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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 501–600 of 1,433 · page 6 of 15

  1. #788 The rate of pressure rise during the period following fuel ignition in a diesel engine is influenced by the length of the ignition delay period and th...
  2. #789 The pressure in an operating diesel engine cylinder continues to rise for a short period after the piston passes top dead center as a result of the __...
  3. #794 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...
  4. #795 The temperature of the contaminated fuel oil fed to the centrifuge shown in the illustration should be __________. Illustration MO-0012 illustration
  5. #796 The greatest difference between the centrifuge bowl shown in the illustration and that of a tubular bowl, with straight, vertical, interior surfaces,... illustration
  6. #798 The device labeled "D", as shown in the illustration, is the bowl __________. Illustration MO-0112 illustration
  7. #799 The area indicated by the letter "W", shown in the illustration is correctly termed the __________. Illustration MO-0112 illustration
  8. #800 What terminates the sludge discharge cycle of the device shown in the illustration? Illustration MO-0112 illustration
  9. #810 After removing the bowl hood of the device shown in the illustration, excessive quantities of sludge are visible. Which of the following statements re... illustration
  10. #821 Differential needle valves used in fuel injectors are directly closed by __________.
  11. #822 Carbon deposit build up on the injection nozzle orifice is least likely to occur when using which type of fuel injector nozzle?
  12. #826 The amount of fuel delivered by a unit injector is controlled by the __________.
  13. #828 Which of the following statements represents the function of the plunger flange labeled "A" shown in the illustration? Illustration MO-0061 illustration
  14. #830 As shown in the illustration of the fuel injection pump, the component labeled "N" would be identified as the _____. Illustration MO-0061 illustration
  15. #833 What is the purpose of the "window" installed in the housing of an individual jerk pump?
  16. #835 The component shown in the illustration would be identified as a ______. Illustration MO-0097 illustration
  17. #836 The component identified as item #15 is used to __________. Illustration MO-0016 illustration
  18. #839 According to the illustration, fuel cutoff timing in the cylinder is controlled with the component that is identified as the letter _________. Illustr... illustration
  19. #841 You are testing a closed fuel injection nozzle using a nozzle tester. A pressure slightly less than design valve opening pressure is applied. If no fu...
  20. #842 Because of the close tolerances used in diesel engine fuel oil pumps, a worn plunger requires __________.
  21. #843 Uneven bolt tightening during the installation of a fuel injection pump can result in __________.
  22. #844 Which of the fuel nozzles listed requires the LEAST maintenance?
  23. #845 Which of the following statements concerning the factors affecting ignition delay is correct?
  24. #846 Poor combustion in a diesel engine can be caused by __________.
  25. #848 Which of the following problems is the main source of fuel pump and injection system malfunctions?
  26. #849 Problems with the diesel engine fuel injection pump are usually caused by __________.
  27. #850 One cause of diesel engine surging can be a result of __________.
  28. #852 Which of the following devices will increase the power output of a diesel engine without increasing its frictional load?
  29. #858 Which of the couplings listed is normally not repairable, and is usually replaced if completely damaged?
  30. #860 What is the maximum allowable clearance permitted between the bearing, shown in the illustration and the shaft along its vertical axis? Illustration M... illustration
  31. #861 What is the normal bearing clearance permitted at the horizontal axis of the shaft for the bearing shown in the illustration? Illustration MO-0121 illustration
  32. #862 After following the prescribed procedures to measure the thrust bearing clearance shown in the illustration, the distance "F" is determined to be 200... illustration
  33. #863 When an additional load is applied to a diesel engine which is using an inadequately inflated air bladder clutch unit, you can expect __________.
  34. #864 Misalignment of the drive shaft and propeller shaft flanges can be detected by using a dial indicator or __________.
  35. #866 The thrust bearing shown in the illustration has over eight years of ahead running time. Measurements show "i1" is 4 mm and "i2" is 1mm. Which of the... illustration
  36. #868 Downcomers installed on auxiliary package boilers are protected from direct contact with hot gases by __________.
  37. #870 When preparing to light off a cold boiler equipped with a return flow fuel oil system, the recirculating valve directs the flow of oil __________.
  38. #871 Which of the automatic boiler controls listed should be tested prior to lighting off an auxiliary boiler?
  39. #872 The purpose of designing some waste heat boilers with sinuous fire tubes, is to __________.
  40. #874 With which of the following types of diesel engine arrangements is a waste heat boiler most likely to produce the maximum steam pressure, temperature,...
  41. #875 Casing drains may be required on a waste heat boiler gas passage side to __________.
  42. #879 Constant capacity, pressure atomizing, fuel burners designed to meet a wide variation in steaming loads on an auxiliary boiler, are __________.
  43. #880 The primary function of a flame safeguard system, as used on an automatically fired auxiliary boiler, is to prevent __________.
  44. #883 The pressuretrol which is installed on an auxiliary boiler senses steam pressure changes and __________.
  45. #884 Which of the following statements describes how the fuel oil enters the whirling chambers of the sprayer plates used in a auxiliary boiler return flow...
  46. #885 The solenoid valves in the fuel oil supply line to an automatically fired auxiliary boiler, are automatically closed by __________.
  47. #886 A variable capacity, pressure atomizing, fuel oil burner functions to __________.
  48. #887 When the steam pressure drops below a set value on an automatically fired auxiliary boiler, fitted with rotary cup atomizers, the combustion control s...
  49. #888 Control of the fuel oil metering valve in an automatically fired auxiliary boiler is accomplished by a __________.
  50. #892 Burner ignition failure in an automatically fired auxiliary boiler would be caused by __________.
  51. #893 In the event of a flame failure in an auxiliary water-tube boiler, you must __________.
  52. #895 A feed pump for an auxiliary boiler might lose suction if the __________.
  53. #896 A safety valve on an auxiliary boiler simmers constantly and cannot be stopped by several quick blow-offs using the hand relieving gear. The problem m...
  54. #898 Before any work is done on a burner in an automatically fired auxiliary boiler, you should always __________.
  55. #899 Before any work is to be carried out on a burner in an automatically fired auxiliary boiler, you should always __________.
  56. #901 Which of the listed items should be secured before performing any maintenance on a solenoid operated air start valve?
  57. #902 If a diesel engine has been stopped because of piston seizure due to severe overheating, the crankcase __________.
  58. #903 The principal hazard to personnel when using a diesel engine fuel nozzle tester is _______.
  59. #905 Which of the following precautions should be taken when cleaning the air filter on a diesel engine equipped with a turbocharger?
  60. #906 Following the failure of one turbocharger on a large, crosshead, main propulsion diesel engine, fitted with multiple turbochargers, which of the follo...
  61. #907 If a tube ruptures in a water-tube auxiliary boiler due to low water, you should ___________.
  62. #909 If a crankcase explosion due to a hot spot were to occur, the size of the explosion is dependent on which of the following?
  63. #910 Which of the following oil mist to air ratios would most likely lead to the most severe crankcase explosion?
  64. #911 In the event of a crankcase rich oil mist to air mixture explosion, where the doors are blown off the engine, which of the following may occur after t...
  65. #912 After stopping a diesel engine with a high main bearing temperature, what is the time one needs to wait before a diesel engine crankcase can be opened...
  66. #913 Which of the following is one of the ways to prevent a scavenging fire on a slow speed diesel engine?
  67. #915 If a scavenging air space fire occurs on a slow speed diesel engine and the engine is stopped, which of the following should be done to prevent distor...
  68. #916 Which of the following would indicate a scavenging air fire in a slow speed diesel engine?
  69. #917 If a diesel engine were running at 20% overload with a smoky exhaust, you should __________.
  70. #918 In accordance with Coast Guard Regulations (46 CFR Part 112), which of the listed starting aids is acceptable for use with the emergency diesel genera...
  71. #919 What device is installed and used as a safety feature to satisfy Coast Guard regulations for the unit shown in the illustration? Illustration MO-0116 illustration
  72. #921 In accordance with 46 CFR Part 46, diesel fuel oil system valves for removing water or impurities are __________.
  73. #923 The governor utilized with the device shown in the illustration has become inoperative while the vessel is underway at sea. Which of the following sta... illustration
  74. #925 What is the primary purpose of the pneumatic component shown in the illustration? Illustration MO-0119 illustration
  75. #931 A diesel generator governor is hunting. After changing the oil, the governor is flushed and the compensation needle valve is adjusted, but the hunting...
  76. #932 The most common contaminate of governor hydraulic fluid is __________.
  77. #933 If the compensating needle valve of a hydraulic governor is opened more than necessary the governor will __________.
  78. #934 A large change in ambient temperature, or using an oil of a viscosity different than the one recommended by the manufacturer in a mechanical hydraulic...
  79. #935 Adjustments to the compensating needle valve in a hydraulic governor should be made with the engine at __________.
  80. #936 If the speeder spring of a main propulsion diesel engine governor breaks while operating at full load, the engine RPM will __________.
  81. #937 The hunting of a diesel engine may be caused by __________.
  82. #938 Governor hunting is caused by __________.
  83. #939 If the operating speed of a diesel engine increases without an apparent change in the engine control settings, you may suspect a __________.
  84. #942 Increasing the oil pressure acting on the power piston of the hydraulic governor shown in the illustration will __________. Illustration MO-0092 illustration
  85. #943 The purpose of the compensating adjustment used in a diesel engine hydraulic governor is to __________.
  86. #944 Which of the following statements is correct concerning the operating function of the governor shown in the illustration? Illustration MO-0096 illustration
  87. #946 According to the illustrated main engine cooling water systems drawing, which of the labeled heat exchangers represents the charge air coolers? Illust... illustration
  88. #949 When a slow-speed diesel engine is used to directly drive a fixed-pitch propeller, how is a stop order met?
  89. #950 With a direct drive main propulsion arrangement, what statement is true?
  90. #952 As it applies to the combustion process associated with diesel engines, what is meant by the term "scavenging"?
  91. #953 If a slow-speed two-stroke cycle diesel engine is fitted with exhaust valves located in the cylinder heads, what scavenging flow-pattern is utilized?
  92. #954 If a slow-speed two-stroke cycle diesel engine is fitted with scavenging air ports and exhaust ports located on opposite sides of the cylinder wall, w...
  93. #960 What is the function of the intake system for a diesel engine?
  94. #967 According to the illustrated diesel engine cooling water systems diagram, what fluid is the low temperature central fresh water thermostat designed to... illustration
  95. #968 According to the illustrated diesel engine cooling water systems diagram, what is the functional description of the low temperature central fresh wate... illustration
  96. #969 According to the illustrated main engine cooling water systems diagram, which of the following heat exchangers would be isolated and bypassed while ma... illustration
  97. #970 According to the illustrated main engine cooling water systems diagram, which of the following labeled heat exchangers represents the main lube oil co... illustration
  98. #971 According to the illustrated main engine cooling water systems drawing, which labeled heat exchangers use sea water as a cooling medium? Illustration... illustration
  99. #972 According to the illustrated main engine cooling water systems drawing, which labeled pump is the main engine sea water cooling water pump? Illustrati... illustration
  100. #973 According to the illustrated main engine cooling water systems drawing, which labeled sea water-cooled heat exchanger would have the highest sea water... illustration

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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