fire engine maintenance unit 1c – diesel engine operation and maintenance 1c-1

Fire Engine Fire Engine MaintenanceMaintenanceFire Engine Fire Engine

MaintenanceMaintenance

Unit 1C – Diesel Engine Operation Unit 1C – Diesel Engine Operation and Maintenanceand Maintenance

1C-1

Lesson ObjectivesLesson 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.

1C-2


• 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.

1C-3

Basic Diesel Engine Basic Diesel Engine OperationOperation

Basic Diesel Engine Basic Diesel Engine OperationOperation

1C-4

Why Do Some Diesel Engines Knock Louder than Others?

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.

1C-5

Pilot Injection SystemPilot 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.

1C-6

Diesel Engines vs. Gasoline Engines

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.

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Diesel Engine EfficiencyDiesel Engine Efficiency

1C-8

Law of Conservation of EnergyLaw of Conservation of Energy

“Energy cannot be created nor destroyed, only converted.”

1C-9

Diesel fuel’s flow of energy starts as a chemical energy and is

converted to mechanical energy.

The Flow of Energy Through a Diesel Engine

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.

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Four-Stroke Diesel EngineFour-Stroke Diesel Engine

• Intake stroke

• Compression stroke

• Power stroke

• Exhaust stroke

1C-11

Intake Compression Power Exhaust

The engine converts energy to work.

Torque and HorsepowerTorque 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

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Diesel Fuel Diesel Fuel versus versus

GasolineGasoline

Diesel Fuel Diesel Fuel versus versus

GasolineGasoline

1C-13

Diesel Fuel(General Characteristics)

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

1C-14

Octane Number vs. Cetane NumberOctane Number

Octane Number vs. Cetane NumberOctane 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.

1C-15

Octane Number vs. Cetane NumberCetane Number

Octane Number vs. Cetane NumberCetane 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.

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On-Road vs. Off-Road Diesel FuelOn-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”)

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No. 2 and No. 1 Diesel FuelsNo. 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.

1C-18

Ultra-Low Sulfur Diesel (ULSD)

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

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Diesel Fuel and Cold WeatherDiesel 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.

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Cloud PointCloud 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.

1C-21

Pour PointPour Point

• Temperature at which a fluid ceases to pour

– The pour point should be 10 degrees lower than the cloud point.

1C-22

B20 with #2 Diesel; B20 with #1 Diesel; B100, all stored at -20 F

(Photo by Gary Willoughby, NDSU)

Preventing Diesel Fuel from GellingPreventing 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.

1C-23

De-gelling a VehicleDe-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.

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Diesel Fuel Handling PracticesDiesel 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.

1C-25

BiodieselBiodiesel

• 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

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Using Biodiesel FuelUsing Biodiesel Fuel

• Biodiesel is a blended fuel—a certain percentage of biological ingredients to a certain percentage of diesel fuel.

– B20 is 20% biodiesel and 80% diesel

• B20 and B40 are the most common blends.

1C-27

Biodiesel Fuel ConcernsBiodiesel 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.

1C-28

Diesel Fuel SystemsDiesel Fuel SystemsDiesel Fuel SystemsDiesel Fuel Systems

1C-29

Fuel TankFuel 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.

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High and Low Pressure LinesHigh 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.

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Primary Filter/Water SeparatorPrimary Filter/Water Separator

• Water and dirt can cause engine to run poorly or damage the injection equipment.

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Water in Fuel Light(WIF)

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.

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Secondary Fuel FilterSecondary Fuel Filter

• The secondary fuel filter removes smaller particles before fuel goes to the injectors.

1C-34

Filter MaintenanceFilter Maintenance

• At a minimum, drain the primary filter once a week.

• Replace the primary and secondary filter when the engine oil is changed.

1C-35

Hand Primer PumpHand 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.

1C-36

Bleeders

Pump

Injection PumpInjection Pump

The injection pump is the device that delivers fuel to the injectors at high pressures.

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Injectors Injectors

• ENOPs should not tamper with, adjust, or attempt any repairs on diesel fuel injections systems.

1C-38

(Click on the picture for an injector demonstration.)

Glow PlugsGlow Plugs

• Assist with heating the combustion chamber

• 1,500 degrees Fahrenheit

• May continue to operate after the engine has started

• High electrical load

1C-39

Electronic Control Module (ECM)Electronic Control Module (ECM)

1C-40

Diesel Engine Diesel Engine ComponentsComponentsDiesel Engine Diesel Engine ComponentsComponents

1C-41

Turbocharger BasicsTurbocharger 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.

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1C-43

Engine Cylinder

Compressed Air Flow

Piston

Compressor

Ambient Air Inlet

CompressorWheel

Turbine Wheel

Exhaust GasDischarge

Wastegate


1C-44

COMPRESSOR SECTION

TURBINESECTION

Compressor Wheel

CompressorAir Discharge

Exhaust Gas Inlet

Compressor Housing

TurbineHousing

Exhaust Gas Outlet

TurbineWheel

Turbocharger ConsiderationsTurbocharger Considerations

1C-45

Turbocharger ConsiderationsTurbocharger 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.

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AftercoolerAftercooler

• Cools the compressed air that was generated by the turbocharger.

• Helps reduce emissions.

• Can become plugged up easily.

• Check aftercooler duct clamps.

1C-47

Air Cleaner/FilterAir 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.

1C-48

Air Cleaner Restriction GaugeAir Cleaner Restriction Gauge

• Tells the operator when your air cleaner is dirty.

• Do not trust the gauge completely; you might have an intake leak.

1C-49

Reasons for Black SmokeReasons for Black Smoke

• Pulling a heavy load (lugging)

• More fuel than air (heavy acceleration)

• Plugged air cleaner

1C-50

Cooling SystemCooling System

• Radiator

• Hoses

• Fan

• Fan clutch

• Belts

• Thermostat

• Heater core

• Coolant

• Coolant passages

• Radiator cap

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RadiatorRadiator

• The radiator is designed to transfer heat away from the engine keeping the engine cool.

• Make sure the radiator is free of debris.

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FanFan

• Pulls air through the radiator, aftercooler, transmission cooler, and air conditioning condenser

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Outside air pulled in

by fan

Exhaust SystemExhaust System

1C-54

Diesel Particulate Filter (DPF)

Diesel Particulate Filter (DPF)

1C-55

Exhaust Gas In

Filter

Wall Flow Filter

Trapped Particulates

Filtered Exhaust Gas

Filter Sections

Non-filtered Exhaust Gas

Exhaust Gas Out

Diesel Particulate Filterand Regeneration

Diesel Particulate Filterand 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.

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RegenerationRegeneration

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

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• 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.

1C-58


• A flashing yellow regeneration indicator light on the dash console tells the driver that he/she should perform a parked regeneration.

1C-59

Flashing


• 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.

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Flashing


• 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.

1C-61

Diesel Engine Power Diesel Engine Power Train ComponentsTrain Components

Diesel Engine Power Diesel Engine Power Train ComponentsTrain Components

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Manual TransmissionManual 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 drive-wheel 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.

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Manual Transmission PrecautionsManual Transmission Precautions

• Do not coast in neutral.

• Do not drive with your hand on gear shifter.

• Do not grind gears when shifting.

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Automatic TransmissionAutomatic Transmission

• Uses an internal clutch to shift between gears.

• Employs a torque converter which allows the vehicle to stop without disengaging the transmission.

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Automatic Transmission Precautions

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.

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ClutchClutch

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.

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Transfer CaseTransfer Case

Connects the front differential to the rear differential.

•High and low range

•In and out

•Hubs – no hubs

•Highway versus off-road

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RetarderRetarder

• Supplements the vehicle braking system through the transmission.

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Dynamic Engine BrakesDynamic Engine Brakes

• Supplements the vehicle braking system through the engine.

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Causes of Low PowerCauses of Low PowerCauses of Low PowerCauses of Low Power

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Throttle LinkageThrottle Linkage

• Look for:

– Dirt under the throttle pedal.

– A frayed throttle cable.

– A miss-adjusted throttle position sensor.

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Plugged Air CleanerPlugged Air Cleaner

• Check and blow out the air cleaner.

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Turbo Outlet ClampsTurbo Outlet Clamps

• If loose, the turbo outlet clamps will make a whistling sound when the engine is under power.

1C-74

Poor Fuel QualityPoor Fuel Quality

• Add diesel additives or drain the fuel tank and add a quality fuel.

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Dirty Fuel FilterDirty Fuel Filter

• Replace the fuel filter.

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Engine Blow-byEngine Blow-by

• Have your engine checked out by a qualified technician since the engine may need major repairs.

1C-77

(Click on the picture for ablow-by demonstration.)

Plugged Diesel Particulate FilterPlugged Diesel Particulate Filter

• Have your engine checked out by a qualified technician since the engine may need major repairs.

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Engine Start Up and Engine Start Up and Shut DownShut Down

Engine Start Up and Engine Start Up and Shut DownShut Down

1C-79

Basic ProceduresBasic 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.

1C-80

EtherEther

• Ether is very explosive and should rarely be used.

• Do not use ether if you have intake heaters or glow plugs.

1C-81


• 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.

1C-82


• 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.

1C-83

fire engine maintenance unit 1c – diesel engine operation and maintenance 1c-1

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