Introduction

NOTE: For Specifications with illustrations, make reference to Specifications for 3304B & 3306B Industrial & Marine Engines, SENR2568. If the Specifications in SENR2568 are not the same as in the Systems Operation, Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Engine Design

3304B Engine

Cylinder And Valve Identification

Bore ... 120.7 mm (4.75 in)

Stroke ... 152.4 mm (6.00 in)

Number of cylinders ... 4

Cylinder arrangement ... in-line

Firing order (injection sequence) ... 1,3,4,2

Direction of rotation (when viewed from flywheel end) ... counterclockwise

The No. 1 cylinder is opposite flywheel end.

3306B Engine

Cylinder And Valve Identification

Bore ... 120.7 mm (4.75 in)

Stroke ... 152.4 mm (6.00 in)

Number of cylinders ... 6

Cylinder arrangement ... in-line

Firing order (injection sequence) ... 1,5,3,6,2,4

Direction of rotation (when viewed from flywheel end) ... counterclockwise

The No. 1 cylinder is opposite flywheel end.

Fuel System

Fuel Flow

Fuel System Schematic
(1) Fuel tank. (2) Fuel return line. (3) Priming pump. (4) Fuel injection nozzle. (5) Fuel injection line. (6) Fuel injection pump. (7) Primary fuel filter. (8) Check valve. (9) Fuel transfer pump. (10) Secondary fuel filter. (11) Constant bleed orifice. (12) Fuel injection pump housing.

Fuel is pulled from fuel tank (1) through primary fuel filter (7) and check valves (8) by fuel transfer pump (9). From the fuel transfer pump the fuel is pushed through secondary fuel filter (10) and to the fuel manifold in fuel injection pump housing (12). The pumping spring in the fuel transfer pump keeps the fuel pressure in the system at 170 to 290 kPa (25 to 42 psi). Constant bleed orifice (11) lets a constant flow of fuel go through fuel return line (2) back to fuel tank (1). This helps keep the fuel cool and free of air. Fuel injection pump (6) gets fuel from the fuel manifold and pushes fuel at very high pressure through fuel injection line (5) to fuel injection nozzle (4). The fuel injection nozzle has very small holes in the tip that change the flow of fuel to a very fine spray that gives good fuel combustion in the cylinder.

Fuel Injection Pump

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

Fuel Injection Pump (Typical Illustration)
(1) Inlet passage. (2) Check valve. (3) Bypass closed port. (4) Spill port. (5) Scroll. (6) Slot. (7) Pump plunger. (8) Spring. (9) Fuel rack. (10) Gear. (11) Lifter. (12) Cam.

The fuel injection pump is moved by cam (12) of the fuel pump camshaft. When the camshaft turns, the cam raises lifter (11) and pump plunger (7) to the top of the strke. The pump plunger always makes a full stroke. As the camshaft turns farther, spring (8) returns the pump plunger and lifter to the bottom of the stroke.

When the pump plunger is at the bottom of the stroke, fuel transfer pump pressure goes into inlet passage (1), around the pump barrel and to bypass closed port (3). Fuel fills the area above the pump plunger.

After the pump plunger begins the up stroke, fuel will be pushed out the bypass closed port until the top of the pump plunger closes the port. As the pump plunger travels farther up, the pressure of the fuel increases. At approximately 690 kPa (100 psi), check valve (2) opens and lets fuel flow into the fuel injection line to the fuel injection nozzle. When the pump plunger travels farther up, scroll (5) uncovers spill port (4). The fuel above the pump plunger goes through slot (6), along the edge of scroll (5) and out spill port (4) back to the fuel manifold. This is the end of the injection stroke. The pump plunger can have more travel up, but no more fuel will be sent to the fuel injection nozzle.

When the pump plunger travels down and uncovers bypass closed port (3), fuel begins to fill the area above the pump plunger again, and the pump is ready to begin another stroke.

The amount of fuel the injection pump sends to the injection nozzle is changed by the rotation of the pump plunger. Gear (10) is attached to the pump plunger and is in mesh with fuel rack (9). The governor moves the fuel rack according to the fuel needs of the engine. When the governor moves the fuel rack, and the fuel rack turns the pump plunger, scroll (5) changes the distance the pump plunger pushes fuel between bypass closed port (3) and spill port (4) opening. The longer the distance from the top of the pump plunger to the point where scroll (5) uncovers spill port (4), the more fuel will be injected.

To stop the engine, the pump plunger is rotated so that slot (6) on the pump plunger is in line with spill port (4). The fuel will now go out the spill port and not to the injection nozzle.

Fuel Injection Nozzle

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

Fuel Injection Nozzle (Typical Illustration)
(1) Carbon dam. (2) Seal. (3) Passage. (4) Filter screen. (5) Orifice. (6) Valve. (7) Diameter. (8) Spring.

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 the inlet passage. Fuel then goes through filter screen (4) and into passage (3) to the area below diameter (7) of valve (6). When the pressure of the fuel that pushes against diameter (7) becomes greater than the force of spring (8), valve (6) lifts up.

This occurs when the fuel pressure goes above the Valve Opening Pressure of the fuel injection nozzle. When valve (6) lifts, the tip of the valve comes off the nozzle seat and the fuel will go through orifices (5) into the combustion chamber.

The injection of fuel continues until the pressure of fuel against diameter (7) becomes less than the force of spring (8). With less pressure against diameter (7), spring (8) pushes valve (6) against the nozzle seat and stops the flow of fuel to the combustion chamber.

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

Fuel Transfer Pump

The fuel transfer pump is a piston pump that is moved by a cam (eccentric) on the camshaft for the fuel injection pump. The transfer pump is located on the bottom side of the fuel injection pump housing.

Fuel Transfer Pump (Start Of Down Stroke) (Typical Example) (Arrows Indicate Fuel Flow Direction)
(1) Push rod. (2) Piston. (3) Outlet check valve. (4) Pumping check valve. (5) Pumping spring. (6) Pump inlet port. (7) Inlet check valve. (8) Pump outlet port.

When the fuel injection pump camshaft turns, the cam moves push rod (1) and piston (2) down. As the piston moves down, inlet check valve (7) and outlet check valve (3) close. Pumping check valve (4) opens and allows the fuel below the piston to move into the area above the piston. Pumping spring (5) is compressed as the piston is pushed down by push rod (1).

As the fuel injection pump camshaft continues to turn, the cam no longer puts force on push rod (1). Pumping spring (5) now moves piston (2) up. This causes pumping check valve (4) to close. Inlet check valve (7) and outlet check valve (3) will open. As the piston moves up, the fuel in the area above the piston is pushed through the outlet check valve (3) and out pump outlet port (8). Fuel also moves through pump inlet port (6) and inlet check valve (7) to fill the area below piston (2). The pump is now ready to start a new cycle.

Fuel Transfer Pump (Start Of Up Stroke) (Typical Example) (Arrows Indicate Fuel Flow Direction)
(1) Push rod. (2) Piston. (3) Outlet check valve. (4) Pumping check valve. (5) Pumping spring. (6) Pump inlet port. (7) Inlet check valve. (8) Pump outlet port.

Oil Flow For Fuel Pump And Governor

Fuel Pump And Governor
(1) Fuel ratio control. (2) Servo. (3) Rear governor housing. (4) Front governor housing. (5) Fuel pump housing. (6) Drain hole. (7) Camshaft. (8) Drain hole. (9) Support.

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

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

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

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

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

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

Governor

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

Governor
(1) Governor spring. (2) Sleeve. (3) Valve. (4) Piston. (5) Governor servo. (6) Fuel rack. (7) Lever. (8) Flyweights. (9) Over fueling spring. (10) Riser. (11) Spring seat. (12) Stop bolt. (13) Load stop bar. (14) Power setting screw. (15) Stop collar. (16) Torque spring. (17) Torque rise setting screw. (18) Stop bar.

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

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

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

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

Engines With Stop Bar

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

Engines With Torque Spring

With the engine at high idle, when the load is increased, engine speed will decrease. Flyweights (8) move in and governor spring (1) pushes riser (10) forward and increases the amount of fuel to the engine. As the load is increased more, governor spring (1) pushes riser (10) farther forward. Spring seat (11) pulls on stop bolt (12). Stop collar (15) on the opposite end has power setting screw (14) and torque rise setting screw (17) that control the maximum amount of fuel rack travel. The power setting screw moves forward and makes contact with torque spring (16). This is the full load balance point. If more load is added to the engine, engine speed will decrease and push riser (10) forward more. This will cause power setting screw (14) to bend (deflect) torque spring (16) until torque rise setting screw makes contact with stop bar (18). This is the point of maximum fuel to the engine.

Governor Servo

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

Governor Servo (Fuel On Position)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

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

Governor Servo (Balanced Position)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

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

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

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

Dashpot

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

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

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

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

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

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

Fuel Ratio Control

Fuel Ratio Control (Engine Stopped)
(1) Inlet air chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil Chamber. (11) Lever.

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

Stem (6) moves lever (11) which will restrict the movement of the fuel rack in the FUEL ON direction only.

With the engine stopped, stem (6) is in the fully extended position. The movement of the fuel rack and lever (11) is not restricted by stem (6). This gives maximum fuel to the engine for easier starts.

After the engine is started, engine oil flows through oil inlet (5) into pressure oil chamber (10). From oil chamber (10) oil flows through oil passage (9) into internal valve (3) and out oil drain passages in stem (6).

Stem (6) will not move until inlet manifold pressure increases enough to move internal valve (3). A line connects the inlet manifold with inlet air chamber (1) of the fuel ratio control.

When inlet manifold pressure increases, it causes diaphragm assembly (2) to move towards the right. This also causes internal valve (3) to move to the right. When internal valve (3) moves to the right, it closes oil passage (9).

When oil passage (9) is closed, oil pressure increases in oil chamber (10). Oil pressure moves piston (8) and stem (6) to the left and into the operating position. The fuel ratio control will remain in the operating position until the engine is shut off.

When the governor control is moved to increase fuel to the engine, stem (6) limits the movement of lever (11) in the FUEL ON direction. The oil in oil chamber (10) acts as a restriction to the movement of stem (6) until inlet air pressure increases.

As the inlet air pressure increases, diaphragm assembly (2) and internal valve (3) move to the right. The internal valve opens oil passage (9), and oil in oil chamber (10) goes to oil drain passage (4). With the oil pressure reduced behind piston (8), spring (7) moves the piston and stem (6) to the right. Piston (8) and stem (6) will move until oil passage (9) is closed by internal valve (3). Lever (11) can now move to let the fuel rack go to the full fuel position. The fuel ratio control is designed to restrict the fuel until the air pressure in the inlet manifold is high enough for complete combustion. It prevents large amounts of exhaust smoke caused by an air-fuel mixture with too much fuel.

Fuel Ratio Control (Increase In Inlet Air Pressure)
(1) Inlet cir chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil Chamber. (11) Lever.

Fuel Ratio Control (Ready for Operation)
(1) Inlet air chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil Chamber. (11) Lever.

Automatic Timing Advance Unit

The automatic timing advance unit (5) is installed on the front of the fuel pump drive shaft.

Automatic Timing Advance Unit
(1) Weights. (2) Springs. (3) Slides. (4) Dowels. (5) Automatic timing advance unit.

The weights (1) in the timing advance are driven by two slides (3) that fit into notches made on an angle in the weights (1). The slides (3) are driven by two dowels (4) in the hub assembly of the gear assembly in the automatic timing advance unit (5). As centrifugal force (rotation) moves weights (1) outward against the force of springs (2), the movement of the notches in the weights (1) will cause the slides (3) to make a change in the angle between the timing advance gear and the two drive dowels (4) in the hub assembly. Since the automatic timing advance unit (5) drives the fuel pump drive shaft, which is connected to the fuel injection pump camshaft, the fuel injection timing is also changed.

Air Inlet And Exhaust System

Engines Without Turbocharger

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

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

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

Engines With Turbocharger

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

Air Inlet And Exhaust System
(1) Exhaust manifold. (2) Inlet manifold pipe. (3) Engine cylinders. (4) Air inlet. (5) Turbocharger compressor wheel. (6) Turbocharger turbine wheel. (7) Exhaust outlet.

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

Air Inlet And Exhaust System (Top Mounted Turbocharger)
(1) Exhaust manifold. (2) Inlet manifold. (8) Turbocharger.

Air Inlet And Exhaust System (Rear Mounted Turbocharger)
(1) Exhaust manifold. (2) Inlet manifold. (8) Turbocharger.

Engines With Turbocharger And Aftercooler (Rear Mounted Turbocharger)

Turbocharger And Aftercooler Installed
(1) Air inlet. (2) Compressor wheel housing. (3) Exhaust outlet. (4) Air outlet. (5) Aftercooler housing. (6) Exhaust manifold. (7) Cylinder head. (8) Turbine housing. (9) Exhaust inlet.

Turbocharger
(1) Air inlet. (2) Compressor wheel housing. (3) Exhaust outlet. (4) Air outlet. (5) Aftercooler housing. (6) Exhaust manifold. (7) Cylinder head. (8) Turbine housing. (9) Exhaust inlet. (10) Air filter. (11) Inlet air pipe for aftercooler.

Aftercooler
(5) Aftercooler housing. (8) Turbine housing. (10) Air filter. (11) Inlet air pipe for aftercooler.

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

Clean inlet air from air filter (10) is pulled through air inlet (1) of the turbocharger by the turning compressor wheel. The compressor wheel causes a compression of the air. The air next goes through inlet air pipe (11) to aftercooler housing (5). The aftercooler cools the air. The air then goes to the inlet manifold which is part of cylinder head (7). When the intake valves open, the air goes into the engine cylinder and is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinder and into exhaust manifold (6). From the exhaust manifold, the exhaust gases go through the blades of the turbine wheel. This causes the turbine wheel and compressor wheel to turn. The exhaust gases then go out exhaust outlet (3) of the turbocharger.

Engines With Turbocharger And Aftercooler (Top Mounted Turbocharger)

Turbocharger And Aftercooler Installed
(1) Aftercooler housing. (2) Exhaust outlet. (3) Turbine wheel housing. (4) Air outlet. (5) Compressor wheel housing. (6) Air inlet. (7) Cylinder head. (8) Exhaust manifold. (9) Exhaust inlet. (10) Cylinder bore.

Turbocharger
(1) Aftercooler housing. (2) Exhaust outlet. (3) Turbine wheel housing. (4) Air outlet. (5) Compressor wheel housing. (6) Air inlet. (8) Exhaust manifold. (9) Exhaust inlet.

Aftercooler
(1) Aftercooler housing. (3) Turbine wheel housing. (4) Air outlet. (7) Cylinder head.

The air inlet and exhaust system components are: air cleaner, aftercooler (if so equipped), inlet manifold, cylinder head, valves and valve system components, exhaust manifold, and turbocharger.

Clean inlet air from the air filter is pulled through the air inlet (6) of the turbocharger by the turning compressor wheel. The compressor wheel causes a compression of the air. On engines with an aftercooler, the air next goes to aftercooler housing (1). The aftercooler cools the air. The air then goes to the inlet manifold which is part of cylinder head (7). When the intake valves open, the air goes into the engine cylinder and is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinder and into exhaust manifold (8). From the exhaust manifold, the exhaust gases go through the blades of the turbine wheel. This causes the turbine wheel and compressor wheel to turn. The exhaust gases then go out exhaust outlet (2) 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.

Air To Air Aftercooler

Air Flow Schematic (Air To Air Aftercooler)

Inlet air is pulled through the air cleaner, compressed and heated by the compressor wheel in the compressor side of the turbocharger to about 148°C (298°F), then pushed through the air to air aftercooler core and moved to the air inlet manifold in the cylinder head at about 43°C (110°F). Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output. The aftercooler core is a separate cooler core installed behind the standard radiator core. Air (ambient temperature) is moved across both cores by the engine fan. This cools the turbocharged inlet air and the engine coolant.

Turbocharger

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

The exhaust gases enter the turbine housing (8) and go through the blades of turbine wheel (10), causing the turbine wheel and compressor wheel (4) to turn.

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

When 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 wheel to turn faster. The increased rpm of the compressor wheel 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.

Turbocharger (Typical Example)
(1) Air inlet. (2) Compressor housing. (3) Nut. (4) Compressor wheel. (5) Thrust bearing. (6) Center housing. (7) Lubrication inlet passage. (8) Turbine housing. (9) Sleeve. (10) Turbine wheel. (11) Exhaust outlet. (12) Sleeve. (13) Oil deflector. (14) Bearing. (15) Lubrication outlet passage. (16) Bearing. (17) Exhaust inlet.

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

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NOTICE
If the high idle rpm or the fuel setting is higher than given in the TMI (Technical Marketing Information) or Fuel Setting And Related Information Fiche (for the height above sea level at and which the engine is operated), there can be damage to engine or turbocharger parts. Damage will result when increased heat and/or friction, due to the higher engine output, goes beyond the engine cooling and lubrication systems abilities.

The bearings for the turbocharger use engine oil for lubrication. The oil comes in through the lubrication inlet passage (7) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the lubrication outlet passage (15) in the bottom of the center section and goes back to the engine lubrication system.

Cylinder Head And Valves

There is one cylinder head for all cylinders. Each cylinder has one intake and one exhaust valve. Each intake and exhaust valve has a valve rotator. The valve rotator causes the valve to turn a small amount each time the valve opens and closes. This action helps keep carbon deposits off of the valve face and valve seat.

The cylinder head has valve seats installed and they can be replaced.

The valve guides can be replaced. There are threads on the inside diameter of the valve guides to hold oil that lubricates the valve stem.

Valve Mechanism

The valve mechanism controls the flow of inlet air and exhaust gases in and out of the cylinders. The valve mechanism consists of rocker arms, push rods, valve lifters and camshaft.

The camshaft is driven by and timed to the crankshaft. When the camshaft turns, the camshaft lobes move the valve lifters up and down. The valve lifters move the push rods which move the rocker arms. Movement of the rocker arms make the intake and exhaust valves open according to the firing order (injection sequence) of the engine. A valve spring for each valve makes the valve go back to the closed position and holds it there.

Lubrication System

System Oil Flow (3304B Engines)

Lubrication System Schematic (Engine Warm)
(1) Oil passage (to front idler gear). (2) Oil passage (to turbocharger and fuel injection pump). (3) Rocker arm shaft. (4) Oil pressure connection. (5) Oil manifold. (6) Piston cooling jets. (7) Camshaft bearing bore. (8) Balancer shaft bearing bores. (9) Oil cooler bypass valve. (10) Oil filter bypass valve. (11) Oil filter. (12) Turbocharger. (13) Oil pump. (14) Oil pan. (15) Engine oil cooler.

Oil pump (13) pulls oil from oil pan (14) and then pushes the oil to oil cooler (15). From the oil cooler the oil goes to oil filter (11) and then to oil manifold (5). From the oil manifold, oil goes to all main bearings, piston cooling jets (6) camshaft and balancer shaft bearings. Oil passages in the crankshaft send oil to the connecting rod bearings. Oil from the front main bearing goes through oil passage (1) to the bearing for the fuel injection pump idler gear.

Flow Of Oil (Engine Cold)
(9) Oil cooler bypass. (10) Oil filter bypass. (11) Oil filter. (12) Turbocharger. (13) Oil pump. (14) Oil pan. (15) Engine oil cooler.

Rocker Arm Oil Supply

Oil passage (2) from No. 3 main bearing sends oil to turbocharger (12) and the fuel injection pump housing on the right side of the engine.

An oil passage from the rear of the cylinder block goes below the head bolt hole and connects with a drilled passage that goes up next to the head bolt hole. A hollow dowel connects the vertical oil passage in the cylinder block to the oil passage in the head. The spacer plate has a hole with a counterbore on each side that the hollow dowel goes through. An O-ring is in each counterbore to prevent oil leakage around the hollow dowel. Oil flows through the hollow dowel into a vertical passage in the cylinder head to the rocker arm shaft bracket. The rocker arm shaft has an orifice to restrict the oil flow to the rocker arms. The rear rocker arm bracket also has an O-ring that seals against the head bolt. This seal prevents oil from going down around the head bolt and leaking past the head gasket or spacer plate gasket. The O-ring must be replaced each time the head bolt is removed from the rear rocker arm bracket.

Holes in the rocker arm shafts let the oil give lubrication to the valve system components in the cylinder head.

After the lubrication oil has done its work, it goes back to the engine oil pan.

There is a bypass valve in the oil pump. This bypass valve controls the pressure of the oil coming from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure increases and the bypass valve will open. This allows the oil that is not needed to go back to the engine oil pan.

With the engine cold (starting conditions), bypass valves (9) and (10) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil cooler (15) and oil filter (11). Oil pump (13) sends the cold oil through the bypass valves around the oil cooler and oil filter to oil manifold (5) in the cylinder block.

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

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

System Oil Flow (3306B Engines)

Lubrication System Schematic (Engine Warm)
(1) Oil passage (to front idler gear). (2) Oil passage (to turbocharger and fuel injection pump). (3) Rocker arm shaft. (4) Oil pressure connection. (5) Oil manifold. (6) Piston cooling jets. (7) Camshaft bearing bore. (8) Oil cooler bypass valve. (9) Oil filter bypass valve. (10) Engine oil cooler. (11) Oil filter. (12) Turbocharger. (13) Oil pump. (14) Oil pan.

Oil pump (13) pulls oil from oil pan (14) and then pushes the oil to oil cooler (10). From the oil cooler the oil goes to oil filter (11) and then to oil manifold (5). From the oil manifold, oil goes to all main bearings, and piston cooling jets (6). Oil passages in the crankshaft send oil to the connecting rod bearings. Oil from the front main bearing goes through oil passage (1) to the bearing for the fuel injection pump idler gear. Oil from the front main bearing also goes to camshaft bearing bore (7). The front camshaft bearing is the only bearing to get pressure lubrication.

Flow Of Oil (Engine Cold)
(8) Oil cooler bypass. (9) Oil filter bypass. (10) Engine oil cooler. (11) Oil filter. (12) Turbocharger. (13) Oil pump. (14) Oil pan.

Rocker Arm Oil Supply

Oil passage (2) from No. 4 main bearing sends oil to turbocharger (12) and the fuel injection pump housing on the right side of the engine.

An oil passage from the rear of the cylinder block goes below the head bolt hole and connects with a drilled passage that goes up next to the head bolt hole. A hollow dowel connects the vertical oil passage in the cylinder block to the oil passage in the head. The spacer plate has a hole with a counterbore on each side that the hollow dowel goes through. An O-ring is in each counterbore to prevent oil leakage around the hollow dowel. Oil flows through the hollow dowel into a vertical passage in the cylinder head to the rocker arm shaft bracket. The rocker arm shaft has an orifice to restrict the oil flow to the rocker arms.

The rear rocker arm bracket also has an O-ring that seals against the head bolt. This seal prevents oil from going down around the head bolt and leaking past the head gasket or spacer plate gasket. The O-ring must be replaced each time the head bolt is removed from the rear rocker arm bracket.

Holes in the rocker arm shafts let the oil give lubrication to the valve system components in the cylinder head.

After the lubrication oil has done its work, it goes back to the engine oil pan.

There is a bypass valve in the oil pump. This bypass valve controls the pressure of the oil coming from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure increases and the bypass valve will open. This allows the oil that is not needed to go back to the engine oil pan.

With the engine cold (starting conditions), bypass valves (8) and (9) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil cooler (10) and oil filter (11). Oil pump (13) sends the cold oil through the bypass valves around the oil cooler and oil filter to oil manifold (5) in the cylinder block.

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

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

Cooling System

Radiator Cooling System (Engines Without Aftercooler)

Coolant Flow For Radiator Cooling System (Dry Manifold)
(1) Radiator. (2) Pressure cap. (3) Inlet line to radiator. (4) Water temperature regulator. (5) Cylinder head. (6) Cylinder block. (7). Inlet line to water pump. (8) Water pump. (9) Internal bypass (shunt) line. (10) Engine oil filter. (11) Engine oil cooler. (12). Elbow. (13) Cylinder liner.

The water pump (8) is on the left front side of the engine. It is gear driven by the timing gears. Coolant from the bottom of the radiator (1) goes to the water pump inlet. The rotation of the impeller in the water pump (8) pushes the coolant through the system.

All of the coolant flow from the water pump (8), in the standard system, goes through the engine oil cooler (11). The elbow (12) on the outlet side of the engine oil cooler (11) connects to the side of the cylinder block (6).

On engines with an additional oil cooler a bonnet is mounted on the engine oil cooler (11). This bonnet sends the coolant flow through the other cooler which is for attachments, such as torque converters. The flow goes through one side on the way into the cooler. At the bottom of the cooler the flow turns and goes back up through the other side and into bonnet again. Then bonnet sends the coolant into the cylinder block (6).

Coolant Flow For Radiator Cooling System (Water Cooled Manifold)
(1) Radiator. (2) Pressure cap. (3) Inlet line to radiator. (6) Cylinder block. (7) Inlet line to water pump. (8) Water pump. (9) Internal bypass (shunt) line. (11) Engine oil cooler. (14) Inlet line. (15) Water cooled manifold or water cooled shield for manifold. (16) Outlet line. (17) Block. (18) Water cooled shield for turbocharger. (19) Return line. (20) Oil cooler (for torque converter or marine gear). (21) Bonnet.

An engine can have a water cooled manifold or a water cooled shield for the manifold (15). If it has either one of these it can also have a water cooled shield for the turbocharger (18). The coolant flow from water pump (8) is divided. Some of the coolant goes through the standard system and some goes into the water cooled manifold or water cooled shield for the manifold (15) at the front of the engine. It comes out at the rear of the engine and goes through return line (19) to the bonnet (21) on the engine oil cooler (11). It mixes with the rest of the coolant from the standard system in the bonnet (21) and goes into the cylinder block (6).

If the engine has a water cooled shield for the turbocharger (18), the supply of coolant for it comes from the bottom of the rear end of the water cooled manifold or water cooled shield for the manifold (15). The coolant goes through the water cooled shield for the turbocharger (18). It goes out through outlet line (16) to block (17) at the top of the water cooled manifold or water cooled shield for the manifold (15). In the block (17) it mixes with the rest of the coolant on the way to the bonnet (21).

Inside the cylinder block (6) the coolant goes around the cylinder liners (12) and up through the water directors into the cylinder head (5). The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder head (5). The coolant goes to the front of the cylinder head (5). Here water temperature regulator (4) controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of the cylinder head (5) is through the internal bypass (shunt) line (9). The coolant from this line goes into the water pump (8) which pushes it through the cooling system again. The coolant from the internal bypass (shunt) line (9) also works to prevent cavitation (air bubbles) in the coolant. When the coolant gets to the correct temperature, the water temperature regulator opens and coolant flow is divided. Some goes through the radiator (1) for cooling. The rest goes through the internal bypass (shunt) line (9) to the water pump (8). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between radiator (1) and internal bypass (shunt) line (9), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (9). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through radiator (1) is too much, and the engine will not get up to normal operating temperature.

The internal bypass (shunt) line (9) has another function when the cooling system is being filled. It lets the coolant go into the cylinder head (5) and cylinder block (6) without going through the water pump (8).

The radiator (1) has a pressure cap (2). This cap controls pressure in the cooling system.

Radiator Cooling System (Engines With Aftercooler)

Coolant Flow For Radiator Cooling System (Jacket Water Aftercooled - JWAC)
(1) Radiator. (2) Pressure cap. (3) Inlet line for radiator. (4) Aftercooler. (5) Aftercooler inlet line. (6) Return line from aftercooler. (7) Internal bypass (shunt) line. (8) Water pump. (9) Inlet line for water pump. (10) Engine oil cooler. (11) Bonnet.

Water pump (8) is on the left front side of the engine. It is gear driven by the timing gears. Coolant from the bottom of radiator (1) goes to the water pump inlet. The rotation of the impeller in water pump (8) pushes the coolant through the system.

The coolant flow from the water pump (8) is divided. Some goes through engine oil cooler (10). Bonnet (11) on the outlet side of engine oil cooler (10) connects to the side of the cylinder block.

On engines with an auxiliary oil cooler a different bonnet is on engine oil cooler (10). This bonnet sends the coolant flow through auxiliary cooler which is for attachments, such as torque converters. The flow goes through one side on the way into auxiliary oil cooler. At the bottom of auxiliary oil cooler, the flow turns and goes back up through the other side and into bonnet again. Then bonnet sends the coolant into the cylinder block.

The remainder of the coolant flow goes through aftercooler inlet line (5) into the core of aftercooler (4). The core of aftercooler (4) is a group of plates and fins. The coolant goes through the plates. The inlet air for the engine goes around the fins. This cools the inlet air. The coolant comes out of the aftercooler (4) at the rear of the engine and goes through return line (6) to bonnet (11) on engine oil cooler (10). It mixes with the rest of the coolant from engine oil cooler (10) in bonnet (11) and goes into the cylinder block.

Coolant Flow For Radiator Cooling System (Jacket Water Aftercooled - JWAC)
(1) Radiator. (2) Pressure cap. (3) Inlet line for radiator. (4) Aftercooler. (5) Aftercooler inlet line. (6) Return line from aftercooler. (7) Internal bypass (shunt) line. (8) Water pump. (9) Inlet line for water pump. (10) Engine oil cooler. (12) Exhaust Manifold. (13) Turbocharger. (14) Auxiliary oil cooler. (15) Bonnet.

Inside the cylinder block, the coolant goes around the cylinder liners and up through the water directors into the cylinder head. The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder head. The coolant goes to the front of the cylinder head. Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of the cylinder head is through internal bypass (shunt) line (7). The coolant from this line goes into water pump (8) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (7) also works to prevent cavitation (air bubbles) in the coolant. When the coolant gets to the correct temperature, the water temperature regulator opens and coolant flow is divided. Some goes through radiator (1) for cooling. The rest goes through internal bypass (shunt) line (7) to water pump (8). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between radiator (1) and internal bypass (shunt) line (7), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (7). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through radiator (1) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (7) has another function when the cooling system is being filled. It lets the coolant go into the cylinder head and cylinder block without going through water pump (8).

Radiator (1) has a pressure cap (2). This cap controls pressure in the cooling system.

Keel Cooling System (Engines Without Aftercooler)

Coolant Flow For Keel Cooling System
(1) Expansion tank. (2) Pressure cap. (3) Inlet line. (4) Internal bypass (shunt) line. (5) Water cooled manifold or water cooled shield for manifold. (6) Outlet line. (7) Block. (8) Water cooled shield for turbocharger. (9) Line to keel cooler. (10) Cylinder head. (11) Cylinder block. (12) Re Return line from keel cooler. (13) Supply line for water pump. (14) Keel cooler tubes. (15) Water pump. (16) Engine oil cooler. (17) Oil cooler for torque converter or marine gear. (18) Bonnet. (19) Return line.

The water pump (15) is on the left front side of the engine. It is gear driven by the timing gears. Coolant from the bottom of the expansion tank (1) goes to the water pump inlet. The rotation of the impeller in the water pump (15) pushes the coolant through the system.

All of the coolant flow from the water pump (15), in the standard system, goes through the engine oil cooler (16). The bonnet (18) on the outlet side of the engine oil cooler (16) connects to the side of the cylinder block (11).

On engines with an additional oil cooler (17), a different bonnet (18) is on the engine oil cooler (16). This bonnet (18) sends the coolant flow through the other oil cooler which is for attachments, such as torque converters. The flow goes through one side on the way into the cooler. At the bottom of the cooler, the flow turns and goes back up through the other side and into bonnet (18) again. Bonnet (18) sends the coolant into the cylinder block (11).

An engine can have a water cooled manifold or a water cooled shield for the manifold (5). If it has either one of these it can also have a water cooled shield for the turbocharger (8). The coolant flow from the water pump (15) is divided. Some of the coolant goes through the standard system and some goes into the water cooled manifold (5) at the front of the engine. It comes out at the rear of the engine and goes through a return line (19) to the bonnet (18) on the engine oil cooler (16). It mixes with the rest of the coolant from the standard system in the bonnet (18) and goes into the cylinder block (11).

If the engine has a water cooled shield for the turbocharger (8), the supply of coolant for it comes from the bottom of the rear end of the water cooled manifold or water cooled shield for the manifold (5). The coolant goes through the water cooled shield for the turbocharger (8). It goes out through outlet line (6) to block (7) at the top of the water cooled manifold or water cooled shield for the manifold (5). In the block (7) it mixes with the rest of the coolant on the way to the bonnet (18).

Inside the cylinder block (11) the coolant goes around the cylinder liners and up through the water directors into the cylinder head (10). The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder head (10). The coolant goes to the front of the cylinder head (10). Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of the cylinder head (10) is through the internal bypass (shunt) line (4). The coolant from this line goes into the water pump (15) which pushes it through the cooling system again. The coolant from the internal bypass (shunt) line (4) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and the coolant flow is divided. Some goes through the keel cooler tubes (14) for cooling. The rest goes through the internal bypass (shunt) line (4) to the water pump (15). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between keel cooler tubes (14) and internal bypass (shunt) line (4), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (4). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through keel cooler tubes (14) is too much, and the engine will not get up to normal operating temperature.

The internal bypass (shunt) line (4) has another function when the cooling system is being filled. It lets the coolant go into the cylinder head (10) and cylinder block (11) without going through the water pump (15).

The keel cooler tubes (14) are normally installed on the bottom of the hull. They are usually made of a metal which has resistance to corrosion because they give off heat from the engine coolant to the sea water which the hull is in. The efficiency of this action is in relation to: the surface area of the keel cooler tubes (14) the rate at which sea water goes around the outside of the keel cooler tubes (14), the temperature of the sea water, and the rate of flow of the engine coolant through the keel cooler tubes (14).

After going through the keel cooler tubes (14) the coolant goes to an expansion tank (1). The expansion tank (1) is a reservoir for the coolant. It is the highest place in the cooling system. It is the place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. The expansion tank (1) has a pressure cap (2) to control the pressure in the cooling system for better operation.

Keel Cooling System (Jacket Water Aftercooled - JWAC)

Cooling System Schematic (Jacket Water Aftercooled - JWAC)
(1) Outlet line. (2) Bypass valve. (3) Bypass line. (4) Expansion tank. (5) Pressure cap. (6) Outlet line. (7) Water cooled manifold. (8) Regulator housing. (9) Aftercooler housing. (10) Outlet line. (11) Water cooled turbocharger. (12) Bypass filter. (13) Inlet line. (14) Inlet line. (15) Cylinder block. (16) Cylinder head. (17) Internal bypass (shunt) line. (18) Duplex strainer. (19) Keel cooler tubes. (20) Water pump. (21) Engine oil cooler. (22) Aftercooler inlet line. (23) Bonnet. (24) Auxiliary oil cooler. (25) Aftercooler outlet line. (26) Turbocharger inlet line.

Water pump (20) is on the left front side of the engine. It is gear driven by the timing gears. Coolant from the bottom of expansion tank (4) goes to the water pump inlet. The rotation of the impeller in water pump (20) pushes the coolant through the system.

The coolant flow from water pump (20) is divided. Some of the coolant flow goes through the engine oil cooler (21). The remainder of the coolant flow goes through aftercooler inlet line (22) into the core of the aftercooler. The core of the aftercooler is a group of tubes. These tubes are in position inside aftercooler housing (9). The coolant goes through the tubes. The inlet air for the engine goes around the tubes.

This cools the inlet air. The coolant comes out at the rear of the engine and goes through aftercooler outlet line (25) to bonnet (23). In bonnet (23), the coolant from the aftercooler mixes with the coolant flow from engine oil cooler (21).

The coolant flow which comes through engine oil cooler (21) goes through bonnet (23). If the engine has a water cooled turbocharger (11), some of the coolant flow from engine oil cooler (21) goes through turbocharger inlet line (26). The coolant flow goes in at the bottom of water cooled turbocharger (11) and comes out at the top. It goes through outlet line (10) to the top of water cooled manifold (7). It goes through water cooled manifold (7) to the front of the engine. It comes out through outlet line (6) and goes into regulator housing (8). The coolant flow mixes with the rest of the coolant from the engine.

The remaining coolant flow through bonnet (23) goes into one side of auxiliary oil cooler (24). At the bottom, the coolant flow turns and goes up the other side of auxiliary oil cooler (24) and into bonnet (23) again. The bonnet sends this flow into cylinder block (15).

Inside cylinder block (15) the coolant goes around the cylinder liners and up through the water directors into cylinder head (16). The water directors send the flow of coolant around the valves and the passages for exhaust gases in cylinder head (16). The coolant goes to the front of cylinder head (16). Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of cylinder head (16) is through internal bypass (shunt) line (17). The coolant from this line goes into water pump (20) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (17) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and the coolant flow is divided. Some goes through keel cooler tubes (19) for cooling. The rest goes through internal bypass (shunt) line (17) to water pump (20). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between keel cooler tubes (19) and internal bypass (shunt) line (17), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (17). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through keel cooler tubes (19) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (17) has another function when the cooling system is being filled. It lets the coolant go into cylinder head (16) and cylinder block (15) without going through water pump (20).

Keel cooler tubes (19) are normally installed on the bottom of the hull. They are usually made of a metal which has resistance to corrosion because they give off heat from the engine coolant to the sea water which the hull is in. The efficiency of this action is in relation to: the surface area of keel cooler tubes (19), the rate at which sea water goes around the outside of keel cooler tubes (19), the temperature of the sea water, and the rate of flow of the engine coolant through keel cooler tubes (19).

After going through keel cooler tubes (19), the coolant goes to an expansion tank (4). Expansion tank (4) is a reservoir for the coolant. It is the highest place in the cooling system. It is in place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. Expansion tank (4) has a pressure cap (5) to control the pressure in the cooling system for better operation.

Some cooling systems have a duplex strainer (18) installed in the line from keel cooler tubes (19). Duplex strainer (18) has two sides. Each side has a strainer which is large enough for the full flow of the cooling system. When the pressure drop across one of the strainers starts to get an increase, the full flow can be changed to the other strainer without stopping the engine.

Some cooling systems also have a bypass filter (12). This is installed between the inlet and outlet lines for keel cooler tubes (19). In this position a small part of the coolant flow goes through bypass filter (12). This flow removes the particles which are too small for removal by duplex strainer (18).

Many cooling systems have a bypass valve (2) and bypass line (3) installed as shown. The bypass valve can be either manually adjusted or automatically adjusted. Both kinds of valves have the same function. They control the temperature of the coolant which goes to the inlet of water pump (20). The valves control the temperature of the coolant by controlling the amount of the coolant through keel cooler tubes (19). The coolant which goes through bypass line (3) is hot. It mixes with the coolant from the keel cooler tubes as it goes into the water pump inlet. Correctly adjusting the flow through bypass line (3) keeps the coolant temperature hot enough for good engine operation and at the same time, cool enough for good aftercooler operation. This adjustment is important for maximum engine performance.

Keel Cooling System (Separate Circuit Aftercooled)

Cooling System Schematic
(1) Outlet line. (2) Expansion tank. (3) Pressure cap. (4) Cylinder block. (5) Cylinder head. (6) Water cooled manifold. (7) Outlet line. (8) Regulator housing. (9) Outlet line. (10) Aftercooler housing. (11) Water cooled turbocharger. (12) Expansion tank. (13) Pressure cap. (14) Bypass filter. (15) Inlet line. (16) Duplex strainer. (17) Inlet line. (18) Bonnet. (19) Inlet line. (20) Inlet line. (21) Auxiliary pump. (22) Engine oil cooler. (23) Auxiliary oil cooler. (24) Duplex strainer. (25) Inlet line. (26) Keel cooler tubes. (27) Internal bypass (shunt) line. (28) Water pump. (29) Outlet line. (30) Bypass filter. (31) Bypass valve. (32) Bypass line. (33) Keel cooler tubes.

This cooling system has two completely separate cooling circuits. One of these circuits is the engine coolant (jacket water) circuit. Normally this circuit cools the engine and all the attachments. The other circuit is the aftercooler circuit. It normally cools the aftercooler only. This type of cooling system keeps the temperatures of the coolant in the two circuits in the correct ranges for the maximum horsepower output.

Aftercooler Circuit

The aftercooler circuit uses auxiliary pump (21). It is on the left front side of the engine below engine oil cooler (22). Auxiliary pump (21) is gear driven by the timing gears. Coolant from keel cooler tubes (33) goes to the inlet of auxiliary pump (21). The rotation of the impeller pushes the coolant through the aftercooler circuit.

All of the coolant flow goes through inlet line (19). Inlet line (19) connects to the aftercooler at the rear of the engine. The coolant goes through the core of the aftercooler to the front of the engine. The core of the aftercooler is a group of tubes. These tubes are in position inside aftercooler housing (10). The coolant goes through the tubes. The inlet air for the engine goes around the tubes. This cools the inlet air. The coolant comes out of the cover of the aftercooler at the front of the engine and into outlet line (29). Outlet line (29) connects to keel cooler tubes (33).

Keel cooler tubes (33) are normally installed on the bottom of the hull in front of the keel cooler tubes for the engine coolant (jacket water) circuit. This position gives the maximum cooling. Keel cooler tubes (33) are usually made of a metal which has resistance to corrosion because they give off heat from the coolant to the sea water which the hull is in. The efficiency of this action is in relation to: the surface area of keel cooler tubes (33), the rate at which sea water goes around the outside of the keel cooler tubes (33), the temperature of the sea water, and the rate of flow of the coolant through keel cooler tubes (33).

After going through keel cooler tubes (33), the coolant goes to the inlet for auxiliary pump (21). An expansion tank (12) is connected to inlet line (25). Expansion tank (12) has the necessary room for the coolant when it expands (uses more space) from being heated.

This system can have duplex strainer (24) installed in the line from keel cooler tubes (33). Duplex strainer (24) has two sides. Each side has a strainer which is large enough for the full flow of the cooling system. When the pressure drop across one of the strainers starts to get an increase, the full flow can be changed to the other strainer without stopping the engine.

Some cooling systems have a bypass filter (30). This is installed between the inlet and outlet lines for keel cooler tubes (33). In this position, a small part of the coolant flow goes through bypass filter (30). This flow removes the particles which are too small for removal by duplex strainer (24).

Many cooling systems have a bypass valve (31) and bypass line (32) installed as shown. The bypass valve can be either manually adjusted or automatically adjusted. Both kinds of valves have the same function.

They control the minimum temperature of the coolant which goes to the aftercooler. Bypass valve (31) controls the temperature of the coolant by controlling the amount of coolant which can go through the bypass line (32) instead of through keel cooler tubes (33). The coolant which goes through bypass line (32) is hot. It mixes with the coolant from keel cooler tubes (33) as it goes to the inlet for auxiliary pump (21). When bypass valve (32) is correctly adjusted, the coolant temperature is as cool as possible without having condensation inside the aftercooler. (Condensation is water which comes out of the air when the air comes in contact with a cool surface). This adjustment gives the engine the coolest inlet air for use at maximum horsepower ratings.

Engine Coolant (Jacket Water) Circuit

Water pump (28) for this circuit is on the left front side of the engine. It is gear driven by the timing gears. Coolant from the bottom of expansion tank (2) goes to the water pump inlet. The rotation of the impeller in water pump (28) pushes the coolant through the circuit.

All of the coolant flow from water pump (28) in this circuit, goes through engine oil cooler (22). Bonnet (18) on the outlet side of engine oil cooler (22) connects to the side of cylinder block (4).

On engines with an auxiliary oil cooler (23), a different bonnet (18) is on the engine oil cooler (22). This bonnet (18) sends the coolant flow through auxiliary oil cooler (23) which is for attachments, such as torque converters. The flow goes through one side on the way in.

At the bottom of auxiliary oil cooler (23) the flow turns and goes back up through the other side and into bonnet (18) again. Bonnet (18) sends the coolant into cylinder block (4).

Some of the coolant which goes through bonnet (18) is sent through inlet line (20) to the bottom of the water cooled turbocharger (11) at the rear of the engine. This coolant goes up through the water cooled turbocharger and out at the top through outlet line (9). Outlet line (9) connects to the top of water cooled manifold (6) near the rear of the engine. The coolant goes through water cooled manifold (6) to the front of the engine. At the front of the engine, the coolant goes through outlet (7) and into regulator housing (8) where the coolant mixes with the coolant from cylinder head (5).

Inside cylinder block (4) the coolant goes around the cylinder liners and up through the water directors into cylinder head (5). The water directors send the flow of coolant around the valves and the passages for exhaust gases in cylinder head (5). The coolant goes to the front of cylinder head (5). Here the water temperature regulator controls the direction of the flow.

If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of cylinder head (5) is through internal bypass (shunt) line (27). The coolant from this line goes into water pump (28) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (27) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and the coolant flow is divided. Some goes through keel cooler tubes (26) for cooling. The rest goes through internal bypass (shunt) line (27) to water pump (28). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between keel cooler tubes (26) and internal bypass (shunt) line (27), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (27). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through keel cooler tubes (26) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (27) has another function when the cooling system is being filled. It lets the coolant go into cylinder head (5) and cylinder block (4) without going through water pump (28).

Keel cooler tubes (26) are normally installed on the bottom of the hull. They are usually made of a metal which has resistance to corrosion because they give off heat from the engine coolant to the sea water which the hull is in. The efficiency of this action is in relation to: the surface area of keel cooler tubes (26), the rate at which sea water goes around the outside of keel cooler tubes (26), the temperature of the sea water, and the rate of flow of the engine coolant through keel cooler tubes (26).

After going through keel cooler tubes (26), the coolant goes to an expansion tank (2). Expansion tank (2) is a reservoir for the coolant. It is the highest place in the cooling circuit. It is the place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. Expansion tank (2) has a pressure cap (3) to control the pressure in the cooling system for better operation.

Heat Exchanger Cooling System (Engines Without Aftercooler)

Coolant Flow For Heat Exchanger Cooling System
(1) Heat exchanger. (2) Expansion tank. (3) Pressure cap. (4) Vent line. (5) Inlet line. (6) Water cooled manifold or water cooled shield for manifold. (7) Outlet line. (8) Outlet line. (9) Block. (10) Return line. (11) Water cooled shield for turbocharger. (12) Cylinder head. (13) Cylinder block. (14) Bonnet. (15) Oil cooler for torque converter or marine gear. (16) Sea water outlet. (17) Supply line to water pump. (18) Supply line. (19) Water pump. (20) Internal bypass (shunt) line. (21) Sea water inlet. (22) Sea water pump. (23) Engine oil cooler.

Water pump (19) is on the left side of the engine. It is gear driven by the timing gears. Coolant from the bottom of expansion tank (2) goes to the water pump inlet. The rotation of the impeller in water pump (19) pushes the coolant through the system.

All of the coolant flow from water pump (19), in the standard system, goes through engine oil cooler (23). Bonnet (14) on the outlet side of engine oil cooler (23) connects to the side of cylinder block (13).

On engines with an additional oil cooler (15), a different bonnet (14) is on engine oil cooler (23). This bonnet (14) sends the coolant flow through the other oil cooler which is for attachments, such as torque converters.

The flow goes through one side on the way into the cooler. At the bottom of the cooler, the flow turns and goes back up through the other side and into bonnet (14) again. Bonnet (14) sends the coolant into cylinder block (13).

An engine can have a water cooled manifold or a water cooled shield for manifold (6). If it has either one of these it can also have a water cooled shield for turbocharger (11). The coolant flow from the water pump is divided. Some of the coolant goes through the standard system and some goes into the water cooled manifold or water cooled shield for manifold (6) at the front of the engine. It comes out at the rear of the engine and goes through return line (10) to bonnet (14) on engine oil cooler (23). It mixes with the rest of the coolant from the standard system in bonnet (14) and goes into cylinder block (13).

If the engine has a water cooled shield for turbocharger (11), the supply of coolant for it comes from the bottom of the rear end of the water cooled manifold or water cooled shield for manifold (6). The coolant goes through the water cooled shield for turbocharger (11). It goes out through outlet line (8) to block (9) at the top of the water cooled manifold or water cooled shield for manifold (6). In block (9) it mixes with the rest of the coolant on the way to bonnet (14).

Inside cylinder block (13) the coolant goes around the cylinder liners and up through the water directors into cylinder head (12). The water directors send the flow of coolant around the valves and the passages for exhaust gases in cylinder head (12). The coolant goes to the front of cylinder head (12). Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of cylinder head (12) is through internal bypass (shunt) line (20). The coolant from this line goes into water pump (19) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (20) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and coolant flow is divided. Some goes through expansion tank (2) and around heat exchanger (1), for cooling. The rest goes through internal bypass (shunt) line (20) to water pump (19). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between heat exchanger (1) and internal bypass (shunt) line (20), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (20). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through heat exchanger (1) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (20) has another function when the cooling system is being filled. It lets the coolant go into cylinder head (12) and cylinder block (13) without going through water pump (19).

The coolant flow from the engine goes through outlet line (7) to expansion tank (2) and heat exchanger (1). Heat exchanger (1) is cooled by sea water sent by sea water pump (22) through supply line (18). The sea water cools the engine coolant in expansion tank (2) and goes out through sea water outlet (16).

Expansion tank (2) is the reservoir for the cooling system. It is the highest place in the cooling system. It is the place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. Expansion tank (2) has a pressure cap (3) to control the pressure in the cooling system for better operation.

Heat Exchanger Cooling System (Jacket Water Aftercooled - JWAC)

Cooling System Schematic
(1) Heat exchanger. (2) Expansion tank. (3) Pressure cap. (4) Vent line. (5) Outlet line. (6) Outlet line. (7) Regulator housing. (8) Aftercooler inlet line. (9) Water cooled manifold. (10) Outlet line. (11) Water cooled turbocharger. (12) Aftercooler housing. (13) Cylinder head. (14) Aftercooler outlet line. (15) Internal bypass (shunt) line. (16) Turbocharger inlet line. (17) Cylinder block. (18) Outlet line. (19) Bonnet. (20) Inlet line. (21) Inlet line. (22) Water pump. (23) Sea water pump. (24) Engine oil cooler. (25) Auxiliary oil cooler. (26) Outlet (for sea water circuit). (27) Bypass valve. (28) Bypass line. (29) Duplex strainer. (30) Inlet (for sea water circuit).

This cooling system has two circuits which work together. The engine coolant (jacket water) circuit cools the aftercooler, the engine and the auxiliary oil cooler. The coolant from this circuit can go through expansion tank (2). In expansion tank (2) this coolant goes around the tubes of heat exchanger (1) while the coolant from the sea water circuit goes through the tubes. In this way the sea water cools the engine coolant (jacket water). The sea water goes through heat exchanger (1) when the engine is running. The engine coolant (jacket water) only goes through expansion tank (2) and around the tubes of heat exchanger (1) when the water temperature regulator in the engine is open.

Sea Water Circuit

The sea water comes in through inlet (30). Sea water pump (23) is driven by the timing gears. The location of sea water pump (23) is on the left front side of the engine below engine oil cooler (24). Rotation of the impeller pushes the sea water through inlet line (21) to heat exchanger (1). In heat exchanger (1) the sea water goes through the tubes and out through outlet line (18) and outlet (26). The engine coolant (jacket water) goes through expansion tank (2) and around the tubes of heat exchanger (1). This cools the engine coolant (jacket water).

Engine Coolant (Jacket Water) Circuit

Water pump (22) for this circuit is on the left front side of the engine. It is gear driven by the timing gears. Coolant from expansion tank (2) goes through inlet line (20) to the water pump inlet. The rotation of the impeller in water pump (22) pushes the coolant (jacket water) through the circuit.

The coolant flow from water pump (22) is divided. Some of the coolant flow goes through engine oil cooler (24). The remainder of the coolant flow goes through aftercooler inlet line (8) into the core of the aftercooler. The core of the aftercooler is a group of tubes. These tubes are in a position inside aftercooler housing (12). The coolant goes through the tubes. This inlet air for the engine goes around the tubes. This cools the inlet air. The coolant comes out at the rear of the engine and goes through aftercooler outlet line (14) to bonnet (19). In bonnet (19) the coolant flow mixes with the coolant flow from engine oil cooler (24).

The coolant flow which comes through engine oil cooler (24) goes through bonnet (19). If the engine has a water cooled turbocharger (11), some of the coolant flow from engine oil cooler (24) goes through turbocharger inlet line (16). The coolant flow goes in at the bottom of water cooled turbocharger (11) and comes out at the top. It goes through outlet line (10) to the top of water cooled manifold (9). It goes through water cooled manifold (9) to the front of the engine. It comes out through outlet line (6) and goes into regulator housing (7). The coolant flow mixes with the rest of the coolant from the engine.

The remainder of coolant flow through bonnet (19) goes into one side of auxiliary oil cooler (25). At the bottom the coolant flow turns and goes up the other side of auxiliary oil cooler (25) and into bonnet (19) again. Bonnet (19) sends this flow into cylinder block (17).

Inside cylinder block (17) the coolant goes around the cylinder liners and up through the water directors into cylinder head (13). The water directors send the flow of coolant around the valves and the passages for exhaust gases in cylinder head (13). The coolant goes to the front of cylinder head (13). Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of cylinder head (13) is through internal bypass (shunt) line (15). The coolant from this line goes into water pump (22) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (15) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and coolant flow is divided. Some goes through expansion tank (2) and around heat exchanger (1) for cooling. The rest goes through internal bypass (shunt) line (15) to water pump (22). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between heat exchanger (1) and internal bypass (shunt) line (15), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (15). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through heat exchanger (1) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (15) has another function when the cooling system is being filled. It lets the coolant go into cylinder head (13) and cylinder block (17) without going through water pump (22).

The coolant flow from the engine goes through outlet line (5) to expansion tank (2) and heat exchanger (1). Heat exchanger (1) is cooled by sea water sent by sea water pump (23) through inlet line (21). The sea water cools the engine coolant in expansion tank (2) and goes out through the outlet for sea water circuit (26).

Expansion tank (2) is the reservoir for the cooling system. It is the highest place in the cooling system. It is the place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. Expansion tank (2) has a pressure cap (3) to control the pressure in the cooling system for better operation.

Heat Exchanger Cooling System (Sea Water Aftercooled - SWAC)

Cooling System Schematic
(1) Heat exchanger. (2) Expansion tank. (3) Pressure cap. (4) Vent line. (5) Outlet line. (6) Outlet line. (7) Regulator housing. (8) Aftercooler outlet line. (9) Water cooled manifold. (10) Outlet line. (11) Water cooled turbocharger. (12) Aftercooler housing. (13) Aftercooler inlet line. (14) Turbocharger inlet line. (15) Cylinder head. (16) Cylinder block. (17) Outlet line. (18) Internal bypass (shunt) line. (19) Inlet line. (20) Water pump. (21) Sea water pump. (22) Engine oil cooler. (23) Auxiliary oil cooler. (24) Bonnet. (25) Outlet for sea water circuit. (26) Bypass line. (27) Bypass valve. (28) Inlet line. (29) Duplex strainer. (30) Inlet for sea water circuit.

This cooling system has two cooling circuits. One of these circuits is the engine coolant (jacket water) circuit. Normally this circuit cools the engine and attachments. The other circuit is the sea water circuit. In this system the sea water cools the aftercooler before it goes to heat exchanger (1) in expansion tank (2). In expansion tank (2), heat exchanger (1) cools the coolant from the engine coolant (jacket water) circuit.

Sea Water Circuit

The sea water comes in through inlet (30). Sea water pump (21) is driven by the timing gears. The location of sea water pump (21) is on the left front side of the engine below engine oil cooler (22). Rotation of the impeller pushes the sea water through aftercooler inlet line (13) to the rear of the engine. Aftercooler inlet line (13) connects to the aftercooler core. The core of the aftercooler is a group of tubes. These tubes are in a position inside aftercooler housing (12). The sea water goes through the tubes. The inlet air for the engine goes around the tubes. This cools the inlet air for the engine. The sea water comes out at the front of the engine. The sea water goes through aftercooler outlet line (8) to heat exchanger (1). Inside heat exchanger (1), the sea water goes through the tubes. The engine coolant (jacket water) goes through expansion tank (2) around the tubes of heat exchanger (1). This cools the engine coolant (jacket water). The sea water comes out of heat exchanger (1) through outlet line (17). Outlet line (17) sends the sea water through the outlet for sea water circuit (25).

This system can have duplex strainer (29) installed as shown. Duplex strainer (29) has two sides. Each side has a strainer which is large enough for the full flow of the sea water circuit. When the pressure drop across one of the strainers starts to get an increase, the full flow can be changed to the other strainer without stopping the engine.

Many cooling systems have a bypass valve (27) and a bypass line (26) installed as shown. Bypass valve (27) can be manually adjusted or automatically adjusted. Both kinds of valves have the same function. They work to control the minimum temperature of the sea water which goes through the aftercooler. The sea water going through outlet line (17) is hot. Bypass (27) controls the amount of the hot sea water which goes through bypass line (26). The hot sea water from bypass line (26) mixes with the sea water from the inlet for sea water circuit (30) as it goes to the inlet line (28) of sea water pump (21). When bypass valve (27) is correctly adjusted, the temperature of the sea water going into the aftercooler is as cool as possible without having condensation inside the aftercooler. (Condensation is water which comes out of the air when the air comes in contact with a cool surface). This adjustment gives the engine the coolest inlet air for use at maximum horsepower ratings.

Engine Coolant (Jacket Water) Circuit

Water pump (20) for this circuit is on the left front side of the engine. It is gear driven by the timing gears. Coolant from expansion tank (2) goes through inlet line (19) to the water pump inlet. The rotation of the impeller in water pump (20) pushes the coolant (jacket water) through the circuit.

The coolant flow from water pump (20) goes through engine oil cooler (22) and bonnet (24). Bonnet (24) is on the outlet side of engine oil cooler (22) and connects to the side of cylinder block (16). On engines with auxiliary oil cooler (23), a different bonnet (24) is on the outlet of engine oil cooler (22). This bonnet (24) sends the coolant into one side of auxiliary oil cooler (23). At the bottom the coolant flow turns and goes up the other side of auxiliary oil cooler (23) and into bonnet (24) again. Then bonnet (24) sends this flow into cylinder block (16).

On engines with a water cooled turbocharger (11) some of the coolant in bonnet (24) goes through turbocharger inlet line (14). This coolant goes in at the bottom of water cooled turbocharger (11). The coolant goes up through water cooled turbocharger (11) and out through outlet line (10). Outlet line (10) sends the coolant into water cooled manifold (9) at the rear of the engine. The coolant goes through water cooled manifold (9) to the front of the engine. At the front of the engine the coolant comes out through outlet line (6) and goes into regulator housing (7). Inside regulator housing (7) the coolant mixes with the remainder of the coolant in cylinder head (15).

Inside cylinder block (16) the coolant goes around the cylinder liners and up through the water directors into cylinder head (15). The water directors send the flow of coolant around the valves and the passages for exhaust gases in cylinder head (15). The coolant goes to the front of cylinder head (15). Here the water temperature regulator controls the direction of the flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The only way for the coolant to get out of cylinder head (15) is through internal bypass (shunt) line (18). The coolant from this line goes into water pump (20) which pushes it through the cooling system again. The coolant from internal bypass (shunt) line (18) also works to prevent cavitation (air bubbles in the coolant). When the coolant gets to the correct temperature, the water temperature regulator opens and coolant flow is divided. Some goes through expansion tank (2) and around heat exchanger (1) for cooling. The rest goes through internal bypass (shunt) line (18) to water pump (20). The proportion of the two flows is controlled by the water temperature regulator.

NOTE: The water temperature regulator is an important part of the cooling system. It divides the coolant flow between heat exchanger (1) and internal bypass (shunt) line (18), as necessary, to maintain the correct operating temperature. If the regulator is not installed, there is no mechanical control, and most of the coolant will take the path of least resistance through internal bypass (shunt) line (18). This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through heat exchanger (1) is too much, and the engine will not get up to normal operating temperature.

Internal bypass (shunt) line (18) has another function when the cooling system is being filled. It lets the coolant go into cylinder head (15) and cylinder block (16) without going through water pump (20).

The coolant flow from the engine goes through outlet line (5) to expansion tank (2) and heat exchanger (1). Heat exchanger (1) is cooled by sea water from sea water pump (21) through aftercooler (12) and inlet line (28). The sea water cools the engine coolant (jacket water) in expansion tank (2) and goes out through sea water outlet (25).

Expansion tank (2) is the reservoir for the cooling system. It is the highest place in the cooling system. It is the place where the volume of the coolant can change because of heating or cooling without causing too much or too little coolant for the cooling system. Expansion tank (2) has a pressure cap (3) to control the pressure in the cooling system for better operation.

Cooling System Components

Water Pump

The centrifugal-type water pump has two seals, one prevents leakage of water and the other prevents leakage of lubricant.

An opening in the bottom of the pump housing allows any leakage at the water seal or the rear bearing oil seal to escape.

Fan

The fan is driven by two V-belts, from a pulley on the crankshaft. Belt tension is adjusted by moving the clamp assembly which includes the fan mounting and pulley.

Coolant For Air Compressor

Coolant Flow In Air Compressor
(1) Outlet hose. (2) Air compressor. (3) Inlet hose.

The coolant for the air compressor (2) comes from the cylinder block through hose (3) and into the air compressor. The coolant goes from the air compressor through hose (1) back into the front of the cylinder head.

Basic Block

Cylinder Block And Liners

A steel spacer plate is used between the cylinder head and the block to eliminate liner counterbore and to provide maximum liner flange support area (the liner flange sits directly on the cylinder block).

Engine coolant flows around the liners to cool them. Three O-ring seals at the bottom and a filler band at the top of each cylinder liner form a seal between the liner and the cylinder block.

Pistons, Rings And Connecting Rods

The piston has three rings; two compression and one oil ring. All rings are located above the piston pin bore. The two compression rings seat in an iron band which is cast into the piston. Pistons in some engines use compression rings with straight sides. Pistons in other engines use compression rings which are of the KEYSTONE type. KEYSTONE rings have a tapered shape and the movement of the rings in the piston groove (also of tapered shape) results in a constantly changing clearance (scrubbing action) between the ring and the groove. This action results in a reduction of carbon deposit and possible sticking of rings.

The oil ring is a standard (conventional) type and is spring loaded. Holes in the oil ring groove provide for the return of oil to the crankcase.

The piston pin bore in the piston is offset (moved away) from the center of the piston 0.76 mm (.030 in). The full floating piston pin is held in the piston by two snap rings which fit into grooves in 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 connecting rod is installed on the piston with the bearing tab slots on the same side as the "V" mark on the piston.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. There is a gear at the front of the crankshaft that drives the timing gears and the engine oil pump. The connecting rod bearing surfaces get oil for lubrication through passages drilled in the crankshaft. A lip type seal and wear sleeve is used to control oil leakage in the front crankshaft seal. A hydrodynamic grooved seal assembly is used to control rear crankshaft oil leakage. The hydrodynamic grooves in the seal lip move lubrication oil back into the crankcase as the crankshaft turns.

Vibration Damper (if equipped)

The force from combustion in the cylinders will cause the crankshaft to twist. This is called torsional vibration. If the vibration is too great, the crankshaft will be damaged. The vibration damper limits torsional vibrations to an acceptable amount to prevent damage to the crankshaft.

The viscous damper is made of a weight (1) in a metal case (3). The small 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.

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

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NOTICE
Inspect the viscous damper for signs of leakage or a dented (damaged) case (3). Either condition can cause weight (1) to make contact with the case and affect damper operation.

Electrical System

The engine 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), disconnect switch, circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits.

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

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

The 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

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NOTICE
Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.

Alternator (3E7577, 3E7578, 3E7892, 7G7889, 4N3986, 4N3987, 5N5692, 8N0999, 5S6698, 3T1888, 3T6352, 112-5041)

The alternator is driven by V-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 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.

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

Alternator (9G9538, 7N9720, 100-5046)

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

Alternator
(1) Fan. (2) Stator winding. (3) Field winding. (4) Regulator. (5) Ball bearing. (6) Roller bearing. (7) Rotor. (8) Rectifier assembly.

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.

Alternator (9G4574, 6T7223, 100-5045)

The alternator is driven by V-belts from the crankshaft pulley. The alternator has three-phase, full-wave rectified output. It is brushless. The rotor and bearings are the only moving parts. The regulator is part of the alternator.

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.

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.

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

Alternator (6T1395, 6T1396)

The alternator is a three phase, self-rectifying charging unit that is driven by V-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 has 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.

Alternator
(1) Slip rings. (2) Fan. (3) Stator assembly. (4) Rotor assembly. (5) Brush and holder assembly.

Starting System Components

Solenoid

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

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

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

Typical Solenoid Schematic

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

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

When two sets of windings in the solenoid are used, they are called the hold-in windings and the pull-in windings. Both have the same number of turns around the cylinder, but the pull-in windings uses a larger diameter wire to produce a greater magnetic field. When the start switch is closed, part of the current flows from the battery through the hold-in windings, 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.

Starter Motor

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

The starter motor has a solenoid. When the start switch is activated, the solenoid will move the starter pinion to engage it with the ring gear on the flywheel of the engine. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine cannot turn the starter motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.

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

Other Components

Circuit Breaker

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

A heat activated metal disc with a contact point makes complete the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset (an adjustment to make the circuit complete again) after it becomes cool. Push the reset button to close the contacts and reset the circuit breaker.

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

Shutoff Solenoid

The rack shutoff solenoid, when activated, moves the shutoff lever in the governor housing which in turn moves the fuel rack to the fuel closed position. The solenoid is activated by a manual control switch.

Wiring Diagrams

Many types of electrical systems are available for these engines. Some charging systems use an alternator and a regulator in the wiring circuit. Others have the regulator inside the alternator. Other starting systems use air or hydraulic motors.

A fuel pressure switch is used in all systems with an external regulator. The switch prevents current discharge (field excitation) to alternator from the battery when the engine is not in operation. In systems where the regulator is part of the alternator, the transistor circuit prevents current discharge to the alternator and the fuel pressure switch is not required.

All wiring schematics are usable with 12, 24, 30 or 32 volts unless the title gives a specific description.

NOTE: Automatic Start-Stop systems are different wiring diagrams. Make reference to the Engine Attachments section of this Service Manual.

The chart that follows gives the correct wire sizes and color codes.

Grounded Electrical Systems

These systems are used in applications when it is not necessary to prevent radio distortion and/or chemical changes (electrolysis) of grounded components.

(Regulator Inside Alternator)

Charging System
(1) Ammeter. (2) Alternator. (3) Battery.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Alternator. (4) Battery. (5) Starter motor.

(Regulator Separate From Alternator)

Charging System
(1) Ammeter. (2) Regulator. (3) Battery. (4) Pressure switch. (5) Alternator.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Regulator. (4) Starter motor. (5) Battery. (6) Pressure switch. (7) Alternator.

(Starting Systems)

Starting System
(1) Start switch. (2) Starter Motor. (3) Battery.

Insulated Electrical Systems

These systems are most often used in applications where radio interference is not desired or where conditions are such that grounded components will have corrosion from chemical change (electrolysis).

(Regulator Inside Alternator)

Charging System
(1) Ammeter. (2) Alternator. (3) Battery.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Alternator. (4) Battery. (5) Starter motor.

(Regulator Separate From Alternator)

Charging System
(1) Ammeter. (2) Regulator. (3) Battery. (4) Pressure switch. (5) Alternator.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Regulator. (4) Starter motor. (5) Battery. (6) Pressure switch. (7) Alternator.

(Starting Systems)

Starting System
(1) Start switch. (2) Starter motor. (3) Battery.

Air Starting System

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

Air Starting System
(1) Starter control valve. (2) Oiler. (3) Relay valve. (4) Air starting motor.

The air starting motor is on the right side of the engine. Normally the air for the starting motor is from a storage tank which is filled by an air compressor installed on the left front of the engine. The air storage tank holds 297 liter (10.5 cu ft) of air at 1720 kPa (250 psi) when filled.

For engines which do not have heavy loads when starting, the regulator setting is approximately 690 kPa (100 psi). This setting gives a good relationship between cranking speeds fast enough for easy starting and the length of time the air starting motor can turn the engine before the air supply is gone.

If the engine has a heavy load which cannot be disconnected during starting, the setting of the air pressure regulating valve needs to be high in order to get high enough speed for easy starting.

The air consumption is directly related to speed, the air pressure is related to the effort necessary to turn the engine flywheel. The setting of the air pressure regulator can be up to 1030 kPa (150 psi) if necessary to get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine as fast and as long as it can turn a lightly loaded engine.

Other air supplies can be used if they have the correct pressure and volume. For good life of the air starting motor, the supply should be free of dirt and water. The maximum pressure for use in the air starting motor is 1030 kPa (150 psi). Higher pressures can cause problems.

Air Starting Motor
(5) Vanes. (6) Gear. (7) Pinion spring. (8) Pinion. (9) Rotor. (10) Piston.

The air from the supply goes to relay valve (3). The starter control valve (1) is connected to the line before the relay valve (3). The flow of air is stopped by the relay valve (3) until the starter control valve (1) is activated. Then air from the starter control valve (1) goes to the piston (10) behind the pinion (8) for the starter. The air pressure on the piston (10) puts the spring (7) in compression and puts the pinion (8) in engagement with the flywheel gear. When the pinion is in engagement, air can go out through another line to the relay valve (3). The air activates the relay valve (3) which opens the supply line to the air starting motor.

The flow of air goes through the oiler (2) where it picks up lubrication oil for the air starting motor.

The air with lubrication oil goes into the air motor. The pressure of the air pushes against the vanes (5) in the rotor (9). This turns the rotor which is connected by the gear (6) to the starter pinion (8) which turns the engine flywheel.

When the engine starts running the flywheel will start to turn faster than the starter pinion (8). The pinion (8) retracts under this condition. This prevents damage to the motor, pinion (8) or flywheel gear.

When the starter control valve (1) is released, the air pressure and flow to the piston (10) behind the starter pinion (8) is stopped, the pinion spring (7) retracts the pinion (8). The relay valve (3) stops the flow of air to the air starting motor.

Hydraulic Starting System

Hydraulic Starting System Diagram
(1) Reservoir. (2) Hand pump. (3) Pressure gauge. (4) Hydraulic starting motor. (5) Starter control valve. (6) Hydraulic pump (driven by engine timing gears). (7) Unloading valve. (8) Filter. (9) Accumulator.

The hydraulic starting motor (4) is used to turn the engine flywheel fast enough to get the engine started. When the engine is running, the hydraulic pump (6) pushes oil through the filter (8) into the accumulator (9). The accumulator (9) is a thick wall cylinder. It has a piston which is free to move axially in the cylinder. A charge of nitrogen gas (N₂) is sealed in one end of the cylinder by the piston. The other end of the cylinder is connected to the hydraulic pump (6) and the hydraulic starting motor (4). The oil from the hydraulic pump (6) pushes on the piston which puts more compression on the nitrogen gas (N₂) in the cylinder. When the oil pressure gets to 20 700 kPa (3000 psi), the accumulator (9) has a full charge. At this point, the piston is approximately in the middle of the cylinder.

The unloading valve (7) feels the pressure in the accumulator (9). When the pressure is 20 700 kPa (3000 psi) the unloading valve (7) sends the hydraulic pump (6) output back to the reservoir (1). At the same time, it stops the flow of oil from the accumulator (9) back to hydraulic pump (6). At this time there is 20 700 kPa (3000 psi) pressure on the oil in the accumulator (9), in the line to the unloading valve (7), in the lines to the hand pump (2) and to the hydraulic starting motor (4).

Before starting the engine, the pressure on the pressure gauge (3) should be 20 700 kPa (3000 psi). When the starter control valve (5) is activated, the oil is pushed from the accumulator (9) by the nitrogen gas (N₂). The oil flow is through the hydraulic starting motor (4), where the energy from the compression of the fluid is changed to mechanical energy for turning the engine flywheel.

Hydraulic Starting Motor

Hydraulic Starting Motor
(1) Rotor. (2) Piston. (3) Thrust bearing. (4) Starter pinion. (A) Oil inlet. (B) Oil outlet.

The hydraulic starting motor is an axial piston hydraulic motor. The lever for the starter control valve pushes the starter pinion (4) into engagement with the engine flywheel at the same time it opens the way for high pressure oil to get into the hydraulic starting motor.

When the high pressure oil goes into the hydraulic starting motor, it goes behind a series of pistons (2) in a rotor (1). The rotor (1) is a cylinder which is connected by splines to the drive shaft for the starter pinion (4). When the pistons (2) feel the force of the oil they move until they are against the thrust bearing (3). The thrust bearing (3) is at an angle to the axis of the rotor (1). This makes the pistons (2) slide around the thrust bearing (3). As they slide, they turn the rotor (1) which connects through the drive shaft and starter pinion (4) to the engine flywheel. The pressure of the oil makes the rotor (1) turn very fast. This turns the engine flywheel fast enough for quick starting.