ASE A1 Engine Repair Practice Test
The reading on the micrometer indicates:
- A. 6.05 mm
- B. 6.00 mm
- C. 5.50 mm
- D. 6.50 mm
57. An OHC engine has a metallic rapping sound behind the harmonic balancer. Which of the following is causing this noise?
- A. A bad exhaust valve.
- B. A worn camshaft bearing.
- C. A broken valve spring.
- D. A worn crankshaft bearing.
Answer A is wrong. A burned or bent exhaust valve results in a misfire and a tapping sound at the top of the engine in the cylinder head.
Answer B is wrong. A worn camshaft bearing on an (OHC) overhead camshaft engine would result in noise at the top off the engine.
Answer C is wrong. A broken valve spring would also result in noise at the top of the engine.
Answer D is correct. Excessive bearing wear results in a knocking or rapping sound. The technician in the question is hearing the front-most bearing making this knock. It has worn past specifications, and the gap has increased. This wear left the bearing, and the journal unprotected.
58. A FWD vehicle's steering wheel and dashboard vibrate with the brake pedal applied and the transmission placed into gear. The MOST likely cause of this vibration is:
- A. A clogged catalytic converter.
- B. A faulty fuel injector.
- C. A faulty axle CV-joint.
- D. A broken engine mount.
Answer A is wrong. A clogged catalytic converter causes a restriction that results in a noticeable drop in power during acceleration.
Answer B is wrong. A clogged or faulty fuel injector would likely cause a vibration in other speeds and gears as well.
Answer C is wrong. A faulty CV-Joint makes a clicking or popping noise while slowly turning corners. The outer CV-joint is typically at fault; it is working at a greater angle.
Answer D is correct. A worn or broken engine mount would result in a vibration that is more noticeable with the brake applied and the transmission placed into gear.
59. A engine's turbocharger is producing too much boost. Which of the following is MOST likely causing this condition?
- A. A stuck open wastegate.
- B. An intake manifold vacuum leak.
- C. A stuck closed wastegate.
- D. None of the above.
Answer A is wrong. The turbocharger wastegate controls the turbocharger's output. It opens to divert exhaust away from the turbine wheel, depriving it of its source of energy.
Answer B is wrong. A vacuum leak in the intake manifold results in a lean air-fuel ratio.
Answer C is correct. The boost sensor is indicating an overboost condition. A stuck closed wastegate, faulty control valve solenoid, or line all result in an overboost condition. Without this necessary reduction in output, excessive manifold and cylinder pressures could damage vital engine components.
Answer D is wrong. The compressor wheel compresses the air-fuel charge; it's denser in comparison to a normally aspirated engine.
60. Technician A says worn valve guides result in excessive oil consumption. Technician B says aluminum heads have valve guide inserts. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. Valve guides are small holes machined into a cylinder head that allow the up and down movement of the intake and exhaust valves. A misaligned or faulty valve to valve seat seal results in overheating.
Answer B is wrong. The valve guides in iron cylinder heads are machined directly into the head. Aluminum heads have valve guide inserts. The inserts are press-fit into slightly smaller holes. They use inserts because aluminum will wear and is not as strong as iron.
Answer C is correct. Both technicians are correct.
Answer D is wrong. Both technicians are correct.