Automotive Technology: A Systems Approach (7th Edition) by Jack Erjavec &
Rob Thompson 1
Question 1
A technician is performing a cylinder leakage test. A hissing sound is heard from
the exhaust pipe. What is the most likely conclusion?
A) Intake valve is leaking
B) Piston rings are worn
C) Head gasket is blown between cylinders
D) Exhaust valve is leaking
Answer: D
Rationale: During a cylinder leakage test, compressed air is introduced into the
cylinder. If the exhaust valve is leaking, the escaping air travels out of the exhaust
system, creating a hissing sound at the tailpipe. An intake leak hisses at the
throttle body, rings leak into the crankcase, and a blown head gasket causes
bubbles in the radiator.
Question 2
,Technician A says that piston rings should be installed with the gaps aligned in a
straight line to improve sealing. Technician B says that ring gaps should be
staggered around the piston to prevent blow-by. Who is correct?
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B
Answer: B
Rationale: Technician B is correct. Ring gaps must be staggered (typically 120
degrees apart for three rings) to prevent the "blow-by" path that would occur if
gaps were aligned. Technician A’s recommendation would cause excessive oil
consumption and compression loss.
Question 3
A vehicle has a misfire that is worst at idle but clears up at higher RPM. This is
most often caused by:
,A) A lean fuel mixture
B) A vacuum leak
C) Worn spark plugs
D) A weak ignition coil
Answer: B
Rationale: Vacuum leaks have the greatest proportional impact on the air-fuel
mixture at idle because the total airflow is low. At higher RPMs, the extra
unmetered air becomes a smaller percentage of total airflow, reducing the misfire
severity.
Question 4
When measuring crankshaft journal wear, "taper" refers to:
A) A difference in diameter between the front and rear of the same journal
B) A journal that is no longer perfectly round (oval shape)
C) A journal that is too small due to grinding
D) A scratch or score mark on the journal surface
, Answer: A
Rationale: "Taper" is measured by comparing the diameter at the front of the
journal to the diameter at the back. "Out-of-round" refers to the diameter
difference 90 degrees apart on the same journal section.
Question 5
Technician A says that engine oil with a higher viscosity (e.g., 20W-50) is always
better for engine protection. Technician B says that using oil with too high a
viscosity can cause slow oil flow during cold starts. Who is correct?
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B
Answer: B
Rationale: Technician B is correct. While high viscosity maintains film strength at
high temps, it flows slowly when cold, causing delayed lubrication to critical
components like camshafts and turbochargers. Modern engines are designed for
specific viscosities (often 0W-20 or 5W-30) to ensure quick cold-start flow.
Rob Thompson 1
Question 1
A technician is performing a cylinder leakage test. A hissing sound is heard from
the exhaust pipe. What is the most likely conclusion?
A) Intake valve is leaking
B) Piston rings are worn
C) Head gasket is blown between cylinders
D) Exhaust valve is leaking
Answer: D
Rationale: During a cylinder leakage test, compressed air is introduced into the
cylinder. If the exhaust valve is leaking, the escaping air travels out of the exhaust
system, creating a hissing sound at the tailpipe. An intake leak hisses at the
throttle body, rings leak into the crankcase, and a blown head gasket causes
bubbles in the radiator.
Question 2
,Technician A says that piston rings should be installed with the gaps aligned in a
straight line to improve sealing. Technician B says that ring gaps should be
staggered around the piston to prevent blow-by. Who is correct?
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B
Answer: B
Rationale: Technician B is correct. Ring gaps must be staggered (typically 120
degrees apart for three rings) to prevent the "blow-by" path that would occur if
gaps were aligned. Technician A’s recommendation would cause excessive oil
consumption and compression loss.
Question 3
A vehicle has a misfire that is worst at idle but clears up at higher RPM. This is
most often caused by:
,A) A lean fuel mixture
B) A vacuum leak
C) Worn spark plugs
D) A weak ignition coil
Answer: B
Rationale: Vacuum leaks have the greatest proportional impact on the air-fuel
mixture at idle because the total airflow is low. At higher RPMs, the extra
unmetered air becomes a smaller percentage of total airflow, reducing the misfire
severity.
Question 4
When measuring crankshaft journal wear, "taper" refers to:
A) A difference in diameter between the front and rear of the same journal
B) A journal that is no longer perfectly round (oval shape)
C) A journal that is too small due to grinding
D) A scratch or score mark on the journal surface
, Answer: A
Rationale: "Taper" is measured by comparing the diameter at the front of the
journal to the diameter at the back. "Out-of-round" refers to the diameter
difference 90 degrees apart on the same journal section.
Question 5
Technician A says that engine oil with a higher viscosity (e.g., 20W-50) is always
better for engine protection. Technician B says that using oil with too high a
viscosity can cause slow oil flow during cold starts. Who is correct?
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B
Answer: B
Rationale: Technician B is correct. While high viscosity maintains film strength at
high temps, it flows slowly when cold, causing delayed lubrication to critical
components like camshafts and turbochargers. Modern engines are designed for
specific viscosities (often 0W-20 or 5W-30) to ensure quick cold-start flow.
