Motor Engineering – MEO CLASS 4 MMD PAPER

17) Which of the following condition may need to be reduced when operating a large, low-speed, main propulsion, diesel engine at low loads?

1. Injection pressures
2. Control air supply pressure
3. Cooling water flow through after coolers
4. Lube oil temperature

ANS.: C

 18)   One function of the fuel pump delivery check valve is to  uscg382

1. prevent carbon deposits from forming on the injector nozzle
2. help the injector needle reseat without dribbling at the nozzle holes
3. provide a prolonged pressure drop in the high pressure steel piping to the injector
4. ensure a fuel leak off between the plunger and barrel which provides lubrication for relative movement

ANS.: B

 19) A closed freshwater cooling system is commonly used with marine diesel engines because the

1. need for water treatment is eliminated
2. cooling water temperature differential is greater
3. cooling water pumps are directly reversible
4. jacket water temperature is more easily controlled

ANS.: D

20)  Fuel droplets injected into a diesel engine cylinder must have adequate penetration to

1. prolong the ignition delay period
2. ensure the beginning of fuel injection
3. thoroughly utilize the air charge
4. allow controlled fuel combustion

ANS.: C

21)   The valve cam slope angle determines the

1. engine torque characteristics
2. acceleration rate of valve opening and closing
3. engine fuel efficiency
4. diameter of intake and exhaust valves

ANS.: B

22) The rate of fuel injection in a diesel engine cylinder depends primarily on uscg502

1. the size of the holes in the fuel nozzle
2. timing of the pump
3. supply pressure to the pump
4. shape of the combustion chamber

ANS.: A

23) Which of the following devices is normally provided to prevent oil starvation in a diesel lubrication system utilizing the “full flow” principle?

1. Duplex strainer
2. Three-way valve
3. Pressure relief bypass line around the filter
4. Mechanical straining filter

ANS.: C

24)   A port-and-helix fuel injection pump having upper and lower plunger helixes is designed to

1. vary fuel delivery and return pressure
2. vary the beginning and ending of injection
3. operate with residual fuels only
4. provide maximum fuel delivery rate

ANS.: B

25) One advantage of hydraulic clutches over mechanical clutches in diesel engine installations is

1. the power is transmitted at very high efficiency of 60%
2. the torsional vibrations are transmitted directly to the reduction gears
3. each clutch has a separate oil gland for reverse operation
4. no mechanical connection exists between the driving and driven elements

ANS.: D

26) An individual injection pump is designed for variable beginning and constant ending of injection. For diesel engines operating at constant speeds, the start of injection will

1. advance as the load increases
2. retard as the load increases
3. remain unchanged regardless of load
4. always occur at top dead center

ANS.: A

27) The amount of fuel injected in a particular time, or degree, of crankshaft rotation is termed

1. metering 
2. timing
3. rate of injection
4. rate of distribution

ANS.: C

28)   In a normally operating diesel engine, the main source of lubricating oil contamination in the crankcase is a result of the

1. metal particles loosened by wear
2. air when no air cleaners are used
3. condensation of water vapors
4. breakdown of the lubricating oil by dilution

ANS.: D

29) On small diesel engines, a noticeable decrease in the time interval between the replacement of the lube filter cartridge indicates

1. piston ring blow-by
2. dirty air filter
3. excessive oil pressure
4. excessive oil temperature

ANS.: A

 30) When the lower edge of the spiral begins to uncover the release port in a jerk pump, the

1. pumping continues until the plunger travels its full stroke
2. effective pumping stroke of the plunger ends
3. pres. drops slowly until the full stroke is attained
4. plunger rotates to the zero delivery position until  next stroke

ANS.: B

31) Some diesel engines are fitted with a thermometer in the cooling water outlet from each cylinder. If the cooling water temperature from all cylinders begins to rise above normal, you should suspect

1. increased blow-by in all cylinders
2. incomplete combustion in all cylinders
3. overloading in all cylinders
4. insufficient fuel delivery to all cylinders

ANS.: C

32)  Proper operation of the main engine reduction gear set requires the operator to monitor uscg695

1. the sump oil level
2. oil flow sight glasses
3. bearing temperatures
4. all of the above

ANS.: D

33)  The duration of fuel injection developed by an individual port-and-helix fuel injection pump, is determined by the

1. total pump stroke
2. pump plunger diameter
3. plunger helix angle
4. effective pump stroke

ANS.: D

34)   Before starting a diesel engine using an attached lube oil pump, the engineer should

1. open the bypass line
2. cut in the lube oil cooler
3. pressurize the lube oil system
4. top off the expansion tank

ANS.: C

35)   A diesel engine using lube oil with too high a viscosity will exhibit

1. a)increased starting difficulty in cold weather
2. b)increased oil consumption
3. c)thickening at higher operating temperatures
4. d)minimal friction losses

ANS.: A

36) If the main propulsion diesel engine governor works irregularly with a jerking motion, a possible cause can be

1. a sticking fuel control linkage
2. a malfunctioning overload cam
3. An unlocked overspeed trip
4. floating valves

ANS.: A

37) During extremely cold weather, while starting an engine, it turns too slowly and fails to start. This problem is most likely the result of

1. High fuel oil viscosity
2. Low fuel oil temperature
3. High lube oil viscosity
4. Energized glow plugs

ANS.: C

38) Prolonged operation of a diesel engine with a closed cooling water system, at lower than normal designed temperatures can –

1. increase power output
2. decrease lube oil viscosity
3. eliminate fuel knock
4. cause sulfuric acid formation

ANS.: D

39)   Which of the listed governor characteristics will greatly affect the load sharing relationship between paralleled diesel generators?-

1. Sensitivity
2. Power
3. Speed droop
4. Compensation

ANS.: C

40) An emergency diesel generator cooling system is equipped with an automotive type thermostat. If the thermostat bellows loses its charge, the thermostat will

1. open, and the coolant temperature will increase
2. open, and the coolant temperature will decrease
3. close, and the engine coolant temperature will increase
4. close, and the coolant temperature will decrease

ANS.: C

 41)   Fuel oil penetration into the cylinder of a diesel engine is

1. dependent on air turbulence
2. reduced by finer atomization
3. increased by finer atomization
4. non-existent in the pre combustion  chamber system

ANS.: B

42) Pre combustion chambers, air cells, and energy cells in high-speed, small bore diesel engines all serve to increase-

1. firing pressure
2. Ignition quality of fuel
3. fuel-air ratio during compression
4. Turbulence

ANS.: D

43) Which of the following statements best describes the operational characteristics of an isochronous governors?-

1. they are suitable for use on main propulsion units
2. they strive to maintain a constant engine speed for all values of steady load
3. they cause a proportional drop in engine speed as the load is increased
4. they have poor sensitivity at high RPM.

ANS.: B

44) Theoretical perfect combustion in a diesel engine yields by-products of

1. aldehydes and carbon dioxide
2. water vapour and carbon monoxide
3. nitrogen and carbon monoxide
4. water vapour and carbon dioxide

ANS.: D

45) Combustion knock can occur in the cylinders of a diesel engine under any condition permitting

1. a shortened ignition delay period
2.  lean fuel/air mixture
3. excess fuel in the combustion chamber
4. rapid vaporisation of injected fuel droplets

ANS.: C

 46)    When excessive fuel dilution is noted in the lube oil, the oil should be-

1. centrifuged`
2. filtered
3. strained
4. changed

ANS.: D

47)  Sticking of diesel engine piston compression rings may be caused by-

1. high compression pressure
2. excessive ring action
3. excessive cylinder lubrication
4. improper ring rotation

ANS.: C

48)   When fuel is injected late into a diesel engine cylinder

1. the exhaust will be clear
2. fuel consumption will be low
3. all the fuel will be burned at top dead center
4. fuel consumption will be high

ANS.: D

49) ME LO inlet temperature should be—

1. 40C
2. 50C
3. 60C
4. 55C

ANS.: A

50) Exhaust temp of one ME cylinder high could mean

1. fuel valves need overhaul
2. exh valve leakage 
3. piston ring blow past
4. all of above

ANS.: D

51)For a 2 stroke engine with exhaust ports—

1. scavenge ports close before exhaust ports
2. exhaust ports close before scavenge ports
3. scavenge ports and exhaust ports close at same time before BDC
4. scavenge ports and exhaust ports close at same time after BDC

ANS.: A

52)For a 2 stroke engine with exhaust valves—

1. Scavenge valve closes before exhaust ports
2. Exhaust valves close before scavenge valves
3. Scavenge and exhaust valves close at same time before BDC
4. Scavenge and exhaust valves close at same time after BDC

ANS.: A

53) The maximum amount of liner wear occurs at—

1. top of liner
2. 1/ 3 downward from top centre
3. midway
4. bottom of liner

ANS.: B

54) Which of the following cannot be removed from fuel oil by centrifuging in the purifier and micro-filtration

1. sodium
2. aluminium and silicon
3. vanadium
4. ash

ANS.: C