ASSIGNMENT 3 Textbook  Assignment: "Internal  Combustion  Engines,"   "Speed Controlling Devices," and "Refrigeration  and  Air  Conditioning,"  chapters  3,  4,  and  5,  pages  3-23 through 5-9. 3-1. An engine cannot be cranked, but it can be barred over. Which of the following  is  the  most  probable fault? 1. Improper  throttle  setting 2. Tripped  overspeed  device 3. Engaged  jacking  gear  interlock 4. Seized  piston 3-2. In an engine that cannot be cranked, but can be barred over, which  of  the  following  systems  is the  most  probable  source  of trouble? 1. Starting 2. Fuel 3. Ignition 4. Lubrication 3-3. Which of the following troubles may be  detected  through  the  scavenging air port? 1. Stuck  piston  rings 2. Seized  bearing 3. Faulty air-starting distributor 4. Scored bearing 3-4. What causes most of the troubles in a  direct  mechanical  lift air-starting   system? 1. Insufficient   lubrication 2. Improper   adjustments 3.   Dirt and gum deposits 4. Inadequate   cooling 3-5. On a rotary distributor timing mechanism,  what  should  you  use  to check  the  contact  between  the  rotor and the body? 1. Feeler  gauge 2. Prussian  blue 3. Clearance  light 4. Micrometer 3-6. Which  of  the  following  practices tends to reduce or eliminate the formation  of  gummy  deposits  that cause upper and lower pistons of pressure-activated    air-starting valves to stick in the cylinders? 1. Increasing the tension of the valve  return  springs 2. Draining  the  storage  tanks  and water  traps  of  the  air-starting system 3. Jacking  the  engine  over manually  before  starting  to free any valves that may be stuck 4. Decreasing  the  tension  of  the valve  return  springs 3-7. If the upper piston of an air-actuated  starting  valve  sticks because  of  gummy  deposits,  what action  should  you  take? 1. Force  alcohol  around  the pistons 2. Blow clean hot air around the pistons 3.   Put light oil or diesel fuel around the piston and work the valve up and down 4. Remove the piston and buff it with  jeweler's  rouge 3-8. In general, what should you do if a pressure-actuated    air-starting valve  is  not  functioning  properly because of a weak return spring? 1. Place another washer on top of the  valve  stem 2. Replace  the  castellated  nut with a heavier one 3. Restress  the  valve  return spring 4. Install a new valve return spring 17