NYC DCAS AUTO MECHANIC (CUNY) EXAM QUESTIONS AND ANSWERS | UPDATED
2026/2027
Core Domains
Engine Repair and Overhaul (Gasoline and Diesel)
Automatic and Manual Transmission Systems
Brake Systems (Hydraulic and Air)
Steering, Suspension, and Wheel Alignment
Electrical and Electronic Systems
Fuel, Ignition, and Emission Control Systems
Diagnostics, Troubleshooting, and Scan Tools
Safety, Ethics, and Shop Operations
Supervision, Training, and Record-Keeping
Introduction
This comprehensive assessment is designed to evaluate mastery of the knowledge and skills
required for the NYC DCAS Auto Mechanic (CUNY) examination (Exam No. 6026). It measures
understanding of engine repair and overhaul, transmission systems, brake systems, steering and
suspension, electrical and electronic systems, fuel and emission controls, diagnostics, safety, and
supervisory responsibilities. The exam employs a multiple-choice structure aligned with the DCAS
Notice of Examination and the task areas specified for the Auto Mechanic (CUNY) title. Emphasis
is placed on real-world application, troubleshooting, and compliance with New York City agency
standard operating procedures. Candidates must demonstrate the ability to overhaul, repair, and
maintain engines and component assemblies, act as troubleshooters using diagnostic equipment,
and supervise the work of other assigned personnel. The examination also assesses mathematical
reasoning, information ordering, and the ability to maintain accurate records of daily work
activities.
SECTION ONE: QUESTIONS 1–100
Question 1
A four-stroke diesel engine completes one power stroke for every how many revolutions of the
crankshaft?
,A. One revolution
B. Two revolutions
C. Three revolutions
D. Four revolutions
🟢 B. Two revolutions
🔴 RATIONALE: In a four-stroke engine, the piston completes four strokes (intake,
compression, power, exhaust) during two complete revolutions of the crankshaft. Only one of
those four strokes produces power.
Question 2
What is the primary function of a turbocharger wastegate?
A. Increase maximum boost pressure
B. Regulate boost pressure to prevent overboost and engine damage
C. Cool the compressed intake air
D. Lubricate the turbocharger bearings
🟢 B. Regulate boost pressure to prevent overboost and engine damage
🔴 RATIONALE: The wastegate diverts exhaust gas around the turbine once the desired boost
pressure is reached, preventing excessive manifold pressure that could damage the engine.
Question 3
A technician observes excessive blue smoke from a diesel engine's exhaust. Which condition is
MOST consistent with this symptom?
A. Coolant entering the combustion chamber
B. Engine oil entering the combustion chamber
C. Excessive fuel delivery
D. Normal regeneration of the diesel particulate filter
🟢 B. Engine oil entering the combustion chamber
🔴 RATIONALE: Blue smoke indicates oil consumption, commonly caused by worn valve
guides, valve stem seals, or piston rings allowing lubricating oil into the combustion chamber.
,Question 4
A diesel engine cranks but fails to start. The technician confirms fuel pressure at the injection
pump inlet is within specification. Which of the following should the technician check NEXT?
A. Replace the starter motor
B. Verify injector actuation and fuel delivery at the cylinders
C. Check tire pressure
D. Replace the alternator
🟢 B. Verify injector actuation and fuel delivery at the cylinders
🔴 RATIONALE: With supply pressure confirmed, the next logical diagnostic step is to verify
that the injectors are receiving the proper electrical or mechanical signal and actually delivering
fuel to the combustion chambers.
Question 5
Which component converts the reciprocating motion of the pistons into rotary motion?
A. Camshaft
B. Crankshaft
C. Flywheel
D. Pushrod
🟢 B. Crankshaft
🔴 RATIONALE: The crankshaft converts the up-and-down (reciprocating) motion of the
pistons into rotational motion that drives the transmission and accessory systems.
Question 6
A vehicle equipped with a diesel particulate filter (DPF) frequently enters regeneration mode.
Which condition is MOST likely to cause this?
A. A clean air filter
B. Excessive short-trip operation preventing passive regeneration
C. A fully charged battery
D. Properly functioning EGR system
, 🟢 B. Excessive short-trip operation preventing passive regeneration
🔴 RATIONALE: Short trips do not allow exhaust temperatures to reach the level required for
passive DPF regeneration, causing soot to accumulate and triggering frequent active
regeneration cycles.
Question 7
What is the purpose of a glow plug in a diesel engine?
A. Ignite the air-fuel mixture during normal operation
B. Pre-heat the combustion chamber for cold starting
C. Measure combustion chamber temperature
D. Regulate fuel injection pressure
🟢 B. Pre-heat the combustion chamber for cold starting
🔴 RATIONALE: Glow plugs heat the combustion chamber during cold starts to help the diesel
engine achieve the temperature required for reliable compression ignition.
Question 8
A diesel engine produces black smoke under acceleration. Which condition is MOST likely
responsible?
A. Coolant entering the combustion chamber
B. Insufficient air intake or excessive fuel delivery
C. Engine oil entering the combustion chamber
D. A faulty glow plug
🟢 B. Insufficient air intake or excessive fuel delivery
🔴 RATIONALE: Black smoke indicates incomplete combustion due to an overly rich air-fuel
ratio, often caused by a restricted air filter, faulty turbocharger, or excessive fuel delivery.
Question 9
During a compression test on a diesel engine, one cylinder reads significantly lower than the
others. The technician performs a leak-down test and hears air escaping from the oil filler cap.
What does this indicate?
2026/2027
Core Domains
Engine Repair and Overhaul (Gasoline and Diesel)
Automatic and Manual Transmission Systems
Brake Systems (Hydraulic and Air)
Steering, Suspension, and Wheel Alignment
Electrical and Electronic Systems
Fuel, Ignition, and Emission Control Systems
Diagnostics, Troubleshooting, and Scan Tools
Safety, Ethics, and Shop Operations
Supervision, Training, and Record-Keeping
Introduction
This comprehensive assessment is designed to evaluate mastery of the knowledge and skills
required for the NYC DCAS Auto Mechanic (CUNY) examination (Exam No. 6026). It measures
understanding of engine repair and overhaul, transmission systems, brake systems, steering and
suspension, electrical and electronic systems, fuel and emission controls, diagnostics, safety, and
supervisory responsibilities. The exam employs a multiple-choice structure aligned with the DCAS
Notice of Examination and the task areas specified for the Auto Mechanic (CUNY) title. Emphasis
is placed on real-world application, troubleshooting, and compliance with New York City agency
standard operating procedures. Candidates must demonstrate the ability to overhaul, repair, and
maintain engines and component assemblies, act as troubleshooters using diagnostic equipment,
and supervise the work of other assigned personnel. The examination also assesses mathematical
reasoning, information ordering, and the ability to maintain accurate records of daily work
activities.
SECTION ONE: QUESTIONS 1–100
Question 1
A four-stroke diesel engine completes one power stroke for every how many revolutions of the
crankshaft?
,A. One revolution
B. Two revolutions
C. Three revolutions
D. Four revolutions
🟢 B. Two revolutions
🔴 RATIONALE: In a four-stroke engine, the piston completes four strokes (intake,
compression, power, exhaust) during two complete revolutions of the crankshaft. Only one of
those four strokes produces power.
Question 2
What is the primary function of a turbocharger wastegate?
A. Increase maximum boost pressure
B. Regulate boost pressure to prevent overboost and engine damage
C. Cool the compressed intake air
D. Lubricate the turbocharger bearings
🟢 B. Regulate boost pressure to prevent overboost and engine damage
🔴 RATIONALE: The wastegate diverts exhaust gas around the turbine once the desired boost
pressure is reached, preventing excessive manifold pressure that could damage the engine.
Question 3
A technician observes excessive blue smoke from a diesel engine's exhaust. Which condition is
MOST consistent with this symptom?
A. Coolant entering the combustion chamber
B. Engine oil entering the combustion chamber
C. Excessive fuel delivery
D. Normal regeneration of the diesel particulate filter
🟢 B. Engine oil entering the combustion chamber
🔴 RATIONALE: Blue smoke indicates oil consumption, commonly caused by worn valve
guides, valve stem seals, or piston rings allowing lubricating oil into the combustion chamber.
,Question 4
A diesel engine cranks but fails to start. The technician confirms fuel pressure at the injection
pump inlet is within specification. Which of the following should the technician check NEXT?
A. Replace the starter motor
B. Verify injector actuation and fuel delivery at the cylinders
C. Check tire pressure
D. Replace the alternator
🟢 B. Verify injector actuation and fuel delivery at the cylinders
🔴 RATIONALE: With supply pressure confirmed, the next logical diagnostic step is to verify
that the injectors are receiving the proper electrical or mechanical signal and actually delivering
fuel to the combustion chambers.
Question 5
Which component converts the reciprocating motion of the pistons into rotary motion?
A. Camshaft
B. Crankshaft
C. Flywheel
D. Pushrod
🟢 B. Crankshaft
🔴 RATIONALE: The crankshaft converts the up-and-down (reciprocating) motion of the
pistons into rotational motion that drives the transmission and accessory systems.
Question 6
A vehicle equipped with a diesel particulate filter (DPF) frequently enters regeneration mode.
Which condition is MOST likely to cause this?
A. A clean air filter
B. Excessive short-trip operation preventing passive regeneration
C. A fully charged battery
D. Properly functioning EGR system
, 🟢 B. Excessive short-trip operation preventing passive regeneration
🔴 RATIONALE: Short trips do not allow exhaust temperatures to reach the level required for
passive DPF regeneration, causing soot to accumulate and triggering frequent active
regeneration cycles.
Question 7
What is the purpose of a glow plug in a diesel engine?
A. Ignite the air-fuel mixture during normal operation
B. Pre-heat the combustion chamber for cold starting
C. Measure combustion chamber temperature
D. Regulate fuel injection pressure
🟢 B. Pre-heat the combustion chamber for cold starting
🔴 RATIONALE: Glow plugs heat the combustion chamber during cold starts to help the diesel
engine achieve the temperature required for reliable compression ignition.
Question 8
A diesel engine produces black smoke under acceleration. Which condition is MOST likely
responsible?
A. Coolant entering the combustion chamber
B. Insufficient air intake or excessive fuel delivery
C. Engine oil entering the combustion chamber
D. A faulty glow plug
🟢 B. Insufficient air intake or excessive fuel delivery
🔴 RATIONALE: Black smoke indicates incomplete combustion due to an overly rich air-fuel
ratio, often caused by a restricted air filter, faulty turbocharger, or excessive fuel delivery.
Question 9
During a compression test on a diesel engine, one cylinder reads significantly lower than the
others. The technician performs a leak-down test and hears air escaping from the oil filler cap.
What does this indicate?
