DIESEL ENGINES CERTIFICATION EXAM
QUESTIONS AND CORRECT ANSWERS
WITH COMPLETE SOLUTIONS
When a Diesel engine is operated under a load, coolant continually comes out of
the radiator overflow and there are bubbles in the radiator. The MOST LIKELY
cause of the problem is... - ANS -Combustion leakage into the cooling system
A Diesel engine with 25,000 miles on a major overhaul has low power and misses.
It also has low compression and the valves and seats are burned. What is the
MOST LIKELY cause of these problems? - ANS -The valves were set too tight
What can happen if the cylinder liner height is too low? - ANS -Combustion
leakage
A Diesel engine suffers from low power under load. Tech A says this could be
caused by restricted fuel filters. Tech B says this could be caused by a restricted
DPF. Who is correct? - ANS -Tech A and Tech B
A new wet-type cylinder liner is being installed in an engine block. Tech A says the
liner height should be checked. Tech B says the liner taper should be checked.
Who is correct? - ANS -Tech A
New cylinder heads are being installed on a Diesel engine and some of the head
bolt holes in the block are partially filled with oil. Tech A says that if the head bolts
are torqued without cleaning the holes, the cylinder block could crack. Tech B
, says that if the head bolts are torqued without cleaning, the bolts could be
stretched. Who is correct? - ANS -Tech A
A newly rebuilt engine has locked up after five minutes of operation. While it was
running, the warm-up temperature was normal. What could have been the cause
of the lockup? - ANS -The main bearings were installed upside down
A diesel engine's DPF needs to be regenerated frequently. This is MOST LIKELY
caused by.... - ANS -Extended idle and light load operation
A Diesel engine has low oil pressure. This could be cause by... - ANS -Diluted lube
oil
What should be checked first on a Diesel engine with a low power complaint? -
ANS -Fuel filter outlet pressure
What should be done first to find the cause of a misfire on a Diesel engine? - ANS
-Find the misfiring cylinder
The engine braking is weak on a Diesel engine equipped with a compression
brake. Tech A says that this could be caused by a struck-open solenoid valve on a
compression brake assembly. Tech B says that the slave piston adjustment(s) may
be loose. Who is correct? - ANS -Tech B
Tech A says that black smoke from a DPF-equipped engine is considered normal.
Tech B says that diesel emission compliance is determined using opacity
measurements. Who is correct? - ANS -Tech B
QUESTIONS AND CORRECT ANSWERS
WITH COMPLETE SOLUTIONS
When a Diesel engine is operated under a load, coolant continually comes out of
the radiator overflow and there are bubbles in the radiator. The MOST LIKELY
cause of the problem is... - ANS -Combustion leakage into the cooling system
A Diesel engine with 25,000 miles on a major overhaul has low power and misses.
It also has low compression and the valves and seats are burned. What is the
MOST LIKELY cause of these problems? - ANS -The valves were set too tight
What can happen if the cylinder liner height is too low? - ANS -Combustion
leakage
A Diesel engine suffers from low power under load. Tech A says this could be
caused by restricted fuel filters. Tech B says this could be caused by a restricted
DPF. Who is correct? - ANS -Tech A and Tech B
A new wet-type cylinder liner is being installed in an engine block. Tech A says the
liner height should be checked. Tech B says the liner taper should be checked.
Who is correct? - ANS -Tech A
New cylinder heads are being installed on a Diesel engine and some of the head
bolt holes in the block are partially filled with oil. Tech A says that if the head bolts
are torqued without cleaning the holes, the cylinder block could crack. Tech B
, says that if the head bolts are torqued without cleaning, the bolts could be
stretched. Who is correct? - ANS -Tech A
A newly rebuilt engine has locked up after five minutes of operation. While it was
running, the warm-up temperature was normal. What could have been the cause
of the lockup? - ANS -The main bearings were installed upside down
A diesel engine's DPF needs to be regenerated frequently. This is MOST LIKELY
caused by.... - ANS -Extended idle and light load operation
A Diesel engine has low oil pressure. This could be cause by... - ANS -Diluted lube
oil
What should be checked first on a Diesel engine with a low power complaint? -
ANS -Fuel filter outlet pressure
What should be done first to find the cause of a misfire on a Diesel engine? - ANS
-Find the misfiring cylinder
The engine braking is weak on a Diesel engine equipped with a compression
brake. Tech A says that this could be caused by a struck-open solenoid valve on a
compression brake assembly. Tech B says that the slave piston adjustment(s) may
be loose. Who is correct? - ANS -Tech B
Tech A says that black smoke from a DPF-equipped engine is considered normal.
Tech B says that diesel emission compliance is determined using opacity
measurements. Who is correct? - ANS -Tech B
