ASE Diesel Practice Test Exam Questions and Answers.
When a diesel engine is operated under a load, coolant continually comes out of the
radiator overflow and there are bubbles in the radiator. Which of these is the most likely
cause?
(A) Too much coolant in the cooling system
(B) A clogged radiator
(C) A stuck-open thermostat
(D) Compression leakage into the cooling system - Correct Answer D
A diesel engine has excessive black smoke when started in the morning. Which of these
could be the cause?
(A) A bad fuel injection nozzle
(B) A restricted fuel filter
(C) A blocked fuel tank vent
(D) A leaking fuel return line - Correct Answer A
Which of these can cause a no-start condition on a HEUI engine?
(A) High fuel pressure
(B) Low injection control pressure (C) High boost pressure
(D) Low boost pressure - Correct Answer B
A diesel engine is hard to start, but runs good after it has been primed and run for a few
minutes. The most likely cause is a:
(A) leaking injector line.
(B) leaking fuel return line.
(C) plugged fuel tank vent.
(D) bad transfer pump check valve. - Correct Answer D
A diesel engine with wet liners has been running too hot, and there is coolant in the
crankcase. The most likely cause is:
(A) a cracked block.
, (B) cracked liners.
(C) leaking liner seals.
(D) a leaking injector seal. - Correct Answer C
Diesel engine cylinder liner protrusion (height) can be adjusted by selecting the correct
size:
(A) cylinder liner.
(B) head gasket.
(C) liner shim.
(D) fire ring. - Correct Answer C
An electronically-controlled diesel engine will not start. Any of these could be the cause
EXCEPT a failed:
(A) camshaft position sensor.
(B) engine control module (ECM). (C) ECM ground circuit.
(D) throttle position sensor (TPS). - Correct Answer D
The cause of a logged fault code in an electronic diesel engine has just been repaired.
Technician A says that the codes should be cleared before releasing the vehicle.
Technician B says that the customer's password should be reset before releasing the
vehicle. Who is right?
(A) A only
(C) Both A and B
(B) B only
(D) Neither A nor B - Correct Answer A
A diesel engine has low power and low turbocharger boost pressure is found. Technician
A says that a leaking exhaust manifold could be the cause. Technician B says that a
plugged turbocharger oil return line could be the cause. Who is right?
(A) A only
(B) B only
(C) Both A and B
When a diesel engine is operated under a load, coolant continually comes out of the
radiator overflow and there are bubbles in the radiator. Which of these is the most likely
cause?
(A) Too much coolant in the cooling system
(B) A clogged radiator
(C) A stuck-open thermostat
(D) Compression leakage into the cooling system - Correct Answer D
A diesel engine has excessive black smoke when started in the morning. Which of these
could be the cause?
(A) A bad fuel injection nozzle
(B) A restricted fuel filter
(C) A blocked fuel tank vent
(D) A leaking fuel return line - Correct Answer A
Which of these can cause a no-start condition on a HEUI engine?
(A) High fuel pressure
(B) Low injection control pressure (C) High boost pressure
(D) Low boost pressure - Correct Answer B
A diesel engine is hard to start, but runs good after it has been primed and run for a few
minutes. The most likely cause is a:
(A) leaking injector line.
(B) leaking fuel return line.
(C) plugged fuel tank vent.
(D) bad transfer pump check valve. - Correct Answer D
A diesel engine with wet liners has been running too hot, and there is coolant in the
crankcase. The most likely cause is:
(A) a cracked block.
, (B) cracked liners.
(C) leaking liner seals.
(D) a leaking injector seal. - Correct Answer C
Diesel engine cylinder liner protrusion (height) can be adjusted by selecting the correct
size:
(A) cylinder liner.
(B) head gasket.
(C) liner shim.
(D) fire ring. - Correct Answer C
An electronically-controlled diesel engine will not start. Any of these could be the cause
EXCEPT a failed:
(A) camshaft position sensor.
(B) engine control module (ECM). (C) ECM ground circuit.
(D) throttle position sensor (TPS). - Correct Answer D
The cause of a logged fault code in an electronic diesel engine has just been repaired.
Technician A says that the codes should be cleared before releasing the vehicle.
Technician B says that the customer's password should be reset before releasing the
vehicle. Who is right?
(A) A only
(C) Both A and B
(B) B only
(D) Neither A nor B - Correct Answer A
A diesel engine has low power and low turbocharger boost pressure is found. Technician
A says that a leaking exhaust manifold could be the cause. Technician B says that a
plugged turbocharger oil return line could be the cause. Who is right?
(A) A only
(B) B only
(C) Both A and B
