Diesel engines final
Technician A says that measurement of the actual amount of exhaust gas delivered to and from a closed loop feedback circuit for the EGR valve is performed by a mass airflow sensor. Technician B says that measurement of the actual amount of exhaust gas delivered to and from a closed loop feedback circuit for the EGR valve is performed by oxygen sensors. Who is correct?
Both Technician A and Technician B
Technician A says the volume of air supplied to the engine by the turbocharger is determined by the geometry of the compressor wheel. Technician B says the volume of air supplied to the engine by the turbocharger is determined by the compressor wheel speed.
Both Technician A and Technician B
__________ is an exhaust gas recirculation system that depends on a VGT to build exhaust backpressure.
High-pressure cooled EGR
__________ is a reddish-brown gas formed from nitric oxide and oxygen.
Nitrogen dioxide
__________ are two separate spring-loaded gears incorporated into a single unit to reduce gear rattle caused by torsional vibration.
Scissor gears
Technician A says contact with fuel will close the rollover valve to prevent fuel from leaking from the tank. Technician B says contact with fuel will close the pressure relief valve to prevent fuel from leaking from the tank. Who is correct?
Technician A
Technician A says spin-on filters are exempt from EPA regulations regarding hazardous waste. Technician B says spin-on filters are regulated by the EPA regarding hazardous waste. Who is correct?
Technician B
Technician A says that Diesel engines require an excess supply of oil relative to the quantity needed to completely burn fuel in the cylinders. Technician B says that Diesel engines require an excess supply of air relative to the quantity needed to completely burn fuel in the cylinders. Who is Correct?
Technician B
Technician A says that EGR rates are much lower in diesel engines than in gasoline-fueled engines. Technician B says that EGR rates are much higher in diesel engines than in gasoline-fueled engines. Who is correct?
Technician B
Technician A says that fuel lines are routed through a vehicle's passenger and driver compartments. Technician B says that fuel lines are not allowed to be routed through a vehicle's passenger or driver compartment. Who is correct?
Technician B
__________ is a measure of oil's resistance to flow.
Viscosity
The __________ is the system responsible for removing excess heat from the air charging the cylinders.
charge air cooler
Many turbochargers use engine ________________ passing through passages cast into the center housing to remove heat.
coolant
When oil turns gray, milky white, or brown, it is usually a sign that __________ has leaked into it.
coolant
The _________ is a system that transfers heat from coolant to the atmosphere.
coolant exchanger
The main purpose of the __________ in a reciprocating engine is to convert the linear motion of the connecting rod assemblies into rotational movement.
crankshaft
The __________ is the top of the piston and is subjected to cylinder pressure and tremendous heat.
crown
Silicone fluid is used in __________ dampeners to tune out harmonic and torsional vibrations.
viscous
A(n) __________ is a turbocharger design that uses a single turbine wheel and two compressor wheels.
series sequential turbocharger
The term __________ describes the force multiplication taking place inside a CR injector.
servo-hydraulic actuator
Holset turbochargers use a __________ nozzle ring to change the opening in the turbine housing.
sliding
A __________ is a piston design that has a portion of the skirt removed on both non-thrust sides of the piston to provide clearance for the crankshaft counterweights.
slipper skirt piston
If ingested, __________ of ethylene glycol will cause fatal kidney failure in humans after a couple of days.
4 ounces
The smallest particle visible to the human eye is __________ microns.
40
The best heavy-duty on-highway diesel engines operate at approximately __________ thermal efficiency.
45%
Eliminating the dead air of the crevice volume area can lower hydrocarbon exhaust emissions by as much as __________%.
50
Approximately __________ of the base stock of synthetic oils is made from polyalphaolefin.
70%
__________ is a system that uses ambient air to remove heat from the pressurized intake air.
Air-to-air aftercooler
__________ premium diesel engines use replacement valve seat inserts.
All
Engine oils are classified by the __________ and will carry a designation indicating their suitability for engine applications.
American Petroleum Institute
__________ is the two-stage amplification of fuel pressure inside the injector that provides improved power output with lower emissions, noise, and fuel consumption, and that produces a unique shape to the injection rate profile.
Amplified common rail
__________ is a process of sending vapors into the air intake, such as in the case of water-methanol injection systems.
Fumigation
The __________ injector incorporates a hydraulic coupler that carries out additional functions.
Bosch CRS3
__________ is the measurement of the correct quantity of fuel for each cylinder required for various speed and load conditions demanded of the engine.
Metering
__________ are a blend of several different oils with different viscosities.
Multigrade oils
Technician A says a piezoceramic actuator can switch fuel on and off in as little as 0.01 second. Technician B says a piezoceramic actuator can switch fuel on and off in as little as 0.001 second. Who is correct?
Neither Technician A nor Technician B
Technician A says compensation is observed when one or more cylinders are cut out and the engine maintains a set idle speed. Technician B says irregular or inconsistent fuel delivery causes the governor to readjust the quantity of fuel metered and correct the engine's speed and that correction is called compensation. Who is correct?
Technician A
__________ is a comparison between measured cylinder volume and the volume of air actually filling a cylinder; expressed as a percentage.
Volumetric efficiency
At low temperatures, the __________ content in diesel fuel can cause it to become too viscous to properly flow through filters and lines.
paraffin
Technician A says VGTs often have a built-in safety default position, which is approximately 50-60% open. Technician B says VGTs often have a built-in safety default position, which is approximately 75-80% closed. Who is correct?
Neither Technician A nor Technician B
Technician A says a linkage movement test is used to inspect the actuator operation on a turbocharger with external linkage. Technician B says a bounce test is used to inspect the actuator operation on a turbocharger with internal linkage. Who is correct?
Neither Technician A nor Technician B
The __________ is a sensor that measures the pressure drop across two points in a gas circuit.
delta pressure differential sensor
High intake temperatures will cause the engine to __________ power or even shut down.
derate
To prevent damage, the engine power needs to be __________ if temperatures exceed threshold values.
derated
Every 45 gallons of fuel consumed by a diesel engine produces enough contaminants to use up to __________ quart(s) of oil.
1
Cast iron is a metal made from iron ore with a carbon content of __________.
3-5%
__________ is the sound a VGT turbocharger can produce when actuator response is slow.
Chuffing
Technician A says it is the job of the primary filter to remove the bulk of free water and contaminants from the fuel. Technician B says it is the job of the secondary filter to remove the bulk of free water and contaminants from the fuel. Who is correct?
Technician A
Technician A says injection rate describes the time delay that occurs between the start of fuel pressurization and the moment when injection actually occurs. Technician B says injection lag describes the time delay. Who is correct?
Technician B
Technician A says long stoke engines will have more wear mid-stoke as well due to a higher amount of minor thrust. Technician B says long stoke engines will have more wear mid-stoke as well due to a higher amount of major thrust. Who is correct?
Technician B
Technician A says to evaluate whether there is excessive internal resistance to flow because of an internal restriction, you must complete a pressure test. Technician B says a pressure drop test must be completed to evaluate whether there is excessive internal resistance to flow because of an internal restriction. Who is correct?
Technician B
__________ Bosch injectors use as much as 250 volts to open.
Third-generation
__________ is a delay from the driver's demand for power from the engine to the point when the engine responds with power proportional to driver demand.
Turbo lag
The __________ is a sensor that measures pressure in the exhaust manifold.
exhaust back pressure (EBP) sensor
The __________ is a cylinder head with no exhaust manifolds on the outside of the cylinder head; instead, short exhaust runs are fed directly to the turbocharger located in the V between the cylinder banks.
reverse-flow cylinder head
A coolant with a pH of __________ is considered neutral.
7
A diaphragm pump is used to supply fuel at low pressure, usually not more than __________ pounds per square inch.
7
Motor oils are comprised typically of __________ base stock.
75-85%
__________ is the process of breaking up liquid fuel into a fine mist.
Atomization
__________ is a raw mineral processed from crude oil.
Base stock
Technician A says Polyalphaolefin is a man-made base stock used in place of mineral oil. Technician B says a base stock is the raw mineral processed from crude oil. Who is correct?
Both Technician A and Technician B
Technician A says a cubic foot of air contains fewer oxygen molecules when it is heated than it does when it is not. Technician B says a cubic foot of air, when heated, weighs less than when it is not heated. Who is correct?
Both Technician A and Technician B
A fourth-generation injector concept from Bosch containing a two-stage nozzle life with two rows of spray holes is called __________.
Coaxial variable nozzle injector
__________ is the base chemical from which the majority of anti-freezes are made.
Ethylene glycol
__________ is measured at the beginning and end of the energization period.
Injector voltage
__________ is the process used to produce a calibration code for a common rail injector.
Pressure wave correction
Technician A says the US Environmental Protection Agency imposes new design features on cylinder components through legislated standards called durability requirements. Technician B says the US Environmental Protection Agency imposes new design features on cylinder components through legislated standards called longevity standards. Who is correct?
Technician A
Technician A says the best method used to identify the location of an oil leak is tracing dye. Technician B says the best method used to identify the location of an oil leak is to use a towel to check for oil deposits. Who is correct?
Technician A
Technician A says the heavy-duty on-board diagnostics system monitors turbo operation using a speed sensor. Technician B says the heavy-duty on-board diagnostics system monitors turbo operation using a mass airflow sensor. Who is correct?
Technician A
Technician A says the piston pin bore is usually offset toward the major side thrust portion of the cylinder. Technician B says a compression test is used to measure the percentage of gas leakage past the piston rings. Who is correct?
Technician A
Technician A says that all diesel engines use replaceable valve guides. Technician B says all premium diesel engines use replaceable valve guides. Who is correct?
Technician B
Technician A says the injector solenoid is energized with current supplied by the fuel injector command piston. Technician B says the injector solenoid is energized with current supplied by the fuel injector control module. Who is correct?
Technician B
Technician A says the most abundant type of NOx initially produced during diesel combustion is nitrous oxide. Technician B says the most abundant type of NOx initially produced during diesel combustion is nitric oxide. Who is correct?
Technician B
Undersized exhaust pipes and mufflers, dents and numerous bends cause exhaust ________________ to increase.
backpressure
The __________ pressure sensor provides regarding ambient air pressure for altitude compensation.
barometric
The __________ is a component located in the fuel system that allows trapped air to escape from the filter when priming.
bleeder screw
The two most important factors influencing _________ are cylinder pressure and temperature.
burn rate
The appropriate __________ code must be entered into the ECM each time a new injector is installed or an injector is moved.
calibration
A(n) __________ is an elliptically shaped piston that expands to a round, symmetrical shape after it is warmed up.
cam ground piston
Increased air density and oxygen content improves __________ quality.
combustion
Injection timing may be advanced in many EGR engines to enable adequate burn time for the slower __________ speeds.
combustion
In a turbocharger, exhaust gases drive a turbine wheel, which is connected to a(n) __________ through a common shaft.
compressor wheel
A(n) __________ is a head design with the intake and exhaust manifolds located on opposite sides of an engine to improve engine breathing characteristics.
cross-flow cylinder head
Thermal __________ can stress a CAC until it cracks.
cycling
On hydraulic actuators used on smaller displacement Navistar engines, the end of the VGT control valve has a __________ cam follower to provide positional feedback to a sensor.
mechanical
Coatings of tool-grade hardness iron carbon alloys can be achieved by a plasma-spraying technique developed by Mercedes-Benz called __________ technology.
nanoslide
Engines not equipped with superchargers have cylinders charged with air at atmospheric pressure and are classified as __________.
naturally aspirated
The __________ engine uses only atmospheric pressure and not pressurized air to charge the cylinders with air.
naturally aspirated
VGTs vary the opening size of the turbine __________ that directs exhaust gas onto the turbine wheel.
nozzle
__________ is a rhythmic change in engine rpm at idle speed caused by uneven delivery of fuel.
Hunting
When gas temperatures increase, molecules spread farther apart, so the gas loses _________.
density
When performing an oil change, the acceptable oil level range is stamped on the oil __________.
dipstick
Surge tanks, overflow reservoirs, and large radiator tanks are used for accommodate coolant __________.
expansion
After a turbo __________, flushing a cooler thoroughly is important to prevent ingestion of debris into an engine.
failure
Because the amount of exhaust energy is low when an engine is lightly loaded, a(n) __________ turbocharger can produce little boost at low speeds.
fixed geometry
A __________ is made from aluminum alloy billets that are stamped into shape using dies.
forged piston
Bosch has developed __________ generations of CR injectors.
four
The size, number, and grade of bolts are increased in __________.
four-stroke diesels
The process of recalibrating injectors during service to compensate for wear and deterioration is __________.
fuel mean value adaptation
The __________ collects fuel from the injectors, fuel pump, and relief valves and returns the fuel to the tank.
fuel return circuit
The __________ allows fuel returned from the engine to cool after absorbing heat from the engine and fuel injectors.
fuel tank
A __________ separator is a filtration device that removes water from fuel and extends the life of a filter.
fuel-water
On a four stroke engine, the cam gear rotates at __________ the engine speed as the crank gear.
half
A __________ vibration sends pressure waves moving back and forth along the crankshaft.
harmonic
The __________ is a system that transfers heat from coolant to the atmosphere.
heat exchanger
A(n) __________ is a piston that has high silicon content.
hypereutectic piston
The __________ is an engine that has only the valves, rocker levers, and bridges located in the cylinder heads above the piston; the camshaft is located in the engine block.
in-block camshaft
An electronically controlled __________ valve will, under certain conditions, restrict excessive airflow into the engine, increasing exhaust gas temperatures.
intake throttle
A(n) __________ seals in compression gases that escape past the top rings and assist in oil control.
intermediate ring
The use of a liquid charge air cooler between two turbochargers connected in series is called __________.
interstage cooling
A system that uses engine coolant to remove heat from pressurized intake air is called a(n) __________.
jacket water aftercooler
The crankshaft is supported along its centerline by the main bearing __________.
journals
Oxygen sensors, also called __________ sensors, are used by some manufacturers as feedback devices for EGR controls.
lambda
A(n) __________ measures the weight of air entering the engine and can detect air inlet restrictions caused by a restricted air filter or intake when pressure drops below a threshold value.
mass airflow sensor
Duramax engines use __________ pressure to move the vane adjustment mechanism.
oil
The __________ is usually a low-tension type of ring and has no significant gas pressure acting upon it.
oil control ring
The __________ is an engine that has the camshaft located in the cylinder head.
overhead camshaft engine
The principle behind all EGR systems is to disrupt the chemical processes that form __________.
oxides of Nitrogen
Replacing combustion __________ with EGR gas is a strategy used by all EGR systems.
oxygen
A(n) __________ is a head design that features intake and exhaust manifolds on the same side of the engine and short, large ports that are joined together to provide a more compact engine design with adequate airflow to the cylinders.
parallel flow head
A __________ is a block design that has holes cast and bored in the block for the cylinders with the pistons inserted directly into these holes.
parent bore block
Measuring and adjusting __________ is one of the most critical operations when rebuilding a sleeved engine.
protrusion
Type IV OAT anti-freeze is __________ and uses non-carboxylate acids, such as benzoate, from benzoic acid, to form the additive package.
red
Because the oil pump can produce more oil flow than the engine can use, an oil pressure __________ is used to control oil pressure.
regulating valve
Heat __________ refers to the amount of heat transferred to the coolant rather than converted into mechanical force driving down the pistons.
rejection
The __________ is the tube that connects the crankcase to the atmosphere in an open crankcase ventilation system; also known as a crankcase ventilation tube.
road draft tube
Cylinder head bolts use specialized __________________.
rolled threads
The __________ is located between the primary filter and the high-pressure fuel injection system.
secondary filter
The __________ is an electrical device, usually a variable-resistance rheostat, that supplies a voltage signal to an analog-type dash gauge proportional to the fuel level.
sending unit
Turbocharger __________ is a condition where the turbocharger passes oil into the exhaust system.
slobber
Symptoms of an EGR cooler leak include high __________ levels in scheduled oil samples, and white smoke with a sweet odor.
sodium
The __________ is the mass of air required to completely burn all fuel in the combustion chamber so no fuel or air remains after combustion.
stoichiometric ratio
A __________ is necessary to allow air into the tank and some fuel vapors to escape.
tank vent
With some engine control systems, the pressure regulator acts as a(n) __________.
temperature sensor
In all liquid-cooled engines, the __________ controls the flow of coolant through the radiator.
thermostat
In the high pressure injection system, __________ is the beginning of the injection event in the combustion cycle relative to crank rotation.
timing
A __________ is a piston design that is dimensionally longer than it is wide, with a full piston skirt.
trunk piston
A(n) __________ is used by VGT turbochargers to rotate the nozzle ring vanes together simultaneously.
unison ring
Turbocharger failure will result if the __________ is seized closed or tampered with to prevent it from opening.
wastegate
Technician A says CAC efficiency is calculated by measuring the temperature differential between the CAC's inlet and outlet. Technician B says because CACs are pressurized and the turbocharger produces excess air, CACs can tolerate small cracks without allowing dirt into the engine entake. Who is correct?
Both Technician A and Technician B
Technician A says a rate-shaping strategy called pilot injection delivers a small quantity of fuel to the combustion chamber 8-10 degrees before the main injection. Technician B says the rate-shaping strategy is called split-shot injection. Who is correct?
Both Technician A and Technician B
Technician A says a traditional technique for clamping cylinder heads to the block requires the use of a torque wrench to tighten the head bolts. Technician B says the head bolts must be tightened in a spiral pattern sequence. Who is correct?
Both Technician A and Technician B
Technician A says bacteria and fungi can multiply throughout a fuel system and eventually clog fuel filters. Technician B says that bacteria and fungi are sometimes referred to as "humbugs." Who is correct?
Both Technician A and Technician B
Technician A says calibration codes are given different names by manufacturers including injection quantity adjustment. Technician B says manufacturers are also called E-Trims and the adaptation value. Who is correct?
Both Technician A and Technician B
Technician A says compressor wheels are made out of titanium alloys. Technician B says compressor wheels are made out of lightweight aluminum. Who is correct?
Both Technician A and Technician B
Technician A says cooled EGR leads to the formation of higher nitric acid levels in the combustion chamber after reactions take place. Technician B says cooled EGR leads to the formation of higher sulfuric acid levels in the combustion chamber after reactions take place. Who is correct?
Both Technician A and Technician B
Technician A says dye penetrant and pressure testing are used to check cylinder heads for cracks. Technician B says that magnetic flux and is used to check cylinder heads for cracks. Who is correct?
Both Technician A and Technician B
Technician A says engine oils are classified by the American Petroleum Institute. Technician B says engine oils carry a designation indicating their suitability for engine applications. Who is correct?
Both Technician A and Technician B
Technician A says excessive skirt clearance will result in piston knock. Technician B says excessive skirt clearance will result in piston slap. Who is correct?
Both Technician A and Technician B
Technician A says high pressurization enhances the atomization of fuel in the combustion chamber. Technician B says high pressurization enhances the distribution of fuel in the combustion chamber. Who is correct?
Both Technician A and Technician B
Technician A says one of the most common processes used to harden bearing surfaces of the crankshaft is induction hardening. Technician B says one of the most common processes used to harden bearing surfaces of the crankshaft is nitriding. Who is correct?
Both Technician A and Technician B
Technician A says overhead camshaft engines often use two camshafts. Technician B says some overhead camshaft engines will use a separate camshaft for the injectors. Who is correct?
Both Technician A and Technician B
Technician A says prolonged idling of diesel engines can cause excessive soot loading and slobber production. Technician B says prolonged idling of diesel engines can cause cylinder glazing. Who is correct?
Both Technician A and Technician B
Technician A says series turbochargers use different sizes of compressor and turbine housings designated as high-pressure turbochargers. Technician B says series turbochargers use different sizes of compressor and turbine housings designated as low-pressure turbochargers. Who is correct?
Both Technician A and Technician B
Technician A says slipper skirt pistons enable the use of shorter connecting rods. Technician B says the use of shorter connecting rods permit the manufacture of vertically smaller, lighter, more compact engines. Who is correct?
Both Technician A and Technician B
Technician A says split fracture connecting rods allow the rod and cap to be separated along a predetermined fracture line. Technician B says proper alignment of the connecting rod and cap is made by matching up the markings on the cap and rod to identify the assembled position. Who is correct?
Both Technician A and Technician B
Technician A says that in the past, coolant has included mixtures of alcohol and water. Technician B says that in the past, coolant has included water mixed with honey and soluble oils. Who is correct?
Both Technician A and Technician B
Technician A says that plastic or rubber tubes are frequently used for air intake construction because they resist corrosion better than metal tubes. Technician B says that plastic or rubber tubes are frequently used for air intake construction because they dampen intake noise better than metal tubes. Who is correct?
Both Technician A and Technician B
Technician A says that some of the scale that collects in the cooling system comes from calcium and magnesium in the water used for cooling. Technician B says that some of the scale that collects in the cooling system is produced by additives in the anti-freeze. Who is correct?
Both Technician A and Technician B
Technician A says that the number of oxygen molecules entering the cylinder will vary with a change in atmospheric pressure. Technician B says that the number of oxygen molecules entering the cylinder will vary with a change in ambient temperature. Who is correct?
Both Technician A and Technician B
The transmission, cylinder head(s), and all other major engine parts are bolted or connected to the __________.
cylinder block
Technician A says that to identify the source of a fuel system leak, you should measure pressure at the injector fuel return. Technician B says that to identify the source of a fuel system leak, you should measure pressure at the high-pressure pump return. Who is correct?
Both Technician A and Technician B
Technician A says the Detroit Diesel's DD series engines can perform an automated fuel system test. Technician B says the automated fuel system test includes an evaluation of the low-pressure system called the Fuel System Integrity Check. who is correct?
Both Technician A and Technician B
Technician A says the fuel tank allows fuel returned from the engine to cool after absorbing heat from the engine and fuel injectors. Technician B says fuel tank pickups used in medium-duty applications are usually integrated with a fuel level sending unit. Who is correct?
Both Technician A and Technician B
Technician A says variable geometry turbochargers (VGTs) are also known as variable nozzle turbochargers. Technician B says variable geometry turbochargers (VGTs) are also known as variable vane turbochargers. Who is correct?
Both Technician A and Technician B
__________ is a method of cleaning up blow-by emissions by recycling crankcase emissions back into the intake manifold.
Closed crankcase ventilation
__________ is the mixing of fuel and air in the cylinders during the injection event.
Distribution
__________ describes the time delay that occurs between the start of fuel pressurization and the moment when injection actually occurs.
Injection lag
Excessive __________ pressure can lower crankcase pressure too much and allow dirt to be drawn into the engine through seals and gaskets.
Negative
Technician A says a piston-type pump is used to supply fuel at low pressure, usually not more than 7 pounds per square inch. Technician B says a gear pump is used to supply fuel at low pressure , usually not more than 7 pounds per square inch. Who is correct?
Neither Technician A nor Technician B
Technician A says altitude variation is the term given to the turbocharger's ability to compensate for altitude change. Technician B says barometric offset is the term given to the turbocharger's ability to compensate for altitude change. Who is correct?
Neither Technician A nor Technician B
Technician A says aluminum, when heated, will expand to three times more than ferrous metal. Technician B says aluminum, when heated, will expand to eight times more than ferrous metal. Who is correct?
Neither Technician A nor Technician B
Technician A says an estimated 50% of new engines are designed with multilayer steel gaskets as standard equipment. Technician B says that all new engines are designed with multilayer steel gaskets as standard equipment. Who is correct?
Neither Technician A nor Technician B
Burn time is expressed in __________ of crankshaft rotation.
degrees
Technician A says cooler cores should be back-flushed with coolant after a turbocharger failure or if a core has become internally restricted. Technician B says cooler cores should be back-flushed with solvent, coolant, and compressed air after a turbocharger failure or if a core has become internally restricted. Who is correct?
Neither Technician A nor Technician B
Technician A says core plugs are designed to relieve pressure from frozen coolant to prevent engine damage. Technician B says core plugs are designed to relieve pressure from heated coolant to prevent engine damage. Who is correct?
Neither Technician A nor Technician B
Technician A says ethylene glycol is both nontoxic and environmentally friendly. Technician B says propylene glycol is very toxic and bad for the environment. Who is correct?
Neither Technician A nor Technician B
Technician A says fuel heaters use engine oil to warm the fuel. Technician B says fuel heaters use electric current or engine oil to warm the fuel. Who is correct?
Neither Technician A nor Technician B
Technician A says fuel pressurized to hundreds of pounds per square inch can easily penetrate skin, causing bodily harm and blood poisoning. Technician B says fuel pressurized to hundreds of pounds per square inch can even cause death. Who is correct?
Neither Technician A nor Technician B
Technician A says peak cylinder pressure should occur 15-20 degrees of crankshaft rotation after top dead cylinder. Technician B says peak cylinder pressure should occur approximately 5-10 degrees of crankshaft rotation after top dead cylinder. Who is correct?
Neither Technician A nor Technician B
Technician A says poor mixing of air and fuel can cause nozzle dribble. Technician B says poor mixing of air and fuel can cause excessive ignition delay time. Who is correct?
Neither Technician A nor Technician B
Technician A says that EGR coolers send exhaust gas through a heat exchanger where its temperature can be reduced from as much as 1000°F (538°C) to approximately 212°F (100°C). Technician B says that EGR coolers send exhaust gas through a heat exchanger where its temperature can be reduced from as much as 1000°F (538°C) to approximately 650°F (343°C). Who is correct?
Neither Technician A nor Technician B
Technician A says that a diesel engine of 350 horsepower typically requires an air intake capacity of close to 500 cubic feet per minute. Technician B says that a diesel engine of 350 horsepower typically requires an air intake capacity of close to 1500 cubic feet per minute. Who is correct?
Neither Technician A nor Technician B
Technician A says that a pulse turbocharger is a solution to the problems of sluggish, low-power performance and high emissions at low engine speeds. Technician B says that a symmetrical turbocharger is a solution to the problems of sluggish, low-power performance and high emissions at low engine speeds. Who is correct?
Neither Technician A nor Technician B
Technician A says that an in-block camshaft arrangement has rockers that directly contact the camshaft.. Technician B says that an in-block camshaft arrangement does not use pushrods. Who is correct?
Neither Technician A nor Technician B
Technician A says that at a molecular level, the forces attracting oil molecules to each other are greater than the forces causing oil molecules to adhere to metal surfaces. Technician B says that at a molecular level, the forces attracting oil molecules to metal surfaces are weaker than the forces causing oil molecules to adhere to one another. Who is correct?
Neither Technician A nor Technician B
Technician A says that currently, the fastest piezo CR injector can produce 4 separate injection events during one combustion cycle. Technician B says that currently, the fastest piezo CR injector can produce 10 separate injection events during one combustion cycle.
Neither Technician A nor Technician B
Technician A says that moving the gear train to the front of the engine can dramatically reduce gear train noise. Technician B says gear train placement has no affect on noise. Who is correct?
Neither Technician A nor Technician B
Technician A says the ability of a bearing to carry a load is known as conformability. Technician B says the ability of a bearing to carry a load is known as dual mass. Who is correct?
Neither Technician A nor Technician B
Technician A says the amount of heat required by a gas, solid, or liquid to produce a temperature change of 1°F within a specified time period is called focused heat. Technician B says the amount of heat required by a gas, solid, or liquid to produce a temperature change of 1°F within a specified time period is called latent heat. Who is correct?
Neither Technician A nor Technician B
Technician A says the best choice for detecting leaks in the positive pressure side of the air intake system is an engine oil analysis. Technician B says the best choice for detecting leaks in the negative pressure side of the air intake system is an ultrasonic test. Who is correct?
Neither Technician A nor Technician B
Technician A says the fourth-generation CRS4 uses an internal hydraulic amplifier to multiply injection pressure at a ratio of 4:1. Technician B says the fourth-generation CRS4 uses an internal hydraulic amplifier to multiply injection pressure at a ratio of 3:1. Who is correct?
Neither Technician A nor Technician B
Technician A says the percentage of liquids refers to the total amount of particles that are suspended in the oil. Technician B says the percentage of gasses refers to the total amount of particles that are suspended in the oil. Who is correct?
Neither Technician A nor Technician B
Technician A says the presence of vertical cracks in the piston bowl usually indicates a bonding problem between the piston skirt and crown. Technician B says the presence of vertical cracks in the piston pin usually indicates a bonding problem between the piston skirt and crown.Who is correct?
Neither Technician A nor Technician B
Technician A says underhood noises during heavily loaded operating conditions can be pinpointed to improper cooler mounting. Technician B says underhood noises during heavily loaded operating conditions can be pinpointed to a defective turbocharger. Who is correct?
Neither Technician A nor Technician B
Technician A says when an ATAAC is used to cool air between each stage of turbocharging, it is often referred to as intercooling. Technician B says during cold weather operation ATAACs require the use of a radiator cover called a winter front to maintain cab heat. Who is correct?
Neither Technician A nor Technician B
__________ is an anti-freeze base that is nontoxic and environmentally friendly.
Propylene glycol
Technician A says Detroit Diesel's DD series engines use sputter bearings. Technician B says Detroit Diesel's DD series engines use pilot bearings. Who is correct?
Technician A
Technician A says a fluted style mixer evenly blends gas into the intake stream around the circumference of the inlet of the intake manifold. Technician B says a cyclone style mixer evenly blends gas into the intake stream around the circumference of the inlet of the intake manifold. Who is correct?
Technician A
Technician A says a pressure test should be used to determine justification for the replacement of a CAC. Technician B says justification for the replacement of a CAC is best determined using a temperature differential test. Who is correct?
Technician A
Technician A says a properly functioning CAC has a maximum temperature differential of 30 degrees Fahrenheit between air intake temperature and outside air when airflow is 30 mph. Technician B says a properly functioning CAC has a maximum temperature differential of 35 degrees Fahrenheit between air intake temperature and outside air when airflow is 48 km/h. Who is correct?
Technician A
Technician A says engine oils tested at 212 o F are referred to as a summer viscosity. Technician B says engine oils tested at 100 o F are referred to as a hot viscosity. Who is correct?
Technician A
Technician A says if the side to side pressure in an ATAAC drops more than 3 psi, you should check the cooler for internal restrictions and leaks. Technician B says if the side to side pressure in an ATAAC drops more than 4 psi, you should check the cooler for internal restrictions and leaks. Who is correct?
Technician A
Technician A says in modern fuel injection systems, injection rate means the quantity of fuel injected per degree of crank angle rotation. Technician B says the fuel rate means the quantity of fuel injected per degree of crank angle rotation. Who is correct?
Technician A
Technician A says most bearing failures are caused by problems with lubrication. Technician B says most bearing failures are caused by normal wear and tear. Who is correct?
Technician A
Technician A says oils with a lower viscosity flow easier than higher viscosities. Technician B says oils with a higher viscosity flow easier than lower viscosities. Who is correct?
Technician A
Technician A says propylene glycol requires a higher concentration than ethylene glycol to provide the same freeze protection. Technician B says propylene glycol requires a lower concentration than ethylene glycol to provide the same freeze protection. Who is correct?
Technician A
Technician A says refinements to ring design, cylinder bore finishing techniques, and engine oils have helped produce engines that can operate for more than a million miles of use before the piston rings need to be replaced. Technician B says refinements to ring design, cylinder bore finishing techniques, and engine oils have helped produce engines that can operate for more than about a half a million miles of use before the piston rings need to be replaced. Who is correct?
Technician A
Technician A says single-piece cylinder head castings are more likely to experience head gasket failure at the rear of the engine where coolant temperatures are hottest. Technician B says the castings are not any more likely to experience head gasket failure at the rear of the engine. Who is correct?
Technician A
Technician A says that a restriction gauge in the air filter housing is connected to the instrument cluster to warn the driver to service the element. Technician B says that an ambient temperature sensor in the air filter housing is connected to the instrument cluster to warn the driver to service the element. Who is correct?
Technician A
Technician A says that a rootes blower is a positive displacement-type air pump driven by the engine directly through the gear train. Technician B says that a rootes blower is a positive displacement-type air pump driven by a viscous coupler. Who is correct?
Technician A
Technician A says that adding EGR systems to most 2002 and later engines was necessary to meet lower NOx emission standards. Technician B says that adding EGR systems to most 2002 and later engines was necessary to meet lower CO emission standards. Who is correct?
Technician A
Technician A says that by reintroducing exhaust gas back into the cylinders, a major reduction in exhaust emissions of oxides of nitrogen is achieved. Technician B says that by reintroducing exhaust gas back into the cylinders, a major reduction in exhaust emissions of carbon dioxide is achieved. Who is correct?
Technician A
Technician A says that cavitation erosion is unique to diesel engines. Technician B says that cavitation erosion is unique to gasoline engines. Who is correct?
Technician A
Technician A says that diesel engines that develop greater power output with smaller displacement have the indirect effect of reducing carbon dioxide emissions. Technician B says that diesel engines that develop greater power output with smaller displacement have the indirect effect of reducing carbon monoxide emissions. Who is correct?
Technician A
Technician A says that hydraulically amplified diesel injection systems are currently capable of injection pressures as high as 37,500 psi (2586 bar). Technician B says that hydraulically amplified diesel injection systems are currently capable of injection pressures as high as 35,000 psi (2413 bar). Who is correct?
Technician A
Technician A says that if ingested, 4 ounces of ethylene glycol will cause fatal kidney failure in humans after a couple of days. Technician B says that if ingested, 4 ounces of propylene glycol will cause fatal kidney failure in humans after a couple of days. Who is correct?
Technician A
Technician A says that rotating a valve slightly each time it opens can eliminate hot spots that can lead to valve burning. Technician B says that rotating there is nothing that can be done to effectively eliminate hot spots. Who is correct?
Technician A
Technician A says that the mass airflow sensor measures the weight of air entering the engine. Technician B says that the barometric pressure sensor measures the weight of air entering the engine. Who is correct?
Technician A
Technician A says that too low of an EGR rate will not obtain the required emission reductions. Technician B says that too low of an EGR rate will starve the combustion process of adequate oxygen. Who is correct?
Technician A
Technician A says that when water and methanol is injected into the intake system, the process of vaporization absorbs heat from the intake air and reduces its temperature. Technician B says that when ethyl ether is injected into the intake system, the process of vaporization absorbs heat from the intake air and reduces its temperature. Who is correct?
Technician A
Technician A says that with some engine control systems, the pressure regulator acts as a fuel temperature sensor. Technician B says that with some engine control systems, the pressure regulator acts as a bypass valve. Who is correct?
Technician A
Technician A says the compressor housing is shaped like the turbine housing but with opposite direction of gas flow. Technician B says the compressor housing is shaped differently from the turbine housing but with the same direction of gas flow. Who is correct?
Technician A
Technician A says the two most important factors influencing burn rate are cylinder pressure and temperature. Technician B says burn rate is not influenced by cylinder pressure. Who is correct?
Technician A
Technician A says thrust bearings are used to control endplay in a crankshaft. Technician B says thrust bearings are used to control torsion in a crankshaft. Who is correct?
Technician A
Technician A says to measure cylinder head warpage, you should check in the longitudinal and diagonal directions as well as across the head deck. Technician B says to measure cylinder head warpage, you should check in the latitudinal and diagonal directions as well across the head deck. Who is correct?
Technician A
Technician A says turbocharger response to nozzle ring movement is an intrusive monitoring strategy that measures boost pressure and compares it with expected values while driving. Technician B says turbocharger response to nozzle ring movement is an intrusive monitoring strategy that measures throttle response and compares it with expected values while driving. Who is correct?
Technician A
Technician A says when two fuel tanks are used, the return flow splitter valve equally divides return fuel flow from the engine to maintain identical fuel levels in each tank. Technician B says when two fuel tanks are used, the flow splitter valve divides return fuel flow from the engine, but is unable to do so equally. Who is correct?
Technician A
Technician A says Miller cycle engines are referred to as a five-stroke cycle because the compression stroke is divided into five phases. Technician B says Miller cycle engines are referred to as a five-stroke cycle because the compression stroke is divided into two phases.
Technician B
Technician A says a break-in period is not needed to seat rings. Technician B says a break-in period is needed for seat rings, in addition to other engine parts including bearings, valve guides, piston pins, and cam bushings. Who is correct?
Technician B
Technician A says a compound turbocharger can be used with a low-pressure, cooled EGR system where the turbocharger does not increase exhaust backpressure for the system. Technician B says a series turbocharger can be used with a low-pressure, cooled EGR system where the turbocharger does not increase exhaust backpressure for the system. Who is correct?
Technician B
Technician A says a fixed geometry turbocharger has the capability of changing boost pressure independent of engine speed and load. Technician B says a variable geometry turbocharger has the capability of changing boost pressure independent of engine speed and load.
Technician B
Technician A says coolant for diesel-fueled engines and coolant for gasoline-fueled engines are identical. Technician B says coolant for diesel-fueled engines and coolant for gasoline-fueled engines are different. Who is correct?
Technician B
Technician A says diesel engine cylinder walls wear out faster than their gasoline engine counterparts. Technician B says gasoline engine cylinder walls wear out faster than their diesel engine counterparts. Who is correct?
Technician B
Technician A says few in-tank electric pumps are the positive displacement, roller vane-type using permanent magnet-type electric motors. Technician B says most in-tank electric pumps are the positive displacement, roller vane-type using permanent magnet-type electric motors. Who is correct?
Technician B
Technician A says optimal timing for emissions positively impacts the fuel economy in North American diesel engines. Technician B says optimal timing for emissions negatively impacts the fuel economy in North American diesel engines. Who is correct?
Technician B
Technician A says reserve alkalinity additives ensure the oil does not become alkaline from products of combustion. Technician B says reserve alkalinity additives ensure the oil does not become acidic from products of combustion. Who is correct?
Technician B
Technician A says that an interference fit dry cylinder sleeve never has a top flange. Technician B says that a slip fit dry cylinder sleeve has a counterbore. Who is correct?
Technician B
Technician A says that in a diesel engine, blow-by leaking past the rings consists primarily of oil. Technician B says that in a diesel engine, blow-by leaking past the rings consists primarily of air. Who is correct?
Technician B
Technician A says that oil accumulations on the compressor wheel and housing are normal when using an open crankcase ventilation system. Technician B says that oil accumulations on the compressor wheel and housing are normal when using a closed crankcase ventilation system. Who is correct?
Technician B
Technician A says that prior to 1985, diesels needed to meet only a standard for exhaust opacity during a throttle snap test. Technician B says that diesels needed to meet only a standard for exhaust opacity during a throttle snap test prior to 1988. Who is correct?
Technician B
Technician A says that servo actuators used by Siemens to open and close nozzle valves are spindle-shaped. Technician B says that servo actuators used by Siemens to open and close nozzle valves are mushroom-shaped. Who is correct?
Technician B
Technician A says that the exhaust manifold becomes hotter than turbine housings when the engine is under load. Technician B says that turbine housings become hotter than the exhaust manifold when the engine is under load. Who is correct?
Technician B
Technician A says that to thoroughly clean cylinder head and block surfaces, you must choose a cleaning pad that removes both soft material and metal. Technician B says that to clean the cylinder head and block surfaces, you must choose a cleaning pad that removes soft material but not metal in order to protect the casting surfaces from damage. Who is correct?
Technician B
Technician A says that when NOx breaks down in the presence of sunlight and heat, it converts to carbon and oxygen gas. Technician B says that when NOx breaks down in the presence of sunlight and heat, it converts to nitrogen and ozone gas. Who is correct?
Technician B
Technician A says that when turbocharger discharge pressure is too low, it can cause an increase in carbon monoxide emissions. Technician B says that when turbocharger discharge pressure is too high, it can cause an increase in nitrogen oxide emissions. Who is correct?
Technician B
Technician A says the cooling system removes excess heat from the engine and releases it to the atmosphere through the thermostat. Technician B says the cooling system removes excess heat from the engine and releases it to the atmosphere through the radiator. Who is correct?
Technician B
Technician A says the principle of inducing current flow by using dissimilar metals and an electrolyte is called the cavitation effect. Technician B says the principle of inducing current flow by using dissimilar metals and an electrolyte is called the galvanic effect. Who is correct?
Technician B
Technician A says the recommended oil change interval is calculated by subtracting the quantity of oil in the oil pan from the number of barrels of fuel burned. Technician B says the recommended oil change interval is calculated by multiplying the quantity of oil in the oil pan by the number of barrels of fuel burned. Who is correct?
Technician B
Technician A says the sound referred to as chuffing is caused by pressure drop. Technician B says the sound referred to as chuffing is caused by turbo surge. Who is correct?
Technician B
Technician A says the term servo-hydraulic actuator describes the force multiplication taking place inside a modular HEUI. Technician B says the term servo-hydraulic actuator describes the force multiplication taking place inside a CR injector. Who is correct?
Technician B
Technician A says when replacing piston rings, the end gaps of all piston rings should be placed 180° apart in a three-ring pack. Technician B says when replacing piston rings, the end gaps of all piston rings should be placed 120° apart in a three-ring pack. Who is correct?
Technician B
__________ is the primary ingredient of engine coolant.
Water
Idle __________ involves making adjustments to injection quantities based on changes to crankshaft speed produced during every power impulse.
adaptation
VGTs use vanes, which are also referred to as __________, around the circumference of the turbine wheel.
airfoils
Using an __________ type ball bearing as a center housing support eliminates the need for a thrust bearing because endplay is controlled by the ball and race assembly rather than a sleeve.
angular
When made from compacted graphite iron, diesel cylinder heads weigh __________ aluminum.
approximately the same as
A(n) __________ is a two-piece piston design that uses a separate aluminum skirt connected to an alloy steel crown through a piston pin.
articulating piston
A(n) __________ is a turbocharger with volutes of two different sizes.
asymmetrical turbocharger
The VGT actuator is adjusted to increase exhaust __________ as required by the EGR system.
backpressure
