Wrap-Up

Ready for Review

• Engine noises can direct the technician to the proper engine area for diagnosis.
• Valve train noises can be caused by small clearances created by wear in the valve train.
• Timing chain noise can be caused by worn guides, stretched chains, or failed tensioners.
• Pre-ignition and detonation are different issues.
• Oil consumption should be tested to determine whether the engine is burning oil.
• Verifying oil pressure is recommended when diagnosing a VVT issue.
• Leaking head gaskets can cause an overheating condition.
• Diagnosing leaking head gaskets can be done using a block tester.
• An exhaust gas analyzer can help determine whether there is a head gasket leak.
• Coolant consumption should be monitored when diagnosing a misfire.
• High-tech engine mounts can be adjusted to compensate for noises.
• Standard motor mounts are major sources of vibrations on the engine.
• A cracked flexplate/flywheel can cause a noise at the rear of the engine.

Key Terms

automotive stethoscope  A tool that uses a long solid metal probe at the end that when held against a solid component transfers sound to the earpieces.

cylinder head temperature (CHT)  A thermistor that changes resistance as the cylinder head changes temperature.

decoupler pulleys  High-tech pulleys that provide belt-drive power to the alternator during acceleration and cruising speeds.

detonation  When detonation occurs, the spark plug ignites the air-fuel mixture, as it should; however, the flame front initiated by the spark plug collides with an undesired flame front.

engine coolant temperature (ECT)  A thermistor that changes resistance as the temperature changes.

front-end accessory drive (FEAD) component  Any front-end accessory drive component that is driven off of the front of the engine.

Review Questions

1. Internal engine noise must be diagnosed before any other issues are looked at because ________.
   • internal engine components can cause performance issues
   • internal engine components are easier to fix
   • mechanical issues are more important
   • they are easier to deal with
2. All of the following statements with respect to head gasket leakage are true except:
   • A leaking head gasket can use all the coolant in the vehicle.
   • A leaking head gasket can increase compression.
   • Head gaskets seal the cylinder block to the cylinder head.
   • Overheating the engine can cause the head gasket to blow.
3. Low oil pressure in an engine causes which one of the following?
   • Ignition timing issues.
   • Damage to the engine components.
   • Fuel injector failure.
   • PCM failure.
4. What is a common cause of detonation within an internal combustion engine?
   • Correct fuel usage.
   • Correct compression ratio.
   • Carbon deposits on the face of the piston.
   • Normal usage of the engine.
5. Oil consumption can cause engine performance issues because of the oil film that is coating the spark plug.
   • True.
   • False.
6. Valve train clearance can cause a running issue because ________.
   • of decreased timing
   • the fuel injector will be on for longer
   • valve train clearance can change the operation of camshaft
   • valves are not opening properly
7. A warped cylinder head can cause all of the following except:
   • An overheating issue.
   • A running issue that may show up as a misfire.
   • A warped cylinder head may cause a fuel injection leak.
   • A warped cylinder head may cause a coolant leak.
8. A timing chain that has been stretched should _________.
   • be replaced with a new chain, guides, and sprockets
   • be reinstalled in the opposite direction so that it can be reused
   • be monitored once the engine is put back into service
   • have the master link replaced to restore tension
9. When the head gasket is leaking exhaust into the cooling system, diagnosing it can be accomplished by _________________.
   • using a scan tool to indicate which cylinder is leaking exhaust into the coolant
   • using a block tester detect to exhaust fumes in the coolant
   • disassembling the cooling system
   • replacing the thermostat
10. With later-model engines having adjustable motor mounts, which of the following could incur an electrical failure?
    • The solenoid that controls the mount.
    • The crankshaft position sensor.
    • A VVT control solenoid.
    • The starter solenoid.

ASE Technician A/Technician B–Style Questions

1. Technician A says that a standard motor mount can mechanically break, which can cause a vibration. Technician B says that an adjustable motor mount will not break, because it can adjust to failures. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
2. Technician A says that pre-ignition situations can cause internal engine component failures. Technician B says that a timing chain that has been stretched can cause a running issue. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
3. Technician A says that engine oil consumption is something that the technician shouldn’t care about. Technician B says some coolant consumption is normal in an engine. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
4. Technician A says that valve train clearance can cause top-end engine noise. Technician B says that lower-end noise usually accompanies internal engine failure. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
5. Technician A says that a failed head gasket can cause a misfire to be created in the engine. Technician B says that a failed head gasket cannot be determined exclusively by a scan tool. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
6. Technician A says that a standard motor mount will never break. Technician B says that an exhaust gas analyzer can be used to verify a head gasket leak. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
7. Technician A says oil leaks could cause the engine to adjust VVT, which could cause a decrease in performance. Technician B says a detonation condition can cause the PCM to advance the timing to try to correct the condition. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
8. Technician A says a normal fuel injector makes the same amount of noise that a GDI injector makes. Technician B says that front-end accessory noise could be the result of a bad bearing in an alternator. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
9. Technician A says that some oil consumption specifications must be verified by the technician. Technician B says that a cracked flexplate/flywheel can cause an engine noise that could be misdiagnosed as an engine misfire. Who is correct?
   • Technician A
   • Technician B
   • Both A and B
   • Neither A nor B
10. Technician A says that coolant burning in the combustion chamber can cause the catalyst to become damaged. Technician B says that engine oil pressure is essential for proper engine operation. Who is correct?
    • Technician A
    • Technician B
    • Both A and B
    • Neither A nor B