Fire Engine Maintenance Unit 1 C Diesel Engine

Fire Engine Maintenance Unit 1 C – Diesel Engine Operation and Maintenance 1 C-1

Lesson Objectives • Identify the basic four-stroke diesel engine operating characteristics. • Describe the differences between diesel fuel and gasoline. • Describe the various major components of a diesel fuel system. • Describe correct operating procedures/parameters of starting a diesel engine. 1 C-2

Lesson Objectives • Describe the major components of a diesel engine. • Discuss the diesel particulate filter and its function in the regeneration process. • Describe basic drive train components of a fire apparatus and their operating characteristics. 1 C-3

Basic Diesel Engine Operation 1 C-4

Why Do Some Diesel Engines Knock Louder than Others? Diesel engines knock because there is an explosion inside the engine every time fuel is injected into the combustion chamber. • The explosion is equivalent to seven tons of force pushing on the piston. 1 C-5

Pilot Injection System • New diesel engines, which are much “quieter, ” have what is called a pilot fuel injection system. • This system is different than the previous systems because several mini injections of fuel are injected into the combustion chamber rather than one big injection. – These mini injections are smaller and more controlled, resulting in a much quieter combustion process. 1 C-6

Diesel Engines vs. Gasoline Engines • Compared to gasoline engines, diesel engines – Are more fuel efficient. – Produce torque at a lower RPM. – Use compression ignition. – Weigh more. 1 C-7 7

Diesel Engine Efficiency 4% Released as heat 30% radiation Enters the cooling system 36% Used to do work 30% Exits through exhaust pipe 1 C-8

Law of Conservation of Energy “Energy cannot be created nor destroyed, only converted. ” Diesel fuel’s flow of energy starts as a chemical energy and is converted to mechanical energy. 1 C-9

The Flow of Energy Through a Diesel Engine • Chemical energy is stored as fuel in the fuel tank. • Fuel injectors atomize the fuel into the cylinder where it is ignited. • As the fuel burns, additional heat is created. • Heat causes a rapid expansion which pushes the piston down. 1 C-10

Four-Stroke Diesel Engine • Intake stroke • Power stroke • Compression stroke • Exhaust stroke The engine converts energy to work. Intake Compression Power Exhaust 1 C-11

Torque and Horsepower Torque – The measurement of how much work can get done. • Torque = force x distance Horsepower – How fast work gets done. • Horsepower = torque ÷ time 1 C-12

Diesel Fuel versus Gasoline 1 C-13

Diesel Fuel (General Characteristics) • Heavier and oilier than gasoline • Evaporates much more slowly than gasoline • Higher energy content than gasoline – Diesel: 140, 000 BTUs (British Thermal Units) – Gasoline: 136, 000 BTUs 1 C-14

Octane Number vs. Cetane Number Octane Number • Octane Number – Determines the fuel grade for gasoline. • Measurement of a fuel’s ability to resist self-ignition when subjected to heat and pressure. – The higher the octane number, the more control there is over the fuel’s ignition point. – Fuel should not start burning before the spark plug fires. • This is an undesirable condition called fuel “knock” or “pre-ignition” and can cause engine damage. 1 C-15

Octane Number vs. Cetane Number • Cetane Number – Used to describe diesel fuel’s ignition characteristic (a measure of the ease with which the fuel is ignited in your engine). – The higher the cetane number, the easier the fuel is to ignite – The lower the cetane number, the harder an engine would be to start and the poorer the ignition characteristic of the fuel. – A cetane number of 40 is common for most diesel engines. 1 C-16

On-Road vs. Off-Road Diesel Fuel • On-Road Diesel Fuel – Used in vehicles that travel on federal, state, and local highways and roads – Road maintenance tax – Yellowish to clear in color • Off-Road Diesel Fuel – Strictly used by vehicles traveling off-road – Not subject to road taxes – Reddish in color (“red fuel”) 1 C-17

No. 2 and No. 1 Diesel Fuels • Number 2 (No. 2) Diesel – Most widely diesel grade having more energy per gallon than No. 1 diesel – Provides improved power and better mileage than No. 1 diesel (heat energy) • Number 1 (No. 1) Diesel – Most widely used fuel in very cold environments – Provides a non-gelling fuel • Winter Grade – In most areas where the weather can become cold, distributors will blend No. 1 and No. 2 diesel together for a winterized fuel. 1 C-18

Ultra-Low Sulfur Diesel (ULSD) • Required fuel for use in all model year 2007 and later highway diesel vehicles and engines • Cleaner-burning diesel fuel with substantially lowered sulfur contents 1 C-19

Diesel Fuel and Cold Weather • Diesel fuel is a hydrocarbon made up of paraffin (wax). The wax stays liquid as long as the outside air temperature stays warm. • Diesel fuel has peculiarities related to low outside air temperatures including hard starting and gelled fuel. 1 C-20

Cloud Point • Temperature at which tiny wax crystals begin to form in diesel fuel – Can affect the ability of the fuel to flow through fuel lines and fuel filters if sufficient wax crystals form • Use diesel fuel additives and winterized diesel fuel to keep the wax crystals small. • Never mix alcohols in diesel fuels. 1 C-21

Pour Point • Temperature at which a fluid ceases to pour – The pour point should be 10 degrees lower than the cloud point. B 20 with #2 Diesel; B 20 with #1 Diesel; B 100, all stored at -20 F (Photo by Gary Willoughby, NDSU) 1 C-22

Preventing Diesel Fuel from Gelling • Buy winter grade fuel in areas where temperatures consistently drop below 50 degrees Fahrenheit. • Add fuel conditioner. • Diesel fuel systems employ fuel heaters to heat the fuel before it reaches the fuel filters. • Keep your fuel tank full. 1 C-23

De-gelling a Vehicle • Place the vehicle in a heated garage where the whole fuel system—fuel lines, fuel filter, water separator, and fuel tank—can be warmed up. • Add an anti-gelling fuel additive to the fuel tank. 1 C-24

Diesel Fuel Handling Practices • Keep your fuel tank full of clean fuel. • Never store diesel fuel in galvanized containers. • Never pour the diesel fuel out of your old fuel filter into the new filter. • Water in diesel fuel can damage an engine. 1 C-25

Biodiesel • Biodiesel is an alternative or additive to standard diesel fuel that is made from biological ingredients instead of petroleum (or crude oil). – Usually made from plant oils or animal fat – Non-toxic and renewable 1 C-26

Using Biodiesel Fuel • Biodiesel is a blended fuel—a certain percentage of biological ingredients to a certain percentage of diesel fuel. – B 20 is 20% biodiesel and 80% diesel • B 20 and B 40 are the most common blends. 1 C-27

Biodiesel Fuel Concerns • Biodiesel fuel has been known to clog fuel filters on older diesel engines. • Biodiesel fuel should not be left in engine fuel tanks over the winter. 1 C-28

Diesel Fuel Systems 1 C-29

Fuel Tank • Use the correct, clean fuel. • Keep the tank full. • Keep dirt out of the tank. – Fuel cap and surrounding area free of debris • Check for restricted fuel tank vent line. 1 C-30

High and Low Pressure Lines • High Pressure Fuel Line – Carries fuel from the tank to the filters and then to the fuel injection pump. • Low Pressure Fuel Line – Carries back to the tank the fuel that is used for lubricating and cooling the injectors, the injector pump, and for bleeding the filters. 1 C-31

Primary Filter/Water Separator • Water and dirt can cause engine to run poorly or damage the injection equipment. 1 C-32

Water in Fuel Light (WIF) • A sensor detects the presence of water in the fuel. • If the WIF light comes on, stop and drain the primary filter immediately. 1 C-33

Secondary Fuel Filter • The secondary fuel filter removes smaller particles before fuel goes to the injectors. 1 C-34

Filter Maintenance • At a minimum, drain the primary filter once a week. • Replace the primary and secondary filter when the engine oil is changed. 1 C-35

Hand Primer Pump • Hand primer pumps are used to fill filters with fuel when servicing fuel system. • Bleeder must be opened to allow air to escape. Pump Bleeders 1 C-36

Injection Pump The injection pump is the device that delivers fuel to the injectors at high pressures. 1 C-37

Injectors • ENOPs should not tamper with, adjust, or attempt any repairs on diesel fuel injections systems. (Click on the picture for an injector demonstration. ) 1 C-38

Glow Plugs • Assist with heating the combustion chamber • 1, 500 degrees Fahrenheit • May continue to operate after the engine has started • High electrical load 1 C-39

Electronic Control Module (ECM) 1 C-40

Diesel Engine Components 1 C-41

Turbocharger Basics • Turbochargers are devices that force more air into the engine. By forcing more air into the combustion chamber, more fuel can be added, creating more horsepower for the engine. – Turbochargers are basically a bolt-on horsepower increaser device with no mechanical connection to the engine. 1 C-42

Turbocharger Basics Compressed Air Flow Engine Cylinder Turbine Wheel Compressor Piston Ambient Air Inlet Compressor Wheel Exhaust Gas Discharge Wastegate 1 C-43

Turbocharger Basics TURBINE SECTION Turbine Housing Exhaust Gas Outlet Compressor Housing Exhaust Gas Inlet Turbine Wheel Compressor Air Discharge COMPRESSOR SECTION Compressor Wheel 1 C-44

Turbocharger Considerations 1 C-45

Turbocharger Considerations • Turbochargers are lubricated and cooled by engine lubricating oil. • Turbochargers operate under severe conditions. – Turbine and compressor speeds can exceed 90, 000 RPM. • Never rev the engine up and then shut it off. • Always let the engine idle down for at least 3 -5 minutes when it is hot or has been in heavy use. 1 C-46

Aftercooler • Cools the compressed air that was generated by the turbocharger. • Helps reduce emissions. • Can become plugged up easily. • Check aftercooler duct clamps. 1 C-47

Air Cleaner/Filter • Check and blow out daily. • Replace damaged air cleaner elements. • Avoid driving an engine with a damaged air cleaner element. • Check intake piping for dirt. 1 C-48

Air Cleaner Restriction Gauge • Tells the operator when your air cleaner is dirty. • Do not trust the gauge completely; you might have an intake leak. 1 C-49

Reasons for Black Smoke • Pulling a heavy load (lugging) • More fuel than air (heavy acceleration) • Plugged air cleaner 1 C-50

Cooling System • Radiator • Coolant • Hoses • Coolant passages • Fan • Radiator cap • Fan clutch • Belts • Thermostat • Heater core 1 C-51

Radiator • The radiator is designed to transfer heat away from the engine keeping the engine cool. • Make sure the radiator is free of debris. 1 C-52

Fan Outside air pulled in by fan • Pulls air through the radiator, aftercooler, transmission cooler, and air conditioning condenser 1 C-53

Exhaust System 1 C-54

Diesel Particulate Filter (DPF) Exhaust Gas In Exhaust Gas Out Filter Non-filtered Exhaust Gas Filter Sections Trapped Particulates Wall Flow Filter 1 C-55

Diesel Particulate Filter and Regeneration • Regeneration is done intermittently or continuously to avoid plugging up the DPF. – Biodiesel fuel use tends to plug DPFs more often resulting in increased regeneration rates. – Using low sulfur diesel (LSD) fuel is harmful to all DPFs. 1 C-56

Regeneration • The yellow regeneration indicator light on the dash tells the operator that some process of regeneration needs to be done (passive, active, or manual). 1 C-57

Regeneration • Regeneration is generally done automatically by passive and active systems without driver involvement. – Passive systems use only the exhaust gas stream to burn out the soot. – Active systems use a fuel burner that heats the filter to soot combustion temperatures. • Regeneration can also be done manually by the driver through a process known as parked regeneration. 1 C-58

Regeneration • A flashing yellow regeneration indicator light on the dash console tells the driver that he/she should perform a parked regeneration. ng hi s a l F 1 C-59

Regeneration • If the yellow regeneration indicator light is flashing and a yellow triangle light appears on the dash console, the driver must perform a parked regeneration. g Fl in h s a 1 C-60

Regeneration • If the red regeneration indicator light comes on, stop the truck immediately in a safe area. To avoid severe engine damage, turn off the engine and call a mechanic. 1 C-61

Diesel Engine Power Train Components 1 C-62

Manual Transmission • The manual transmission is connected to the engine through the clutch. • The input shaft of the transmission, therefore, turns at the same revolutions per minute as the engine. • Gears inside the transmission change the vehicle's drivewheel speed and torque in relation to engine speed and torque. • The selection of gears is done manually by working the gear shift lever and clutch. 1 C-63

Manual Transmission Precautions • Do not coast in neutral. • Do not drive with your hand on gear shifter. • Do not grind gears when shifting. 1 C-64

Automatic Transmission • Uses an internal clutch to shift between gears. • Employs a torque converter which allows the vehicle to stop without disengaging the transmission. 1 C-65

Automatic Transmission Precautions • Do not leave the transmission engaged when the vehicle is stopped for long periods of time. • Do not hold vehicle on hill with transmission. • Use the proper gear for the type of driving. • Come to complete stop when shifting directions. 1 C-66

Clutch Connects the engine to the transmission. • Do not ride the clutch. • Do not hold the clutch in while visiting. • Do not coast with the clutch disengaged. • Do not slip the clutch. 1 C-67

Transfer Case Connects the front differential to the rear differential. • High and low range • In and out • Hubs – no hubs • Highway versus off-road 1 C-68

Retarder • Supplements the vehicle braking system through the transmission. 1 C-69

Dynamic Engine Brakes • Supplements the vehicle braking system through the engine. 1 C-70

Causes of Low Power 1 C-71

Throttle Linkage • Look for: – Dirt under the throttle pedal. – A frayed throttle cable. – A miss-adjusted throttle position sensor. 1 C-72

Plugged Air Cleaner • Check and blow out the air cleaner. 1 C-73

Turbo Outlet Clamps • If loose, the turbo outlet clamps will make a whistling sound when the engine is under power. 1 C-74

Poor Fuel Quality • Add diesel additives or drain the fuel tank and add a quality fuel. 1 C-75

Dirty Fuel Filter • Replace the fuel filter. 1 C-76

Engine Blow-by • Have your engine checked out by a qualified technician since the engine may need major repairs. (Click on the picture for a blow-by demonstration. ) 1 C-77

Plugged Diesel Particulate Filter • Have your engine checked out by a qualified technician since the engine may need major repairs. 1 C-78

Engine Start Up and Shut Down 1 C-79

Basic Procedures • If possible, start your engine and let idle for 2 to 3 minutes before moving. • Slowly throttle the engine until the coolant is up to operating temperature. • Never idle your engine for more than 5 minutes. • Shut down after 5 minutes if engine has been run hard or when exhaust temperature is below 300 degrees Fahrenheit. • If your engine must idle, set throttle between 1, 000 and 1, 200 RPMs. 1 C-80

Ether • Ether is very explosive and should rarely be used. • Do not use ether if you have intake heaters or glow plugs. 1 C-81

Lesson Objectives • Identify the basic four-stroke diesel engine operating characteristics. • Describe the differences between diesel fuel and gasoline. • Describe the various major components of a diesel fuel system. • Describe correct operating procedures/parameters of starting a diesel engine. 1 C-82

Lesson Objectives • Describe the major components of a diesel engine. • Discuss the diesel particulate filter and its function in the regeneration process. • Describe basic drive train components of a fire apparatus and their operating characteristics. 1 C-83