MEK (Motor) asked Questions Part 3

101. Which of the bearings listed is most widely used for main and connecting rod bearings of modern diesel engines?
A. Steel-lined
B. Poured babbitt, self-aligning
C. Split roller
D. Precision insert

102. Which of the following statements is false?
A. The fuel oil sulfur level is one of the important criteria for choice of TBN level of cylinder oil.
B. The use of anti-polishing rings or flame rings increases the consumption of cylinder oil
C. Excessive cylinder oil feed can lead to harmful deposits in piston top land area
D. None of the above
103. When preparing to light off a cold boiler equipped with a return flow fuel oil system, the recirculating valve directs the flow of oil
A. directly to the fuel oil heater inlet for further warm-up
B. back to the fuel oil settler for further filtration
C. back to the suction side of the service pump
D. directly to the deep tanks
104. Prompt correction of speed of diesel engines driving alternators, without having massive fluctuations is ensured by incorporating:
A. Load limiting devices
B. Load sharing devices
C. Load sensing devices
D. Load shedding devices
105. In a uniflow scavenged marine 2-stroke diesel engine, the scavenge ports in a cylinder liner are machined
A. Only for a part of the circumference, at an angle almost tangential to the circumference of the liner
B. All around the circumference at right angles to the circumference of the liner
C. only for a part of the circumference, at right angles to the circumference of the liner
D. All around the circumference at an angle almost tangential to the circumference of the liner
106. If the tappet clearance between the rocker arm tappet and exhaust valve stem is excessive then:
A. The valve will open early and close later
B. The valve will open later and close early
C. The valve will open and close later
D. The valve will open and close early
107. In order to reduce thermal loading on the upper part of the liner and increase the effectiveness of cylinder lubrication, modern 2-stroke marine diesel engines are designed to have:
A. Cermet coated piston rings, bore cooled liners and uniflow scavenging
B. High top land of piston crown and deeper cylinder cover with top land of crown extending into cylinder cover at TDC
C. Low top land of the piston crown with bore cooled cylinder liner
D. Bore cooled cylinder liner and bore cooled piston crown with toroidal shape combustion chamber
108. Which of the following conditions can lead to reduced power developed by a main engine?
A. High scavenge air temperature
B. Choked air suction filter of a turbocharger
C. Blow past in one or more units
D. All of the above.
109. Which of the following can be done to reduce the cold corrosion of Main Engine cylinder liners using high sulphur fuel oil
A. Increasing cylinder oil feed rate
B. Using high TBN cylinder oil
C. Increasing scavenge air temperature
D. Decreasing cylinder oil feed rate
110. When m/e is running in emergency condition which of the alarms can't be bypassed
1. LO low pressure
2. Jacket water high temp
3. Piston cooling water high temp
4. All the above
111. Which of the following will be required to be done in order to reduce sulphur corrosion of main Engine Components?
A. Increasing the atomization pressure of fuel injectors
B. Fitting exhaust valves with valve rotators
C. Running engine at or near normal sea load
D. Decreasing the F.O. purifier feed rate , running two purifier in series one acting as purifier and other as clarifier
112. Where boiler point temp high?
A) Riser
b) Superheater
c) Primary steam drum
d) Secondary steam drum
113. Sudden stop of diesel engine (multiple choices)
A. air in system
B. water in system
C. air filter chocked
D. water in air filter
114. Mixed lubrication consist of
1. Mix two lubes oil
2. Contimanitiön of hydrodynamic lube oil.
3. Mixed grease and oil
115. The muffling of exhaust gas noise in 4 stroke auxiliary engines in achieved by
(a) Allowing the gas to expand.
(b) Change the direction of their flow.
(c) Cool the gas with injected water.
(d) Cool the gas with scavenge air.
116. An auxiliary engine turbo-charger makes strange noises when the load changes. The engine parameters however are absolutely fine. An external examination of turbocharger parameters as stated in the manual also reveals nothing. Would you
(a) Continue to run the engine and wait for some time
(b) Stop the engine for a while and make some checks
(c) Reduce the load of the engine
(d) Run it on steady load to make some checks.
117. To avoid the engine running too long on critical speed during start up it is necessary to
(a) Start at speeds above critical speed.
(b) Start at speeds just below critical speed and quickly move across the critical speed.
(c) Start at maximum speed and quickly bring down to just above critical speed.
(d) Eliminate totally the hazards of critical speed by ignoring it.
118. Supercharging an existing medium speed naturally aspirated engine will
(a) Reduce weight of the engine.
(b) Reduce bulk of the engine.
(c) Increase existing power.
(d) Increase piston speed.
(e) Reduce fuel consumption
119. When using low sulfur fuel oil for Emission Control Areas (ECA???S), ideally the TBN of the cylinder oil used should be
A. Lower than normal
B. Higher than normal
C. Same as normal
D. Same as normal if the feed is kept higher
120. Which of the following functions is done by a cam operating an exhaust valve?
A. It governs the timing of opening and closing of the valve.
B. It governs the speed at which the valve operates
C. It governs the amount of opening of the valve
D. All of the above
121. In the latest concept of Variable Geometry Turbocharging, _______angle can be varied to match the turbocharger at varying engine loads
A. Compressor vane
B. Turbine blade
C. Nozzle ring blade
D. Diffuser ring blade
122. The primary function of a flame safeguard system, as used on an automatically fired auxiliary boiler, is to prevent
A. accidental dry firing and overpressure
B. uncontrolled fires in the furnace
C. explosions in the boiler furnace
D. explosions in the boiler furnace
123. Directional intake ports in diesel engines are used to
A. reduce air charge turbulence
B. induce air swirl
C. deflect hot combustion gas away from the valves
D. oppose the effects of piston induced squish
124. Why does a chain stretch in service?
A. Due to plastic elongation
B. Due to high temperature expansion
C. Due to wear on rollers and bushes
D. Due to the phenomenon of creep
125. Which of the following methods is normally used to lubricate bearings in a small high-speed diesel engine?
A. Splash lubrication
B. Pressure lubrication
C. Sight feed lubricators
D. Mechanical lubricators
126. External fouling of boiler tubes can lead to:
A. Greater steam generation
B. Tube corrosion
C. Tube Erosion
D. Protection of tube against corrosion
127. What is the purpose of the inlet grid provided within the exhaust gas casing in the gas flow path, prior entry to turbocharger ?
A. To filter out any unburned carbon
B. To absorb and dampen the pressure fluctuation
C. To reduce noise in the constant pressure exhaust piping
D. To prevent any broken piston rings finding their way to turbine
128. The main function of tie rods in the construction of large, low speed diesel engines is to
A. stiffen the bedplate in way of the main bearings to increase the engine's longitudinal strength
B. accept most of the tensile loading that results from the firing forces developed during operation
C. mount the engine frame securely to the hull to prevent shaft coupling misalignment
D. connect the crosshead solidly to the piston rod
129. The fall in speed that occurs in a diesel engine equipped with governor, on increase of load is called:
A. Offset
B. Speed drop
C. Speed droop
D. Speed offset
130. Which of the following factors governs the lower limit of thrust bearing clearance?
A. To allow some oil leakage to prevent overheating
B. Reduction of oil viscosity
C. Alignment of crankshaft
D. To allow the thrust pads to tilt and generate the oil wedge
131. Which of the following can result in cracking of piston crown?
A. Deposits in cooling spaces
B. Impingement of fuel due to faulty injection
C. Insufficient piston cooling oil flow
D. All of the above
132. The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to
A. precipitate silica from solution
B. reduce corrosion in the heating coil
C. prevent clogging and erosion in the coil
D. maintain zero water hardness
133. What does the NLGI number of a grease indicate?
A. The oxidation resistance of the grease
B. The consistency of the grease i.e how fluid or non fluid
C. Demulsibility of the grease
D. The shelf life of the grease
134. Which of the following layers of a thin shell bearing gives it its fatigue strength?
A. The overlay
B. The inter lay
C. The backing
D. The barrier layer
135. Which of the following is a reasonable statement about water washing of turbine side of a T/C ?
A. It leads to thermal shock and reduces the life of the T/C
B. It leads to thermal shock and not so effective as solid washing
C. If properly carried out keeping rpm, load, temperature limits & other factors into account; it is quite safe and more effective than solid washing
D. It should never be carried out as most of the engine manufacturers recommend against the same
136. Which of the following statements correctly describes the phenomenon of surging in a 2-stroke crosshead type engine?
A. Due to sudden increase in engine load the exhaust gases may flow back through scavenge ports causing surge
B. Due to sudden decrease in engine load the turbocharger pressure ratio drops . This causes high pressure downstream of T/C in scavenge trunk causing flow reversal of scavenge air
C. Due to sudden increase in engine load , the T/C turbine rpm may increase suddenly increasing the compressor pressure ratio to surge
D. Due to sudden decrease in engine load , the turbocharger may stall as the higher pressure downstream in exhaust system may cause reversal of flow of exhaust gases
137. If the boiler tubes are scaled on the water side then
A. Heat conduction through the tubes will be very high leading to rapid evaporation
B. The boiler furnace can get damaged due to excessive temperatures
C. The surface of the tube will be overheated as heat transfer is impaired
D. The natural circulation of water within the boiler will be more efficient
138. Fins are installed on the generating tube surfaces in waste heat boilers to
(A) Prevent soot fires in the exhaust system
(B) Prevent exhaust gas erosion of the tubes
(C) Increase the velocity of exhaust gas flow
(D) Increase the rate of heat transfer
139. Any steering gear system alarm can only be successfully acknowledged from
A. The bridge
B. The engine control room
C. The steering compartment
D. The ship's office
140. To check the setting of the over speed trip on a diesel powered generator, you would use a
A. tachometer
B. torsion meter
C. dynamometer
D. pony brake
141. Which of the following specifications/qualities of cylinder oils counter corrosive wear?
A. Viscosity
C. Detergency
D. Specific gravity
142. What is meant by elastohydrodynamic lubrication?
A. Formation of hydrodynamic film under high pressure with minor elastic deformation of mating surfaces, distributing load over a greater area
B. Addition of extreme pressure additive (EP) to the lubricant
C. Addition of Viscosity index improvement additive
D. Addition of elastomer based additives
143. In a bypass type filtering system for a medium or high speed diesel engine, the lube oil bypassing the filter
A. returns directly to the suction side of the pump
B. returns directly to the sump
C. flows to the engine bearings
D. flows through a second-stage strainer, reheater, and returns to the sump
144. Which type of boiler burner has max turn down ratio?
a. Pressure set
b. spinning cup
c. Spill type
d. Y-jet type
145. Most steam traps respond well to cleaning. But when a thermodynamic trap fails to operate after cleaning, the next course of action should be
A. throttle the steam outlet valve
B. renew the trap
C. lap the disc and seat the trap
D. throttle the steam inlet valve
146. Types of corrosion in fresh water of D/E
a. Stress b. hot corrosion c. bimetallic d. selective phase corrosion
147. Which of the following types of damages are metal seatings of a valve subject to? Choose the correct alternative.
A. Corrosion, Erosion, Abrasion, Deformation
B. Corrosion, Fatigue failure, brittle fracture, caustic cracking C. Erosion, caustic cracking, brittle fracture, Clover leafing D. None of the above
148. When A/E stand by F.O.heater to be used for main engine
A. Sudden opening F.O. inlet valve pressurized and damage the heater
B. F.O. in vapor lock inside heater allow steam
C. F.O. inlet valve causes pressure drop M/E F.O. pressure standby water is not pressurized may cause sudden change in engine /per load/rpm
D. heater leaking.
149. Viscosity of fuel oil used for ME was 145cst, new fuel comes whose viscosity was more than earlier, what u should do
a) Increase temp setting
b) Change setting of viscotherm
c) Do nothing
d) Open steam valve manually more
150. After prolonged operation, jerk type fuel pumps wear on the top edge of plunger and edges of spill ports and helix due to erosion by high pressure fuel as it spills. This wear would result in
A. Late start of injection and early end of injection
B. Early start of injection and late end of injection
C. Early start of injection and early end of injection
D. Late start of injection and late end of injection
151. Labyrinth seal fitted on the back surface of a compressor wheel of a turbocharger:
A. Prevents bearing lube oil contamination
B. Prevents bearing lube oil being sucked into the air stream
C. Helps to keep the shaft cool by controlled leakage of air
D. None of the above
152. It is a known fact that centrifugal pumps require priming for pumping liquids , as they cannot handle air and will lose suction due to air entry . But on the other hand T/Cs use centrifugal compressors for supercharging. Which of the following do you think makes a centrifugal compressor to pump air and behave differently than the centrifugal pumps?
A. Presence of air cooler
B. Presence of Labyrinth seal
C. High speed of rotation, very fine internal clearances and large impeller diameters
D. Difference in principle of operation
153. If an operating auxiliary boiler has a water pH reading of 7, you should
A. bottom blow the boiler
B. treat the water with caustic soda
C. treat the water with chemical scavengers
D. reduce the water alkalinity to recommended readings
154. In case of 2-stroke marine diesel engines, the top part of the liner forming the combustion chamber experiences very high pressure induced mechanical stresses as well as high thermal stresses. Which of the following is a correctly designed liner for catering both the above stresses?
A. Thick top portion with jacket cooling to take care of both the high mechanical and thermal stresses
B. Thick top portion to take care of high mechanical stresses while bore cooling to reduce thermal gradients
C. Thin top portion to reduce thermal gradients and hence thermal stresses while supporting ribs to take care of mechanical stresses
D. Thick top portion to take care of high mechanical stresses with jacket cooling combined with allowance for thermal expansion to minimize the thermal stresses
155. Which of these fuel oil impurities can cause maximum abrasive damage?
A. Water
B. Ash
C. Catalytic fines
D. Sodium
156. In modern marine 2-stroke diesel engines, ________________ is sometimes used as a coating on the underside of the exhaust valve disc, to reduce the rate of hot corrosion.
A. Monel
B. Chromium
C. Inconel
D. Cermet
157. Irregular circumferential wear of liner due to diminishing neutralizing capacity of cylinder oil away from lubricating holes is known as:
A. Micro seizure
B. Scuffing
C. Scoring
D. Clover leafing

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