Deck 12: Engine Breathing

Question 1

Which of the following is NOT an intake system component?

A) charge air cooler
B) air cleaner
C) turbocharger
D) catalytic converter

Answer 1

catalytic converter

Question 2

Which of the following is NOT part of the exhaust system?

A) catalytic converter
B) turbocharger
C) pyrometer
D) charge air cooler

Answer 2

charge air cooler

Question 3

What would be a typical maximum intake restriction specification for a naturally aspirated diesel engine?

A) 15 inches H₂O
B) 15 inches Hg
C) 25 inches H₂O
D) 25 inches Hg

Answer 3

15 inches H₂O

Question 4

What would be a typical maximum intake restriction specification for a turbocharged diesel engine?

A) 15 inches H₂O
B) 15 inches Hg
C) 25 inches H₂O
D) 25 inches Hg

Question 5

Which of the following is the most accurate method of checking out an air filter between service intervals?

A) remove and test with a trouble light
B) test with a manometer
C) blow out with an air nozzle
D) tap on floor to loosen dust

Question 6

What is used in conjunction with an EGR system on most commercial diesel engines?

A) water injection
B) Roots blower
C) tip turbine
D) cooling heat exchanger

Question 7

What component rotates in the compressor housing of a turbocharger?

A) impeller
B) turbine
C) turbine shaft
D) shaft bearings

Question 8

Which of the following does most to define how fast a turbocharger rotates?

A) exhaust gas pressure
B) exhaust gas heat
C) ambient temperature
D) ambient pressure

Question 9

What is the critical flow area inside the turbine housing of a turbocharger known as?

A) diffuser
B) impeller gate
C) volute
D) turbine outlet

Question 10

What should be used to measure the radial play of a turbine shaft?

A) micrometer
B) thickness gauges
C) digital calipers
D) dial indicator

Question 11

Which of the following steps must be performed after installing a reconditioned turbocharger?

A) check turbine endplay
B) check turbine shaft radial play
C) prime the turbo oil circuit
D) replace the turbo studs

Question 12

After running a diesel engine under heavy load, how long should the engine be idled before shutdown?

A) one minute
B) five minutes
C) fifteen minutes
D) thirty minutes

Question 13

What is used to cool an air-to-air charge air cooler?

A) ram air
B) engine coolant
C) engine lubricant
D) engine fan

Question 14

What is used as the cooling medium in heat exchangers known as aftercoolers and intercoolers?

A) ram air
B) engine coolant
C) engine lubricant
D) engine fan

Question 15

Which of the following specs is the usual start-test spec when testing an air-to-air, boost air heat exchanger?

A) 5 psi
B) 15 psi
C) 30 psi
D) 50 psi

Question 16

Which of the following components usually makes detailed tuning of diesel engine intake manifolds unnecessary?

A) charge air cooler
B) precleaner
C) positive air cleaner
D) turbocharger

Question 17

Which of the following would ensure that the breathing efficiency of a pair of intake valves on one diesel engine cylinder was identical?

A) air to air cooler
B) crossflow valve configuration
C) tune intake manifold
D) parallel port valve configuration

Question 18

Which of the following components would be associated with a variable geometry turbocharger?

A) wastegate
B) pyrometer
C) liquid cooling
D) charge air cooling

Question 19

Which of the following is an example of a tuned diesel engine exhaust manifold?

A) dedicated exhaust headers
B) twin exhaust pipes
C) pulsed manifolds
D) wastegates

Question 20

When a rain cap is used on a vertical exhaust stack, in which direction should the opening flap be pointed?

A) forward
B) rearward
C) inside
D) outside

Question 21

When the unison ring in a variable nozzle (VN) type turbocharger is moved, which of the following changes?

A) vane pitch
B) pulse frequency
C) inlet flow area
D) bypass flow area

Question 22

Which sound dampening principle is based on sound waves being reflected back toward their source?

A) absorption
B) pulsation
C) restriction
D) resonation

Question 23

In a sound absorption type muffler, what is sonic energy converted to?

A) friction, then heat
B) mechanical vibration
C) pressure
D) noise

Question 24

What is the housing containing the muffler, catalytic converters, SCR, and diesel particulate filter (DPF) known as?

A) exhaust pipe
B) engine silencer
C) resonator housing
D) exhaust gas aftertreatment canister

Question 25

Where would you most likely find a thermocouple pyrometer on a current highway diesel engine?

A) 12-inches downstream from the turbo
B) diesel particulate filter (DPF)
C) exhaust gas recirculation (EGR) heat exchanger
D) selective catalytic reduction (SCR) circuit

Question 26

Which of the following operating conditions is more likely to cause a diesel engine, catalytic converter to plug?

A) light load, cold temperature operation
B) high load, lugdown
C) light load, rated speed operation
D) high load, operation in torque rise

Question 27

Which of the following best describes the role of an exhaust gas recirculation (EGR) system on a current diesel engine?

A) reduction converter
B) soot filter
C) dilutes the intake charge
D) combusts NOx

Question 28

What happens when a wastegate actuator is in its default position?

A) all exhaust gas bypasses the turbine housing
B) all exhaust gas is routed through the turbine housing
C) all intake air bypasses the charge air cooler
D) all intake air bypasses the compressor housing

Question 29

Technician A says that a VG turbocharger functions like a small turbo when engine loads are light. Technician B says that a VG turbocharger functions like a large turbo when engine output is high. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 30

Which of the following statements best describes how EGR functions to reduce NOx emissions?

A) reduces oxygen intake to the engine
B) routes HC into engine cylinder
C) routes PM into engine cylinder
D) cools down the intake charge

Question 31

What is the functional difference between C-EGR and I-EGR?

A) C-EGR system run warmer
B) I-EGR is managed within the cylinder head
C) I-EGR costs more
D) C-EGR systems must be managed by the engine ECM

Question 32

Which type of valve configuration is more likely to be used with quiescent combustion technology?

A) parallel port
B) series-parallel
C) crossflow
D) two valve per cylinder

Question 33

When a turbocharger is set up to impart drive torque to the crankshaft, which of the following terms describes the system?

A) Series turbocharging
B) Series-parallel turbocharging
C) Compound turbocharging
D) Paralleling

Question 34

What term does Detroit Diesel use to describe their compound turbocharger on DD-series engines?

A) variable geometry (VG)
B) pulsed turbocharging
C) direct drive turbocharging
D) axial power turbine (APT)

Question 35

Technician A says that a DD axial power turbine (APT) uses a constant geometry (CG) turbine principle. Technician B says that Detroit Diesel claim their APT can add over 100 horsepower to engine output potential. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 36

While pressure testing an isolated Cummins charge air cooler (CAC), the pressure drops from 30 psi to 25 psi in 15 seconds. Technician A says that the CAC is leaking. Technician B says that the pressure drop-off is within specification and the CAC can be returned to service. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 37

What is the function of the stainless steel liner used in the cylinder head exhaust tract of some diesel engine cylinder heads?

A) insulation to maximize rejected heat discharge to the turbine housing
B) helps protect service personnel from serious burns
C) enables high sulfur fuel to be combusted in electronically controlled diesel engines
D) all of the above