ASE A1 COMPREHENSIVE EXAM 2025/2026 QUESTIONS
WITH SOLUTIONS MARKED A+
✔✔Technician A says that engine cylinders wear most at the top of the ring travel.
Technician B says that the difference in cylinder bore measurements taken parallel and
perpendicular to the crankshaft will indicate cylinder bore taper. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. Technician A is correct because most
wear to the engine cylinder is at he top where ring loading is the greatest. Technician B
is wrong because the difference in bore measurements taken at points parallel and
perpendicular to the crankshaft will indicate cylinder bore out-of-roundness.
✔✔A tapping noise can be heard coming from the upper part of an engine running at
idle. Which of the following could be the cause?
A. Valve clearance out of adjustment
B. Worn rocker arm shaft
C. Loose exhaust manifold
D. All of the above - ✔✔The correct answer is D. Tapping noises are most often caused
by loose valvetrain clearances or worn components. However, a tapping sound that
may sound like a valvetrain noise can actually be caused by an exhaust leak at the
exhaust manifold/cylinder head juncture.
✔✔An engine's upper and lower center main bearings show more wear than the ones
toward either end of the crankshaft. Technician A says this wear pattern could be due to
a bent crankshaft and replacing it with one that is straight will fix the problem.
Technician B says that the cylinder block main bearing bores are misaligned and the
problem can be fixed by align boring or honing the block. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. A bent crankshaft could cause more
wear on both bearings in the center of a block; straightening or replacing the crankshaft
would be the correct repair. A warped block would cause wear on either the upper or
the lower bearing, depending on how the block was warped.
✔✔Blue-gray smoke comes from the exhaust of a vehicle during deceleration. Of the
following, which is the LEAST likely cause?
A. Worn valve guides.
B. Broken valve seals.
C. Worn piston rings.
D. Clogged oil return passages. - ✔✔The correct answer is C. Worn piston rings will
usually make an engine smoke worse under acceleration. All of the other causes can
,allow oil to be drawn through the valve guides under the high intake vacuum that occurs
during deceleration.
✔✔When a cylinder head is disassembled, the stem height on one of the valve is found
to be too high. Which of the following can correct this?
A. Regrind the valve
B. Regrind the valve seat
C. Install a new valve seat
D. Install a shim - ✔✔The correct answer is C. Installing a new valve seat will position
the valve lower in the head and reduce stem height. A and B are incorrect because
grinding the valve or seat will place the valve higher in the head and increase the stem
height. D is also wrong; shims are used to correct valve spring installed height.
✔✔All of the following methods can be used to find cracks in aluminum heads EXCEPT:
A. Pressure test
B. Magnetic particle detection
C. Visual inspection
D. Dye penetrant - ✔✔The correct answer is B. Magnetic particle detection can only be
used on ferrous (iron and steel) parts.
✔✔Technician A says that before installing an oil pump, it should be primed with clean
engine oil. Technician B says that before installing an oil pump, the position of the
pickup screen should be checked to make sure it fits closely to the bottom of the oil pan.
Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is C, both technicians are right. The oil pump
should be filled with oil during engine reassembly to prevent it from cavitating or sucking
air during engine start-up. To prevent the pickup from sucking air and subsequent oil
starvation and engine damage, make sure the pickup screen is positioned close to the
bottom of the oil pan to ensure it is always submerged in oil.
✔✔Crankshaft journals should be measured for:
A. Diameter
B. Out-of-round
C. Taper
D. All of the above - ✔✔The correct answer is D. The crankshaft main and rod journals
should be inspected and measured for diameter, out-of-round, and taper wear.
✔✔All of the following can cause low oil pressure EXCEPT:
A. Diluted engine oil
B. Worn pistons
C. Excessive bearing clearance
, D. Clogged oil pump pickup - ✔✔The correct answer is B. Worn pistons can cause
noise and accelerate ring and bore wear, but would not cause low oil pressure. Diluted
oil, excessive bearing clearance and a clogged pump pickup can all cause low oil
pressure.
✔✔While conducting a cylinder leakage test, bubbles are seen in the coolant in the
radiator. Technician A says a failed exhaust valve is the cause. Technician B says a
failed intake valve is the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is D, neither technician is right. If a failed
exhaust valve was the cause, air would be heard from the exhaust pipe. If the intake
valve failed, air would be heard from the carburetor or throttle valve assembly. If
bubbles are seen in the radiator coolant the cause could be a leaking cylinder head
gasket or a cracked head or block.
✔✔Technician A says that umbrella valve seals are installed in their operating position
during cylinder head assembly. Technician B says that positive valve seals are position
by the valve. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is D, neither technician is right. Umbrella
seals are installed by pushing the seal down on the valve stem until it touches the valve
guide boss. It will be positioned correctly the first time the valve opens. Positive seals
are tapped into place on the guide boss during assembly using a special installation tool
and a small mallet.
✔✔Technician A says that excessive grinding of valve faces and seats allows the valve
tips to move too far away from their spring seats. Technician B says grinding the stem
tips helps to correct minor changes in valve spring installed height. Who is right?A.
Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. The stem tip height increases with valve
or seat grinding. Grinding stem tips can change the stem tip height, but will have no
effect on the valve spring installed height. That measurement is controlled by the height
of the keeper grooves above the spring seat of the head. Valve spring installed height is
corrected by installing shim(s) between the valve spring and cylinder head.
✔✔Technician A says that excessive cylinder head or block deck resurfacing on a
pushrod engine can change the geometry between the valve stem tip and rocker arm.
Technician B says that excessive grinding of the valve face and seat changes the
geometry between the valve stem tip and rocker arm. Who is right?
WITH SOLUTIONS MARKED A+
✔✔Technician A says that engine cylinders wear most at the top of the ring travel.
Technician B says that the difference in cylinder bore measurements taken parallel and
perpendicular to the crankshaft will indicate cylinder bore taper. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. Technician A is correct because most
wear to the engine cylinder is at he top where ring loading is the greatest. Technician B
is wrong because the difference in bore measurements taken at points parallel and
perpendicular to the crankshaft will indicate cylinder bore out-of-roundness.
✔✔A tapping noise can be heard coming from the upper part of an engine running at
idle. Which of the following could be the cause?
A. Valve clearance out of adjustment
B. Worn rocker arm shaft
C. Loose exhaust manifold
D. All of the above - ✔✔The correct answer is D. Tapping noises are most often caused
by loose valvetrain clearances or worn components. However, a tapping sound that
may sound like a valvetrain noise can actually be caused by an exhaust leak at the
exhaust manifold/cylinder head juncture.
✔✔An engine's upper and lower center main bearings show more wear than the ones
toward either end of the crankshaft. Technician A says this wear pattern could be due to
a bent crankshaft and replacing it with one that is straight will fix the problem.
Technician B says that the cylinder block main bearing bores are misaligned and the
problem can be fixed by align boring or honing the block. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. A bent crankshaft could cause more
wear on both bearings in the center of a block; straightening or replacing the crankshaft
would be the correct repair. A warped block would cause wear on either the upper or
the lower bearing, depending on how the block was warped.
✔✔Blue-gray smoke comes from the exhaust of a vehicle during deceleration. Of the
following, which is the LEAST likely cause?
A. Worn valve guides.
B. Broken valve seals.
C. Worn piston rings.
D. Clogged oil return passages. - ✔✔The correct answer is C. Worn piston rings will
usually make an engine smoke worse under acceleration. All of the other causes can
,allow oil to be drawn through the valve guides under the high intake vacuum that occurs
during deceleration.
✔✔When a cylinder head is disassembled, the stem height on one of the valve is found
to be too high. Which of the following can correct this?
A. Regrind the valve
B. Regrind the valve seat
C. Install a new valve seat
D. Install a shim - ✔✔The correct answer is C. Installing a new valve seat will position
the valve lower in the head and reduce stem height. A and B are incorrect because
grinding the valve or seat will place the valve higher in the head and increase the stem
height. D is also wrong; shims are used to correct valve spring installed height.
✔✔All of the following methods can be used to find cracks in aluminum heads EXCEPT:
A. Pressure test
B. Magnetic particle detection
C. Visual inspection
D. Dye penetrant - ✔✔The correct answer is B. Magnetic particle detection can only be
used on ferrous (iron and steel) parts.
✔✔Technician A says that before installing an oil pump, it should be primed with clean
engine oil. Technician B says that before installing an oil pump, the position of the
pickup screen should be checked to make sure it fits closely to the bottom of the oil pan.
Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is C, both technicians are right. The oil pump
should be filled with oil during engine reassembly to prevent it from cavitating or sucking
air during engine start-up. To prevent the pickup from sucking air and subsequent oil
starvation and engine damage, make sure the pickup screen is positioned close to the
bottom of the oil pan to ensure it is always submerged in oil.
✔✔Crankshaft journals should be measured for:
A. Diameter
B. Out-of-round
C. Taper
D. All of the above - ✔✔The correct answer is D. The crankshaft main and rod journals
should be inspected and measured for diameter, out-of-round, and taper wear.
✔✔All of the following can cause low oil pressure EXCEPT:
A. Diluted engine oil
B. Worn pistons
C. Excessive bearing clearance
, D. Clogged oil pump pickup - ✔✔The correct answer is B. Worn pistons can cause
noise and accelerate ring and bore wear, but would not cause low oil pressure. Diluted
oil, excessive bearing clearance and a clogged pump pickup can all cause low oil
pressure.
✔✔While conducting a cylinder leakage test, bubbles are seen in the coolant in the
radiator. Technician A says a failed exhaust valve is the cause. Technician B says a
failed intake valve is the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is D, neither technician is right. If a failed
exhaust valve was the cause, air would be heard from the exhaust pipe. If the intake
valve failed, air would be heard from the carburetor or throttle valve assembly. If
bubbles are seen in the radiator coolant the cause could be a leaking cylinder head
gasket or a cracked head or block.
✔✔Technician A says that umbrella valve seals are installed in their operating position
during cylinder head assembly. Technician B says that positive valve seals are position
by the valve. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is D, neither technician is right. Umbrella
seals are installed by pushing the seal down on the valve stem until it touches the valve
guide boss. It will be positioned correctly the first time the valve opens. Positive seals
are tapped into place on the guide boss during assembly using a special installation tool
and a small mallet.
✔✔Technician A says that excessive grinding of valve faces and seats allows the valve
tips to move too far away from their spring seats. Technician B says grinding the stem
tips helps to correct minor changes in valve spring installed height. Who is right?A.
Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ✔✔The correct answer is A. The stem tip height increases with valve
or seat grinding. Grinding stem tips can change the stem tip height, but will have no
effect on the valve spring installed height. That measurement is controlled by the height
of the keeper grooves above the spring seat of the head. Valve spring installed height is
corrected by installing shim(s) between the valve spring and cylinder head.
✔✔Technician A says that excessive cylinder head or block deck resurfacing on a
pushrod engine can change the geometry between the valve stem tip and rocker arm.
Technician B says that excessive grinding of the valve face and seat changes the
geometry between the valve stem tip and rocker arm. Who is right?
