Automotive Information Flashcards

What is the purpose of a vehicle's PCV (Positive Crankcase Ventilation) valve?

Answer: To vent blow-by gases from the crankcase back into the intake

The PCV valve routes harmful blow-by gases from the crankcase back into the intake manifold to be burned rather than released into the atmosphere.

Which type of brake uses hydraulic pressure to squeeze brake pads against a rotor?

Answer: Disc brake

Disc brakes use a hydraulic caliper to squeeze brake pads against a spinning rotor, creating friction to slow the vehicle.

What does a vehicle's alternator do while the engine is running?

Answer: Generates AC current converted to DC to charge the battery and power electronics

The alternator generates alternating current (AC) which is converted to direct current (DC) to recharge the battery and supply power to the vehicle's electrical systems.

What is 'engine displacement'?

Answer: The total volume swept by all pistons in one complete revolution

Engine displacement is the total volume swept by all pistons during one complete cycle, typically measured in liters or cubic inches.

Which component in an automatic transmission uses fluid coupling to transmit power from the engine?

Answer: Torque converter

The torque converter uses fluid coupling to transmit engine power to the transmission, allowing the vehicle to stop without stalling the engine.

What is the function of the vehicle's EGR (Exhaust Gas Recirculation) system?

Answer: To recirculate a portion of exhaust gases back into the intake to reduce NOx emissions

The EGR system recirculates a portion of exhaust gases back into the combustion chamber to lower peak combustion temperatures and reduce nitrogen oxide (NOx) emissions.

When a car's wheel is out of balance, what is the most common symptom?

Answer: Vibration felt in the steering wheel or seat at highway speeds

An unbalanced wheel creates vibration that is typically felt through the steering wheel or floorboard, especially at highway speeds.

What does 'overhead cam' (OHC) mean in engine design?

Answer: The camshaft is located in the cylinder head above the valves

In an overhead cam engine, the camshaft is mounted in the cylinder head directly above the valves, eliminating pushrods and allowing for higher RPM operation.

What is the purpose of a vehicle's sway bar (stabilizer bar)?

Answer: To reduce body roll during cornering by linking opposite wheels

The sway bar connects opposite wheels through short links and reduces body roll during cornering by transferring force from the compressed side to the extended side.

What type of oil rating system is used in the US to classify motor oil by viscosity?

Answer: SAE ratings

The Society of Automotive Engineers (SAE) viscosity rating system (e.g., 5W-30) classifies motor oil by its flow characteristics at cold and operating temperatures.

A vehicle is pulling to one side when braking. What is the most likely cause?

Answer: A stuck or seized brake caliper on one side

A seized caliper on one side applies more braking force to that wheel than the other, causing the vehicle to pull toward the side with the stuck caliper.

In a four-stroke engine, what occurs during the 'compression' stroke?

Answer: Both valves are closed while the piston moves up, compressing the air-fuel mixture

During the compression stroke, both intake and exhaust valves are closed and the piston moves upward, compressing the air-fuel mixture before ignition.

What does the 'W' in a motor oil designation like 5W-30 stand for?

Answer: Winter

The 'W' stands for Winter, indicating the oil's viscosity rating at low temperatures to ensure proper cold-weather starting and initial lubrication.

Which sensor measures the amount of oxygen in the exhaust to help regulate the air-fuel mixture?

Answer: O2 (oxygen) sensor

The oxygen sensor (O2 sensor) monitors oxygen content in exhaust gases and sends signals to the ECU to adjust the air-fuel ratio for optimal combustion and emissions.

What is the purpose of a differential in a vehicle's drivetrain?

Answer: To allow drive wheels to rotate at different speeds when turning

The differential allows the outer wheel to rotate faster than the inner wheel during a turn, preventing tire scrub and allowing smooth cornering.

What is 'detonation' (engine knock) in a gasoline engine?

Answer: Uncontrolled premature ignition of the air-fuel mixture before the spark plug fires

Detonation (knock) occurs when the compressed air-fuel mixture ignites spontaneously before the spark plug fires, creating a characteristic knocking sound and potentially damaging the engine.

What is the primary function of anti-lock brakes (ABS)?

Answer: To prevent wheel lockup during hard braking, maintaining steering control

ABS prevents wheels from locking up during emergency braking by rapidly modulating brake pressure, allowing the driver to maintain steering control.

Which component seals the combustion chamber between the cylinder block and cylinder head?

Answer: Head gasket

The head gasket seals the joint between the engine block and cylinder head, preventing combustion gases, coolant, and oil from mixing or leaking externally.

What does a vehicle's mass airflow (MAF) sensor measure?

Answer: The amount of air entering the engine to help calculate fuel delivery

The MAF sensor measures the mass of air entering the engine, and the ECU uses this data to calculate the correct fuel injection quantity for the proper air-fuel ratio.

If a car's temperature gauge rises to the red zone while driving, what should the driver do first?

Answer: Safely pull over and shut off the engine to prevent damage

An overheating engine can suffer severe damage quickly; the correct response is to safely stop and shut off the engine to allow it to cool before investigating the cause.