Question 1

Diesel Fuel System

Accepted Answer

The system responsible for delivering fuel to the diesel engine for combustion.

Question 2

Injection Pump

Accepted Answer

A device that pressurizes and meters fuel into the injectors.

Question 3

Turbocharger

Accepted Answer

A device that increases the density of the air entering the engine to improve combustion efficiency.

Question 4

Glow Plug

Accepted Answer

A heating element used to preheat the combustion chamber for easier starting in cold conditions.

Question 5

Compression Ignition

Accepted Answer

The process in which fuel ignites due to the high temperature resulting from compression.

Question 6

Engine Coolant

Accepted Answer

A liquid used to transfer heat away from the engine and maintain optimal operating temperature.

Question 7

Fuel Filters

Accepted Answer

Filters that remove impurities from the diesel fuel before it enters the engine.

Question 8

Air-to-Air Cooling

Accepted Answer

A cooling system that uses outside air to cool the engine coolant.

Question 9

EGR System

Accepted Answer

Exhaust Gas Recirculation system, which reduces nitrogen oxide emissions by recirculating a portion of the exhaust gas back into the intake.

Question 10

Valve Clearance

Accepted Answer

The specified gap between the valve stem and the rocker arm or cam follower.

Question 11

Governor

Accepted Answer

A device that controls the engine speed by regulating the amount of fuel delivered to the engine.

Question 12

Fuel Injector

Accepted Answer

A device that delivers fuel into the combustion chamber at high pressure.

Question 13

Camshaft

Accepted Answer

A rotating shaft with protrusions (cams) that open and close the engine's valves.

Question 14

Fuel Pump

Accepted Answer

A device that draws fuel from the fuel tank and delivers it to the injection pump.

Question 15

Cylinder Liner

Accepted Answer

A replaceable sleeve that provides a wear-resistant surface for the piston to move within the cylinder.

Question 16

Crankshaft

Accepted Answer

A rotating shaft that converts the reciprocating motion of the pistons into rotational motion.

Question 17

Engine Oil Cooler

Accepted Answer

A heat exchanger that cools the engine oil to prevent overheating.

Question 18

Piston Rings

Accepted Answer

Rings that seal the combustion chamber and prevent oil from entering the combustion chamber.

Question 19

Timing Belt

Accepted Answer

A belt that connects the crankshaft and camshaft(s) to synchronize their rotation.

Question 20

Air Filter

Accepted Answer

A device that removes dust and other particles from the air entering the engine.

Question 21

Water Pump

Accepted Answer

A device that circulates engine coolant through the cooling system.

Question 22

Cylinder Head

Accepted Answer

The top part of the engine that houses the valves, spark plugs, and fuel injectors.

Question 23

Exhaust Manifold

Accepted Answer

A pipe that collects exhaust gases from the engine cylinders and directs them to the exhaust system.

Question 24

Intercooler

Accepted Answer

A heat exchanger that cools the compressed air from the turbocharger before it enters the engine.

Question 25

Piston Pin

Accepted Answer

A hollow pin that connects the piston to the connecting rod.

Question 26

Main Bearings

Accepted Answer

Bearings that support the crankshaft and allow it to rotate freely.

Question 27

Fuel Tank Vent

Accepted Answer

A device that allows air to enter the fuel tank to replace the fuel consumed by the engine.

Question 28

Intake Manifold

Accepted Answer

A system of pipes or passages that distributes air to the engine cylinders.

Question 29

Compression Ratio

Accepted Answer

The ratio of the cylinder's volume at the bottom dead center (BDC) to its volume at the top dead center (TDC).

Question 30

Exhaust Gas Temperature (EGT)

Accepted Answer

The temperature of the exhaust gases leaving the combustion chamber.

Question 31

Throttle Valve

Accepted Answer

A valve that regulates the amount of air entering the engine.

Question 32

Crankcase Ventilation System

Accepted Answer

A system that removes blow-by gases from the crankcase and prevents pressure buildup.

Question 33

Valve Lash

Accepted Answer

The clearance or gap between the valve stem and the rocker arm when the valve is fully closed.

Question 34

Serpentine Belt

Accepted Answer

A single, continuous belt that drives multiple engine accessories such as the alternator, water pump, and air conditioning compressor.

Question 35

Fuel Priming Pump

Accepted Answer

A hand-operated pump used to manually prime the fuel system after it has been serviced or drained.

Question 36

Fuel Pressure Regulator

Accepted Answer

A device that maintains a constant fuel pressure in the fuel system.

Question 37

Piston Cooling Jets

Accepted Answer

Small nozzles that spray oil onto the underside of the pistons to help dissipate heat.

Question 38

Valve Timing

Accepted Answer

The precise opening and closing of the engine's valves in relation to the piston's position.

Question 39

Crankshaft Position Sensor

Accepted Answer

A sensor that detects the position and rotational speed of the crankshaft.

Question 40

Valve Stem Seal

Accepted Answer

A seal that prevents oil from entering the combustion chamber through the valve stems.

Question 41

Timing Chain

Accepted Answer

A chain that connects the crankshaft and camshaft(s) to synchronize their rotation.

Question 42

Exhaust Gas Recirculation Cooler (EGR Cooler)

Accepted Answer

A heat exchanger that cools the recirculated exhaust gases before they enter the intake manifold.

Question 43

Fuel Heater

Accepted Answer

A device that preheats the diesel fuel to prevent gelling in cold weather.

Question 44

Pushrod

Accepted Answer

A rod that transfers motion from the camshaft to the rocker arms or valve lifters.

Question 45

Cetane Number

Accepted Answer

A measure of the ignition quality of diesel fuel.

Question 46

Valve Spring

Accepted Answer

A spring that closes the engine valves after they have been opened by the camshaft.

Question 47

Fuel Pressure Sensor

Accepted Answer

A sensor that monitors the pressure of the fuel in the fuel system.

Question 48

Exhaust Aftertreatment System

Accepted Answer

A system that reduces harmful emissions in the exhaust gases, such as diesel particulate filter (DPF) and selective catalytic reduction (SCR).

Question 49

Belt Tensioner

Accepted Answer

A device that maintains proper tension on the belts to prevent slippage.

Question 50

Piston Skirt

Accepted Answer

The lower part of the piston that guides it within the cylinder and provides stability.

ASE School Bus Certification Tests S2 - Diesel Engines Flashcards