ASE A1 Engine Repair Practice Test
46. The engine overheats after replacing the lower radiator hose and adding coolant. Which of the following is MOST likely causing this condition?
- A. A faulty water pump impeller.
- B. A leaking head gasket.
- C. A faulty fan motor relay.
- D. An air pocket in the cooling system.
Answer A is wrong. After draining an engine's coolant, stubborn air pockets can form in the cooling system.
Answer B is wrong. A leaking head gasket produces tiny air bubbles in the radiator neck, overheating, and white-colored exhaust.
Answer C is wrong. A faulty fan motor relay is not the MOST likely answer.
Answer D is correct. Air pockets form after draining the engine's coolant. Some vehicles are more prone to this problem than others.
47. A vehicle is emitting black-colored exhaust. Which of these could be the cause?
- A. Oil is burning in the combustion chamber.
- B. Coolant is burning in the combustion chamber.
- C. A rich air-fuel ratio.
- D. A lean air-fuel ratio.
Answer A is wrong. Oil burning in the combustion chamber results in blue-gray exhaust.
Answer B is wrong. Coolant entering the combustion chamber results in white-colored exhaust.
Answer C is correct. A rich air-fuel ratio causes black-colored exhaust.
Answer D is wrong. A rich air-fuel ratio produces high HC emissions and black sooty deposits around the tailpipe.
48. All of the following statements are true about an engine's PCV system EXCEPT:
- A. A stuck closed PCV valve results in excessive crankcase pressure.
- B. A stuck open PCV valve results in a rough idle.
- C. Oil leakage indicates a problem with the system.
- D. The PCV valve should not rattle when shaken.
Answer A is wrong. A stuck closed PCV valve causes excessive crankcase pressure.
Answer B is wrong. A stuck open PCV valve or leaking hose results in a rough idle and drivability issues.
Answer C is wrong. Oil leakage indicates a problem with the system.
Answer D is correct. The PCV valve should rattle when shaken.
49. A cylinder power balance test indicates two adjacent cylinders are underperforming. Which of the following is causing this test result?
- A. A faulty fuel injector.
- B. A bad exhaust valve.
- C. Worn piston rings.
- D. A leaking head gasket.
Answer A is wrong. A faulty fuel injector will only affect the cylinder it services.
Answer B is wrong. A faulty exhaust valve will affect only one cylinder.
Answer C is wrong. Worn piston rings affect all of the engine's cylinders.
Answer D is correct. Perform a cylinder power balance test to compare each cylinder's effectiveness and find a weak or problem cylinder(s). For example, a leaking or blown head gasket can leak compression between two adjacent cylinders.
50. Technician A says insufficient hydraulic lifter preload results in excessive valve train noise. Technician B says excessive hydraulic lifter preload produces a high intake manifold vacuum. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is correct. Insufficient lifter preload will cause valve train noise.
Answer B is wrong. Excessive hydraulic lifter preload causes a low intake manifold vacuum.
Answer C is wrong. With a hydraulic lifter, first set the gap to zero lash and then set the preload.
Answer D is wrong. This initial zero lash adjustment prevents valve tap and is why hydraulic lifters have a quieter operation.