CAT Basic Engine

Course Overview

This course introduces the student to basic diesel engine theory and service procedures. Caterpillar engine systems and applications will be studied. Several Caterpillar Engines will be presented with emphasis on the 3406 due to its high field population. The following course curriculum has been developed using the reference materials and tooling listed on the following pages. Substitute materials and tooling may be used at the discretion of the instructor. Course Exercises and lab assignments may require modification if substitute materials and tooling are used.

Engine Fundamentals

Caterpillar Engine Fundamentals

UNIT 1: Introduction to Caterpillar Diesel Engines Lesson 1: Caterpillar Engine Product Line, Applications Lesson 2: Diesel Engine Components and Operation Lesson 3: Engine Performance Terminology UNIT 2: Air Intake and Exhaust Systems Lesson 1: Intake and Exhaust System Components, Operation, and Maintenance Lesson 2: Remove, Inspect, and Install Air and Exhaust System Components UNIT 3 Lubrication Systems and Oil Lesson 1: Lube System Components and Operation Lesson 2: Remove, Inspect, and Install Lube System Components UNIT 4: Cooling Systems Lesson 1: Cooling System Components and Operation Lesson 2: Remove, Inspect, and Install Cooling System Components UNIT 5: Diesel Fuel and Mechanically Controlled Fuel Systems Lesson 1: Diesel Fuel Lesson 2: Caterpillar 3406 New Scroll Fuel System Lesson 3: Remove, Inspect, and Install Fuel System Components Lesson 4: Caterpillar Sleeve Metering Fuel Systems Lesson 5: 3116/26 Mechanical Unit Injector Fuel Systems UNIT 6: Engine Disassembly, Inspection, and Assembly Lesson 1: 3406 Disassembly and Inspection Lesson 2: Caterpillar 3406 Engine maintenance UNIT 7: Electronically Controlled Fuel Systems Lesson 1: Caterpillar Electronic Fuel Systems

Table of Contents

Table Of Contents

Objectives

This course prepares Caterpillar dealer entry-level service technicians for more advanced training on specific engines and systems. After successfully completing this course, a student will be able to: -

-

-

Identify the wide range of engines in the Caterpillar Product Line. Identify various diesel engine applications. Explain basic diesel engine theory. Define engine performance terms. Identify basic diesel engine components and their function. Describe the following engine systems: Air intake and exhaust systems Lubrication system Cooling system Fuel system and governor Demonstrate the ability to disassemble and inspect Caterpillar 3406 diesel engine with a mechanical governor. Demonstrate the ability to reassemble and perform necessary adjustments on a Caterpillar 3406 diesel engine with a mechanical governor. Explain the operation of the Caterpillar Sleeve Metering Fuel System. Explain the operation of the Caterpillar 3116/26 Mechanical Unit Injector Fuel System. Explain the operation of and identify components used in Caterpillar electronically controlled engines using EUI and HEUI fuel systems.

Objectives

Caterpillar Engine Fundamentals

Objective: At the completion of this lesson the student will be able to identify a wide range of Caterpillar engines and their applications. References: Industrial Engine Selection Guide Harness the Power (Cat Truck Engines for 1998) Caterpillar Marine Engine Selection Guide

LECH9163 LEXT8138 LECM8477

Introduction: Caterpillar engines are known around the world for their durability, performance, and efficiency. Whether they are used in earthmoving equipment, on-road or off-road vehicles, industrial power situations, marine installations, or electric power generation, Caterpillar engines have set new standards for decades. To give customers a competitive advantage, Caterpillar is constantly working to push performance to higher levels. Today's line of Caterpillar engines offers some of the most advanced engineering features available. These include electronic controls, hydraulically actuated electronically controlled unit injectors (HEUI), and other exclusive technologies that dramatically reduce engine emissions.

Lesson 1: Engine Product Line and Applications

Lesson 1: Caterpillar Engine Product Line and Applications

Objective: The student will be able to identify diesel engine components and explain the principles of diesel engine operation. References: The Engine Book Introduction to Diesel Engines 3400 Engine Major Component Performance Guide 3406 Engine Components and Systems

LEBQ9801 TECB6005 SEBD0794 CD-ROM

Introduction: Caterpillar develops and builds four-stroke-cycle diesel engines to satisfy the requirements of Caterpillar-built equipment as well as a wide variety of equipment built by other manufacturers. To effectively perform diagnosis, repair, and service, it is necessary to have a complete understanding of the operating principles and construction of diesel engines.

Lesson 2: Diesel Engine Components

Lesson 2: Identify Caterpillar Diesel Engine Components and Explain Principles of Diesel Engine Operation

This CD-ROM presentation will review the major engine components and systems of the Caterpillar 3406B diesel engine.

Fig. 1.2.1 Caterpillar 3406B Engine

Caterpillar 3406B Engine Years of diesel experience have provided Caterpillar with the technology necessary to design and build high quality engines that offer maximum performance at a low overall cost. The specific design considerations for the 3406B include: • • • • • • • •

Reliability Serviceability Long Life before Overhaul is Needed Low Overhaul costs Application Flexibility Fuel Economy Oil Control Performance

Caterpillar has always emphasized strength and quality, and continues to do so with the 3406B. The 3406B is a heavy-duty, in line, 6cylinder, diesel engine. The engine has a 5.4 inch bore, 6.5 inch stroke and a displacement of 893 cu. in.

The major engine components will now be discussed in detail.

Fig. 1.2.2 Cylinder Block

Cylinder Block One of the major components in a diesel engine that must exhibit maximum strength is the cylinder block. To provide maximum strength, the block is precision cast using a combination of alloys.

Fig. 1.2.3 Cylinder Head

Cylinder Head The cylinder head is designed to have excellent structural strength and ridgidity. The cylinder head has passed rigorous, deep thermal cycle shock testing for assured durability. This results in a cylinder head with significant resistance to cracking. The steel or aluminum spacer plate that is used between the cylinder head and the block eliminates the need for deep counterbores in the cylinder block. Deep counterbores decrease the structural integrity of the block and are prone to cracking.

Fig. 1.2.4 3406B Crankshaft

3406B Crankshaft The crankshaft is a carbon steel forging that is total hardened. Many other diesel engine manufacturers induction harden their crankshafts only at the journals and fillets. This process can leave a stress riser at the boundary between the hardened and unhardened areas. The patented Caterpillar total-hardening process hardens the entire surface of the crankshaft, creating a longer wearing and stronger crankshaft. With the entire surface of the crankshaft hardened, the possibility of cracking is reduced.

Fig. 1.2.5 3406C Crankshaft

3406C Crankshaft With the introduction of the 3406C, the size of the rod bearing has been significantly increased (projected area by 19%). The wider bearing spreads the load over a greater surface area, dramatically decreasing the bearing load while increasing the bearing life. This photo shows a former rod bearing on the new crankshaft to demonstrate the increase in bearing area. Additionally, this change increases the oil film thickness by 50% and gives the 3406C the largest rod bearing capacity in its class, eliminating mid-life bearing roll-ins.

Fig. 1.2.6 Connecting Rods

Connecting Rods The forged boron steel connecting rod is hardened and shot peened for stress relief. The tapered-end design provides additional pin to bore contact area during the power stroke. This results in extra strength and durability of the piston and rod assembly. New with the 3406C is a larger, stronger connecting rod with a much larger rod bearing. In fact, the wider 3406C rod bearing has the greatest load carrying capacity of any heavy duty engine in its class. By spreading the firing loads over a larger surface area, load carrying capacity, bearing reliability, and service life are all dramatically increased for all ratings.

Fig. 1.2.7 Pistons

Pistons Pistons are critical to the design, life, and overall performance of an engine. The Caterpillar 3406B Engine's three-ring piston is an aluminum alloy casting with a cast-in nickel iron band for the compression rings. The nickel iron band provides improved groove strength and resists wear. The three-ring piston design provides excellent compression and oil control while reducing friction and heat buildup. This results in extended piston, ring and liner life and reduces maintenance cost at overhaul time. The piston rings are nodular iron for strength and durability. The oil and intermediate rings are chrome coated, while the top ring is plasma coated. Both coatings provide excellent wear and scuffresistant properties.

Fig. 1.2.8 Cylinder Liners

Cylinder Liners Cylinder liners are made of a cast molybdenum alloy iron for an extra margin of hardness. The internal surface of each liner is induction hardened, then ground in a cross-hatched pattern to aid in oil control. O-rings are used to seal the liner to block coolant cavity. A liner band is used to seal the top of the liner. Because the engine is rigid, these seals remain seated and provide excellent liner sealing.

Fig. 1.2.9 Valves

Valves Exhaust and intake valves in the 3406B Engine are extremely wear resistant for long life. Three materials are used in the exhaust valves. The stems are made of a hardened stainless steel. A special alloy is used for the heads to provide high temperature strength. The seating faces of the valve are made of Stellite for high temperature wear resistance. Intake valve heads and stems are made from stainless steel and are hardened for resistance to wear.

Fig. 1.2.10 Valve Seat Inserts

Valve Seat Inserts When the valve seats become worn or damaged, valve seat inserts are replaceable. Intake inserts are a stainless steel alloy and the exhaust inserts are a nickel base alloy. Each valve has a rotator which moves the valve face 3° relative to the valve seat during one complete cycle of the engine. This assures uniform wear for longer valve life and helps prevent burned valves.

Fig. 1.2.11 Camshaft

Camshaft The camshaft is made of a special alloy steel that is drop forged and hardened for reliability and durability. The camshaft gear is heated and pressed on during installation.

Fig. 1.2.12 BrakeSaver

BrakeSaver The 3406B has an optional BrakeSaver hydraulic retarder that provides smooth, quiet and efficient vehicle braking. The BrakeSaver develops a retarding capability of 360 hp and maintains normal engine temperatures on long downhill grades. The hydraulic operation of the BrakeSaver provides smooth, gradual engagement, reducing the possibility of skids or jackknives. By relieving the service brakes of the severe wear caused by downhill braking, the BrakeSaver extends brake lining, drum, and tire life. This reduces user maintenance costs.

Fig. 1.2.13 Fuel System

Fuel System The 3406B utilizes a direct injection, scroll type, high pressure fuel system. The system is very efficient, allowing short injection duration and excellent fuel atomization. This results in lower emissions and improved fuel economy.

Fig. 1.2.14 Fuel Injection Nozzle

Fuel Injection Nozzle Injection nozzles can be replaced in the field. The six hole tip atomizes the high pressure fuel flow in the combustion chamber for complete, efficient combustion.

Fig. 1.2.15 Fuel Injection Pump

Fuel Injection Pump Individual scroll-type fuel pumps for each cylinder require no balancing and maintain fuel efficiency without periodic adjustment.

Fig. 1.2.16 Spring/Hydraulic Timing Advance

Spring Hydraulic Timing Advance The speed sensitive timing advance mechanism optimizes performance and makes starting easy. Earlier 3406B Engines used a spring/hydraulic system. As engine speed increases, timing is advanced hydraulically using engine oil. As engine speed decreases, a large spring pushes the timing mechanism toward the retarded position. The spring/hydraulic system has a timing advance capability of 9 degrees.

Fig. 1.2.17 Hydraulic Timing Advance

Hydraulic Timing Advance A double hydraulic automatic timing advance was introduced on the 3406B Engines, serial number 4MG3600 and up. In this system, the timing mechanism advances and retards hydraulically using engine oil. A spool valve actuated by flyweights controls the flow of oil in the timing mechanism. This fully hydraulic system has a timing advance capability of 12 degrees.

Fig. 1.2.18 Governor

Governor The Caterpillar 3406B features a full range governor. The hydraulically assisted governor maintains nearly constant speed over rolling terrain similar in effect to automatic speed control in automobiles. This reduces gear shifts and accelerator changes, resulting in improved trip times and less driver fatigue.

Fig. 1.2.19 Turbocharger

Turbocharger 3406B turbochargers are performance matched for each horsepower rating. Their low inertia design reacts rapidly to load demands while delivering full-rated power to the altitude limit appropriate for the application of the engine. This results in improved combustion efficiency and more work per gallon of fuel.

Component Locations

Fig. 1.2.20 Engine Component Locations

Engine Component Locations Located on the front of the engine are: • Air compressor drive cover • Timing advance cover • Vibration damper • Coolant pump

Fig. 1.2.21 Engine Component Locations

Engine Component Locations On the right side of the engine are the: • Turbocharger • Exhaust manifold • Oil filter • Oil cooler • Breather and tube assembly

Fig. 1.2.22 Engine Component Locations

Engine Component Locations Located on the left side are the: • Air compressor mounting location • Injection lines • Hand priming pump • Starter location • Fuel filter • Fuel transfer pump • Fuel injection pump Depending on the application, the engine may also be equipped with a different arrangement on the fuel filter and priming pump locations. Some engines will also have an aftercooler.

Fig. 1.2.23 Transmission Oil Cooler

Transmission Oil Cooler If used, the transmission oil cooler is installed on the right side of the engine.

Objective: The student will be able to define essential engine performance terminology and calculate engine displacement, compression ratio, and horsepower. References: Glossary of Terms

LEXQ8150

Introduction: To understand diesel engine design and performance, it is necessary to know the terminology and math calculations that apply to diesel engines.

Lesson 3: Engine Performance Terminology

Lesson 3: Engine Performance Terminology

Fig. 1.3.1

There are many factors that determine the performance of an engine. The operating conditions that an engine is exposed to and the specific application an engine is placed in can affect the performance of the engine. Many of the determining factors for performance, however, are determined by the manufacturer of the engine. Some of the basic specifications that a manufacturer makes on an engine that affect performance of the engine are: Bore Stroke Displacement Compression Ratio The performance of an engine is typically rated by comparing power output and/or efficiency of the engine. These evaluations can be measured in several different ways. The basis for these measurements and the manufacturer’s specifications must be known in order to better understand the effects that all of these factors and measurements have on engine performance.

BORE

TDC STROKE

BDC CRANKSHAFT AT TDC

CRANKSHAFT AT BDC

Fig. 1.3.2

Top Dead Center (tdc) Top dead center (tdc) is a term used to describe the position of the piston when the piston is at its highest point in the cylinder. This occurs when the crankshaft and the connecting rod are fully extended and straight with one another. Many events in the operation of the engine are identified by crankshaft position, measured in degrees either before or after tdc. Bottom Dead Center (bdc) Bottom dead center (bdc) is a term used to describe the position of the piston when the piston is at its lowest point in the cylinder. This occurs when the crankshaft and the connecting rod are fully retracted and straight with one another. Bore (B) Bore is a term used to describe the diameter of a single cylinder in an engine. Bore is typically measured in millimeters or inches. Stroke (L) Stroke is a term used to describe the distance that a piston travels in the cylinder of the engine. The stroke is measured as the difference between the position of the piston at BDC to TDC. The amount of stroke is determined by the design of the crankshaft. The stroke is equal to exactly twice the throw of the crankshaft. Stroke is typically measured in millimeters or inches.

Engine Displacement The bore, the stroke, and the number of cylinders all determine the displacement of an engine. The displacement of an engine is simply the amount of volume displaced by all cylinders in an engine during one complete rotation. The displacement of an engine can be calculated using the following formula: Displacement = π x r2 x L x n Where... π r2 radius L n

= = = = =

22/7 radius x radius 1/2 bore stroke number of cylinders in the engine DIESEL ENGINE 17 TO 1

Fig. 1.3.3

Compression Ratio The compression ratio of an engine is determined by the cylinder displacement and the combustion chamber volume. In order to calculate the compression ratio use the following formula: CR = Total Cylinder Volume / Combustion Chamber Volume Typical compression ratios of diesel engines range from 11:1 to 22:1. This is significantly higher than the compression ratio of a typical gasoline engine. Diesel engines utilize higher compression ratios to increase the pressure within the combustion chamber. Higher pressures will cause an increase in the temperature of the air and fuel in the combustion chamber. This high temperature (approximately 1000°F) will cause the diesel fuel to ignite without the use of a spark plug.

Atmospheric Conditions In order to produce the desired levels of power, diesel engines require a large volume of air. Therefore the atmospheric pressure, the ambient air temperature, and the relative humidity of the air play a large role in the performance characteristics of the engine. It is the atmospheric air pressure that is present that forces the air into the engine. Atmospheric pressure is the pressure that is exerted on the earth’s surface due to the weight of the atmosphere (the air surrounding the earth). Atmospheric pressure is greatest at sea level because there is more air above the air at sea level than there is above the air at the top of a mountain. Refer to figure...

3657 M. 64.12 kPa

WEIGHT OF AIR ON EARTH'S SURFACE

12,000 FT. 9.3 PSI

2438 M.

8,000 FT.

75.15 kPa

10.9 PSI

1219 M.

4,000 FT.

87.50 kPa

12.7 PSI

101.35 kPa SEA LEVEL

SEA LEVEL 14.7 PSI

EARTH'S SURFACE

Fig. 1.3.4

As an example, due to increased pressure at sea level the air is more dense than the air on top of a mountain. The dense air allows for more air molecules to flow into the cylinder. This allows for the fuel to be more completely burned in a diesel engine, which produces more power. This is why engines perform better in lower altitudes, the air is more dense. Ambient air temperature also plays a role in how much air can flow into an engine. The lower the temperature of the air, the more dense the charge of air is that enters the cylinders. The greater the density of the air, the more power that can be produced efficiently in the engine. Humidity is also an important factor in diesel engine combustion. Humidity is a relative measure of the amount of moisture that is suspended in the air. The suspended moisture has a cooling effect on the air as it enters the engine. Therefore, the greater the humidity of the air, the colder the air, the denser the air, the more power that can be produced efficiently in the engine.

Air Intake and Exhaust Systems

Unit Objectives: The student will be able to: 1. Identify air intake and exhaust system components in an engine installation. 2. Remove, inspect, and install air and exhaust system components on a Caterpillar 3406B or 3406C engine.

Unit2: Air Intake and Exhaust

Unit 2

Lesson 1: Air Intake and Exhaust

Lesson 1: Identify Air Intake and Exhaust Systems

Objectives: The student will be able to explain the operation of the air intake and exhaust system and identify related components. References: Air Intake and Exhaust Presentation 3406E Operation and Maintenance Manual Turbochargers Air System Specifications Handout

CD-ROM SEBU6758 SEBV0550 Copy

Introduction: Efficient diesel engine operation requires that the proper amount of air can enter the combustion chamber and the exhaust gases can exit with minimal restriction. Both inlet air and exhaust gas temperatures are also critical for maximum engine performance and life.

Air Inlet and Exhaust System Fig. 2.1.1 Introduction

Introduction This first system we will discuss is the Air Inlet and Exhaust system.

Fig. 2.1.2 Air System Components.

Air System Components The Air Inlet and Exhaust System contains the following components: • • • • •

Air cleaner Turbocharger Aftercooler Cylinder head, valves, and pistons Exhaust manifold

Fig. 2.1.3 Air Cleaner

Air Cleaner Air is drawn into the engine through the air cleaner. The air cleaner houses a filter element which removes foreign material from the air before it enters the engine. There are several different types of air cleaners currently available on Caterpillar engines. Always refer to the operation and maintenance manual of the engine for the most accurate maintenance procedures.

Fig. 2.1.4 Typical Service Indicator

Engine air cleaners should be serviced on a regular basis. Many air cleaners are equipped with a service indicator. The indicator monitors the amount of restriction through the air cleaners. The service indicator is the most accurate method to use to determine when the air cleaners are in need of service. Engine air cleaner elements should be serviced, cleaned or replaced, when either the yellow diaphragm enters the red zone or the red piston locks into the visible position.

Fig. 2.1.5 Dry Element Air Cleaner

Dry element air cleaners are by far the most common type of air cleaners used on Caterpillar engines. Dry element air cleaners are typically composed of a pleated paper filter media that is used to remove the dirt from the incoming air. This type of air filter requires replacement or cleaning when the service indicator is tripped.

Fig. 2.1.6 Dry Element Cleaning

Dry element air cleaners can usually be cleaned with filtered, dry air with a maximum pressure of 207 kPa (30 psi). The element should be cleaned from the clean side out, holding the tip of the air nozzle parallel to the pleats of the air cleaner.

Fig. 2.1.7 AIRSEP Filters

Another type of air cleaner that is found on Caterpillar engines, most commonly in high performance marine applications, is the AIRSEP. The AIRSEP elements are a pleated fiber filter media that is impregnated with a special petroleum based fluid. This allows the AIRSEP elements to flow a high volume of air with little restriction, but still clean the air before it enters the engine. These elements are reusable, but the elements require a special maintenance procedure. The AIRSEP filters must be cleaned using the 102-9720 Cleaning Kit. Follow the guidelines in the operation and maintenance manual.

Fig. 2.1.8 Simple Cap Precleaner

Precleaner Many engines are also equipped with a precleaner. The precleaner is located before the inlet to the main air cleaner. The purpose of the precleaner is to collect much of the dirt before the air cleaner. This increases the service life of the air cleaner. The simplest type of precleaner is a simple mesh cap at the top of the air filter housing inlet.

Fig. 2.1.9 Dust collection bowl

Another type of precleaner that is used on Caterpillar equipment is a spirally vaned drum. The vanes cause the incoming air to spin. Because the dirt that is drawn in is heavier than the air, the dirt is forced to the outside due to the spinning action. The dirt then falls into a collection bowl. Precleaners should be inspected and emptied on a daily basis.

Fig. 2.1.10 Turbocharger

Turbocharger Many diesel engines are equipped with a turbocharger in order to improve the performance and the efficiency of the engine. The turbocharger receives clean air flow from the air cleaner. The rotation of the turbocharger compressor wheel draws air in, compresses it and delivers it under pressure to the cylinders.

Advantages of Turbochargers • Power • Efficiency

Fig. 2.1.11 Advantages of Turbochargers

Advantages of Turbochargers Turbocharging has several important advantages: 1. Power - Compressed air has more oxygen per volume. With more oxygen in the cylinder, more fuel can be injected for a higher energy output. 2. Efficiency - Turbocharging allows a more efficient combustion for improved emissions and fuel consumption.

Fig. 2.1.12 Turbocharger Operation

Turbocharger Operation When the turbocharger compresses the intake air, the temperature of the air is increased. Hot air has less density, thus less oxygen. If the hot compressed air is delivered to the engine, some of the efficiency gained by compression will be lost. This is where the aftercooler comes into play. The aftercooler lowers the temperature of the air before its enters the cylinders.

Aftercooler • Air to Air Aftercooler • Jacket Water Aftercooler

Fig. 2.1.13 Aftercooler

Aftercoolers Aftercoolers are used in conjunction with turbochargers in order to lower the temperature of the air coming from the turbocharger before the air enters the cylinders. This causes the air to be more dense, therefore contain more oxygen in a given volume. This increase in oxygen in the cylinders translates into greater power and efficiency from the engine. There are different types of aftercoolers that are used on Caterpillar engines: All aftercoolers serve the same purpose however, remove heat from inlet air providing cooler and more dense air to the cylinder.

Fig. 2.1.14 Air to Air Aftercooler (ATAAC)

Air to Air Aftercooler (ATAAC) With the air to air aftercooled system, a separate cooler core is installed in front of the vehicle engine radiator. Ambient temperature air is moved across the aftercooler core by the engine fan. Pressurized air from the turbocharger is cooled by the air to air aftercooler before entering the intake manifold. This is an extremely effective method for cooling the turbocharged air when a large volume of fresh cool air can be pushed through the aftercooler. For this reason this is the configuration found most often in on-highway truck applications.

Fig. 2.1.15 Jacket Water Aftercooler (JWAC)

Jacket Water Aftercooler (JWAC) The jacket water aftercooler system has a coolant charged core assembly. It uses the engine coolant in order to cool the air charge entering the cylinders. Coolant from the water pump flows through the aftercooler core. Pressurized air from the turbocharger is cooled by the aftercooler before entering the intake manifold.

SEPERATE CIRCUIT AFTERCOOLER TURBOCHARGER AFTERCOOLER AUXILIARY WATER PUMP

AFTERCOOLER WATER COOLING CIRCUIT

JACKET WATER COOLING CIRCUIT

JACKET WATER PUMP

Fig. 2.1.16 Separate Circuit Aftercooler

Separate Circuit Aftercooler (SCAC) A separate circuit aftercooler system is similar to the jacket water aftercooler system with minor differences. A separate cooling circuit from the jacket water of the engine is used to cool the engine. The jacket water acts as normal, cooling the engine head, block, transmission oil, etc. The separate circuit aftercooler system has a dedicated water pump, lines, and heat exchanger for the aftercooler. This system is typically used in applications where maximum aftercooling is required. Many marine applications utilize separate circuit aftercoolers in conjunction with a heat exchanger that is designed to use the keel water for cooling the circuit. Many of Caterpillar’s large mining trucks also use this type of aftercooler.

From the air cleaner (turbocharger/aftercooler, if equipped) the incoming air enters the inlet manifold. The inlet manifold directs the air into the cylinder head.

Fig. 2.1.17 Intake Stroke

Intake Stroke Air fills the inlet ports in the cylinder head. On the INTAKE stroke as the piston travels down in the cylinder the intake valves open, and air fills the volume of the cylinder.

Fig. 2.1.18 Compression Stroke

Compression Stroke On the COMPRESSION stroke, as the piston begins to travel up, the intake valves close. The air that is trapped in the cylinder is compressed. Compressing the air raises the air temperature to a point where it will cause fuel to ignite when it is injected into the cylinder.

Fig. 2.1.19 Power Stroke

Power Stroke When the piston nears the top of its travel, fuel is injected into the cylinder. The fuel mixes with the hot air and combustion begins. The energy released by the combustion forces the piston down producing the POWER stroke.

Fig. 2.1.20 Exhaust Stroke

Exhaust Stroke Near the end of the POWER stroke the exhaust valves open. Any residual pressure from combustion will rush into the exhaust manifold. On the upward or EXHAUST stroke the gases are pushed out of the cylinder by the piston. At the top of the stroke the exhaust valves close and the cycle starts over.

Fig. 2.1.21 Exhaust Flow

Exhaust Flow Exhaust gases leaving the cylinder enter the exhaust manifold and are then routed to the turbocharger, if equipped. The hot exhaust gases flowing out of the cylinders contain substantial unused heat energy. The turbocharger exhaust turbine captures some of this heat energy.

Fig. 2.1.22 Turbocharger Operation

Turbocharger Operation The exhaust gases flow past the blades of the turbine wheel and cause the turbine wheel to rotate. The turbine wheel is connected by a shaft to the compressor wheel. The exhaust gases push the turbine and subsequently the compressor wheel to a high RPM, about 80,000 130,000 RPM. This causes the intake air to be compressed. When the load on the engine increases, more fuel is injected into the cylinders. The increased combustion generates more exhaust gases causing the turbine and compressor wheel to turn faster. As the compressor wheel turns faster, more air is forced into the engine.The maximum rpm of the turbocharger is controlled by the fuel setting, the high idle speed setting and the height above sea level.

Fig. 2.1.23 Exhaust Flow

Exhaust Flow From the turbocharger (if equipped), the exhaust gases pass through the exhaust pipe, the muffler, and the exhaust stack.

CATERPILLAR ENGINE AIR SYSTEMS SPECIFICATIONS Maximum inlet air temperature - 120°F ambient Maximum air cleaner restriction New filter - 15" H2O Used filter - use air filter service indicator On-highway diesel engines - 25" H2O Other diesel engines - 30" H2O Natural gas engines - 15" H2O Maximum aftercooler restriction Jacket Water Aftercooler - 3" Hg Air-to-Air Aftercooler - 4" Hg Maximum exhaust temperature Turbocharged - 1200°F (a small number of engines may be higher) Naturally aspirated - 1300°F Maximum exhaust restriction Turbocharged - 27" H2O Naturally aspirated - 34" H2O On-highway diesel engines - 40" H2O Maximum inlet manifold temperatures Turbocharged - 325°F Turbocharged, Jacket Water Aftercooled - 245°F Turbocharged, Separate Circuit Aftercooled (85°F water) - 125°F Turbocharged, Air-to-Air Aftercooled - 150°F

Conversion data .5 psi = 1" Hg = 1' H2O = 3.5 kpa 1 psi = 2" Hg = 2' H2O = 7 kpa 15 psi = 30" Hg = 30' H2O = 103 kpa

Lubrication Systems and Oil

Unit 3 Lubrication Systems and Oil

Unit Objectives: The student will be able to: 1. Explain the function of the engine lubrication system and its components. 2. Identify proper oil classifications for diesel engines. 3. Explain a normal oil maintenance schedule for a Caterpillar 3406E engine. 4. Remove, inspect, and install lubrication system components on a Caterpillar 3406B or 3406C engine. Unit References: 3406 Lube System Presentation Oil Development at Caterpillar CG-4, The Preferred Oil Oil and Your Engine Oil in Your Engine 3406E Operation and Maintenance Manual 3406B Service Manual 3406C Service Manual Unit 3 Quiz

Tooling: 8T0461 Serviceman’s Tool Set or Equivalent 1U5750 Diesel Engine Repair Stand 1U5749 Engine Adapter Plate

CD-ROM Copy LEDQ7315 SEBD0640 LEVP9001 SEBU6758 SEBR0544 SEBR0550 Copy

Objectives: The student will be able to explain the operation of the lubrication system and identify related components. References: 3406 Lube System Presentation Oil Development at Caterpillar CG-4, The Preferred Oil Oil and Your Engine Oil in Your Engine 3406E Operation and Maintenance Manual

CD-ROM Copy LEDQ7315 SEBD0640 LEVN9001 SEBU6758

Introduction: The lubrication system in a diesel engine is more important than ever due to the demands of the high performance, low-emission engines of today. Not only is the lube system required to provide clean oil to the proper places in the engine but the oil itself must withstand higher temperatures and extended drain intervals while maintaining a low rate of consumption.

Lubrication System Components

Lesson 1: Identify Lubrication System Components and Their Operation.

This presentation will review components and operation of a Caterpillar 3406 lube system. This system is typical of a Caterpillar engine, but some engines will differ. Engines that use the HEUI fuel system will differ significantly.

Fig. 3.1.1 Caterpillar 3406 Engine

Introduction This presentation covers the lubrication system of a Caterpillar 3406B or 3406C engine for illustrative purposes. Refer to the systems operation manual for a particular engine of interest.

Fig. 3.1.2 Lubrication System Components

Lubrication System Components The lubrication system contains the following components: 1. 2. 3. 4. 5. 6. 7. 8. 9.

Oil pick-up tube and suction bell Oil pump Oil pressure relief valve Oil cooler bypass valve Oil cooler Oil filter bypass valve Oil filter Oil supply to turbocharger Oil supply to engine

Fig. 3.1.3 Oil Passages

Oil Passages The lubrication system inside the engine includes the following components: 1. Oil manifold (gallery) in block 2. Piston cooling jet 3. Oil passage to main and cam bearings 4. Camshaft and main bearing oil passage 5. Front oil supply for lifters 6. Rear oil supply for lifters 7. Front oil supply to rocker shaft 8. Rear oil supply to rocker shaft 9. Oil supply to fuel pump

Fig. 3.1.4 Front Gear Train Lubrication

Front Gear Train Lubrication The lubrication for the front gear train includes the: 1. Oil supply to idler gear shaft 2. Oil supply to accessory drive Let’s trace the flow of oil through each component.

Fig. 3.1.5 Oil Pump Oil Flow

Oil Pump Oil Flow Lubricating system flow begins as the pump draws oil from the oil pan sump. The oil pump pick up tube has a suction bell at the open end which is located low in the pan sump. The suction bell contains a screen to prevent foreign material from entering the oil pump. Many Caterpillar engines are designed to work in applications that may require the engine be at a steep angle. A track type tractor for example, typically is used in applications that require the machine and engine be at a relatively steep angle from the horizontal. In order to ensure that all of the engine oil does not collect in one end of the oil pan, away from the suction bell, many engines also have a scavenge oil pump. A scavenge oil pump is nothing more than an oil pump that ensures that there is always oil in the main sump. This keeps the lubrication system from being starved of oil at steep slopes.

Fig. 3.1.6 Oil Pump Description

Oil Pump Description The oil pump is a positive displacement gear type pump, driven by the crankshaft gear.

HOUSING DRIVE GEAR INLET OIL

OUTLET OIL FORCE

MESHING GEAR TEETH IDLER GEAR

Fig. 3.1.7 Gear Pump

The basic gear pump is the type most commonly found on Caterpillar engines. This pump has two gears in mesh. One gear is driven by the engine and the other is an idler gear. The two gears rotate in opposite directions capturing the engine oil, and drawing it around the inside of the housing. When the teeth come together in mesh the oil is forced out of the teeth and flows through the pump outlet to the rest of the lubrication system.

INNER GEAR OUTLET PORT

OUTER GEAR

INLET PORT

Fig. 3.1.8 Rotor Pump

Some Perkins engines use a rotor type pump. This pump has an inner gear and a outer gear that are in mesh with one another. The inner gear is driven by the engine. The centerline of the outer gear is offset from the inner gear and is free to turn. As the inner gear is turned it causes the outer gear to rotate. Engine oil is drawn into the pump through the inlet and carried in the space between the two rotating parts to the outlet. On the outlet side the inner gear and the outer gear come into mesh with one another and force the oil to be pushed out the outlet port of the pump.

Fig. 3.1.9 Oil Pump Relief Valve

Oil Pump Relief Valve The oil pump has an integral pressure relief valve which controls the maximum system operating pressure. Limiting the pressure helps to reduce leaks and prolong seal life.

Fig. 3.1.10 Oil Pump Relief Valve

Oil Pump Relief Valve The valve will remain on its seat (closed) until the oil pressure at the pump rises above the pressure that is exerted by the spring in the valve. As pressure in the system nears the maximum, it will force the valve off its seat and allow some oil to bypass to the low pressure side of the pump. If the pressure in the system continues to rise, the valve plunger will move farther down allowing more flow to bypass. When the engine oil is cold it will be thick or have a high viscosity, and will resist flowing. During cold engine start ups the oil will resist flowing through the engine. Pressure will build quickly, causing the valve to open.

Fig. 3.1.11 Oil Cooler

Oil Cooler Many engines are equipped with an oil cooler assembly. The cooler utilizes an engine oil to coolant heat exchanger. Hot engine oil passing through the cooler element transfers heat to the engine coolant. This cooling of the oil helps to maintain the lubricating properties of the oil under heavy engine load.

Fig. 3.1.12 Oil Cooler Bypass Valve

Oil Cooler Bypass Valve During cold start ups, the cold oil will also resist flowing through the oil cooler. To prevent this resistance from causing oil starvation, an oil cooler bypass valve is incorporated into the cooler assembly. This bypass valve senses oil pressure between the inlet and outlet of the cooler. It is designed to open and bypass oil flow around the cooler when the oil is cold and thick.

Fig. 3.1.13 Oil Filter

Oil Filter The oil filter base mounts at least one filter element. Most Caterpillar engines use spin-on style full flow filters in order to remove damaging foreign materials from the engine oil.

Fig. 3.1.14 Oil Filter Bypass Valve

Oil Filter Bypass Valve The engine oil flows in the outside of the filter, through the filter media, and out the hole in the center of the filter under normal operating conditions. However, the filter element resists cold oil flow. It also resists oil flow when it becomes dirty. To prevent damage to the element and possible oil starvation to the system, the filter base is equipped with a filter bypass valve. The bypass valve senses the pressure differential across the element and will open, bypassing oil flow around the element if the pressure becomes excessive. This is one reason why proper maintenance procedures are so important. Dirty filters can lead to serious problems.

Fig. 3.1.15 Turbocharger Lubrication

Turbocharger Lubrication The turbocharger oil supply line is connected to the outlet of the filter base. An adequate supply of cooled, clean oil is essential to turbocharger life. Thus, the turbocharger receives oil flow before other engine components. Oil cools, and lubricates the bearings of the turbocharger. Oil flow from the turbocharger is returned to the oil pan. This is also why hot shutdowns or high rpm shutdowns of the engine are bad. Insufficient oil flow under these conditions could lead to premature failure of the turbocharger. The turbocharger needs the oil to cool and to lubricate its bearings.

Fig. 3.1.16 Piston Cooling Jets

Piston Cooling Jets Clean, cooled oil is directed from the filter base to the oil manifold in the engine block. The piston cooling jets are connected to the oil manifold and direct a small stream of oil to the underneath side of the pistons for cooling. This helps to cool the pistons to a uniform temperature and provide a longer service life of the pistons.

Fig. 3.1.17 Oil Supply to Bearings

Oil Supply to Bearings Each pair of main and camshaft bearings is connected by an oil passage that is drilled in the block. The drilled passage receives oil through an intersecting drilled passage that is connected to the oil manifold.

Fig. 3.1.18 Oil Supply to Crankshaft Bearings

Oil Supply to Crankshaft Bearings A groove around the inside of the upper main bearing shells supplies oil flow to internal drilled passages in the crankshaft. The internal crankshaft passages supply oil to the connecting rod bearings.

Fig. 3.1.19 Valve Lifter Lubrication

Valve Lifter Lubrication A groove around the outside of the front and rear camshaft bearings supply oil flow to the front and the rear valve lifter passages. Each lifter body, roller and lower push rod socket receive lubrication from these passages.

Fig. 3.1.20 Rocker Shaft Lubrication

Rocker Shaft Lubrication The rear rocker shaft receives oil flow from the rear valve lifter oil passage. The front rocker shaft receives oil flow from a drilled passage connected to the front camshaft supply passage. Drilled passages in the rocker shafts supply the upper valve train with oil flow. This is also used to supply oil to the compression release brake (Jake Brake), if equipped.

Fig. 3.1.21 Front Gear Train Lubrication

Front Gear Train Lubrication The front gear train idler gear and the accessory drive receive oil flow from an internal drilled passage that is connected to the front camshaft oil passage.

Fig. 3.1.22 Air Compressor Lubrication

Air Compressor Lubrication The air compressor receives oil from the oil passage to the accessory drive, through passages in the timing gear housing and the accessory drive gear.

Fig. 3.1.23 Fuel System Lubrication

Fuel System Lubrication In a typical Caterpillar pump and line fuel system the fuel pump, governor and hydraulic timing advance unit receive oil flow from a port on the side of the block. This port is connected to the number three main and camshaft passage.

Fig. 3.1.24 Caterpillar BrakeSaver

BrakeSaver Option Since the BrakeSaver retarder option becomes an integral part of the lubrication system, we will review the operation of the BrakeSaver along with the changes to the lubrication system the option requires. As we learned earlier, the BrakeSaver retarder is a hydraulic retarder that provides smooth, efficient vehicle breaking on long downhill grades.

Fig. 3.1.25 BrakeSaver Oil Pump

Brake Saver Oil Pump Engines equipped with a BrakeSaver retarder have a two section oil pump. The front section of the pump supplies oil for the lubrication of the engine. The path of the oil from the front section is the same as the standard oil pump, except the oil does not go to the oil cooler. The oil from the front section of the pump flows directly to the oil filter. The rear section of the oil pump supplies oil for BrakeSaver operation and oil cooling.

Fig. 3.1.26 Oil Pump Bypass Valve

Oil Pump Bypass Valve When the oil is cold, the high viscosity causes the bypass valve to open and drain the oil from the rear section of the pump back into the oil pan.

BrakeSaver Control

Fig. 3.1.27 BrakeSaver Control

BrakeSaver Control When the BrakeSaver retarder is in operation, the braking force available is in direct relation to the amount of oil in the compartment. The BrakeSaver control valve determines the amount of oil delivered to the unit.

Fig. 3.1.28 BrakeSaver Operation

BrakeSaver Operation When the oil is warm, the oil is sent to the BrakeSaver control valve. If the BrakeSaver control lever is in the OFF position, spring force holds the valve spool against the cover at the air inlet end of the control valve. With the valve spool in this position, the valve directs the warm oil to the oil cooler. From the oil cooler the oil goes back through the BrakeSaver control valve and returns to the oil pan.

Fig. 3.1.29 BrakeSaver Operation

BrakeSaver Operation If the BrakeSaver control lever is in the ON position, air pressure moves the valve spool to the right against the spring force. Engine oil from the oil pump is sent through the control valve to the BrakeSaver. After the oil goes through the BrakeSaver, it returns to the BrakeSaver control valve. The valve then directs the oil to the oil cooler. From the cooler, the oil again returns to the control valve and is sent back to the oil pan.

Fig. 3.1.30 BrakeSaver Lubrication

BrakeSaver Lubrication Lubrication for the BrakeSaver retarder is provided by an outside oil line from the engine lubrication system. This oil lubricates the piston ring seals and the lip-type seals under all conditions of BrakeSaver retarder operation. The drain line returns the oil to the oil pan.

Fig. 3.1.31 BrakeSaver Components

BrakeSaver Components The BrakeSaver housing is fastened directly to the rear face of the flywheel housing. The BrakeSaver retarder consists of the housing, stator and rotor. The rotor is attached to the crankshaft and rotates in a space between the stator and the housing.

Fig. 3.1.32 BrakeSaver Rotor

BrakeSaver Rotor The rotor has pockets on the outer circumference of both sides and four holes to permit equal oil flow to both sides.

Fig. 3.1.33 BrakeSaver Housing

BrakeSaver Housing The BrakeSaver housing and the stator are fastened to the flywheel housing and cannot turn. Both the housing and the stator have pockets on their inside surfaces in alignment with the pockets in the rotor.

Fig. 3.1.34 BrakeSaver Operation

BrakeSaver Operation When the BrakeSaver retarder is in operation, engine oil comes into this compartment from a passage in the bottom of the housing. The rotor, turning with the crankshaft, throws this oil outward into the stator and the housing compartment. The pockets or vanes on the turning rotor, force the oil to flow in the BrakeSaver compartment.

Fig. 3.1.35 BrakeSaver Operation

BrakeSaver Operation If the area in the stator and housing were smooth, the rotor and oil would turn inside the compartment with little opposition. However, both the stator and housing have vanes which are opposite the rotor. These vanes oppose the flow of the oil in the compartment induced by the rotor. It is this resistance of the oil flow that creates the retarding action of the BrakeSaver retarder. This resistance to the oil flow creates heat in the oil which is removed by the oil cooler.

ENGINE OIL FUNCTIONS In the modern diesel engine, engine oil must perform four basic tasks without having a negative impact on engine performance and longevity of the engine. These functions of the oil are discussed here. Lubrication The engine oil provides a film of protection between the moving parts of the engine. This oil film reduces friction, wear, and heat in the engine. In order to maintain the proper thickness of this oil film the engine must run at the correct temperature, the engine oil pump must produce the correct pressure, and the oil must have the correct viscosity. Cooling The combustion that takes place in the engine produces a tremendous amount of heat, especially on the pistons. The engine oil is the primary cooling agent for the pistons. Much of the heat is removed by the oil that is between the cylinder wall and the piston and by "splash" oil thrown off moving parts. Additionally, many engines have piston cooling jets that spray oil at the underside of the pistons, providing a tremendous cooling effect to the pistons. This is a primary reason that engine oil is required to withstand high temperatures without losing its properties. Cleaning As the engine operates there will be some amount of blowby. There will also be some amount of foreign debris in the engine from one source or another. It is the responsibility of the engine oil to carry the contaminants out of the moving engine components, so that the contaminants will be cleansed from the system by the engine oil filter. This is especially important in the engines equipped with the HEUI fuel system. The HEUI fuel system uses engine oil to operate. The engine oil helps to keep contaminants from collecting in the engine. Sealing The engine oil creates a film between the piston rings and the cylinder walls. This film not only lubricates, but also helps to seal the combustion chamber of the engine off from the crankcase. This helps to prevent blowby.

OIL DEVELOPMENT AT CATERPILLAR Lubricating oil used in the first Caterpillar Diesel, introduced in 1931, was straight mineral crankcase oil. When the engines began experiencing ring sticking and cylinder liner scratching, it became apparent that a more effective oil was needed. In 1935, the first additive crankcase oil was developed in a cooperative effort of several U.S. oil companies and Caterpillar. The performance standards for this and subsequent oil were established by tests performed on a single cylinder test engine designed and built by Caterpillar specifically for oil testing. This initial crankcase oil was named "Superior Lubricants for Caterpillar Engines" and was sold only through Caterpillar Dealers. The test, run by engine manufacturers, required that the single cylinder test engine be disassembled after it had run for a designated period of time at a pre-determined load and speed. Pistons were inspected, and the color change caused by lacquering was observed and recorded. Other critical factors such as ring wear and deposits were measured. In 1958, Caterpillar established the Series 3 classification. It wasn’t until 1970, that the API (American Petroleum Institute) recognized the need to revise its classification system. The API, SAE, and ASTM collaborated in this effort. Their new system was based on the same type of performance specifications which Caterpillar and others had been using. Caterpillar was able to drop its classification system in 1972. The new API/SAE system established CD, CC and other SAE letter designations for oil classifications. These referred to performance levels in engine tests. A list of all brand name API-rated oils is included in the Engine Manufacturers Association Lubricating Oils-Data Book, available from your Caterpillar Dealer, Caterpillar form number SEBU5939. Caterpillar recommends that you use (SOS) Fluid Sampling, a service offered by most Caterpillar Dealers. An analysis of your engine oil can show the presence of metal wear particles which can indicate acid attack or other abnormal wear. Before taking an oil sample, operate the engine until it is at the normal operating temperature. A sampling valve and adapter is available to take an oil sample while the engine is running. Fill the new sample bottle approximately 75% full. If a sample is taken from the oil drain stream do not get the sample from the first part or the last part of the oil drain. Use caution to prevent burns or injuries caused by the hot oil. Fill out the sample and shipment labels. Make sure engine serial number, miles on oil, and unit number are indicated.

Lab Exercises: Using a lab engine, explain lubrication system and components including oil cooler, oil filter, sump, and location of oil pump. Install the engine onto a 1U5750 repair stand with 1U5749 adapter. Using the appropriate 3406 Service Manual as a guide, remove the oil filter base from the 3406 lab engine and disassemble. Take note of the oil filter bypass valve. Remove oil cooler taking note of core and circulation path of oil and path of coolant. Remove oil pan and oil pump. Disassemble oil pump taking note of gears and relief valve. Inspect oil pump using specifications from the Service Manual. Install lubrication system components removed in previous procedures using the Service Manual as a guide.

Unit 4: Cooling Systems

UNIT 4 Cooling Systems

Unit Objectives: The student will be able to: 1. Identify the components of engine cooling systems and explain their function. 2. Explain cooling system maintenance and characteristics of diesel engine coolant. 3. Remove, inspect, and install cooling system components on a Caterpillar 3406B or 3406C engine. Unit References: Cooling System Design Fundamentals Coolant and Your Engine A Close Look at Cat Extended Life Coolant 3406B Service Manual 3406C Service Manual Unit 4 Quiz Tooling: 8T0461 Serviceman's Tool Set or equivalent 9S8140 Pressurizing Group 5P0957 Battery/Coolant Tester 8T5296 Coolant Test Kit

LEKQ7353 SEBD0970 LEDQ7330 SEBR0544 SEBR0550 Copy

Objectives: The student will be able to explain the operation of the engine cooling system and identify related components. References: Cooling System Design Fundamentals Coolant and Your Engine A Close Look at Cat Extended Life Coolant

LEKQ7353 SEBD0970 LEDQ7330

Introduction: A diesel engine is dependent on the cooling system to achieve maximum performance and engine life. Cooling system problems may include small annoying leaks, fuel economy complaints, accelerated engine wear, or sudden catastrophic engine failure. If the flow of coolant in the engine stops for even a short amount of time, there is a high risk of significant damage to the engine.

Lesson 1: Cooling System Components

Lesson 1: Identify Cooling System Components and Function

Fig. 4.1.1 Cooling System and Energy Distribution

The cooling of an engine depends on the principles of conduction, convection, and radiation of heat energy in order to keep the engine running at the proper operating temperature. The coolant receives the heat that is conducted to it from the metal components of the engine; the engine block, the cylinder head, etc. The coolant is then forced by the water pump from the engine to the radiator. At the radiator the heat energy is transferred by convection to the air moving across the fins of the radiator. In addition the engine also radiates a certain amount of energy to the atmosphere directly in the form of heat that is given off from the engine to the surrounding air. The components of a cooling system for an engine are extremely simplistic. The basic components of every cooling system include: The water jacket The water temperature regulator(s) (thermostat(s)) The radiator (or heat exchanger) The pressure cap The water pump Hoses The engine may also have some type of coolant cooled aftercooler, oil cooler, hydraulic cooler, or transmission cooler. Some marine or stationary systems may have a heat exchanger in place of the radiator. The pump is what causes the coolant to flow in the cooling system. Inside the engine are coolant passages that the water flows in. These passages include what is sometimes called a "water jacket." The water jacket is the large cavity in the block and the head that surrounds the cylinders of the engine. This cavity is normally full of coolant and is what keeps the engine at a uniform temperature.

Fig. 4.1.2 Water Temperature Regulator

The water temperature regulator(s) (thermostat(s)) regulate the flow of coolant to the radiator. When the engine is cold, the water temperature regulator is closed and the water coming from the engine is closed off from the radiator. The water is then recirculated through the water pump, back into the engine. This helps the engine acheive operating temperature more quickly. When the engine is warm, the water temperature regulator allows the coolant to flow to the radiator to be cooled before reentering the engine. The water temperature regulator is not strictly fully open or fully closed. The water temperature regulator modulates between open and closed in order to keep a constant temperature in the engine. Proper engine temperature is very important. An engine that runs too cold will not operate at a high enough temperature to have efficient combustion and will lead to sludge buildup in the lubrication system of the engine. An engine that runs too hot will overheat and may lead to serious damage of the engine.

Fig. 4.1.3 Radiator

The radiator is the component of the cooling system that rejects the heat from the coolant to the air. A radiator has tubes that the coolant flows through most generally from the top of the radiator to the bottom. At the bottom of the radiator there is a hose leading to the pump to start the circulation over again. The tubes have fins attached to them that help to reject the heat to the air moving across the radiator.

Fig. 4.1.4 Pressure Cap

Perhaps the most overlooked component of the cooling system is the pressure cap. The pressure cap has a relief valve that will not allow the pressure of the cooling system to exceed a predetermined level. The pressure cap maintains a certain amount of pressure in the cooling system. This is very important because, by increasing the pressure of the cooling system by 1 psi, the boiling point of the coolant is raised 3.25 degrees F. This allows coolant to run hotter wihout boiling. A typical cooling system will have anywhere from a 7 psi to a 12 psi pressure cap, so this can have a significant effect on the cooling of an engine.

Objectives: Using the appropriate Caterpillar 3404 Service Manual, the student will demonstrate the ability to correctly remove, inspect, and install cooling system components. References: 3406B Service Manual 3406C Service Manual

SEBR0544 SEBR0550

Introduction: To effectively perform diagnosis, repair, and service on a diesel engine cooling system, it is necessary to be able to remove, inspect, and install the related components.

Lesson 2: Remove and Install Cooling System Components

Lesson 2: Remove and Install Cooling System Components

Unit 4 Lesson 2

4-2-2

Engine Fundamentals

Lab Exercises Using a lab engine or engine installed in a vehicle, show students cooling system components and explain their function including coolant pump, regulator, and radiator. Test radiator cap using 9S8140 Pressurizing Group. Test coolant using 8T5296 Coolant Test Kit. Using a lab tear-down engine, remove water pump and discuss failure mode (bad seal, loose, eroded, or cracked impeller). Remove temperature regulator (thermostat). Point out importance of the seal around the thermostat and trace flow of the bypass circuit.

Unit 5: Diesel Fuel

UNIT 5 Diesel Fuel Characteristics Mechanically Controlled Fuel Systems

Unit Objectives: 1. The student will be able to explain the characteristics of diesel fuel and proper fuel system maintenance procedures for Caterpillar engines. 2. The student will be able to identify and explain the operation of the following Caterpillar fuel systems: new scroll, sleeve metering, and mechanical unit injector. 3. The student will be able to remove and install 3406 New Scroll Fuel System, plunger and barrel group, nozzles, timing advance, and injection pump and governor group. The student will demonstrate the ability to test a fuel nozzle.

Unit References: Diesel Fuels and Your Engine 3406E Operation and Maintenance Manual Fuel Contamination Control Caterpillar New Scroll Fuel System Introduction Using 5P4150 Nozzle Tester Group Testing 7000 Series Nozzles 3406B Service Manual 3406C Service Manual

SEBD0717 SEBU6758 PEHP7046 CD-ROM SEHS7292 SEHS9083 SEBR0544 SEBR0550

Unit References: (Continued) Fuel Nozzle Testing The Sleeve Metering Fuel System The Sleeve Metering Fuel System CD-ROM 3116/26 Mechanical Unit Injector Presentation Unit 5 Quiz Tooling: 8T0461 Serviceman's Tool Set or equivalent 6V4186 Pin 9S9082 Turning Tool 1P7408 Thermo-hydrometer 5P5195 Fuel Line Wrench 5P0144 Fuel Line Socket 8S2244 Extractor 8T5287 Wrench 5P4150 Nozzle Test Group 6V2170 Tube Assembly 6V2171 Tube Assembly 5P7448 Adapter 8T3139 Spanner Wrench 8T3198 Nozzle Tube 8T3199 Nozzle Screw 6V6983 Adapter 1B4206 Nut 8S2270 Collector Assembly 6V4089 Nozzle Reamer 6V7025 Nozzle Seal Guide 1U9725 Nozzle Adapter Wrench

LEVP9167 LEBQ9802 LERV9802 CD-ROM

Lesson 1: Diesel Fuel

Lesson 1: Diesel Fuel

Objectives: The student will be able to explain diesel fuel characteristics and related maintenance. References: Diesel Fuels and Your Engine 3406E Operation and Maintenance Manual Fuel Contamination Control

SEBD0717 SEBU6758 PEHP7046

Introduction: Diesel fuel is by far the largest expense related to owning and operating a diesel engine. The characteristics, quality, and handling of the fuel affect the performance and life of the engine.

Heating Value of Diesel Fuel

HEAT VALUE PER GALLON IN BTU 1D Diesel

137,000

2D Diesel

141,800

Gasoline Butane Propane

125,000 103,000 93,000

Fig. 5.1.1 Heating values of various fuels

The heating value of a fuel is defined as the amount of heat produced by burning a specific weight of fuel. This is an indicator of how much available energy is available in a specific amount of fuel. The chart above shows the heating values for various common fuels. 1D diesel is winter blended diesel, and 2D diesel is summer blended diesel. Notice that both blends of diesel fuel have a significantly higher heating value than any of the other fuels listed. What this means is that in a given amount of diesel fuel there is more energy available to be turned into useful work. This is one of the significant advantages to using diesel power as a source of energy.

Objectives: The student will be able to explain the operation of the Caterpillar New Scroll Fuel System. References: Caterpillar New Scroll Fuel System Introduction

CD-ROM

Introduction: The Caterpillar New Scroll Fuel System has been in production since 1980 on the 3300 series engines. When the 3406B was released in 1983, the New Scroll Fuel System was added to help improve emissions, performance, and fuel economy. Another benefit of the New Scroll Fuel System is that the individual injection pumps do not need adjustment or calibration.

Lesson 2: Caterpillar 3406 New Scroll Fuel System

Lesson 2: Caterpillar 3406 New Scroll Fuel System

This presentation covers the Caterpillar New Scroll Fuel System.

Fig. 5.2.1 Caterpillar 3406B Engine

Caterpillar 3406B Engine The Caterpillar 3406A was introduced in 1973. Since then, a number of changes have been made to meet the demand for an even more reliable and economical product, while meeting governmental regulations. The 3406B, released in 1983, is an example of these changes. The major change to this engine was the fuel system. The New Scroll Fuel System had been in production since 1980 on the 3300 engines. This fuel system is a key factor in the emissions, performance and fuel economy improvements in the 3406B. In 1991, the fuel system was changed to incorporate a more aggressive fuel camshaft to improve emissions. In 1992 the 3406C was introduced. There were no changes to the mechanical fuel system.

Fig. 5.2.2

Caterpillar 3406 Fuel Injection Pump Groups In the top view we can see how the 3406A Engine Fuel Injection Pump had a long drive because there wasn’t room for the pump housing under the air compressor. In the lower view we see the 3406B/C Fuel Injection Pump. It is shorter, but more massive. The shorter length of the 3406B/C pump leaves more room for servicing.

Fig. 5.2.3 Injection Pump Camshafts

Injection Pump Camshafts Many of the changes and improvements were internal, and can’t be seen. Here we see the fuel injection pump camshafts. The 3406A is at the top. The 3406B camshaft below it is larger and heavier, and is driven by a gear on the left end. The 3406B cams have a different configuration--they have a faster lift and shorter duration, increasing fuel injection pressures and reducing the time of injection, for greater fuel efficiency. An eccentric on the camshaft operates the piston-type fuel transfer pump. With the changes for emissions in 1988, the nose of the camshaft changed. The 10 degrees helix on the front was changed to a 15 degrees helix and the hole in the front was enlarged to accommodate a different timing advance unit. The emission changes for 1991 was a bearing diameter and lobe shape change only.

Fig. 5.2.4 3406 Fuel Flow

This is a schematic of the 3406B/C engine fuel system. We’ll use the schematic to follow the flow of fuel from the supply tank to the injector in the cylinder. The transfer pump (5) pulls fuel from the fuel tank (1) through the supply shutoff valve (3) through the primary fuel filter (4) to the fuel transfer pump itself. The transfer pump then pressurizes the fuel and pushes it though the hand priming pump (7), into the secondary fuel filter (6) and into the fuel manifold (8) under moderate pressure. A bypass valve inside the fuel transfer pump maintains moderate fuel pressure. With moderate fuel pressure inside the fuel manifold and the void (vacuum) inside the high pressure pumps, the fuel is loaded into the cavity of the high pressure pump. The high pressure pumps now meter a small amount of fuel and sends it though the high pressure fuel lines (9) and through the head adapter (10) to the injection nozzle (11) at a very high pressure. When the fuel pressure in the high pressure fuel lines gets above the nozzle opening pressure the fuel is injected into the combustion chamber. With both very high pressure and very small holes in the tip of the nozzle, the fuel is atomized and gives complete combustion in the cylinder. Any air and some fuel is sent out of the fuel manifold through the return line (15) back to the supply tank. The tank drain (2) is used to remove water, sediment and foreign material and to drain the supply tank. The fuel tank cap (16) must be vented to atmosphere to keep vacuum from forming inside the fuel tank.

Fig. 5.2.5 3306 Fuel Flow

3306 Fuel Flow This is a schematic of the 3306B/C engine fuel system. We’ll use the schematic to follow the flow of fuel from the supply tank to injection in the cylinder. The transfer pump (6) pulls fuel from the fuel tank (9) through the supply shut off valve (3) through the primary fuel filter (4) through the hand priming pump (5) into the transfer pump itself. The transfer pump then pressurizes the fuel and pushes it through the secondary fuel filter (7) and to the fuel manifold in the injection pump housing (8). A bypass valve inside the fuel transfer pump maintains moderate fuel pressure. With moderate fuel pressure inside the fuel manifold and the void (vacuum) inside the high pressure pumps, the fuel is loaded into the cavity of the high pressure pump. The high pressure pumps now meter a small amount of fuel and sends it though the external high pressure fuel lines (9) at a very high pressure to the fuel injection nozzle (10). When the fuel pressure in the high pressure fuel lines gets above the nozzle opening pressure the fuel is injected into the combustion chamber. With both very high pressure and very small holes in the tip of the nozzle, the fuel is atomized and gives complete combustion in the cylinder. A constant bleed valve (11) lets a constant flow of fuel go through the fuel return line (12) back to the fuel tank (1). This helps keep the fuel cool and free of air. There is also a manual bleed valve that can be used when the fuel priming pump is used to remove air from the system. The supply tank drain (2) is used to remove water, sediment, foreign material and to drain the supply tank. The fuel cap must be vented to atmosphere to keep a vacuum from forming inside the fuel tank.

Fig. 5.2.6 Fuel System Components

Fuel System Components In this view we can see some of the components of the 3406B fuel injection system on the engine. Visible are the fuel injection pump housing, the governor housing, the fuel transfer pump and the external fuel injection lines.

Fig. 5.2.7 3306 Fuel System Components

3306 Fuel System Components In this view we can see some of the components of the 3306B/C fuel injection system on the engine. Visible are the fuel injection pump housing, the governor housing, the fuel transfer pump, fuel injection lines, the fuel filter and base and the fuel priming pump.

Fig. 5.2.8 Fuel Transfer Pump

Fuel Transfer Pump The fuel transfer pump is located on the bottom of the 3406B/C pump housing and on the side of the 3304B or 3306B/C pump housing. It is activated by the eccentric on the fuel pump camshaft inside the housing and can deliver up to 51 gallons of fuel per hour at 25 psi. This is a spring pumping piston type pump where actual fuel pressure on the engine may vary from 20-45 psi depending on engine operating conditions. The pump only supplies what the engine requires, plus the amount returned to tank. (About 9 gallons per hour). It is a single piston, single action pump with three one-way check valves. The check valves are: inlet, pumping and outlet. This drawing shows that pumping and fill occur on the same pump stroke. Here, the tappet is almost completely extended and the return spring has forced the piston to the top of the pump. This upward motion of the piston opens the inlet check valve and fuel enters the inlet cavity (green). The pumping check valve at the top of the piston is closed and the piston pushes fuel into the outlet cavity (red). This pressurized fuel opens the outlet check valve at the outlet port. There is no pressure relief valve in this pump because fuel outlet pressure is controlled by the force of the piston spring.

Fig. 5.2.9 3406 Injection Pump

3406 Injection Pump The area shown in red is the fuel gallery of the 3406B/C fuel pump. This area is pressurized by the fuel transfer pump. The cutaway shows the placement of the pump groups within the pump housing. Fuel enters and leaves the pump group by way of the hardened hollow dowel. This dowel is in the housing to protect it from erosion caused by the high pressure spill pulses.

Fig. 5.2.10 3306 Injection Pump

3306 Injection Pump This is a cutaway of a similar area of the 3306B/C fuel pump. Notice the similarity of the two different pumps.

Fig. 5.2.11 3406 Fuel Rack

3406 Fuel Rack The area shown in the slide is a cutaway of the engine side of the 3406B/C fuel pump housing. This cutaway shows a complete pump in the center and a cutaway pump on the right. We can see the relationship of the pump groups and the rack as the gear segment engages the rack. Also note the lifters and return springs.

Fig. 5.2.12 Fuel Metering

Fuel Metering We’ll use a cutaway pump to see how fuel is metered and delivered to the fuel injection nozzles. This is a scroll type fuel system with a left-hand cut scroll on the pump plunger. The gear on the bottom of the plunger is engaged into the rack. Rack movement rotates the plunger in the pump barrel and changes the relationship of the scroll to the spill port (arrow). The camshaft/follower/lifter mechanism moves the plunger up and down in the barrel. In this position, the plunger is at the bottom of its stroke. Fuel is coming into the barrel through the spill port in the back side of the barrel and through the fill port.

Fig. 5.2.13 Fuel Delivery

Fuel Delivery Now, the cam has lifted the plunger so the fill port and spill port are just closed. This is the start of the effective stroke of the plunger and the beginning of injection. As the fuel in the barrel is pressurized, the reverse flow check valve is lifted off its seat in the pump bonnet. This sends pressurized fuel through the fuel lines to the injection nozzle. Injection continues until the end of the effective stroke, when the scroll in the plunger lines up with the spill port in the barrel.

Fig. 5.2.14 End of Fuel Delivery

End of Fuel Delivery At the end of the effective stroke, the spill port is opened by the scroll, fuel pressure is released and the reverse flow check valve closes. During the entire pumping cycle the groove on the plunger is positioned over the bleed back passage.

Fig. 5.2.15 Bleed Passage

Bleed Passage When the groove in the plunger is in this position, it is aligned with the pressure bleed back passage in the barrel. This bleeds of fuel that goes between the barrel and the plunger and prevents fuel dilution in the engine oil.

Fig. 5.2.16 Reverse Flow Check Valve

Reverse Flow Check Valve The reverse flow check valve keeps the fuel injection line full of fuel between injection strokes. Pressurized fuel (approximately 1000 psi) is kept in the injection line, ready for the next pump stroke. When the engine and injection pump are stopped, the groove (arrow) bleeds the pressure in the injection line to equalize with the residual pressure in the pump.

Fig. 5.2.17 Reverse Flow Check Valve Operation

Reverse Flow Check Valve Operation When fuel pressure in the barrel above the plunger reaches 100 psi, the valve is lifted off its seat and fuel flows out the cavity through the bonnet to the injection line. The check valve spring keeps the valve seated when fuel is at transfer pump pressure. This means that fuel can enter the injections lines only during the injection stroke, helping to eliminate cylinder wash down if an injection nozzle is stuck open.

Fig. 5.2.18 Reverse Flow Check Valve

Reverse Flow Check Valve Pressurization continues until the scroll opens the spill port and the pressure in the pump barrel is released. This seats the check valve, but the pressurized fuel in the injection line opens the return flow check valve. Fuel will return to the pump barrel and flow out the spill port until pressure in the injection line drops to 1000 psi. At that point, the return flow check valve spring will seat the valve. When the engine is shut off, a small groove in the face of the check valve allows the 1000 psi pressure to bleed off.

Fig. 5.2.19 3406 Fuel Manifold Cover

3406 Fuel Manifold Cover The high pressure fuel that exits through the spill ports goes through the hollow dowel into the fuel manifold and hits the cover plate. These highly pressurized fuel pressure pulses cause polish spots that are lined up with the spill ports on the manifold cover plate of the 3406B/C fuel system.

Fig. 5.2.20 3306 Fuel Manifold Cover

3306 Fuel Manifold Cover On the 3300 series engines, a spring steel pulse deflector is provided in the fuel manifold. This protects the aluminum manifold cover from the force of the released fuel pressure pulses.

Fig. 5.2.21 Governor Operation

Governor Operation At the point the rack screw (green) first comes in full contact with the torque spring, the rack is at full load point (rated). As demand horsepower increased, with the rack at rated position, the engine speed decreases as the engine goes into lug (full throttle with rpm less than rated rpm). Depending upon the rigidity of the torque spring, at some point, the governor spring causes the rack screw to begin to depress the torque spring. As this occurs, the rack position increases allowing more fuel to be injected per stroke. This increase in rack position continues until the torque screw (violet) contacts the stop lar. This is the full torque position of the rack.

Fig. 5.2.22 Governor Operation

Governor Operation The flyweights swing out as rpm increases. This moves the riser to compress the governor spring and the pivoting lever moves the sleeve and spool toward the "fuel off" direction.

Fig. 5.2.23 Valve Spool - "Fuel Off"

Valve Spool - "Fuel Off" As the valve spool moves in the direction shown, a passage in the piston opens and allows pressurized oil to enter the chamber behind the piston. At the same time, the spool closes the passage behind this chamber. The pressurized oil forces the piston and rack toward the "fuel off" position. With no load on the engine, the rack will move until the low idle setting is reached. This setting is determined by the amount of force put on the governor spring by the throttle resting against the low idle stop screw.

Fig. 5.2.24 Governor Operation

Governor Operation If the engine were to slow down, the flyweights would swing in which would move the riser away from the governor spring and the pivoting lever moves the sleeve and spool toward the "fuel on" direction.

Fig. 5.2.25 Valve Spool - "Fuel On"

Valve Spool - "Fuel On"This spool movement blocks the passage in the piston and opens the drain passage behind the chamber. Now pressurized oil forces the piston and the rack in the direction shown (fuel on) so fuel delivery is increased until the desired rpm is obtained. The back and forth movement of the rack in the "fuel off" direction and in the "fuel on" direction will continue until there is a balance between the governor spring force and the flyweight force.

Fig. 5.2.26 Valve Spool - Stabilized Fuel Position

Valve Spool - Stabilized Fuel Position This drawing shows the balance point of the servo spool and piston. When flyweight force equals governor spring force, the valve spool blocks the oil in the chamber behind the piston. Rack position does not change and engine rpm is constant.

Fig. 5.2.27 Fuel Ratio Control Function

Fuel Ratio Control Function The fuel ratio control mounts on the rear of the governor housing. Its purpose is to limit smoke and improve fuel economy during rapid acceleration. It does this by controlling rack movement in the fuel ON direction until there is enough (boost pressure) to allow complete combustion in the cylinders. With the fuel ratio control properly adjusted, it also minimizes the amount of soot in the engine.

Fig. 5.2.28 Fuel Ratio Control Operation

Fuel Ratio Control Operation A stem extends out of the fuel ratio control. This stem fits in a notch in a lever which contacts the end of the rack in the servo valve. Air inlet pressure (boost) is sensed by a diaphragm in the control. This diaphragm pushes against a spring and spool. The spool movement controls the oil flow which moves a piston connected to the stem. The stem is out of the way during startup, so full rack is available on all mechanical 3406s. The same is true of 3300s, but beginning with the 1994 3306C truck engine, the stem is partially retracted during startup, but does not go to full retraction until the engine develops oil pressure.

Fig. 5.2.29 Fuel Ratio Control Operation

Fuel Ratio Control Operation When boost is low, the stem is in the set (cocked) position and the lever limits rack movement in the fuel ON direction. As boost pressure increases, The stem extends and moves away from the lever and the rack can move to the left allowing more fuel to be supplied by the injection pumps. When manifold pressures of approximately one-half rated boost or above is reached, full fuel rack travel is available. Thus. anytime there is sufficient boost, the stem of the fuel ratio control is extended and does not control or affect the movement of the rack. This permits smooth, rapid acceleration but at a rate that allows complete combustion and low emissions.

Fig. 5.2.30 Fuel Shutoff Solenoid

Fuel Shutoff Solenoid A fuel shutoff solenoid is located on the rear of the governor. There are two types. One is energized to run, the other is energized to shut down. The one shown is an energized to run solenoid. When the engine’s electrical system is energized (key on), the solenoid is activated and it releases linkage to allow rack movement in any direction (fuel on - fuel off). When the electrical system is shut off (key off), the solenoid is deactivated and movement of the rack is prevented in the fuel ON direction, causing the engine to shut down. A diode is connected between the two terminals of the solenoid. The diode eliminates electric spikes (high voltage generated by the coil of the solenoid when it is de-energized) that might damage other electronic circuitry in the vehicle electrical system.

Objectives: The student will demonstrate the ability to correctly remove and install 3406 fuel system components and test a nozzle. References: 3406B Service Manual SEBR0544 3406C Service Manual SEBR0550 Test Sequence for Caterpillar 7000 Series Fuel Nozzles SEHS9083 Fuel Nozzle Testing LEVN9167 Introduction: The Caterpillar 3406 fuel system normally requires very little adjustment during the life of the engine. Normal maintenance may require replacement of components such as filters, nozzles, and transfer pump. Fuel system repairs may involve removal of plunger and barrel groups from the fuel injection pump, repair of the timing advance, or removal of the complete fuel system from the engine.

Lesson 3: Remove, Inspect and Install Fuel System Components

Lesson 3: Remove, Inspect and Install Fuel System Components

Lesson 4: Sleeve Metering Fuel System

Lesson 4: Sleeve Metering Fuel System

Objectives: The student will be able to explain how the Sleeve Metering Fuel System operates. References: The Sleeve Metering Fuel System 3208 Sleeve Metering Fuel System CD-ROM Diesel Fundamentals and Service - Thiessen, Dales

LEBQ9802 LERV9802 Textbook

Introduction: The Caterpillar Sleeve Metering Fuel System was most recently used on the 3208 engine. The 3208 was a popular mid-range on-highway truck engine until 1991 and saw continued use in marine and industrial applications for many more years.

Objectives: The student will be able to explain how the Mechanical Unit Injector Fuel System works. Lesson 5 References: 3116/26 Mechanical Unit Injector Presentation

CD-ROM

Introduction: The Mechanical Unit Injector fuel system provides improvements in performance and emissions when compared to some pump and line fuel systems. Caterpillar has used the Mechanical Unit Injector in small engines such as the 3116/3126 and large engines such as the 3500 and 3600 series. Tooling: None

Lesson 5: 3116/26 Mechanical Unit Injector Fuel System

Lesson 5: 3116/26 Mechanical Unit Injector Fuel System

Introduction: This presentation covers the Mechanical Unit Injector Fuel System used in the Caterpillar 3116/26 engine.

Fig. 5.5.1 1.1/1/2 Liter Engine Fuel Flow

1.1/1.2 Liter Engine Fuel Flow The 1.1 liter engine fuel system utilizes a mechanical unit injector combining both the nozzle assembly and the high pressure fuel injection pump. The fuel transfer pump) pulls fuel from the fuel tank through an in-line primary filter and sends fuel to a spin-on type secondary fuel filter. From the fuel filter, fuel enters a drilled passage at the rear of the cylinder head. The drilled passage carries fuel to a gallery around each unit injector and provides a continuous flow of fuel to all of the unit injectors. Unused fuel exits the cylinder head, passes through a 1.3 mm (.050 in.) pressure regulating orifice and a check valve and returns to the fuel tank. This system is very compact and eliminates external high pressure fuel lines. Additionally, this system allows very high injection pressures and short injection times to aid exhaust emission control.

Fig. 5.5.2 Unit Injector

Unit Injector The fuel injection system for this engine is a mechanical unit injector type. The fuel injection pump and nozzle are combined in one injector assembly for each cylinder. All high pressure lines are eliminated. Fuel lines consist of supply lines to and from the cylinder head, fuel filter and fuel transfer pump. Fuel is supplied to each injector by an internal passage running the full length of the head. Each unit injector has its own fuel rack, controlled by the governor with a control shaft which actuates all of the unit injectors simultaneously.

Fig. 5.5.3 Unit Injector Cut-away

Unit Injector Cut-away The large extension on the side of the injector is the hold-down clamp. Shown at the bottom of the injector cut-away is the rack. Its movement controls the rotation of the helix on the scroll of the plunger, thus determining the volume of fuel to be injected into the cylinder. The unit injector consists of a scroll-type high pressure plunger and injector nozzle. Effective stroke of the plunger, during which high pressure fuel is injected, is controlled by the scroll position which is actuated by the governor and rack.

This system is basically like other Caterpillar scroll type fuel systems except the high pressure pumps are separated and individually positioned above each combustion chamber thereby eliminating the need for high pressure fuel lines. Total plunger stroke is always the same and determined by the cam lobe lift and rocker arm motion. The effective stroke, however, is determined by the scroll position. The plunger rotates about its vertical axis to move the scroll, hence lengthening or reducing the effective stroke. During the time both ports are covered, fuel is injected. Fuel pressure forces the check valve off its seat for injection, and once pressure drops, a spring closes the check valve. Fuel surrounds the injector from the top oring to the raised sealing ring at the base of the nozzle cone.

Fig. 5.5.4 Injector Linkage

Injector Linkage The injector racks are actuated by a control shaft that is bolted to the top of the cylinder head. The governor actuates the control shaft which simultaneously moves all the injector racks to regulate fuel delivery. The power setting screw is also located on the control shaft. Note the synchronizing screws on the control shaft linkages at each injector location except No. 1.

Fig. 5.5.5 Governor

Governor The governor is mounted high on the left side on the front housing of the engine. It is driven by the cam gear in the front gear train. The governor regulates fuel delivery through a linkage to the control shaft which moves all of the injector racks simultaneously. The governor is a full range, flyweight type, with a floating fulcrum linkage. Additionally, a speed sensitive torque cam provides torque curve shaping. The fuel transfer pump is located in the forward portion of the governor housing. Power is set at the rack control shaft linkage under the valve cover using a dial position indicator. Governor adjustments are set on a dynamic bench test machine. The governor is also sealed after bench setting and is not to be adjusted except on the governor bench.

Fig. 5.5.6 Injector Sychronization

Injector Sychronization The injectors can be synchronized with the rocker arm assemblies in place such as when the valve setting and fuel injector timing is adjusted during preventive maintenance.

Fig. 5.5.7 Injector Sychronization

Injector Sychronization Injector synchronization is much easier with the rocker arms removed. Injector synchronization must be performed whenever the control linkage has been loosened or an injector is removed. Only the injector that was removed must be synchronized unless the injector removed was the No. 1 injector. In that case, all injectors must be synchronized since the No. 1 injector is used as a reference during the setting procedure. The valve clearance and fuel timing should be checked after installing the rocker arm assemblies.

Unit 7: Electronically Controlled Fuel Systems

UNIT 7 Electronically Controlled Fuel Systems

Unit Objectives: The student will be able to identify the following Caterpillar electronically controlled fuel systems: Programmable Electronic Engine Control (PEEC) Electronic Unit Injector (EUI) Hydraulic Electronic Unit Injector (HEUI) The student will remove and install the following components on a 3406E engine using the proper tooling and reference literature: camshaft injector injector sleeve Unit References: Caterpillar EUI Fuel System CD-ROM Cat 3406E Operation and Maintenance Video Caterpillar 3126B Engine CD-ROM 3406E Service Manual 3406E Service Manual Unit 7 Quiz Tooling: 8T0461 Serviceman's Tool Set or equivalent 9U7530 Service Tools for 3406E

RENR1391 LEVP3828 RENR1390 RENR1275 SENR5580 Copy

Objectives: The student will be able to explain the operation of the Programmable Electronic Engine Control (PEEC), Electronic Unit Injector (EUI), and Hydraulic Electronic Unit Injector (HEUI) fuel systems. References: Caterpillar EUI Fuel System CD-ROM Cat 3406E Operation and Maintenance Video Caterpillar 3126B Engine CD-ROM

RENR1391 LEVN3828 RENR1390

Introduction: In 1987, Caterpillar introduced the Programmable Electronic Engine Control (PEEC) fuel system on the 3406 on-highway truck engine to allow these engines to meet exhaust emission regulations. The PEEC fuel system retained the mechanical fuel injection portion of the fuel system but added electronic components for governor and timing control. In an on-going effort to provide optimum performance and fuel economy while meeting emission regulations, Caterpillar has applied the Electronic Unit Injector fuel system to the following engines: 3176 (Introduced in 1988) 3406E and 3176B (Introduced in 1993) C-10 (3176C) (Introduced in 1995) C-12 (3196) (Introduced in 1995) 3500B (Introduced in 1995)

Lesson 1: Review Caterpillar Elecctronic Systems

Lesson 1: Review Caterpillar Electronic Systems

The Hydraulic Electronic Unit Injector (HEUI) fuel system was introduced in the 3126 Caterpillar engine in 1995, and later into the 3408, and 3412 Caterpillar engines to provide even more flexibility in controlling fuel delivery.