C OF Q 310T MAIN EXAMINATION 2026/2027 QUESTIONS AND SOLUTIONS RATED A+

C OF Q 310T CORE EXAMS SET 2026/2027 QUESTIONS AND
SOLUTIONS RATED A+
✔✔When using series turbocharging, the first stage of cooling or interstage cooling is:

a) always performed by a JWAC with a secondary cooling system.
b) performed by an aluminum air-to-air aftercooler (ATAAC).
c) performed by a JWAC.
d) not necessary when using an ATAAC. - ✔✔c) performed by a JWAC.

✔✔What is the most likely cause of cracked ATAAC mounting brackets?

a) Thermal cycling (repeated heating and cooling)
b) Loosened mounting bolts/hardware
c) Mounting brackets that are too rigidly secured
d) Vibration - ✔✔c) Mounting brackets that are too rigidly secured

✔✔Air inlet temperature of 100°F, may increase outlet exhaust temperatures by
approximately ________.

a) 400°F
b) 450°F
c) 300°F
d) 350°F - ✔✔c) 300°F

✔✔A diesel engine "snap test" should not be performed when ambient temperatures
exceed __________.

a) 80°F
b) 40°C
c) 27°F
d) 80°C - ✔✔a) 80°F

✔✔Air generated by gas bypassing cylinder rings is called __________ gas.

a) exhaust
b) by pass
c) blow-by
d) boost - ✔✔c) blow-by

✔✔An open crankcase ventilation system in a diesel directs blow-by gases to the
____________.

a) intake manifold
b) exhaust manifold

,c) atmosphere
d) crankcase - ✔✔c) atmosphere

✔✔Maximum crankcase vacuum allowed at high idle when a CDR is incorporated
would be ____________.

a) 2"
b) 1"
c) 0"
d) 4" - ✔✔d) 4"

✔✔Where is the MAF sensor located?

a) In the intake manifold
b) After the intercooler
c) After the air filter
d) In the exhaust stream - ✔✔c) After the air filter

✔✔Caterpillar's emission strategy system is known as ____________.

a) DGI
b) VIVA
c) They don't have one
d) CGI - ✔✔d) CGI

✔✔Air intake filter performance testing on a turbo charged diesel engine is performed at
____________.

a) rated HP
b) no load
c) idle
d) high idle - ✔✔d) high idle

✔✔What is the expected service life of a medium-duty air filter?

a) 1600 hours
b) 1200 hours
c) 2000 hours
d) 900 hours - ✔✔a) 1600 hours

✔✔What is the flash point of Ethyl ether?

a) -65°F
b) 160°F
c) 320°F

, d) -49°F - ✔✔d) -49°F

✔✔What happens to the mass of intake airflow into an engine when the EGR is
enabled?

a) The mass becomes cooler.
b) The mass increases.
c) Nothing happens.
d) The mass decreases. - ✔✔d) The mass decreases.

✔✔Which of the following reasons best explains why air induction system noise is
louder on a diesel-fueled engine than on a gasoline-fueled engine?

a) The use of a turbocharger
b) Increased amount of valve overlap
c) Smaller clearance volumes in cylinders
d) Larger engine displacement - ✔✔b) Increased amount of valve overlap

✔✔What effect will high inlet air temperature combined with high humidity have on
engine performance?

a) Lower power output compared with cooler, drier conditions
b) Increased power compared with cooler, drier conditions
c) Reduced engine emissions compared with cooler, drier conditions
d) No difference in power output compared with cooler, drier conditions - ✔✔a) Lower
power output compared with cooler, drier conditions

✔✔Which of the following instruments is best used to measure air inlet restrictions?

a) Vacuum gauge
b) 0-5 psi (0-34 kPa) gauge
c) Mercury manometer
d) Water manometer - ✔✔d) Water manometer

✔✔What is the primary use for a resonator box on the air inlet of a diesel engine?

a) Tuning the intake passage for better airflow
b) Pre-cleaning air of water and dirt
c) Dampening intake noise
d) Increasing air turbulence for improved combustion - ✔✔c) Dampening intake noise

✔✔The service interval of an air filter is best determined by which of the following?

a) Time in service
b) Measurement of air filter restriction