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Retired questions · Motor Plants and Auxiliary Boilers
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Engine · 159 questions

Retired questions · Motor Plants and Auxiliary Boilers - USCG Exam Questions

These are retired questions the Coast Guard no longer draws exams from. They stay online for reference; the current questions are in Motor Plants and Auxiliary Boilers.

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 Retired questions · Motor Plants and Auxiliary Boilers questions

Questions 101–159 of 159 · page 2 of 2

  1. #712 Item #16 of the piston shown in the illustration is a/an __________. MO-0011 illustration
  2. #718 During main engine performance testing it is noticed that the firing pressure in one cylinder is lower than the average, but cylinder compression pres...
  3. #720 Excessively worn, or polished ends on a diesel engine valve spring, indicate __________.
  4. #721 What will cause valve stem blow-by to the valve section shown in the illustration? Illustration MO-0030 illustration
  5. #725 Worn main bearings will cause the compression ratio of a diesel engine to __________.
  6. #732 Which of the following procedures should be carried out to permit the continued operation of a crosshead engine with a leaky after cooler?
  7. #733 While at sea, the first engineer reports the jacket water expansion tank water has become discolored and has a smell of exhaust on a slow speed two st...
  8. #738 The part labeled "G", as shown in the illustration, is a __________. MO-0040 illustration
  9. #749 Which of the following statements is true concerning the air starting valve, labeled "III", as shown in the illustration? See Illustration MO-0046 illustration
  10. #750 During the starting of a diesel engine, compression gases are prevented from backing into the air starting system, shown in the illustration, by the _... illustration
  11. #751 In a direct cylinder admission air starting system, once the engine begins to fire, the air starting check valve illustrated, is closed by __________.... illustration
  12. #759 The cylinders labeled "B" and "C" in the illustration are used to __________. MO-0125 illustration
  13. #760 The component labeled "A" on the engine reversing device shown in the illustration, performs its function by transmitting _______. MO-0125 illustration
  14. #762 You are the Chief Engineer on a Ro/Ro vessel powered by a MAN two stroke, direct reversing, slow speed diesel engine. While maneuvering into New York...
  15. #764 In a by-pass type lubrication system for a diesel engine, the dirty oil line to the centrifuge should be taken from the __________.
  16. #765 The device shown in the illustration is classified as a/an __________. MO-0008 illustration
  17. #766 The device shown in the illustration is a __________. MO-0008 illustration
  18. #772 The device shown in figure "A" of the illustration is used to __________. MO-0042 illustration
  19. #773 The illustrated device is used to __________. MO-0050 illustration
  20. #774 The component labeled as part #20 in the illustration is used to __________. MO-0050 illustration
  21. #777 Which of the following test indicators should be considered the most significant factor in determining as to whether or not a diesel generators lube o...
  22. #784 Both crosshead type and trunk type lubricating oil are received on board a vessel. These two oils cannot be interchanged due to which of the following...
  23. #786 The time between injection and ignition of the fuel is known as __________.
  24. #792 As Chief Engineer of a slow speed diesel propelled vessel operating with constant slip, when considering the effect on the fuel consumption in barrels...
  25. #793 You are on board a vessel with a slow speed crosshead type engine. The fuel just received has a significantly lower sulfur content then the previous b...
  26. #797 In the device shown in the illustration, the component lettered "A" is the __________. MO-0012 illustration
  27. #801 Which of the following precautions should be taken prior to starting the separator shown in the illustration? MO-0127 illustration
  28. #804 Heavy fuel oil used in the system shown in the illustration, will have the lowest viscosity __________. MO-0058 illustration
  29. #807 From the graph shown in the illustration, determine the size of the regulating ring required for the proper operation of the fuel oil centrifuge if th... illustration
  30. #808 Using the graph shown in the illustration, the oil being separated has a specific gravity of .87 kg/dm3 at 72.5°C. What will be the specific gravity i... illustration
  31. #809 From the graph shown in the illustration, if the separating temperature required is to be 167°F, and the specific gravity of the oil is .98 kg/dm3 at... illustration
  32. #812 Which of the following conditions would be the most probable cause for the 'low oil temperature after preheater' LED indicators, as shown in the illus... illustration
  33. #813 As shown in the illustration, which of the following conditions would be responsible for a "low pressure in oil outlet" alarm to be indicated? MO-0127 illustration
  34. #814 If item "F" begins leaking during operation, which of the following operating conditions will NOT occur? MO-0112 illustration
  35. #815 While operating the fuel oil centrifuge shown in the illustration, the bowl fails to open for sludge ejection. The probable cause is that __________.... illustration
  36. #816 When reassembling the bowl of the centrifuge, shown in the illustration, the alignment mark on the locking ring passes the bowl cover mark in excess o... illustration
  37. #817 While operating the fuel oil centrifuge shown in the illustration, the fuel oil is being continuously ejected with the sludge and the seal water. The... illustration
  38. #818 If the bowl of a disk type centrifugal purifier when operated as a separator is not primed, the __________.
  39. #824 Regarding the fuel injector shown in the illustration, the purpose of piece No. 38 is to __________. MO-0059 illustration
  40. #827 The indicated position of the fuel injection pump plunger as shown in the illustration, will provide fuel delivery to the diesel engine in an amount a... illustration
  41. #829 As shown in the illustration of the fuel injection pump, the section designated as "M" is referred to as the __________. Illustration MO-0061 illustration
  42. #847 Diesel fuel oil having a low cetane rating can result in __________.
  43. #859 When installing the bearing cap on the device shown in the illustration, which of the precautions listed must be observed? Illustration MO-0121 illustration
  44. #865 The gear drive, shown in the illustration, can have the backlash determined best by using a __________. MO-0091 illustration
  45. #873 Which of the following is necessary for all waste heat boiler installations, regardless of design or manufacturer?
  46. #876 As shown in the illustration, the function of component "1" is to ________. MO-0128 illustration
  47. #877 As shown in the illustration, what component would normally be installed at location "D" ? MO-0128 illustration
  48. #878 As shown in the illustration, the component labeled "H" would be identified as a ________. MO-0128 illustration
  49. #889 In the water level electrode assembly, shown in the illustration, the feed pump should restart when the level of the water reaches the position indica... illustration
  50. #890 Which of the following types of feed water regulators is commonly used with a water-tube, natural circulation, auxiliary boiler?
  51. #897 When checking for the presence of sulfite in the feed water of an auxiliary boiler, you are in essence checking __________.
  52. #900 The starter control valve in the hydraulic system shown in the illustration is malfunctioning. Before removing the valve, you must first __________. M... illustration
  53. #908 What is the best way of stopping an over speeding diesel engine?
  54. #922 A propulsion engine, using the speed control circuit shown in the illustration, fails to function at speeds lower than the low end of the critical spe... illustration
  55. #926 The pneumatic circuit shown in the illustration is part of a complex large low speed engine control system. Which of the following statements describe... illustration
  56. #927 If the input signal rises above the set point of '17A', shown in the illustration, but remains below the set point of '17B', the output from '22A' wil... illustration
  57. #928 Which of the operating positions, for valve "A" shown in the illustration, should be chosen to maintain the circuit in continuous flow, regardless of... illustration
  58. #929 Which of the following statements describes the primary reason for the device shown in the illustration to be incorporated into the air start system?... illustration
  59. #930 The reversing cams of some four-stroke/cycle diesel engines are brought into position by __________.

Motor Plants and Auxiliary Boilers questions: what to expect

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

This retired set holds 159 Motor Plants and Auxiliary Boilers questions the Coast Guard no longer draws on exams. They stay online for reference; the current Motor Plants and Auxiliary Boilers module is the one to study.

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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The Engine pool holds the current U.S. Coast Guard questions for engineering credentials, from QMED ratings through DDE and Assistant Engineer up to Chief. Answer any question to see the correct choice instantly.