ASE A1 Engine Repair Practice Test
46. After replacing the lower radiator hose and adding coolant, the engine continues to overheat. 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 results in 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 also results in high HC's 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 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. Crossed ignition wires affect two adjacent cylinders.
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 with the others. For example, a leaking or blown head gasket can leak compression between two adjacent cylinders.
50. Technician A says that insufficient hydraulic lifter preload results in excessive valve train noise. Technician B says excessive hydraulic lifter preload results in 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.