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Motor Plants and Auxiliary Boilers - USCG Exam Questions

Diesel engine theory and operation, fuel and lubrication systems, starting and reversing, and auxiliary boilers.

Every question below is a real U.S. Coast Guard exam question with four choices. Answer one and the correct choice is revealed instantly, with the USCG reference and illustration where the question uses one.

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All Motor Plants and Auxiliary Boilers questions

Questions 601–700 of 1,433 · page 7 of 15

  1. #974 What type of propeller thrust reversing method (or methods) is or are used with a main propulsion slow-speed crosshead type diesel engine installation...
  2. #975 Diesel engines powering large vessels that drive fixed-pitch propellers through a non-reversing reduction gear are of what type?
  3. #976 The component shown in the illustration, labeled "I", is the __________. Illustration SE-0013 illustration
  4. #977 In addition to achieving a speed reduction for efficient propeller operation, what statement represents other possible functional purposes for reducti...
  5. #978 The purpose of the main diesel engine reduction gears is to __________.
  6. #979 What would be the most accurate description of the illustrated cutaway drawing of a reduction gear as used for medium-speed diesel propulsion? Illustr... illustration
  7. #980 Which of the following methods is used to lubricate main propulsion medium-speed diesel engine reduction gears?
  8. #981 In what location is heavy fuel oil kept above the flash point, but below the boiling point of water?
  9. #982 In what location is heavy fuel oil kept below the flash point?
  10. #983 In an HFO service system, what is the immediate destination of the fuel unconsumed by the main propulsion diesel engine?
  11. #985 By what means are two sections of propulsion line shafting typically joined together?
  12. #986 What statement is true concerning oil-lubricated stern tube bearings?
  13. #987 What is the primary purpose of self-aligning spherically-seated line shaft bearings?
  14. #988 In addition to checking the lube oil sump level and temperature of a line shaft steady bearing, what else must be checked for?
  15. #989 When checking a water-lubricated stern tube bearing while underway, what should be checked for?
  16. #990 The most important factor in engine performance is the actual power output at the end of the crankshaft available for doing work. This is known as ___...
  17. #991 Which of the following relationships exist between the temperature developed in a combustion space, and the compression ratio of the engine?
  18. #995 According to the illustrated diesel propulsion plant fresh water cooling systems diagram, in which subsystem is the deaerator located? Illustration MO... illustration
  19. #996 According to the illustrated main and auxiliary diesel engine cooling water systems diagram, which of the following heat exchangers are connected dire... illustration
  20. #997 Corrosion inhibitors and/or soluble oils are added to diesel engine cooling systems to __________.
  21. #1003 What would be the primary indication that a heavy fuel oil purifier supply pump suction strainer needed cleaning?
  22. #1004 What would be the primary indication that a fuel oil service system booster pump duplex suction strainer needed to be shifted over and cleaned?
  23. #1005 According to the illustrated diesel engine fuel treatment and fuel service systems schematic, what is the purpose of the valve labeled "1"? Illustrati... illustration
  24. #1007 When monitoring a heavy fuel oil treatment plant, what would be an indication that the treatment plant throughput volume is less than the main engine...
  25. #1008 According to the illustrated diesel engine fuel treatment and fuel service systems schematic, what would be the appropriate valve configuration for op... illustration
  26. #1009 According to the illustrated diesel engine fuel treatment and fuel service systems schematic, what statement is true concerning the valves labeled "4"... illustration
  27. #1013 Injection pressure in a common rail fuel system is controlled by __________.
  28. #1014 In a diesel engine jacket water cooler, with sea water cooling the engine jacket cooling water, what statement is true?
  29. #1015 In a diesel engine lube oil cooler, with sea water cooling the lubricating oil, what statement is true?
  30. #1018 Which of the devices listed is commonly used to compensate for the expansion and minor misalignments occurring between the main turbine rotor and the...
  31. #1019 What type of clutch is used in the illustrated medium-speed diesel engine reduction gear? Illustration MO-0085 illustration
  32. #1020 The pinion gear shown in the illustration, is located __________. Illustration MO-0086 illustration
  33. #1021 What type of clutch is pictured in the illustration? Illustration MO-0089 illustration
  34. #1022 If oil discharges are detected when the scavenging air receiver drains are blown on a slow-speed, two-stroke, turbocharged, aftercooled engine, what i...
  35. #1023 Upon conducting a machinery space round on a main propulsion diesel, you detect a significant amount of water discharge when blowing down the charge a...
  36. #1024 Upon conducting a machinery space round on a slow-speed main propulsion diesel, you detect a significant amount of oil discharge when blowing down the...
  37. #1025 You are asked by the watch or duty engineer to check for any evidence for turbocharger surging. What should you check for?
  38. #1086 An oil-operated, direct reversing mechanism on a large, low-speed, main propulsion diesel engine, can serve to __________.
  39. #1089 When starting a diesel engine at temperatures below 70°F, the frictional resistance to turning will be __________.
  40. #1091 Which of the following test indicators should be considered the most significant factor in determining as to whether or not a diesel-generator's lube...
  41. #1100 A diesel engine with a combustion chamber located between the crowns of two pistons is known as a/an __________.
  42. #1102 Which factor determines the size of the ring dam for a fuel oil centrifugal purifier?
  43. #1110 The purpose of the interlocked three-way valve shown in the illustration is to __________. Illustration MO-0058 illustration
  44. #1115 The section of the turbocharger which would be connected to the aftercooler inlet is labeled __________. Illustration MO-0080 illustration
  45. #1135 Diesel engine jacket water is used in the fresh water distillation process as the __________.
  46. #1136 A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water __________.
  47. #1137 What would be considered a normal temperature increase between the inlet and outlet jacket cooling water of a medium or high-speed diesel engine opera...
  48. #1138 Which operating parameter may need to be decreased when running a large main propulsion diesel engine at low load conditions?
  49. #1139 Using a cooling water temperature of 225°F (107.2°C), instead of 180°F (82.2°C) in an auxiliary diesel engine, will __________.
  50. #1140 As a general rule, what would be the recommended operating water jacket outlet temperature range for medium-speed marine diesels setup with closed tre...
  51. #1141 In a diesel engine closed fresh water cooling system, the cooling water pressure drop through the engine is 10 psig, and the pressure drop through the...
  52. #1142 In a diesel engine jacket water cooler, with sea water cooling the fresh water, the __________.
  53. #1143 In a diesel engine closed fresh water cooling system employing a radiator, proper water temperature can be obtained by __________.
  54. #1144 If the jacket water temperature rises rapidly above normal in a diesel engine, you should FIRST __________.
  55. #1149 The diesel engine shown in the illustration, is provided with an auxiliary blower to __________. Illustration MO-0003 illustration
  56. #1160 Which of the following statements is correct concerning the operating function of the governor shown in the illustration? Illustration MO-0096 illustration
  57. #1165 When the timing gear backlash for a Roots-type blower has become excessive, the problem is properly repaired by __________.
  58. #1167 Heavy fuel oils generally have an upper average ash content of 0.1% by weight. Which of the following conditions could be expected if the ash content...
  59. #1170 If a single cylinder relief valve on a main propulsion diesel engine begins to lift, but it is not possible to secure the engine, which of the followi...
  60. #1173 What would be the first indication that a tube leak has occurred in area '23'? Illustration MO-0111 illustration
  61. #1174 If the wearing rings of device '7' shown in the illustration become worn, how will the evaporation rate in '23' be affected? Illustration MO-0111 illustration
  62. #1175 Which of the conditions listed would indicate a large condenser tube leak within the distiller shown in the illustration? Illustration MO-0111 illustration
  63. #1176 If valve "D" is opened during the normal operation of the distiller shown in the illustration, which of the events listed will occur? Illustration MO-... illustration
  64. #1182 When cleaning a duplex strainer, it is important for __________.
  65. #1183 If a diesel engine has been stopped because of piston seizure due to severe overheating, the crankcase __________.
  66. #1184 The lower water seal on a diesel engine wet cylinder liner must allow for liner axial movement. This seal is most commonly a __________.
  67. #1186 Why are some diesel engine cylinder liners plated on the wearing surface with porous chromium?
  68. #1187 The diesel engine shown in the illustration utilizes the type of cylinder construction identified as __________. Illustration MO-0007 illustration
  69. #1192 Bouncing of the valve gear in a diesel engine can be caused by __________.
  70. #1193 Excessive wear at part #11, as shown in the illustration, would result in __________. Illustration MO-0027 illustration
  71. #1194 Oil accumulating in the exhaust piping or manifold of a diesel engine can be caused by __________.
  72. #1199 If the speed of the propeller is 135 RPM, the speed of the engine camshaft shown in the illustration will be __________. Illustration MO-0003 illustration
  73. #1200 Which of the following statements would apply when checking the valve clearance of the unit shown in the illustration? Illustration MO-0074 illustration
  74. #1201 When inspecting the valve mechanism shown in the illustration, normal maintenance would include __________. Illustration MO-0074 illustration
  75. #1202 After testing your medium-speed engine's exhaust valve springs you find one with a spring constant that is lower than specified by design and a length...
  76. #1203 When a naturally aspirated four-stroke cycle diesel engine is converted for supercharging, which of the following changes must be made to the valve ti...
  77. #1204 While inspecting diesel engine combustion space components, which components would you consider for particular scrutiny for evidences of high temperat...
  78. #1206 The intake and exhaust valves used in a diesel engine are returned to their seats by __________.
  79. #1208 The valve cam slope angle determines the __________.
  80. #1209 A four-stroke cycle auxiliary diesel engine fuel cam has shifted from its original position during maintenance. To ensure correct timing of the fuel p...
  81. #1213 The pinion of an auxiliary diesel-electric starting motor normally engages the flywheel ring gear by means of a/an __________.
  82. #1214 In a Bendix starter drive, the pinion engagement with the flywheel ring gear is initiated by __________.
  83. #1215 Hydraulic starters are installed on many lifeboat diesel engines instead of comparable air start systems, because __________.
  84. #1216 A pre-arrival test is being performed with the engine on bridge control. The vessel has a slow speed engine with mechanical starting air system (not e...
  85. #1217 During maneuvering on a slow speed diesel engine vessel, a low starting air system pressure alarm is activated. Local starting air receivers' pressure...
  86. #1225 Which of the following test indicators should be considered the most significant factor in determining as to whether or not a diesel generator's lube...
  87. #1226 Crankcase explosions in propulsion diesel engines result from __________.
  88. #1227 Which of the following effects will excessively cold lube oil have on the operation of a diesel engine?
  89. #1228 Lube oil in the fresh water cooling system of a diesel engine may result from a __________.
  90. #1229 What could cause the bypass valve in a full-flow lubrication system to open?
  91. #1230 While underway, a slow-speed diesel engine lube oil sump level slowly begins to decrease. Which of the following should be checked?
  92. #1232 While bunkering heavy fuel, what quick/easy test can one perform onboard to determine the compatibility of 'old' with 'new' fuel?
  93. #1234 Does sulfur content of heavy fuel oil effect the fuel rate of a diesel engine and why or why not?
  94. #1235 Catalytic fines comprised of aluminum oxide and/or silicon dioxide are a common contaminant of residual fuels. Which diesel engine components would be...
  95. #1236 Fuel combustion in a diesel engine cylinder should begin just before the piston reaches top dead center and should __________.
  96. #1239 During the change over period from residual to distillate fuel the final fuel filters clog at a decreasing time interval. What is the most likely caus...
  97. #1240 What operational difficulties are associated with fuel incompatibility?
  98. #1241 A motor vessel has three centrifuges to pre-treat the fuel which can be configured to operate in series, parallel, and series-parallel. A large quanti...
  99. #1242 A motor vessel has two centrifuges to pre-treat fuel to the engine(s) which may be configured to operate in series or parallel. A large quantity of wa...
  100. #1244 In pre-treating fuel oil on a motor vessel, what would you consider the most important factor to prevent high temperature corrosion on an engine's com...

Motor Plants and Auxiliary Boilers questions: what to expect

Q How many Motor Plants and Auxiliary Boilers questions are in the Engine pool?

There are 1,433 Motor Plants and Auxiliary Boilers questions on this site, every one released by the U.S. Coast Guard or taken from the National Maritime Center's sample examinations, with its correct answer. The exam draws its Motor Plants and Auxiliary Boilers module from the same pool.

Q What score do I need to pass the Motor Plants and Auxiliary Boilers module?

Most USCG exam modules, including Motor Plants and Auxiliary Boilers, require 70 percent to pass. Rules of the Road modules require 90 percent.

Q Are these the real USCG Motor Plants and Auxiliary Boilers exam questions?

Yes. They are the published U.S. Coast Guard questions, matched to the National Maritime Center's 2026 sample examinations. Answer any question to see the correct choice, the USCG reference and the illustration where the question uses one.

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