ASE A1 Engine Repair Practice Test
11. After replacing a swollen lower radiator hose, the engine continues to overheat. Which of the following is MOST likely causing this condition?
- A. A faulty water pump impeller.
- B. A bad head gasket.
- C. A faulty replacement lower radiator hose.
- D. Air pockets in the cooling system.
Answer A is wrong. A faulty water pump impeller would cause overheating. If the system's coolant was drained, suspect an air pocket in the cooling system.
Answer B is wrong. A leaking head gasket would result in coolant leaking into the combustion chamber and white-colored exhaust.
Answer C is wrong. A faulty replacement lower radiator hose 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.
12. RTV (Room Temperature Vulcanizing) aerobic sealant:
- A. Cures in the absence of air.
- B. Is safe for use with oxygen sensors.
- C. Is used primarily inside of the engine.
- D. Cures in the presence of air.
Answer A is wrong. RTV (Room Temperature Vulcanizing) is an aerobic sealant meaning that it cures in the presence of air.
Answer B is wrong. Keep RTV away from sensors. Don't use RTV sealant on high-temperature components like oxygen sensors and exhaust manifolds.
Answer C is wrong. Anaerobic sealers are used on smooth, machined components and dry in the absence of air.
Answer D is correct. Pliable silicone sealants like RTV are most common when repairing or rebuilding an engine. They absorb engine vibrations and fill imperfect surfaces on engine parts.
13. A high mileage engine has a knocking sound that goes away as it warms and reaches operating temperature. Which of these is MOST likely causing this noise?
- A. Loose crankshaft main bolts.
- B. Loose flywheel bolts.
- C. Piston to wall clearance.
- D. A loose timing belt.
Answer A is wrong. A loose crankshaft main bolts are not likely to go away as the engine reaches operating temperature.
Answer B is wrong. Loose flywheel bolts are not likely to go away as the engine reaches operating temperature.
Answer C is correct. The piston is rocking back and forth in its bore, it expands as the engine reaches operating temperature, the clearance between it and the cylinder wall decreases, and so does the noise known as piston slap.
Answer D is wrong. A loose timing belt makes a slapping sound at the front of the engine whenever it is running.
14. Technician A says preignition occurs when a flame front ignites in the combustion chamber before the spark plug fires. Technician B says installing the wrong spark plug in an engine can result in detonation. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. There are several causes for these conditions. Most have to do with temperature and timing.
Answer B is wrong. The heat range of a spark plug depends on the design of the center electrode and the length of the ceramic insulator surrounding it. A spark plug with too high of a heat range can cause ping, detonation, and preignition problems.
Answer C is correct. Both technicians are correct. Detonation is caused by colliding flame fronts in an internal combustion engine.
Answer D is wrong. Preignition is when a flame ignites in the combustion chamber before the spark plug fires and reveals itself as a slight knocking sound heard during acceleration.
15. A turbocharged engine emits blue-gray exhaust. Which of the following would result in this condition?
- A. A leaking fuel injector.
- B. Faulty turbocharger oil seals.
- C. A leaking head gasket.
- D. A faulty turbocharger wastegate.
Answer A is wrong. Leaking fuel injectors result in black-colored (fuel) exhaust and a rich air-fuel ratio.
Answer B is correct. Faulty turbocharger bearings result in oil seal failure and blue-gray (oil) exhaust.
Answer C is wrong. A leaking head gasket results in the white-gray (coolant) exhaust.
Answer D is wrong. The wastegate opens to divert some of the exhaust away from the turbine. It deprives the turbocharger of exhaust pressure, its source of energy. Without this necessary reduction in output, manifold and cylinder pressures would damage vital engine components.