ASE A1 Engine Repair Practice Test

26. Technician A says camshaft duration is the distance the camshaft's lobe lifts the valve off the valve seat and into the cylinder. Technician B says valve overlap occurs when the intake and exhaust valves remain open at the same time. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

26.

Answer A is wrong. Camshaft duration, lift, and overlap are factors that contribute to valve timing and, ultimately, engine performance. Duration refers to time; it affects the valve's opening and closing, and how long the valve stays open. It's measured in degrees of crankshaft rotation.

Answer B is correct. As the engine cycles, there's a time when the intake and exhaust valves remain open at the same time (valve overlap). Valve overlap is an essential function in valve timing.

Answer C is wrong. The exhaust gases flowing through the exhaust valve and manifold help draw the fresh air-fuel charge through the intake valve and into the combustion chamber. This timing is a good thing and known as valve overlap.

Answer D is wrong. Measure from the nose to the heel of the cam lobe with an outside micrometer, and then deduct the base circle. This results in an accurate measurement of the cam lobe lift.

27. A vehicle is emitting black exhaust from its tailpipe under all driving conditions. This is because:

  • A. There is oil in the combustion chamber.
  • B. There is coolant in the combustion chamber.
  • C. There is too much fuel in the combustion chamber.
  • D. There is too much air in the combustion chamber.

27.

Answer A is wrong. Excess oil in the combustion chamber results in blue/gray smoke.

Answer B is wrong. Excess coolant in the combustion chamber results in white smoke.

Answer C is correct. Excess fuel in the combustion chamber results in black smoke.

Answer D is wrong. Excess air in the combustion chamber results in a lean fuel condition.

28. The top compression ring groove of a piston has worn excessively, and the gap is found to be larger than specifications. The technician would MOST likely:

  • A. Use a tapered ring set to repair this piston.
  • B. Use oversized rings to repair this piston.
  • C. Use a ring groove cleaner to repair the grooves.
  • D. Replace the piston.

28.

Answer A is wrong. Many manufacturers install tapered rings on their pistons factory. The compression pressure actually help the ring seal against the cylinder.

Answer B is wrong. Installing a larger piston ring would not repair this condition.

Answer C is wrong. This was done to remove carbon from the ring grooves before measurements were taken.

Answer D is correct. Replace the damaged piston.

29. During initial inspection the technician notices that there’s a strong sulfur odor emitting from the vehicle’s tailpipe. The customer states that the vehicle has been getting poor fuel mileage. The MOST likely cause of this condition is:

  • A. A lean fuel condition.
  • B. Leaking head gasket.
  • C. Worn piston rings.
  • D. A rich fuel condition.

29.

Answer A is wrong. A lean fuel condition would not cause this condition.

Answer B is wrong. A leaking head gasket would result in gases escaping the seal and fluids such as coolant leaking in. The vehicle would likely emit white smoke from it's tailpipe.

Answer C is wrong. Worn piston rings will result in gray smoke emitting from the tailpipe.

Answer D is correct. A rich fuel condition will result in a sulfur smell coming from the vehicle's tailpipe.

30. A technician performs a battery capacity test on a vehicle that will not start. The test results in a reading of 9.1 volts at 70° F. Technician A says the battery has failed the capacity test. Technician B says battery voltage readings will increase as temperature decreases. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

30.

Answer A is correct. If the capacity voltage goes below 9.6 volts at 70° F the battery has failed the capacity test.

Answer B is wrong. The voltage reading gets lower as the outside temperature drops.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.