ASE A1- Engine Repair exam verified with correct answers
2026/2027 version
Which of the following is NOT a method of correcting excessive valve stem-to-guide
clearance?
A. Knurling the valve stem
B. Knurling the guide
C. Reaming for oversize
D. Guide replacement- correct answer>>>The correct answer is A. The valve stem is
hardened and cannot be knurled.
A vacuum gauge is connected to the intake manifold of an engine running at idle. The
pointer on the gauge fluctuates rapidly but steadies as the engine speed is increased.
The test results indicate:
A. A leaking intake manifold gasket
B. Worn valve guides
C. Late ignition timing
D. A weak valve spring- correct answer>>>The correct answer is B. Worn valve guide
could cause the needle to fluctuate rapidly at idle but steady as the engine speed is
increased. A leaking intake manifold gasket or late ignition timing would cause a steady
low reading. A weak valve spring would cause the gauge needle to fluctuate as engine
speed increased.
A technician takes a compression reading on a 4-cylinder engine, and gets readings of
140, 135, 135, and 40 psi. Then he preforms a wet compression test, and the readings
are almost the same as those in the first test. Technician A says that a burned valve
could cause these readings. Technician B says that a broken piston ring could cause
these readings. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is A, only technician A is
correct. A burned valve will not allow the cylinder to build compression, and the results
from wet and dry compression tests will be the same. If piston rings (or worn cylinder
walls) were at fault, compression readings from a wet test would exceed dry test results.
Technician A says that retarded valve timing can cause high cylinder compression
readings. Technician B says that a lean air/fuel mixture can cause a high intake
manifold vacuum reading. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is D, neither technician is right.
Technician A is wrong because retarded valve timing will cause the valves to open and
close at the wrong time, thereby reducing compression and manifold vacuum readings.
,Retarded valve timing can be caused by a loose timing belt or chain jumping one or
more teeth. Technician B is wrong because a low but steady manifold vacuum reading
may be caused by a lean air/fuel mixture. Air leaks or vacuum leaks can cause a lean
condition and are common causes of rough idle, hesitation, stalling and hard starting. If
the mixture is artificially enriched by injecting propane into the induction system, and
engine running lean should speed up and the vacuum reading should rise.
An engine is being rebuilt and the crankshaft connecting rod journals have been ground
undersize. Specifications show that the original connecting rod journal size was 2.1228-
in. 2.1236-in. If the journals now measure 2.1032-in., what size bearings should be
used?
A. 0.001-in. undersize
B. 0.010-in. undersize
C. 0.020-in. undersize
D. 0.030-in. undersize- correct answer>>>The correct answer is C. Adding 0.020 to
2.1032 is 2.1232, which is right in the middle of the standard specifications, so 0.020-in.
undersize bearings should be used.
Camshaft lift is defined as:
A. the distance the valves are open
B. the height of the lobes on the camshaft
C. the time the valves stay closed
D. the time the valves stay open- correct answer>>>The correct answer is B. The
distance the valves are opened is defined as valve lift. The time the valves stay open is
usually referred to as duration.
A compression test shows that one cylinder is too low. A leakage test on that cylinder
shows that there is excessive leakage. During the test, air could be heard coming from
the tailpipe. Which of the following could be the cause?
A. Broken piston rings
B. Bad head gasket
C. Bad exhaust gasket
D. An exhaust valve not seating- correct answer>>>The correct answer is D. If an
exhaust valve is not seating, air will leak from the combustion chamber by way of the
valve out to the tailpipe and make an audible sound. Broken rings or a bad head gasket
would have air leaking through the oil filler or cooling system.
Technician A says that main bearing oil clearance can be checked with plastigage.
Technician B says that main bearing oil clearance can be checked with a dial bore
gauge. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is C, both technicians are
right. Either method can be used to check main bearing oil clearance.
, Technician A says that the burned valve could be the result of too little valve lash.
Technician B says excessive valve lash could cause very fast camshaft wear. Who is
right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is C, both technicians are
right. A clearance ramp cushions the take up of clearance between the rocker arm or
cam follower. Excessive lash causes the came lobe to be contacted after the clearance
ramp has passed. Too little valve lash results in not enough time for heat to be carried
from the valve into the seat and its coolant jacket.
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- correct answer>>>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- correct answer>>>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- correct answer>>>The correct answer is A. A bent crankshaft could
cause more wear on both bearings in the center of a block; straightening or replacing
2026/2027 version
Which of the following is NOT a method of correcting excessive valve stem-to-guide
clearance?
A. Knurling the valve stem
B. Knurling the guide
C. Reaming for oversize
D. Guide replacement- correct answer>>>The correct answer is A. The valve stem is
hardened and cannot be knurled.
A vacuum gauge is connected to the intake manifold of an engine running at idle. The
pointer on the gauge fluctuates rapidly but steadies as the engine speed is increased.
The test results indicate:
A. A leaking intake manifold gasket
B. Worn valve guides
C. Late ignition timing
D. A weak valve spring- correct answer>>>The correct answer is B. Worn valve guide
could cause the needle to fluctuate rapidly at idle but steady as the engine speed is
increased. A leaking intake manifold gasket or late ignition timing would cause a steady
low reading. A weak valve spring would cause the gauge needle to fluctuate as engine
speed increased.
A technician takes a compression reading on a 4-cylinder engine, and gets readings of
140, 135, 135, and 40 psi. Then he preforms a wet compression test, and the readings
are almost the same as those in the first test. Technician A says that a burned valve
could cause these readings. Technician B says that a broken piston ring could cause
these readings. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is A, only technician A is
correct. A burned valve will not allow the cylinder to build compression, and the results
from wet and dry compression tests will be the same. If piston rings (or worn cylinder
walls) were at fault, compression readings from a wet test would exceed dry test results.
Technician A says that retarded valve timing can cause high cylinder compression
readings. Technician B says that a lean air/fuel mixture can cause a high intake
manifold vacuum reading. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is D, neither technician is right.
Technician A is wrong because retarded valve timing will cause the valves to open and
close at the wrong time, thereby reducing compression and manifold vacuum readings.
,Retarded valve timing can be caused by a loose timing belt or chain jumping one or
more teeth. Technician B is wrong because a low but steady manifold vacuum reading
may be caused by a lean air/fuel mixture. Air leaks or vacuum leaks can cause a lean
condition and are common causes of rough idle, hesitation, stalling and hard starting. If
the mixture is artificially enriched by injecting propane into the induction system, and
engine running lean should speed up and the vacuum reading should rise.
An engine is being rebuilt and the crankshaft connecting rod journals have been ground
undersize. Specifications show that the original connecting rod journal size was 2.1228-
in. 2.1236-in. If the journals now measure 2.1032-in., what size bearings should be
used?
A. 0.001-in. undersize
B. 0.010-in. undersize
C. 0.020-in. undersize
D. 0.030-in. undersize- correct answer>>>The correct answer is C. Adding 0.020 to
2.1032 is 2.1232, which is right in the middle of the standard specifications, so 0.020-in.
undersize bearings should be used.
Camshaft lift is defined as:
A. the distance the valves are open
B. the height of the lobes on the camshaft
C. the time the valves stay closed
D. the time the valves stay open- correct answer>>>The correct answer is B. The
distance the valves are opened is defined as valve lift. The time the valves stay open is
usually referred to as duration.
A compression test shows that one cylinder is too low. A leakage test on that cylinder
shows that there is excessive leakage. During the test, air could be heard coming from
the tailpipe. Which of the following could be the cause?
A. Broken piston rings
B. Bad head gasket
C. Bad exhaust gasket
D. An exhaust valve not seating- correct answer>>>The correct answer is D. If an
exhaust valve is not seating, air will leak from the combustion chamber by way of the
valve out to the tailpipe and make an audible sound. Broken rings or a bad head gasket
would have air leaking through the oil filler or cooling system.
Technician A says that main bearing oil clearance can be checked with plastigage.
Technician B says that main bearing oil clearance can be checked with a dial bore
gauge. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is C, both technicians are
right. Either method can be used to check main bearing oil clearance.
, Technician A says that the burned valve could be the result of too little valve lash.
Technician B says excessive valve lash could cause very fast camshaft wear. Who is
right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B- correct answer>>>The correct answer is C, both technicians are
right. A clearance ramp cushions the take up of clearance between the rocker arm or
cam follower. Excessive lash causes the came lobe to be contacted after the clearance
ramp has passed. Too little valve lash results in not enough time for heat to be carried
from the valve into the seat and its coolant jacket.
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- correct answer>>>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- correct answer>>>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- correct answer>>>The correct answer is A. A bent crankshaft could
cause more wear on both bearings in the center of a block; straightening or replacing
