National Maritime Center Providing Credentials to Mariners U.S.C.G. Merchant Marine Exam (Sample Examination) Page 1 of 19
Choose the best answer to the following Multiple Choice Questions. 1. A Bendix drive starting motor disengages the drive gear from the flywheel by. o (A) spring force (B) having the flywheel impart a torque to the starter pinion o (C) rotation of the starting cam o (D) applying accumulator pressure 2. On the cylinder indicator diagram illustrated, the maximum rise in pressure occurs during the period labeled as. Illustration MO-0033 o (A) G (B) H o (C) J o (D) K 3. Some main propulsion diesel engine uses sea water to directly cool the. o (A) cylinder heads o (B) exhaust valves (C) scavenging air o (D) injectors 4. The diesel engine component labeled "5", shown in the illustration is known as the. Illustration MO-0122 o (A) heat sink space o (B) piston crown o (C) connecting rod end assembly (D) piston thrust washer 5. Open combustion chambers are designed to. o (A) eliminate carbon buildup o (B) improve piston cooling o (C) prevent air charge turbulence (D) provide proper fuel/air mixing Page 2 of 19
6. When an engine fitted with a hydraulic starting system starts up, the starter is protected from the higher speed of the engine by. o (A) the immediate increase in hydraulic pressure (B) the overrunning clutch o (C) closing the starting check valves o (D) the pivoting of the shaft from being engaged with the flywheel 7. A main propulsion diesel engine is normally shutdown by. o (A) shutting off the air supply o (B) overspeeding the engine (C) securing the fuel supply o (D) securing the ignition system 8. As engine RPM is increased from idle speed to full load speed, which of the conditions listed will decrease? o (A) Compression ratio (B) Air/Fuel ratio o (C) Compression pressure o (D) Lube oil pressure 9. As a general rule, what would be the recommended operating water jacket outlet temperature range for medium-speed marine diesels setup with closed treated fresh water cooling systems and fitted with vented expansion tanks? o (A) 105 to 120 F o (B) 135 to 150 F (C) 165 to 180 F o (D) 195 to 215 F 10. Starting aids, such as glow plugs, are usually installed on. o (A) large, direct drive diesel engines o (B) diesel engines designed to burn residual fuels o (C) medium-speed, four-stroke cycle diesel engines (D) small diesel engines with electric motor starters Page 3 of 19
11. In a Roots-type rotary blower, the volume of air delivered is directly proportional to. (A) engine speed o (B) engine load o (C) brake horsepower o (D) brake specific fuel consumption If choice A is selected set score to 1. 12. Starting systems for large, direct reversing diesel engines are usually. o (A) hydraulic starting motors o (B) electric starting motors (C) direct air admission o (D) vane type air motors 13. The control rack to a unit injector regulates fuel delivery by. o (A) altering spring tension on the plunger (B) rotating the plunger and position of the helix o (C) regulating the lift of the check valve o (D) altering the actual length of the plunger stroke 14. The pressure-volume diagrams illustrated are of four internal combustion engine cycles. Which one represents the theoretical diesel cycle? Illustration MO-0102 o (A) A (B) B o (C) C o (D) D 15. A spring-loaded relief valve is located on some lube oil filters in full flow systems to. o (A) prevent over pressurization of the filter cartridge o (B) prevent over pressurization of the filter casing (C) bypass the filter should it become clogged o (D) limit the lube oil outlet pressure Page 4 of 19
16. The power/expansion stroke shown in the illustration is indicated by the diagram numbers. Illustration MO-0025 (A) 1 through 3 o (B) 1 through 4 o (C) 3 through 6 o (D) 4 through 6 If choice A is selected set score to 1. 17. Which lubricating oil additive is used in diesel engines to reduce the tendency for sludge and varnish to form on the engine parts? o (A) Flash point improvers o (B) Pour point improvers (C) Inhibitors o (D) Foam suppressors 18. In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in. o (A) increased engine back pressure (B) sulfuric acid corrosion o (C) surface pitting of the turbocharger compressor blades o (D) moisture impingement on the turbocharger compressor blading 19. The cubic inch (or liter) displacement of a cylinder is determined by the diameter of the piston and the. o (A) length of the crankshaft o (B) volume of the clearance space o (C) weight of the piston (D) length of the stroke 20. A "Blotter test" is a test performed on the lube oil of a diesel engine which can determine. o (A) the specific gravity of the oil o (B) the flash point of the oil (C) a change in the oils viscosity o (D) the TBN number of the oil Page 5 of 19
21. Differential needle valves used in fuel injectors are directly closed by. o (A) cam action (B) spring force o (C) fuel oil pressure o (D) firing pressure 22. 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. o (A) indicated horsepower (B) brake horsepower o (C) net horsepower o (D) friction horsepower 23. The diesel engine shown in the illustration is a. Illustration MO-0007 o (A) four-stroke cycle engine at the end of the compression stroke o (B) two-stroke cycle engine at the end of the compression stroke (C) four-stroke cycle engine at the end of the exhaust stroke o (D) two-stroke cycle engine at the beginning of the power stroke 24. A mixture of 45% cetane and 55% alpha-methyl-naphthalene is found to have the same ignition delay as a sample of diesel oil. The sample can be described as having a/an. o (A) cetane number of 55 (B) cetane number of 45 o (C) octane number of 55 o (D) octane number of 45 25. The greatest turbulence in a diesel engine cylinder is created by the. (A) shape of the combustion chamber o (B) fuel injection spray pattern o (C) cylinder swept volume o (D) degree of penetration of the fuel oil droplets If choice A is selected set score to 1. Page 6 of 19
26. Maintaining the proper fuel oil temperature will result in. o (A) the elimination of valve wear (B) improved atomization o (C) a decrease in cylinder blow-by o (D) a decrease in cylinder mean effective pressure 27. When starting a diesel engine at temperatures below 70 F, the frictional resistance to turning will be. o (A) reduced by increasing lube oil pressure o (B) controlled by reducing the compression ratio (C) proportional to the lube oil viscosity o (D) eliminated by heating the intake air 28. The principal characteristic of an isochronous governor is it will. o (A) slow the machine down as the load is increased o (B) shut down the engine if it overspeeds o (C) display excessive speed droop (D) maintain a constant speed with variations of load 29. Lube oil pumps taking suction from the sump of most small marine engines are usually. o (A) diaphragm type o (B) centrifugal type (C) positive displacement type o (D) eductor type 30. Reduction gear lube oil temperatures for keel cooler installations are generally. o (A) lower than raw water-cooled installations (B) higher than raw water-cooled installations o (C) identical to raw water-cooled installations o (D) lower than raw water-cooled installations, but the pressure will be higher Page 7 of 19
31. If a particular liquid has a specific gravity of 0.96 kg/dm 3 at 77 F, what will be the specific gravity of the liquid, as determined from the graph shown in the illustration, if the temperature is increased to 167 F? Illustration MO-0113 o (A) 0.910 kg/dm 3 o (B) 0.915 kg/dm 3 o (C) 0.920 kg/dm 3 (D) 0.925 kg/dm 3 32. Fuel injection systems are designed to primarily meter fuel, atomize fuel, and. o (A) create turbulence in the combustion chamber o (B) aid in completing cylinder scavenging (C) inject fuel at the proper time o (D) minimize fuel penetration into the cylinder 33. What type of engine lubrication oil filter system sends filtered oil directly to the high-pressure supply gallery? o (A) centrifugal purifier system o (B) bypass system (C) shunt system o (D) batch system 34. As shown in the illustration of the fuel injection pump, the function of the area designated as "G" is to. Illustration MO-0061 (A) provide a fuel supply to the pump o (B) lubricate the plunger o (C) control the fuel injection rate o (D) relieve excessive injector discharge pressure If choice A is selected set score to 1. 35. After cooling of a turbocharged diesel engine will result in. o (A) higher torque but lower brake horsepower o (B) lower torque but higher brake horsepower (C) higher torque and higher brake horsepower o (D) lower torque and lower brake horsepower Page 8 of 19
36. Which of the bearings listed below is most widely used for the main and connecting rod bearings of a high-speed diesel engine? o (A) Poured Babbitt, self-aligning o (B) Split roller o (C) Steel-lined (D) Precision insert 37. Which of the following devices is normally provided to prevent oil starvation in a diesel engine lubrication system utilizing the "full flow" principle? o (A) Duplex strainer o (B) Three-way valve (C) Pressure relief bypass line around the filter o (D) Mechanical straining filter 38. During diesel engine warm-up, which type of valve lash adjuster compensates for the change in length of the exhaust valve stem? o (A) Mechanical (B) Hydraulic o (C) Pneumatic o (D) Electrical 39. Precombustion chambers differ from turbulence chambers in that precombustion chambers. o (A) allow fuel injection directly into the space above the piston o (B) do not contain the fuel injector nozzle tip o (C) contain the major portion of the total clearance volume (D) contain a smaller portion of the total clearance volume 40. One advantage of dry cylinder liners used in a diesel engine is the. o (A) lower thermal expansion rate over wet liners o (B) greater heat transfer rate than wet liners o (C) greater wear resistance than wet liners (D) procedure to replace dry liners is simpler than for wet liners Page 9 of 19
41. The piston pin shown in the illustration should be classified as. Illustration MO-0011 o (A) fixed o (B) full floating (C) semi-floating o (D) anchored 42. Bearing "crush" as applied to diesel engine main bearings, will result in. (A) positive seating of the bearings in their housings o (B) above normal operating temperatures o (C) damage to the journals o (D) damage to the bearings If choice A is selected set score to 1. 43. Injection pressure in a common rail fuel system is controlled by. o (A) engine speed o (B) varying the fuel pump piston stroke o (C) varying the injector needle valve clearance (D) a bypass valve 44. The formation of carbon monoxide in diesel exhaust gases is reduced by. o (A) spraying water into the exhaust pipe o (B) keeping the exhaust system free of carbon deposits (C) maintaining proper combustion and scavenging o (D) avoiding light load operation 45. What type of temperature transmitter would be most suitable for measuring diesel engine exhaust and boiler stack temperatures and generates its own electromotive force? o (A) Resistance temperature detector (B) Thermocouple pyrometer o (C) Radiation pyrometer o (D) Thermistor probe Page 10 of 19
46. The arrangement and shape of the cams on a diesel engine camshaft directly control which of the listed groups of operating conditions? o (A) Speed, torque, and horsepower production (B) Firing order, valve timing, and valve lift o (C) Fuel consumption, efficiency, and cylinder pressure o (D) Scavenge pressure, compression ratio, and exhaust pressure 47. The purpose of the energy cell, or air cell, is to. o (A) cause auto-ignition in the cell rather than in the main combustion chamber (B) create a high turbulence within the main combustion chamber o (C) allow the spray to hit the piston rim rather than the cooler cylinder wall o (D) make a blast in the main chamber prior to the piston expansion stroke 48. Auxiliary diesel engines can be automatically shut down as a result of. o (A) low lube oil temperature (B) low lube oil pressure o (C) high exhaust temperature o (D) high cooling water pressure 49. A two-stroke cycle diesel engine requires less starting air than a four-stroke cycle diesel engine, of equal displacement, because the two-stroke cycle diesel engine. o (A) has little or no internal friction o (B) has a lower effective compression ratio o (C) operates with scavenge air under a positive pressure (D) operates without energy absorbing intake and exhaust strokes 50. Clearance volume scavenging in a turbocharged, four-stroke cycle diesel engine is accomplished. (A) during the valve overlap period o (B) with only the exhaust valve open o (C) at a pressure below atmospheric o (D) without cooling the cylinders or pistons If choice A is selected set score to 1. Page 11 of 19
National Maritime Center Providing Credentials to Mariners MO-0007 6/3/2016 Adapted for testing purposes only from WOODYARD, Pounder's Marine Diesel Engines and Gas Turbines, Ninth Edition Copyright 2009 Elsevier Ltd. Further reproduction prohibited without permission. Page 12 of 19
National Maritime Center Providing Credentials to Mariners MO-0011 6/3/2016 Adapted for testing purposes only from EMD645E9 Engine Maintenance Manual Copyright Electro-Motive Division, General Motors Further reproduction prohibited without permission. Page 13 of 19
National Maritime Center Providing Credentials to Mariners MO-0025 Fig. 1 Fig. 2 Fig. 3 F A B E D G H I C J T Fig. 4 Fig. 5 Fig. 6 L N O S K R P M V Adapted for testing purposes only from Description of and Operating Instructions for Sulzer Diesel Engines, RND-M. Sulzer Brothers Limited. Page 14 of 19 Further reproduction prohibited without permission.
National Maritime Center Providing Credentials to Mariners MO-0033 Adapted for testing purposes only from Hunt, Modern Marine Engineer's Manual, Vol. II, Third edition. 2002 The Cornell Maritime Press. Page 15 of 19 Further reproduction prohibited without permission.
National Maritime Center Providing Credentials to Mariners MO-0061 7/23/2015 Adapted for testing purposes only from KATES/LUCK, Diesel and High Compression Gas Engines, 3 rd edition Copyright 1974 by American Technical Society Further reproduction prohibited without permission. Page 16 of 19
National Maritime Center Providing Credentials to Mariners MO-0102 8/31/2016 Adapted for testing purposes only from LILLY, Diesel Engine Reference Book Copyright 1984 by Butterworth and Co. (Publishers) Ltd. Further reproduction prohibited without permission. Page 17 of 19
National Maritime Center Providing Credentials to Mariners MO-0113 9/13/2016 Adapted for testing purposes only from Instruction Manual and Parts List, Mineral Oil Separator with Self-Cleaning Bowl, Model OSA 20-02-066 Copyright Westfalia Separator Further reproduction prohibited without permission. Page 18 of 19
National Maritime Center Providing Credentials to Mariners MO-0122 9/30/2016 Adapted for testing purposes only from EMD 645E9 Turbocharged Engine Maintenance Manual Copyright 1973 Electro-Motive Division, General Motors. Further reproduction prohibited without permission. Page 19 of 19