NYC
Auto Mechanic (Diesel) Exam Prep 2026
| DCAS Exam No. 2105 | 150+ Practice
Questions with Correct Answers &
Detailed Rationales
This document contains:
✓ Correct Answers
✓ Comprehensive Questions
✓ Detailed Rationales 150+
Practice Quizs
✓ Exam Prep 2026.
, Which of the following procedures would be used to inspect a CAC for an external restriction? -
CORRECT ANS Compare outside air temperature with intake manifold air temperature
Tech A says that when using plastigauge, plastigauge that becomes wider indicates a smaller oil
clearance between a crankshaft and main bearing. Tech B says that the plastigauge will become
narrower when bearing oil clearances are smaller. Who is correct? - CORRECT ANS Tech
A1
If an upper radiator hose collapses after an engine cools, what is the most likely cause? -
CORRECT ANS Overconcentrated anti-freeze-to-water solution.
Technician A says that a restricted fuel filter will produce a low power complaint under load but
will not cause the engine to stall at idle Technician B says hot fuel can cause a low power
complaint under load but will not cause the engine to stall at idle - CORRECT ANS Both
Technician A and Technician B
tech A says that cylinder misfires can be detected on a common rail engine by slightly cracking
open the fuel line to each injector when the engine is running tech B says that it is important to
place a shop towel over the injector when checking for misfires to prevent pressurized fuel from
penetrating the skin who is correct? - CORRECT ANS Neither
the presence of cavitation on a wet cylinder liner is most likely caused by - CORRECT
ANS B: low cylinder pressures
Technician A says tracking oil consumption for a few weeks for a truck with a complaint of high
oil consumption is the best place to start diagnosing the problem Technician B says pulling down
the main bearing caps to inspect for worn bearings is the best place to start diagnosing the
problem - CORRECT ANS Tech A 2
Auto Mechanic (Diesel) Exam Prep 2026
| DCAS Exam No. 2105 | 150+ Practice
Questions with Correct Answers &
Detailed Rationales
This document contains:
✓ Correct Answers
✓ Comprehensive Questions
✓ Detailed Rationales 150+
Practice Quizs
✓ Exam Prep 2026.
, Which of the following procedures would be used to inspect a CAC for an external restriction? -
CORRECT ANS Compare outside air temperature with intake manifold air temperature
Tech A says that when using plastigauge, plastigauge that becomes wider indicates a smaller oil
clearance between a crankshaft and main bearing. Tech B says that the plastigauge will become
narrower when bearing oil clearances are smaller. Who is correct? - CORRECT ANS Tech
A1
If an upper radiator hose collapses after an engine cools, what is the most likely cause? -
CORRECT ANS Overconcentrated anti-freeze-to-water solution.
Technician A says that a restricted fuel filter will produce a low power complaint under load but
will not cause the engine to stall at idle Technician B says hot fuel can cause a low power
complaint under load but will not cause the engine to stall at idle - CORRECT ANS Both
Technician A and Technician B
tech A says that cylinder misfires can be detected on a common rail engine by slightly cracking
open the fuel line to each injector when the engine is running tech B says that it is important to
place a shop towel over the injector when checking for misfires to prevent pressurized fuel from
penetrating the skin who is correct? - CORRECT ANS Neither
the presence of cavitation on a wet cylinder liner is most likely caused by - CORRECT
ANS B: low cylinder pressures
Technician A says tracking oil consumption for a few weeks for a truck with a complaint of high
oil consumption is the best place to start diagnosing the problem Technician B says pulling down
the main bearing caps to inspect for worn bearings is the best place to start diagnosing the
problem - CORRECT ANS Tech A 2
