ASE A1 Engine Repair Practice Exam
100 Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A Instant Download Pdf
1. A vehicle emits white-colored exhaust from its tailpipe at all engine
speeds. Which of these could be the cause?
A. Worn piston rings.
B. A leaking head gasket.
C. Worn valve seals.
D. A leaking fuel injector.
A leaking head gasket results in a coolant leak from the jacket into the
cylinder, producing white-gray exhaust. Worn piston rings result in blue/gray
exhaust. Leaking valve seals result in oil entering the combustion chamber. A
leaking fuel injector results in black sooty exhaust.
2. RTV (Room Temperature Vulcanizing) aerobic sealant:
A. Cures in the absence of air.
B. Cures in the presence of air.
C. Is used primarily inside of the engine.
D. Is safe for use with oxygen sensors.
RTV is an aerobic sealant, meaning it cures in the presence of air. Keep RTV
away from sensors. Anaerobic sealers are used on smooth, machined
components.
3. A high mileage engine has a knocking sound that goes away as it warms
and reaches operating temperature. Which of these is MOST likely
causing this noise?
A. Loose crankshaft main bolts.
B. Loose flywheel bolts.
, C. Piston to wall clearance.
D. A loose timing belt.
The piston is rocking back and forth in its bore; it expands as the engine
reaches operating temperature, the clearance between it and the cylinder
wall decreases, and so does the noise (piston slap).
4. Technician A says preignition occurs when a flame front ignites in the
combustion chamber before the spark plug fires. Technician B says
installing the wrong spark plug in an engine can result in detonation.
Who is correct?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A or B
Preignition is when a flame ignites in the combustion chamber before the
spark plug fires. A spark plug with too high a heat range can cause ping,
detonation, and preignition problems. Both technicians are correct.
5. A turbocharged engine emits blue-gray exhaust. Which of these could be
the cause?
A. A leaking fuel injector.
B. Faulty turbocharger oil seals.
C. A leaking head gasket.
D. A faulty turbocharger wastegate.
Turbocharger oil seals are heat-resistant steel rings. Excessive crankcase
pressure, shaft end-play, a clogged oil drain, and oil seal failure result in oil
entering the turbine housing—the burning oil results in the blue-gray
exhaust.
6. During a cylinder leakage test, Technician A says that any cylinder with
over 20% leakage has excessive leakage. Technician B says that air
leaking from the tailpipe indicates a cracked cylinder. Who is correct?
A. Technician A
B. Technician B
, C. Both A & B
D. Neither A nor B
If cylinder leakage exceeds 20%, check for air escaping the tailpipe, the PCV
valve opening in the rocker arm cover, and the top of the throttle body. Air
leaking from the tailpipe usually indicates an exhaust valve leak, not a
cracked cylinder.
7. During a compression test, a cylinder has 40% of the specified
compression reading. When the tech performs a wet test, the
compression reading on this cylinder has 75% of the specified reading.
The cause of the low compression reading could be:
A. Worn piston rings
B. A burned exhaust valve
C. A bent intake valve
D. A worn camshaft lobe
If compression increases during a wet test, this indicates worn piston rings.
Compression would not increase if an exhaust valve is burned, intake valve is
bent, or camshaft lobe is worn.
8. A ridge has formed on an engine block just above the piston ring's travel.
Which of the following is used to remove the ridge?
A. A cylinder ridge reamer
B. A flexible beaded hone
C. Both A and B
D. Neither A or B
A cylinder ridge reamer is the proper tool to remove a ridge formed above
piston ring travel. A flexible hone is used for surface finishing, not ridge
removal.
9. A vehicle briefly blows blue-gray exhaust smoke from its tailpipe only in
the morning or after it's been sitting for a while. Which of the following
is causing the condition?
A. Leaking cylinder head gasket
B. Leaking valve stem seals
100 Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A Instant Download Pdf
1. A vehicle emits white-colored exhaust from its tailpipe at all engine
speeds. Which of these could be the cause?
A. Worn piston rings.
B. A leaking head gasket.
C. Worn valve seals.
D. A leaking fuel injector.
A leaking head gasket results in a coolant leak from the jacket into the
cylinder, producing white-gray exhaust. Worn piston rings result in blue/gray
exhaust. Leaking valve seals result in oil entering the combustion chamber. A
leaking fuel injector results in black sooty exhaust.
2. RTV (Room Temperature Vulcanizing) aerobic sealant:
A. Cures in the absence of air.
B. Cures in the presence of air.
C. Is used primarily inside of the engine.
D. Is safe for use with oxygen sensors.
RTV is an aerobic sealant, meaning it cures in the presence of air. Keep RTV
away from sensors. Anaerobic sealers are used on smooth, machined
components.
3. A high mileage engine has a knocking sound that goes away as it warms
and reaches operating temperature. Which of these is MOST likely
causing this noise?
A. Loose crankshaft main bolts.
B. Loose flywheel bolts.
, C. Piston to wall clearance.
D. A loose timing belt.
The piston is rocking back and forth in its bore; it expands as the engine
reaches operating temperature, the clearance between it and the cylinder
wall decreases, and so does the noise (piston slap).
4. Technician A says preignition occurs when a flame front ignites in the
combustion chamber before the spark plug fires. Technician B says
installing the wrong spark plug in an engine can result in detonation.
Who is correct?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A or B
Preignition is when a flame ignites in the combustion chamber before the
spark plug fires. A spark plug with too high a heat range can cause ping,
detonation, and preignition problems. Both technicians are correct.
5. A turbocharged engine emits blue-gray exhaust. Which of these could be
the cause?
A. A leaking fuel injector.
B. Faulty turbocharger oil seals.
C. A leaking head gasket.
D. A faulty turbocharger wastegate.
Turbocharger oil seals are heat-resistant steel rings. Excessive crankcase
pressure, shaft end-play, a clogged oil drain, and oil seal failure result in oil
entering the turbine housing—the burning oil results in the blue-gray
exhaust.
6. During a cylinder leakage test, Technician A says that any cylinder with
over 20% leakage has excessive leakage. Technician B says that air
leaking from the tailpipe indicates a cracked cylinder. Who is correct?
A. Technician A
B. Technician B
, C. Both A & B
D. Neither A nor B
If cylinder leakage exceeds 20%, check for air escaping the tailpipe, the PCV
valve opening in the rocker arm cover, and the top of the throttle body. Air
leaking from the tailpipe usually indicates an exhaust valve leak, not a
cracked cylinder.
7. During a compression test, a cylinder has 40% of the specified
compression reading. When the tech performs a wet test, the
compression reading on this cylinder has 75% of the specified reading.
The cause of the low compression reading could be:
A. Worn piston rings
B. A burned exhaust valve
C. A bent intake valve
D. A worn camshaft lobe
If compression increases during a wet test, this indicates worn piston rings.
Compression would not increase if an exhaust valve is burned, intake valve is
bent, or camshaft lobe is worn.
8. A ridge has formed on an engine block just above the piston ring's travel.
Which of the following is used to remove the ridge?
A. A cylinder ridge reamer
B. A flexible beaded hone
C. Both A and B
D. Neither A or B
A cylinder ridge reamer is the proper tool to remove a ridge formed above
piston ring travel. A flexible hone is used for surface finishing, not ridge
removal.
9. A vehicle briefly blows blue-gray exhaust smoke from its tailpipe only in
the morning or after it's been sitting for a while. Which of the following
is causing the condition?
A. Leaking cylinder head gasket
B. Leaking valve stem seals
