ASE A1- Engine Repair Exam 2025
Questions and Answers
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 - 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
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,C. Both A and B
D. Neither A or B - ANSWER✔✔-The correct answer is C, both technicians are right. Either
method can be used to check main bearing oil clearance.
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 - 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 - 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
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,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 - 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 - 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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 3
, 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 - 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 - 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.
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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 4
Questions and Answers
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 - 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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 1
,C. Both A and B
D. Neither A or B - ANSWER✔✔-The correct answer is C, both technicians are right. Either
method can be used to check main bearing oil clearance.
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 - 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 - 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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 2
,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 - 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 - 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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 3
, 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 - 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 - 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.
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
FOR STUDY PURPOSES ONLY COPYRIGHT © 2025 ALL RIGHTS RESERVED 4
