Auto and Shop: Engine Systems and Repair Flashcards

What does an engine's displacement measurement (e.g., 2.0L) refer to?

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

Engine displacement is the total volume swept by all pistons moving from bottom dead center to top dead center in one revolution.

A vehicle produces white smoke from the exhaust on a warm day. What does this most likely indicate?

Answer: Coolant burning in the combustion chamber

White smoke from the exhaust typically indicates coolant is leaking into the combustion chamber, often due to a blown head gasket.

Which of the following best describes valve overlap in an engine?

Answer: When both intake and exhaust valves are partially open at the same time

Valve overlap is the brief period at the end of the exhaust stroke and beginning of the intake stroke when both valves are partially open simultaneously.

What is the primary purpose of engine oil in a vehicle?

Answer: Lubricate moving parts to reduce friction and wear

Engine oil lubricates the moving metal components of the engine to minimize friction, reduce wear, and help dissipate heat.

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

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

Detonation (knock) occurs when the air-fuel mixture ignites prematurely or unevenly in the cylinder, causing a characteristic knocking sound.

A timing belt breaks while the engine is running. What is likely to happen in an interference engine?

Answer: Pistons and valves will collide, causing severe damage

In an interference engine, the piston and valve paths overlap, so a broken timing belt causes pistons to strike open valves, causing catastrophic engine damage.

What tool is used to measure the pressure inside an engine's cylinders?

Answer: Compression tester

A compression tester is threaded into each spark plug hole to measure the peak pressure developed when the piston moves up on the compression stroke.