Auto and Shop: Engine Systems and Repair Flashcards

What is the purpose of the camshaft in a 4-stroke engine?

Answer: Open and close intake and exhaust valves

The camshaft uses lobes to push on valve lifters, opening and closing the intake and exhaust valves at precisely timed intervals.

A car engine runs hot and the temperature gauge reads high. The coolant level is normal. What is the most likely cause?

Answer: Faulty thermostat stuck closed

A thermostat stuck in the closed position prevents coolant from circulating through the radiator, causing the engine to overheat.

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

Answer: Head gasket

The head gasket forms a seal between the cylinder head and the engine block to contain combustion pressure and prevent coolant or oil leaks.

What does a PCV (Positive Crankcase Ventilation) valve do?

Answer: Vents crankcase gases back into the intake manifold

The PCV valve recirculates blow-by gases from the crankcase back into the intake manifold to be burned, reducing emissions.

An engine has low compression in one cylinder. What is the most likely cause?

Answer: Worn or damaged piston rings

Worn piston rings allow combustion gases to bypass the piston and escape into the crankcase, reducing compression in that cylinder.

What type of engine uses glow plugs instead of spark plugs?

Answer: Diesel engine

Diesel engines use glow plugs to preheat the combustion chamber, since they ignite fuel by compression rather than a spark.

What is the function of the crankshaft in an engine?

Answer: Convert linear piston motion into rotational motion

The crankshaft converts the up-and-down (linear) motion of the pistons into the rotational motion that ultimately drives the vehicle.