ASE Diesel Practice Test Exam Questions And Answers With
Complete Solutions Latest Exam 2026
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 - 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 - 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 - 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. - 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. - 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. - 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). - 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 - ANSWER - A
Complete Solutions Latest Exam 2026
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 - 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 - 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 - 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. - 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. - 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. - 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). - 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 - ANSWER - A
