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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 201–300 of 1,433 · page 3 of 15

  1. #309 Which of the following procedures should be carried out when a large, low-speed, diesel engine is operated with one cylinder secured?
  2. #311 During maneuvering operations for a direct reversing large, low-speed, main propulsion diesel engine, which of the following actions is used to stop t...
  3. #312 The line identified as "I" in the illustration is used to __________. Illustration MO-0066 illustration
  4. #314 Valve cages are used on some large diesel engines to __________.
  5. #316 A diesel engine crankcase ventilation system __________.
  6. #317 A safety crankcase cover differs from other diesel engine access doors in that it is fitted with a __________.
  7. #319 According to the illustration, fuel delivery to the cylinder is terminated and controlled with the component that is identified as the letter ________... illustration
  8. #322 There are two glands provided where the piston rod exits the cylinder shown in the illustration. The purpose of the top gland is to __________. Illust... illustration
  9. #323 The diesel engine shown in the illustration, the exhaust manifold is indicated by the letter __________. Illustration MO-0003 illustration
  10. #324 The opening of an exhaust valve on a modern, large, low-speed, main propulsion diesel engine, may be actuated by __________.
  11. #325 The exhaust ports shown in the illustration are identified with the letter '____'. Illustration MO-0003 illustration
  12. #326 The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by __________.
  13. #327 The insertion of shims between the foot of a marine type connecting rod and a bearing box would result in __________.
  14. #331 The diesel engine water inlet jumper illustrated is represented by the letter or number __________. Illustration MO-0122 illustration
  15. #339 Which of the listed cylinder head design features is shown in the illustration? Illustration MO-0013 illustration
  16. #341 The diesel engine rocker arms shown in the illustration serve to __________. Illustration MO-0122 illustration
  17. #346 During the power stroke, the side thrust of a trunk type piston is a result of the angle __________.
  18. #351 Which of the bearings listed below is most widely used for the main and connecting rod bearings of a modern high-speed diesel engine?
  19. #353 Auxiliary diesel engines can be automatically shut down as a result of __________.
  20. #354 Lube oil pumps taking suction from the sump of most small marine engines are usually __________.
  21. #355 When a generator diesel engine is operated at partial load, as compared to full load, a decrease will occur in the average __________.
  22. #356 Which of the routine maintenance procedures listed is required for starting air receivers?
  23. #357 When starting a diesel engine at temperatures below 70°F, the frictional resistance to turning will be __________.
  24. #359 Starting air check valves are held firmly on their seats by __________.
  25. #361 In addition to the main starting air compressor, another air compressor, driven by a separate power source, is installed to __________.
  26. #363 An accumulator used in a hydraulic starting system is generally located between the __________.
  27. #364 Which of the listed diesel engine starting systems is most susceptible to difficulties in cold weather?
  28. #365 Starting systems for large, direct reversing, main propulsion diesel engines are usually __________.
  29. #370 In a direct cylinder admission air starting system, once the engine begins to fire, the air starting check valve illustrated, is closed by __________.... illustration
  30. #372 In a medium-speed marine propulsion engine equipped with direct admission air starting valves, the cylinders without air starting valves fire first be...
  31. #373 Air motors used for starting some auxiliary diesel engines are generally the type known as a/an __________.
  32. #374 Which internal combustion engine starting system uses a vane type fluid motor?
  33. #375 The illustration is of a/an __________. Illustration MO-0044 illustration
  34. #376 Hydraulic starters are installed on many lifeboat diesel engines instead of comparable air start systems, because __________.
  35. #377 Which type of starter motor is normally used in a diesel engine hydraulic starting system?
  36. #378 When an engine fitted with a hydraulic starting system starts up, the starter is protected from the higher speed of the engine by __________.
  37. #379 The purpose of the engine-driven hydraulic pump in an auxiliary diesel engine hydraulic starting system is to __________.
  38. #380 In a Bendix starter drive, the pinion engagement with the flywheel ring gear is initiated by __________.
  39. #381 In a diesel engine starting motor equipped with a Bendix drive, the pinion moves and meshes with the flywheel ring gear due to __________.
  40. #382 Which of the following operating characteristics of the Bendix drive friction clutch is associated with a Bendix drive starter?
  41. #383 A Bendix drive starting motor disengages the drive gear from the flywheel by __________.
  42. #385 Electric starting motors for diesel engines require high current for operation and __________.
  43. #386 Auxiliary diesel engine electric starting motors use __________.
  44. #387 Diesel engine electric starting motors generally require heavier duty motors and operate at higher voltages than comparable starting motors for gasoli...
  45. #390 The cylinders labeled "B" and "C" in the illustration are used to __________. Illustration MO-0125 illustration
  46. #391 Intercoolers installed on starting air compressors, reduce the possibility of __________.
  47. #392 According to the diagram shown in the illustration, the lube oil system can best be described as a __________. Illustration MO-0007 illustration
  48. #393 Which of the following devices is normally provided to prevent oil starvation in a diesel engine lubrication system utilizing the 'full flow' principl...
  49. #394 The lube oil pump used in a diesel engine is normally a __________.
  50. #395 A diesel engine exposed to widely varying ambient temperatures should use a lubricating oil with __________.
  51. #396 Two important considerations for the proper lubrication of a diesel engine include, the delivery of the oil in sufficient amount, and the __________.
  52. #397 A diesel engine should use which type of lubricating oil?
  53. #398 The highest indicated lube oil pressure in a diesel engine should be expected when the engine oil is _________.
  54. #399 The TBN value of diesel engine lube oil refers to its ability to __________.
  55. #400 Which lubricating oil additive is used in diesel engines to reduce the tendency for sludge and varnish to form on the engine parts?
  56. #401 On most modern diesel engines, the main and connecting rod bearings receive their lubricating oil by __________.
  57. #402 A well-lubricated bearing surface always appears __________.
  58. #404 Lube oil filters remove contaminants more efficiently if the oil being filtered is __________.
  59. #405 Which of the following should always be checked prior to starting a diesel engine?
  60. #406 Which of the listed diesel engine operating conditions should be checked immediately after any diesel engine is started?
  61. #407 The most crucial time for any bearing with regards to diesel engine lubrication is __________.
  62. #408 In a normally operating diesel engine, the main source of lubricating oil contamination in the crankcase is a result of the __________.
  63. #409 Before starting a diesel engine that has an engine driven lube oil pump, the operator should __________.
  64. #410 How often should the lubricating oil of a diesel engine be changed?
  65. #411 A spring-loaded relief valve is located on some lube oil filters in full flow systems to __________.
  66. #413 Most large main propulsion diesel engines use a duplex lube oil strainer to __________.
  67. #414 A magnetic strainer is primarily used in diesel engine reduction gear oil systems to remove small particles of __________.
  68. #416 How is the illustrated strainer element cleaned during engine operation? Illustration MO-0057 illustration
  69. #419 Maximum lube system operating pressure for a diesel engine is normally regulated by a/an __________.
  70. #420 The lube oil cooler is located after the lube oil filter in order for __________.
  71. #421 Which of the following statements is true concerning a main diesel engine oil cooler?
  72. #422 Heat exchangers are most commonly found in a small auxiliary diesel engine __________.
  73. #423 Reduction gear lube oil temperatures for keel cooler installations are generally __________.
  74. #424 One advantage of a vacuum feed sight glass indicator used on cylinder lubricators over the discharge side liquid filled type sight glass is __________...
  75. #425 Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are __________.
  76. #426 The rate of cylinder lubricating oil metered to each cylinder of a large, low-speed, main propulsion diesel engine is __________.
  77. #427 The device shown in figure "A" of the illustration is used to __________. Illustration MO-0042 illustration
  78. #428 The illustrated device is used to __________. Illustration MO-0050 illustration
  79. #430 The adverse effects of burning high sulfur fuel can be compensated for by using a cylinder oil having sufficient __________.
  80. #431 The device shown in the illustration is classified as a/an __________. Illustration MO-0008 illustration
  81. #432 The device shown in the illustration is a __________. Illustration MO-0008 illustration
  82. #433 The purpose of an oil mist detector in a main propulsion diesel engine is to warn of __________.
  83. #434 Which of the following problems could develop due to the accumulation of oil vapors in the crankcase of a diesel engine?
  84. #435 Crankcase explosions in propulsion diesel engines result from __________.
  85. #436 For diesel engine piston cooling, lubricating oil can be supplied to the pistons by a/an __________.
  86. #437 Shaker, circulation, and spray are the three general methods used in __________.
  87. #440 A 'Blotter test' is a test performed on the lube oil of a diesel engine which can determine ______.
  88. #441 If the analysis of used lube oil indicates a high content of iron particles, this could indicate __________.
  89. #442 A decrease in the flash point of diesel engine lube oil indicates the lube oil has become __________.
  90. #443 Starting aids such as glow plugs, are installed on __________.
  91. #445 Which of the combustion chambers shown in the illustration is referred to as an "energy cell" used in some small diesel engines? Illustration MO-0068 illustration
  92. #446 The purpose of the energy cell, or air cell, is to __________.
  93. #447 A multi-orifice fuel injection nozzle is usually used with which of the listed types of combustion chamber?
  94. #448 Open combustion chambers are designed to __________.
  95. #449 What type of marine engine has a fuel nozzle and combustion chamber located between two pistons in a common cylinder liner?
  96. #451 Precombustion chambers differ from turbulence chambers in that precombustion chambers __________.
  97. #452 Starting aids, such as glow plugs, are usually installed on __________.
  98. #453 The combustion of fuel for the illustrated engine is initiated by __________. Illustration MO-0020 illustration
  99. #454 Which of the listed types of precombustion chambers is used in the diesel engine shown in the illustration? Illustration MO-0007 illustration
  100. #455 The desirable properties of a marine fuel oil should include __________.

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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