ASVAB Auto and Shop: Engine Systems and Repair 4 — Questions and Answers
Question 1: What is the purpose of the intake manifold on an engine?
- Collect and route exhaust gases away from cylinders
- Distribute air or air-fuel mixture to each cylinder (Correct answer)
- House the engine's oil filter
- Connect the fuel tank to the fuel pump
Correct answer: Distribute air or air-fuel mixture to each cylinder
The intake manifold distributes the incoming air (or air-fuel mixture on carbureted engines) evenly to each cylinder's intake port.
Question 2: Which engine stroke draws the air-fuel mixture into the cylinder?
- Compression stroke
- Power stroke
- Exhaust stroke
- Intake stroke (Correct answer)
Correct answer: Intake stroke
During the intake stroke, the piston moves down and the intake valve opens, drawing the air-fuel mixture into the cylinder.
Question 3: What does an oil pressure warning light indicate?
- The oil needs to be changed immediately
- Oil pressure is dangerously low, risking engine damage (Correct answer)
- The oil filter is clogged
- The engine is using too much oil
Correct answer: Oil pressure is dangerously low, risking engine damage
The oil pressure warning light indicates that oil pressure has dropped below a safe level, which can lead to severe engine damage if not addressed immediately.
Question 4: What is the function of piston rings in an engine?
- Balance the rotating assembly
- Seal combustion gases and control oil on the cylinder wall (Correct answer)
- Connect the piston to the crankshaft
- Dampen vibration between cylinders
Correct answer: Seal combustion gases and control oil on the cylinder wall
Piston rings seal the combustion chamber against blow-by, transfer heat from the piston to the cylinder wall, and control oil film on the cylinder walls.
Question 5: A mechanic torques cylinder head bolts in a specific pattern. Why is this important?
- To prevent stripping the bolt threads
- To ensure even clamping pressure and prevent head gasket failure (Correct answer)
- To align the valve timing marks
- To set the correct valve clearance
Correct answer: To ensure even clamping pressure and prevent head gasket failure
Torquing head bolts in the correct sequence distributes clamping force evenly across the head gasket, preventing warping and premature gasket failure.
Question 6: What happens to engine performance when the air filter becomes severely clogged?
- Fuel pressure increases
- The engine runs lean and loses power
- The engine runs rich, loses power, and fuel consumption increases (Correct answer)
- The spark plugs foul more slowly
Correct answer: The engine runs rich, loses power, and fuel consumption increases
A clogged air filter restricts airflow, causing a rich air-fuel mixture, power loss, and reduced fuel economy.
Question 7: What is the role of the flywheel in an engine?
- Drive the water pump
- Store rotational energy to smooth out engine impulses (Correct answer)
- Seal the rear of the crankshaft
- Control fuel injection timing
Correct answer: Store rotational energy to smooth out engine impulses
The flywheel stores rotational (kinetic) energy to smooth power delivery between the firing pulses of the pistons.
ASVAB Auto and Shop: Engine Systems and Repair 4
What is the purpose of the intake manifold on an engine?