ASE A1 (Engine Repair) Practice Exam (Cumulative): Questions
& 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
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 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 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
B. Technician B only
C. Both A and B
D. Neither A or B - 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 - 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 - 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.
& 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
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 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 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
B. Technician B only
C. Both A and B
D. Neither A or B - 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 - 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 - 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.
