ASE A1 Engine Repair Practice Test
21. An engine gradually overheats at cruising speeds but returns to normal at idle. Both of the engine's electric cooling fans are functioning correctly. Which of the following is MOST likely causing this condition?
- A. A restriction in the radiator.
- B. A stuck closed fan relay.
- C. A faulty radiator cap.
- D. A leak in the cooling system.
Answer A is correct. An internal restriction in the radiator alters the coolant flow, causing the engine to overheat. Inspect the radiator for external damage and use an infrared thermometer to find internal restrictions.
Answer B is wrong. If the fan relay is stuck closed, the fan motor will operate whenever the ignition is pressed or turned ON.
Answer C is wrong. A problem with the radiator cap would also affect the engine's operating temperature at idle.
Answer D is wrong. A leak in the cooling system results in engine overheating at all speeds.
22. During a cylinder leakage test, the technician hears a hissing sound at the tailpipe. This sound is caused by:
- A. A leaking head gasket.
- B. A burned exhaust valve.
- C. Worn piston rings.
- D. A bent intake valve.
Answer A is wrong. Perform a cylinder leakage or leak-down test after a cylinder balance and a cylinder compression test have indicated an issue with a cylinder. It indicates the percentage of leakage and pinpoints the part causing the leak.
Answer B is correct. Listen for air escaping through the tailpipe, indicating a problem with the exhaust valve.
Answer C is wrong. Air escaping through the oil fill cap or dipstick indicates worn piston rings.
Answer D is wrong. Listen for air hissing through the throttle body or carburetor. This sound indicates a problem with the intake valve. It’s allowing compression to seep past the valve and its seat.
23. A faulty ECT sensor results in all of the following EXCEPT:
- A. A rich air-fuel ratio.
- B. An inoperative torque converter clutch.
- C. Blue-gray exhaust emitting from the tailpipe.
- D. An inoperative engine cooling fan.
Answer A is wrong. Symptoms of a faulty (ECT) engine coolant temperature sensor include a rich air-fuel ratio and poor fuel mileage. They're (NTC) or negative temperature coefficient thermistors. As the coolant's temperature increases, the sensor's resistance decreases.
Answer B is wrong. The ECM uses this signal to control the engine's cooling fans, fuel injectors, and transmission (TCC) torque converter clutch actuator.
Answer C is correct. The ECT's signal informs the ECM of the engine's operating temperature. A false signal may result in a rich air-fuel ratio, black-colored exhaust, and soot around the tailpipe.
Answer D is wrong. The ECM uses this signal to control engine cooling fans and fuel injector pulse width.
24. A longitudinal engine makes a loud, whirring noise that gets louder when the engine is revved. Which of the following is causing this condition?
- A. A faulty viscous fan clutch.
- B. A worn accessory belt.
- C. A weak electric cooling fan motor.
- D. A cracked fan blade.
Answer A is correct. A seized viscous fan clutch makes a whirring noise because the clutch is locked and not slipping, spinning the fan blades at engine speed at all times.
Answer B is wrong. A worn accessory belt squeals. Visually inspect the belt at a pulley for cracks and excessively worn edges from pulley misalignment.
Answer C is wrong. A weak electric fan motor results in engine overheating.
Answer D is wrong. Bent, cracked, or missing fan blades cause an imbalance and a vibration. This problem can result in damage to the water pump bearings and seals.
25. Technician A says if the teeth on the flywheel's ring gear are worn, the ring gear can be removed and replaced. Technician B says that minor scoring on the surface of a flywheel can be removed by resurfacing. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. Flywheels are found on vehicles equipped with manual transmissions. If the ring gear on a flywheel is damaged, it can often be removed and replaced.
Answer B is wrong. Scoring on the surface of a flywheel can be removed by resurfacing. The ring gear can be replaced, making it reusable. The starter ring gear for an automatic transmission is part of its flexplate. A cracked flexplate is always replaced with a new one.
Answer C is correct. Resurfacing a flywheel ensures it has the proper flatness and finish. The surface area must be smooth and not warped.
Answer D is wrong. Warpage reduces the contact area of the flywheel, allowing it to slip. This slipping causes excessive heat, hotspots, and glazing.