ASE A1 Engine Repair Practice Test
The reading on the micrometer above 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 of 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 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 vehicle with an eight-cylinder engine and a manual transmission has a knocking sound at the back of the engine whenever the engine is running. Which of these could be the cause?
- A. A worn timing belt.
- B. A loose harmonic balancer.
- C. Loose flywheel bolts.
- D. A faulty power steering pump.
Answer A is wrong. A loose and worn timing belt makes a flapping sound at the front of the engine.
Answer B is wrong. A loose harmonic balancer makes a knocking noise at the front of the engine.
Answer C is correct. Manual transmissions have flywheels that absorb engine pulses transferred through the crankshaft. Loose flywheel (manual transmission) or flexplate (automatic transmission) bolts knock at the back of the engine whenever the engine is running.
Answer D is wrong. A faulty power steering pump makes a moaning or whining noise at the front of the engine that gets louder during turns.
59. The oil pressure switch on an engine may be faulty. All of the following are true about oil pressure switches EXCEPT:
- A. Test this switch with a digital multimeter.
- B. The warning lamp turns off as oil pressure rises.
- C. This sensor is a variable resistor.
- D. Set the meter to Ohms to check for continuity.
Answer A is wrong. Use a digital multimeter set to Ohms. They can be tested for operation with the engine not running and then with the engine running.
Answer B is wrong. Oil pressure switches are normally closed. The oil pressure warning light illuminates when the ignition is first turned on and goes out after the engine starts and the oil pressure rises.
Answer C is correct. The switch contacts are either open or closed; variable resistors have many positions.
Answer D is wrong. Set the meter to Ohms to check for continuity.
60. During a cylinder leakage test, a hissing sound is heard from the throttle body. This sound indicates:
- A. The engine has a bad exhaust valve.
- B. The engine has worn piston rings.
- C. The engine has a bad intake valve.
- D. The engine has a leaking head gasket.
Answer A is wrong. A hissing sound from the tailpipe indicates a leaking exhaust valve or seat. The exhaust valve leads to the exhaust manifold /tailpipe.
Answer B is wrong. Worn piston rings cause air to escape through the PCV outlet.
Answer C is correct. A leaking intake valve will result in a hissing sound from the throttle body. It can be heard by removing the air tube and opening the throttle plate. The intake valve is leaking air into the intake manifold.
Answer D is wrong. A faulty head gasket or a crack in the block's deck area or cylinder head allows compression to leak into the coolant jacket. It results in air bubbles appearing in the radiator neck. It can be heard by removing the air tube and opening the throttle plate. The intake valve is leaking air into the intake manifold.