ASE T2 Diesel Engines Practice Exam

ASE T2 Diesel Engines Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary function of a diesel engine’s glow plugs?
• Start the fuel injection pump
• Increase engine compression
• Preheat the combustion chamber for cold starting
• Cool the cylinder head
• Preheat the combustion chamber for cold starting

Glow plugs heat the combustion chamber to ensure the diesel fuel ignites more easily in cold conditions.

• Which component converts mechanical energy from the engine into

electrical energy?

• Starter motor
• Alternator
• Battery 1 / 4

• Solenoid
• Alternator

The alternator generates electricity to recharge the battery and power electrical systems while the engine is running.

• What is the main purpose of a diesel engine turbocharger?
• Reduce engine noise
• Increase air intake pressure to improve combustion
• Control exhaust emissions
• Lubricate the cylinder walls
• Increase air intake pressure to improve combustion

A turbocharger compresses intake air, allowing more oxygen into the combustion chamber, which improves efficiency and power output.

• Which type of diesel fuel injection system uses a high-pressure pump to

deliver fuel directly into the combustion chamber?

• Mechanical unit injector
• Common rail
• Distributor-type pump
• Carbureted injection
• Common rail

The common rail system maintains high-pressure fuel in a shared rail, allowing precise timing and quantity for direct injection.

• What is the typical compression ratio range for a diesel engine?
• 5:1 to 7:1 2 / 4

• 8:1 to 10:1
• 14:1 to 25:1
• 28:1 to 35:1
• 14:1 to 25:1

Diesel engines use higher compression ratios to ignite fuel without spark plugs.

• What is the main purpose of the engine oil in a diesel engine?
• To cool the fuel injectors
• To lubricate moving parts and reduce friction
• To clean the air filter
• To power the turbocharger
• To lubricate moving parts and reduce friction

Engine oil forms a film between moving parts, preventing wear and overheating.

• Which component controls the fuel quantity delivered to the engine?
• Fuel filter
• Fuel pump
• Fuel injector
• Governor
• Governor

The governor regulates fuel delivery to maintain engine speed under varying loads. 3 / 4

• What is the purpose of the engine coolant?
• Clean the fuel system
• Lubricate the engine
• Remove excess heat and maintain optimal engine temperature
• Increase compression
• Remove excess heat and maintain optimal engine temperature

Coolant circulates through the engine and radiator, preventing overheating and maintaining efficiency.

• What could cause white smoke from a diesel engine’s exhaust?
• Fuel leaks in the injection system
• Incomplete combustion due to low temperature
• Excessive oil consumption
• Air filter clog
• Incomplete combustion due to low temperature

White smoke often indicates unburned fuel or condensation in the exhaust, typically from cold starts.

• Which diesel engine component is responsible for air intake timing?
• Camshaft
• Crankshaft
• Injector pump
• Turbocharger
• Camshaft
• / 4