ASE A1 Engine Repair Practice Test
1. 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 flow of coolant, 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 continuously.
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.
2. 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. Performed a cylinder leakage or leak-down test after a cylinder balance, and a cylinder compression test has verified the problem cylinder. It indicates the percentage of leakage and pinpoints the part causing the leak.
Answer B is wrong. 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 correct. 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.
3. 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 make adjustments to engine 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 and black-colored exhaust at the tailpipe.
Answer D is wrong. The ECM uses this signal to make adjustments to engine cooling fans and the fuel injectors.
4. 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.
Answer C is wrong. A weak electric fan motor results in engine overheating.
Answer D is wrong. Bent, cracked, or missing blades cause an imbalance and a vibration. This problem can result in damage to the water pump bearings and seals.
5. An vehicle has black-colored exhaust and a lack of power when accelerating. Technician A says a rich air-fuel ratio may have clogged the catalytic converter. Technician B says to use a back pressure tester to test for a restriction in the exhaust system. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. When a vehicle is running rich, the catalytic converter is working harder and running hotter than intended. This heat can damage the substrate and cause it to melt and degrade. The melted substrate results in excessive backpressure.
Answer B is wrong. Perform a backpressure test to confirm a clogged catalytic converter. Backpressure testers test for restrictions in the exhaust flow. Remove the upstream oxygen sensor to install the tester.
Answer C is correct. Both technicians are correct; a melted substrate results in excessive backpressure.
Answer D is wrong. A clogged catalytic converter causes a restriction that results in a noticeable drop in power during acceleration.