3306B GENERATOR SET ENGINE Caterpillar


Systems Operation

Usage:

Introduction

NOTE: For Specifications with illustrations, make reference to Specifications for 3306B Generator Set Engine, RENR1286. If the Specifications in RENR1286 are not the same as in the Systems Operation, Testing & Adjusting, look at the printing date on the front cover of each book. Use the Specifications given in the book with the latest date.

Engine Design


Cylinder And Valve Location

Bore ... 120.7 mm (4.75 in)

Stroke ... 152.4 mm (6.00 in)

Number of Cylinders ... 6

Cylinder Arrangement ... in line

Valves per Cylinder ... 2

Combustion ... Direct Injection

Firing Order (Injection Sequence) ... 1, 5, 3, 6, 2, 4

Rotation of Crankshaft (when viewed from flywheel end) ... counterclockwise

NOTE: The No. 1 cylinder is opposite the 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 valves. (9) Fuel transfer pump. (10) Secondary fuel filter. (11) Constant bleed valve. (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). A bypass valve in the fuel transfer pump keeps the fuel pressure in the system at 170 to 280 kPa (25 to 40 psi). Constant bleed valve (11) lets a constant flow of fuel go through fuel return line (2) back to fuel tank (1). The constant bleed valve returns approximately 34 liters (9 gal) per hour of fuel and air to the fuel tank. This helps keep the fuel cool and free of air. Fuel injection pump (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
(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 lobe.

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

When the pump plunger is at the bottom of the stroke, fuel 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
(1) Carbon dam. (2) Seal. (3) Passage. (4) Filter screen. (5) Orifices. (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 fuel injection 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 fuel injection 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 fuel injection nozzle seat and stops the flow of fuel to the combustion chamber.

The fuel injection nozzle cannot 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 (lobe) 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) (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.


Fuel Transfer Pump (Start Of Up Stroke) (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 camshaft 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.

Oil Flow For Fuel Injection Pump And Governor


Fuel Pump And Governor
(1) Cover. (2) Governor 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 cover (1) and back into another passage in the rear governor housing. Now the oil goes into the compartment for the governor controls. Drain hole (8) keeps the oil at the correct level. The oil in this compartment is used for lubrication of the governor control components and the oil is the supply for the dashpot.

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

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

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) Overfueling spring. (10) Riser. (11) Spring seat. (12) Stop bolt. (13) Torque spring. (14) Power setting screw. (15) Torque rise setting screw. (16) Stop collar. (17) Stop bar.

The 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, overfueling 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 overfueling spring. The riser moves to the rear and reduces the amount of fuel to the low idle requirement of the engine.

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

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

Governor Servo


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.

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).

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


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.

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).

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.

Air Inlet And Exhaust System

Air-To-Air Aftercooler (ATAAC)

The components of the air inlet and exhaust system control the quality and the amount of air available for combustion. These components are the air cleaner, turbocharger, aftercooler, cylinder head, valves and valve system components, piston and cylinder, and exhaust manifold.


Air-To-Air Aftercooler Air Flow Schematic
(1) Inlet manifold. (2) Aftercooler core. (3) Air line. (4) Exhaust outlet from turbocharger. (5) Turbine side of turbocharger. (6) Compressor side of turbocharger.


Air-To-Air Aftercooler Air Inlet And Exhaust System
(2) Aftercooler core. (4) Exhaust outlet. (5) Turbine side of turbocharger. (6) Compressor side of turbocharger. (7) Exhaust manifold. (8) Exhaust valve. (9) Inlet valve. (10) Air inlet.

Inlet air is pulled through the air cleaner, compressed and heated by the compressor wheel in compressor side of turbocharger (6) to about 150°C (300°F), then pushed through the air-to-air aftercooler core (2) and moved to the inlet manifold (1) at about 43°C (110°F).

Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output. Air-to-air aftercooler core (2) is a separate cooler core installed in front of the standard engine radiator core. Ambient temperature air is moved across both cores by the engine fan. This cools the turbocharged inlet air and the engine coolant.

From the Air-to-air aftercooler core the air is forced into the cylinder head to fill the inlet ports. Air flow from the inlet port into the cylinder is controlled by the inlet valves.

There is one inlet and one exhaust valve for each cylinder. Inlet valves open when the piston moves down on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet port is pulled into the cylinder. The inlet valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again, it is on the exhaust stroke. The exhaust valves open, and the exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston makes the exhaust stroke, the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again.

Exhaust gases from exhaust manifold (7) enter turbine side of the turbocharger (5) and cause the turbine wheel to turn. The turbine wheel is connected to the shaft which drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet pipe, the muffler and the exhaust stack.

Jacket Water Aftercooler (JWAC)

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


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


Air Flow Schematic
(1) Exhaust manifold. (3) Engine cylinders. (4) Air inlet. (5) Turbocharger compressor wheel. (6) Turbocharger turbine wheel. (7) Exhaust outlet. (8) Aftercooler.

Clean inlet air from the air cleaner is pulled through the air inlet (4) of the turbocharger by the turning turbocharger compressor wheel (5). The compressor wheel causes a compression of the air. The air goes through the aftercooler and then into the inlet manifold. When the inlet valves open, the air goes into the engine cylinders (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 turbocharger 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.

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

Turbocharger


Turbocharger (Typical Example)
(1) Air inlet. (2) Compressor housing. (3) Compressor wheel. (4) Bearing. (5) Oil inlet port. (6) Bearing. (7) Turbine housing. (8) Turbine wheel. (9) Exhaust outlet. (10) Oil outlet port. (11) Exhaust inlet.

The exhaust gases go into turbine housing (7) through exhaust inlet (11) and push the blades of turbine wheel (8). The turbine wheel is connected by a shaft to compressor wheel (3).

Clean air from the air cleaner is pulled through the compressor housing air inlet (1) by the rotation of compressor wheel (3). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power because it makes it possible for the engine to burn more air and fuel during combustion.

When the load on the engine increases, more fuel is injected into the cylinders. This makes more exhaust gases, and will cause the turbine and compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, more air is forced into the engine. The increased flow of air gives the engine more power because it makes it possible for the engine to burn additional fuel with greater efficiency.

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


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 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 fuel setting adjustment is done at the factory for a specific engine application. The governor housing and turbocharger are sealed to prevent changes in the adjustment of the fuel and the high idle speed setting.

Bearings (4 and 6) for the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (5) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the oil outlet port (10) 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 inlet and one exhaust valve. Each inlet 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 inlet 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


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 orifices. (7) Camshaft bearing bore. (8) Engine oil cooler bypass valve. (9) Engine oil filter bypass valve. (10) Engine oil cooler. (11) Engine oil filter. (12) Turbocharger. (13) Engine oil pump. (14) Oil pan.

Engine oil pump (13) pulls oil from oil pan (14) and then pushes the oil to engine oil cooler (10). From the engine oil cooler the oil goes to engine oil filter (11) and then to oil manifold (5). From the oil manifold, oil goes to all main bearings, and piston cooling orifices (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.

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

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 Opring 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.


Rocker Arm Oil Supply

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 engine oil pump. This bypass valve controls the pressure of the oil coming from the engine oil pump. The engine 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), engine oil cooler bypass valve (8) and engine oil filter bypass valve (9) will open and give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through engine oil cooler (10) and engine oil filter (11). Engine oil pump (13) sends the cold oil through the bypass valves around the engine oil cooler and engine 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 engine oil cooler and engine oil filter.

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


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

Cooling System

Coolant Flow (Engine With Air-To-Air Aftercooler)


Coolant Flow (Engine With Air-To-Air Aftercooler)
(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 line (shunt). (10) Engine oil filter. (11) Engine oil cooler. (12) Elbow. (13) Cylinder liners.

This engine has a pressure type cooling system. The pressure type cooling system has two advantages. The first advantage is that the cooling system can have safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type system prevents cavitation (the sudden making of low pressure bubbles in liquids by mechanical forces) in the water pump. With this type system, it is more difficult for an air or steam pocket to be made in the cooling system.

NOTE: In air-to-air aftercooled systems, a coolant mixture with a minimum of 30 percent ethylene glycol base antifreeze must be used for efficient water pump performance. This mixture keeps the cavitation temperature range of the coolant high enough for efficient performance.

NOTE: Water temperature regulator is an important part of the cooling system. It divides coolant flow between radiator and internal bypass line as necessary to maintain the correct temperature.

If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

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

The coolant enters the block and flows around cylinder liners (13) and up through the coolant directors into cylinder head (5). The coolant directors make the coolant flow around the valves and around the exhaust ports (passages) in the cylinder head. The coolant now goes to the front of the cylinder head. At the front of the cylinder head water temperature regulator (4) controls the direction of the coolant flow. If the coolant temperature is less than normal for engine operation, the water temperature regulator is closed. The coolant must go through internal bypass line (9) to the water pump. When the coolant gets to the temperature of normal operation the water temperature regulator opens and most of the coolant flows through radiator inlet line (3) to the radiator. A part of the coolant still goes through internal bypass line (9).

Coolant Flow (Engine With Aftercooler)


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

This engine has a pressure type cooling system. The pressure type cooling system has two advantages. The first advantage is that the cooling system can have safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type system prevents cavitation (the sudden making of low pressure bubbles in liquids by mechanical forces) in the water pump. With this type system, it is more difficult for an air or steam pocket to be made in the cooling system.

NOTE: In jacket water aftercooled systems, a coolant mixture with a minimum of 30 percent ethylene glycol base antifreeze must be used for efficient water pump performance. This mixture keeps the cavitation temperature range of the coolant high enough for efficient performance.

NOTE: Water temperature regulator is an important part of the cooling system. It divides coolant flow between radiator and internal bypass line as necessary to maintain the correct temperature. If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather.

In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

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 the engine oil cooler (10). This bonnet sends the coolant flow through the auxiliary oil cooler. 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.

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.

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. The pistons 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 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

The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. It is used for reduction of torsional vibrations and stops the vibration from building up to amounts that can cause damage.


Cross Section Of A Vibration Damper
(1) Weight. (2) Case.

The vibration damper is installed on the front of the crankshaft. The damper has a weight in a metal housing. The space between the weight and the housing is filled with a thick fluid. The weight moves in the housing to limit the torsional vibration.


NOTICE

Inspect the viscous damper for signs of leakage or a dented (damaged) case (2). Either condition can cause weight (1) to make contact with the case and affect damper operation.


Electrical System

Grounding Practices

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

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

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

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

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

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

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

Engine 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, 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.


NOTICE

The disconnect switch, 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 can operate only after the disconnect switch is put in the ON position.

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

The low amperage circuit and the charging circuit are both connected to the same side of the ammeter. The starting circuit connects to the opposite side of the ammeter.

Charging System Components


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


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

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

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

The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnetic 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.

Starting System Components

Solenoid

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

a. Closes the high current starting motor circuit with a low current start switch circuit.
b. Engages the starting motor pinion with the ring gear.


Typical Solenoid Schematic

The solenoid switch is made of an 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 starting motor begins to turn the flywheel of the engine.

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

When two sets of windings in the solenoid are used, they are called the hold-in 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.

Starting Motor

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

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


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

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