created in the air cleaner housing. As inlet air passes through air cleaner (1) to the turbocharger (2), crankcase fumes are drawn out of the engine breather through breather hose (4). Once in the air cleaner housing, the oil vapor is removed from the gases, the oil is returned to the engine oil pan through drain line (5). The fumes are directed to the turbocharger compressor inlet. As inlet air passes through the air cleaner (1) to the turbocharger (2), a crankcase vacuum will exist with this system. This system reduces oil consumption, prevents turbocharger compressor wheel and aftercooler core fouling, and extends air cleaner life.

The system is entirely enclosed and virtually maintenance free. Refer to the Operation & Maintenance for cleaning interval for the air filter elements.

Cylinder Head And Valves

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 inlet and exhaust valves can be replaced. The valve guide bore is machined in and is a part of the cylinder head.

Lubrication System

Schematic Of Lubrication System
(1) Front engine cover. (2) Cylinder head. (3) Oil supply to turbocharger (earlier engine models). Later engine models turbocharger oil supply comes from the cylinder block, not oil filter base. (4) Oil filters. (5) Oil manifold. (6) Piston cooling jet. (7) Oil pump. (8) Oil pump cover. (9) Oil pump bypass valve. (10) Oil pump suction bell. (11) Oil cooler bypass valve. (12) Oil filter bypass valve. (13) Oil cooler base. (14) Oil cooler.

The lubrication system uses a six lobe, rotor type oil pump (7). Bolts hold the oil pump cover (8) on the front engine cover (1). 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 (9), in the oil pump cover (8), controls the pressure of the oil coming from oil pump (7). The pump can put more oil into the system than needed. When the pressure of the oil going into the engine is more than 380 to 550 kPa (55 to 80 psi), the oil pump bypass valve (9) will open. This permits the oil that is not needed to bypass the system.

Oil from the oil pan is pulled through the oil pump suction bell (10) by oil pump (7). The oil is sent by the pump to an oil passage in the front engine cover (1). Oil from this passage goes to the cylinder block and on to the oil cooler base (13). The oil cooler base (13) is on the left side of the engine, near the front of the engine. Oil cooler bypass valve (11), in the oil cooler base (13), will let the oil go around the oil cooler (14) 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 oil cooler base (13) will let oil go around oil filters (4) if there is a restriction in the oil filters.

There are three pressure outlets on the bottom of the oil cooler base. The larger pressure outlet in the center is for an oil pressure switch. This pressure outlet connects to an oil passage that goes from the oil cooler to the oil filters. The two other pressure outlets connects to an oil passage that comes from the oil filters and to the engine block.

Oil from the oil filters (4) goes through a passage in the cylinder block to oil manifold (5). 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.

Some of the oil goes around the grooves and down through passages to the main bearing bores. The main bearing bores in the cylinder block have grooves to let oil to to piston cooling jets (6) that spray oil to cool the pistons and lubricate the piston pin. The remaining 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.

Schematic Of Oil Passages In Crankshaft

NOTE: No. 1 main bearing surface (journal) does not have an oil passage to a connecting rod bearing surface (journal).

On earlier model engines, oil from the oil filters also goes through oil supply to turbocharger (3) to the center housing of the turbocharger for lubrication of the bearings. On later model engines, turbocharger oil supply comes from the cylinder block oil passages and not an external oil filter base. Oil from the turbocharger goes to the oil pan.

Oil for the rocker arms comes from the oil manifold (5) 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

Heat Exchanger Without Aftercooler (Engines With 275 HP Or Less)

Jacket Water System

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

Water pump (6) is installed on the front face of the front cover for the engine and is V-belt driven 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 (11) and up to the cylinder heads. From the cylinder heads the coolant goes forward through orifices (8) to the front cover for the engine.

Part of the coolant on the left side of cylinder block (11) goes to the engine oil cooler (12). Then a part of the coolant goes to the marine gear oil cooler (13) and the remainder goes to the bottom left opening in watercooled turbocharger (14). Coolant from the marine gear oil cooler goes to the bottom right opening in the watercooled turbocharger. Coolant leaves the turbocharger from two lines at the top and goes to watercooled turbocharger support (10). Coolant then goes to the right side and left side watercooled exhaust manifolds (7). 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 (6) or to heat exchanger (3).

Flow Of Coolant
(4) Inside bypass. (5) 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 to through inside bypass (4) to water pump (6). 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 (4) and the coolant goes to the heat exchanger and into expansion tank (1). Expansion tank (1) is divided into an upper and lower compartment by a baffle. From the lower compartment of the expansion tank most of the coolant goes to the inlet for water pump (6).

A small part of the coolant from the lower compartment of expansion tank (1) goes through a small vent tube into the upper compartment of expansion tank (1). This coolant goes through shunt line (2) to the inlet of water pump (6). This shunt type system keeps a positive pressure on the inlet of water pump (6) at all times.

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.

Location Of Water Temperature Regulators

Sea Water System

Sea Water System Schematic
(1) Sea water pump. (2) Heat exchanger. (3) Strainer. (4) Exhaust elbow. (5) Sea water inlet. (6) Sea water outlet.

Sea water pump (1) is installed on the left side of the front cover for the engine. The pump is driven by belts from the crankshaft pulley.

Sea water is pulled through sea water inlet (5) and through strainer (3) by sea water pump (1). From the sea water pump, the sea water is pushed to heat exchanger (2) and then to exhaust elbow (4). The sea water is then discharged through sea water outlet (6).

Heat Exchanger Without Aftercooler (Engines With More Than 275 HP)

Jacket Water System

Cooling System Schematic
(1) Expansion tank. (2) Shunt line. (3) Heat exchanger. (4) Inside bypass. (5) Housing for water temperature regulators. (6) Water pump. (7) Watercooled exhaust manifolds. (8) Orifices (between cylinder heads and front cover for the engine). (9) Watercooled exhaust elbows. (10) Watercooled turbocharger support. (11) Cylinder block. (12) Engine oil cooler. (13) Watercooled turbocharger.

Water pump (6) is installed on the front face of the front cover for the engine and is V-belt driven 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 (11) and up to the cylinder heads. From the cylinder heads the coolant goes forward through orifices (8) to the front cover for the engine.

Part of the coolant on the left side of cylinder block (11) goes to the engine oil cooler (12). Then the coolant goes to watercooled turbocharger (13). Coolant leaves the turbocharger from two lines at the top and goes to watercooled turbocharger support (10). Coolant then goes to the right side and left side watercooled exhaust manifolds (7). 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 (6) or to heat exchanger (3).

Flow Of Coolant
(4) Inside bypass. (5) Housing for water temperature regulators. (14) Passage to lower part of expansion tank. (15) Return to housing for water temperature regulators. (16) Water temperature regulators (two). (A) Flow with warm coolant. (B) Flow with cold coolant.

If the coolant is cold (cool), the water temperature regulators (16) will be closed. The coolant will to through inside bypass (4) to water pump (6). If the coolant is warm, the water temperature regulators (16) will be open. When the water temperature regulators (16) are open, they make a restriction in the inside bypass (4) and the coolant goes to the heat exchanger (3) and into expansion tank (1). Expansion tank (1) is divided into an upper and lower compartment by a baffle. From the lower compartment of the expansion tank most of the coolant goes to the inlet for water pump (6).

A small part of the coolant from the lower compartment of expansion tank (1) goes through a small vent tube into the upper compartment of expansion tank (1). This coolant goes through shunt line (2) to the inlet of water pump (6). This shunt type system keeps a positive pressure on the inlet of water pump (6) at all times.

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.

Location Of Water Temperature Regulators

Sea Water System

Sea Water System Schematic
(1) Sea water pump. (2) Heat exchanger. (3) Strainer. (4) Marine gear oil cooler. (5) Exhaust elbow. (6) Sea water inlet. (7) Sea water outlet.

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

Sea water is pulled through sea water inlet (6) and through strainer (3) by sea water pump (1). From the sea water pump, the sea water is pushed to heat exchanger (2) and then to marine gear oil cooler (4). The sea water then goes to exhaust elbow (5) and is discharged through sea water outlet (7).

Heat Exchanger With Aftercooler

Jacket Water System

Cooling System Schematic
(1) Expansion tank. (2) Shunt line. (3) Heat exchanger. (4) Inside bypass. (5) Housing for water temperature regulators. (6) Water pump. (7) Watercooled exhaust manifolds. (8) Orifices between cylinder heads and front cover for the engine. (9) Watercooled exhaust elbows. (10) Watercooled turbocharger support. (11) Cylinder block. (12) Engine oil cooler. (13) Watercooled turbocharger.

Water pump (6) is installed on the front face of the front cover for the engine and is V-belt driven 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 (11) and up to the cylinder heads. From the cylinder heads the coolant goes forward through orifices (8) to the front cover for the engine.

Part of the coolant on the left side of cylinder block (11) goes to the engine oil cooler (12). Then the coolant goes to watercooled turbocharger (13). Coolant leaves the turbocharger from two lines at the top and goes to watercooled turbocharger support (10). Coolant then goes to the right side and left side watercooled exhaust manifolds (7). 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 (6) or to heat exchanger (3).

If the coolant is cold (cool), the water temperature regulators (16) will be closed. The coolant will to through inside bypass (4) to water pump (6). If the coolant is warm, the water temperature regulators (16) will be open. When the water temperature regulators (16) are open, they make a restriction in the inside bypass (4) and the coolant goes to the heat exchanger (3) and into expansion tank (1). Expansion tank (1) is divided into an upper and lower compartment by a baffle. From the lower compartment of the expansion tank most of the coolant goes to the inlet for water pump (6).

Flow Of Coolant
(4) Inside bypass. (5) Housing for water temperature regulators. (14) Passage to lower part of expansion tank. (15) Return to housing for water temperature regulators. (16) Water temperature regulators (two). (A) Flow with warm coolant. (B) Flow with cold coolant.

A small part of the coolant from the lower compartment of expansion tank (1) goes through a small vent tube into the upper compartment of expansion tank (1). This coolant goes through shunt line (2) to the inlet of water pump (6). This shunt type system keeps a positive pressure on the inlet of water pump (6) at all times.

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.

Location Of Water Temperature Regulators

Sea Water System

Sea Water System Schematic
(1) Sea water pump. (2) Aftercooler. (3) Marine gear oil cooler. (4) Heat exchanger. (5) Strainer. (6) Exhaust elbow. (7) Sea water inlet. (8) Sea water outlet.

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

Sea water is pulled through sea water inlet (7) and through strainer (5) by sea water pump (1). From the sea water pump, the sea water is pushed to the aftercooler (2) and then to heat exchanger (4). The sea water then goes to marine gear oil cooler (3) and to exhaust elbow (6). The sea water is then discharged through sea water outlet (8).

Keel Cooled Without Aftercooler

Jacket Water System

Cooling System Schematic
(1) Expansion tank. (2) Keel cooler. (3) Shunt line. (4) Lower expansion tank. (5) Inside bypass. (6) Housing for water temperature regulators. (7) Watercooled exhaust manifolds. (8) Water pump. (9) Orifices (between cylinder heads and front cover for the engine). (10) Watercooled exhaust elbows. (11) Watercooled turbocharger support. (12) Cylinder block. (13) Engine oil cooler. (14) Watercooled turbocharger.

Water pump (8) is installed on the front face of the front cover for the engine and is V-belt driven 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 (9) to the front cover for the engine.

Part of the coolant on the left side of cylinder block (12) goes to the engine oil cooler (13). Then the coolant goes to the watercooled turbocharger (15). Coolant from the cooler for the marine gear oil goes to the watercooled turbocharger. Coolant leaves the turbocharger from two lines at the top and goes to the watercooled turbocharger support (11). Coolant then goes to the right side and left side watercooled exhaust elbows (10) and then on to watercooled exhaust manifolds (7). 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 (8) or to lower expansion tank (4).

Flow Of Coolant
(5) Inside bypass. (6) Housing for water temperature regulators. (16) 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 to through inside bypass (5) to water pump (8). 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 (5) and the coolant goes to the lower expansion tank (4). From the lower expansion tank (4) most of the coolant goes through keel cooler (2) and to the inlet for water pump (8).

A small part of the coolant from the lower compartment of expansion tank (4) goes through a small vent tube into the upper compartment of expansion tank (1). This coolant goes through shunt line (3) to the inlet of water pump (8). This shunt type system keeps a positive pressure on the inlet of water pump (8) at all times.

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.

Location Of Water Temperature Regulators

Keel Cooled With Aftercooler

Jacket Water System

Cooling System Schematic
(1) Expansion tank. (2) Keel cooler. (3) Shunt line. (4) Lower expansion tank. (5) Inside bypass. (6) Housing for water temperature regulators. (7) Watercooled exhaust manifolds. (8) Water pump. (9) Orifices (between cylinder heads and front cover for the engine). (10) Watercooled exhaust elbows. (11) Watercooled turbocharger support. (12) Cylinder block. (13) Engine oil cooler. (14) Watercooled turbocharger.

Water pump (8) is installed on the front face of the front cover for the engine and is V-belt driven 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 (9) to the front cover for the engine.

Part of the coolant on the left side of cylinder block (12) goes to the engine oil cooler (13). Then the coolant goes to the watercooled turbocharger (14). Coolant leaves the turbocharger from two lines at the top and goes to the watercooled turbocharger support (11). Coolant then goes to the right side and left side watercooled exhaust elbows (10) and then on to watercooled exhaust manifolds (7). 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 (8) or to lower expansion tank (4).

Flow Of Coolant
(5) Inside bypass. (6) 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 to through inside bypass (5) to water pump (8). 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 (5) and the coolant goes to the lower expansion tank (4). From the lower expansion tank (4) most of the coolant goes through keel cooler (2) and to the inlet for water pump (8).

A small part of the coolant from the lower compartment of expansion tank (4) goes through a small vent tube into the upper compartment of expansion tank (1). This coolant goes through shunt line (3) to the inlet of water pump (8). This shunt type system keeps a positive pressure on the inlet of water pump (8) at all times.

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.

Location Of Water Temperature Regulators

Auxiliary Water System

Auxiliary Water System Schematic
(1) Auxiliary water pump. (2) Aftercooler. (3) Marine gear oil cooler. (4) Keel cooler.

The auxiliary water pump (1) is installed on the left side of the front cover for the aftercooler and the marine gear oil cooler. The pump is driven by a V-belt from the crankshaft pulley.

Raw water is pulled through the auxiliary water pump inlet (1). From the auxiliary water pump the raw water is pushed to the aftercooler (2) and the to the marine gear oil cooler (3) from there it enters the keel cooler (4) and is returned to the auxiliary water pump.

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 inserts are used for the inlet and exhaust valves and can be replaced.

Pistons, Rings And Connecting Rods

The pistons may have two or three rings which are located above the piston pin bore. There is one or two 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 connecting 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 endplay of the crankshaft is controlled by the thrust bearing on No.4 main bearing.

Vibration Dampers

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.

Rubber Mounted Vibration Damper

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

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.

Viscous Vibration Damper

Cross Section Of A Viscous Vibration Damper
(1) Cast iron weight. (2) Space (between weight and case). (3) Case.

The viscous damper is made of a cast iron weight (1) in a metal case (3). The space (2) between the case and weight is filled with a thick fluid. The fluid permits the weight to move in the case to cause a reduction of vibrations of the crankshaft.

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.

Grounding Practices

Proper grounding for the engine electrical systems is necessary for proper engine performance and reliability. Improper grounding will result in uncontrolled and unreliable electrical circuit paths which can result in damage to main bearings and crankshaft journals surfaces. Uncontrolled electrical circuit paths can also 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, a frame to starting motor ground, or direct frame to engine ground.

Ground wires/straps should be combined at ground studs dedicated for ground use only. The engine alternator must be battery (-) grounded with a wire size adequate to handle full alternator charging current.

Charging System Components

Alternator Components (Typical Illustration)
(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: field winding, stator windings, six rectifying diodes, and 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 (magnet 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 is passed 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 and 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 senses 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.

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 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 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 Schematic
(1) Reset button. (2) Disc in open position. (3) Contacts. (4) Disc. (5) Battery circuit terminals.

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 current 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.

Magnetic Pickup

(1) Magnetic lines of flux. (2) Wire coils. (3) Gap. (4) Pole piece. (5) Ring gear.

The magnetic pickup is a single pole, permanent magnet generator made of wire coils (2) around a permanent magnet pole piece. As the teeth of the ring gear (5) cut through the magnetic lines of flux (1) around the pickup, an AC voltage is generated. The frequency of this voltage is directly proportional to engine speed.

The engine speed frequency signal (AC) is sent to the speed control where a conversion is made to a DC voltage level.