Motor Engineering – MEO CLASS 4 MMD PAPER

121) The diameter of a piston is usually less at the crown than at the skirt, in order to

1. facilitate the installation of piston rings
2. allow for the expansion of the piston during operation
3. prevent crankcase vapors from entering the combustion chamber
4. reduce wearing of the upper cylinder liner

ANS.: B

122) Which of the following manufacturing methods is recommended for diesel engine fuel injection line piping?

1. Cold rolled
2. Electric resistance welded
3. Seamless drawn
4. Straight seam

ANS.: C

123)   Exhaust pipes of multiple engine installations are not to be interconnected, but are to be run separately to the atmosphere

1. unless arranged to prevent the return of gases to an idle engine
2. to a point not lower than the highest load line
3. at a location segregated from other ventilation systems
4. and shall be protected by a rain guard or similar device

ANS.: A

124)   Which of the bearing types listed is most commonly used in smaller vessel main propulsion reduction gears as thrust bearings?

1. ball bearings
2. poured bearings
3. sleeved bearings
4. tapered roller bearings

ANS.: D

125)   The main reason for using bimetallic piston rings is to

1. increase engine thermal efficiency
2. educe specific fuel consumption
3. reduce the probability of ring fracture
4. allow for ring expansion

ANS.: C

126)   A spring-loaded centrifugal flyweight governor responds to reduced engine load with an immediate increase in

1.  Pilot valve oil pressure
2.  Speeder spring force
3.  compensation needle valve clearance
4.  centrifugal force on the flyweights

ANS.: D

127) The reason why the pneumatic reversible roller guide of fuel pump could oscillate is

1. incorrect clearance in the air cylinder guideway/ reverse arm bushing
2. too large air pressure drop
3. insufficient air supply
4. all of above

ANS.: D

128) Reasons for exhaust valve hammering could be-

1. deficiency in oil supply
2. errors in air spring
3. excessive leakage in the HP oil system
4. all of above

ANS.: D

129) error in the air spring system causing exhaust valve hammer can be due to—

1. air pressure too high
2. maladjusted safety/ drain valve
3. supply pressure not corresponding with safety valve opening pressure
4. all of above

ANS.: D

130) deficiency in oil supply causing exhaust valve hammering can be due to-

1. foaming oil due to air leak at pump suction
2. too low oil supply pressure
3. too high oil temperature (MECC ) causing low viscocity
4. all of above

ANS.: D

131) excessive difference between combustion pressure and compression pressure in a ME cylinder can be due to-

1. low scavenge air pressure
2. change in exhaust valve timing
3. burnt exhaust valves
4. all of above

ANS.: D

132) the difference between water washing and dry cleaning the TC turbine is

1. there is no difference one is wet, the other is dry
2. wet washing requires reduced load
3. dry cleaning requires reduced load
4. none of the above

ANS.: B

133) oscillations of pneumatic reversible roller guide for fuel pump can cause-

1. mechanical damage to air cylinder
2. leakages on maneuvering air
3. loss of engine maneuverability
4. all of above

ANS.: D

134) During maneuvering the MECYL feed rate is usually

1. 125% of service feed rate
2. 50%
3. 200%
4. 300%

ANS.: A

135) The difference between the max combustion pressure and compression pressure in a 2 stroke engine cylinder unit is

1. 40 bars
2. 10 bars
3. 70 bars
4. 65 bars

ANS.: A

136) The air spring pressure to prevent ME exhaust valve hammer is in the region of—

1. 2 kg
2. 7kg
3. 12 kg
4. 14 kg

ANS.: B

137) Your indicator diagram from one of the main engine cylinders is shown. P Comp normal, P Max is low–What kind of steps do you think is necessary to rectify the failure?

1. Check fuel injector valve, fuel injection timing, fuel pump suction valve and fuel pump lead
2. Clean air cooler and turbocharger air cooler
3. Adjust fuel pump lead only during operation
4. Increase fuel pump setting.

ANS.: A

138) Your indicator diagram is as shown. What kind of steps do you think are necessary to rectify the failure? Pc normal pm high

1. Check if fuel injection is too early or fuel pump lead too large
2. Check if fuel injection valve is correctly by adjusted.
3. Check that you have correctly viscosity/fuel preheating.
4. Replace the fuel valve.

ANS.: A

139) A drawn indicator diagram from one of the main engine cylinders is as shown. What kind of steps are necessary to rectify the failure?—pc and pm both low

1. Overhaul the unit to determine faults such as: piston ring blow-by, exhaust valve malfunction, clogged scavenging ports, delayed ignition etc.
2. Adjust fuel pump lead to inject more fuel so as to maintain power balance
3. Change fuel injection valve
4. Check fuel pump safety valve.

ANS.: A

140) During inspection of piston and liners through scavenging ports, piston rings on all units were found as shown (micro seizure). The best way to stop its progress is:

1. Increase cylinder oil consumption, determine fuel quality and readjust the fuel oil purifiers
2. Increase cylinder oil consumption
3. Replace all piston rings
4. Run engine at lower load.

ANS.: A

141) During inspection and calibration of one unit, you observe the situation shown. The conclusion is clover leafing. The main engine uses high grade TBN cylinder oil. What do you have to do in order to reduce wear?—depression on either side of all lub orifices—like 10 paise coin

1. Decrease jacket cooling water temperature to avoid heat stress
2. Increase the jacket cooling water temperature to avoid the sulphur dew point
3. Increase cylinder oil consumption to neutralize the sulphur
4. Contact engine maker for advice.

ANS.: B

142) Your vessel is entering a tropical area and high humidity is expected. To avoid condensation in the main engine’s air cooler, it is recommended to:

1. Operate the engine with slightly open drain cocks, scavenging to get rid of the water
2. Reduce speed.
3. Decrease the air temperature so proper draining can be achieved from the air cooler
4. Increase scavenging air temperature to above dew point

ANS.: D

143) During inspection of the crank bearing for one of the units in the main engine, the bearing shell was found as follows: Surface of the white metal was black and very hard.  Patches of black incrustations have worn grooves in the journal. What was the cause?

1. Dirt in the lubricating oil
2. Wrong casting of bearing shell
3. Water in the lubricating oil during service
4. Bearing shell service time exceeded.

ANS.: C

144) When carrying out piston overhaul, it is important to clean the ring grooves properly. Why?

1. To make sure gas pressure can enter freely on top of and behind the piston ring
2. To make the rings fit in the groove
3. All rings must be changed to maintain a perfect sealing
4. That piston rings can move freely in the grooves.

ANS.: A

145) During operation of the main engine, the exhaust temperature increases on one of the cylinders. The turbocharger starts surging and smoke from the turbocharger inlet air filter occurs. What is the probable cause?

1. A High back pressure in the exhaust system
2. Turbocharger failure
3. Fuel valve stick in open position.
4. Scavenge box fire

ANS.: D

145.You are having a blow-by on the main engine, but due to the circumstances, it is impossible to stop and do a piston overhaul. What is the correct action to take?

1. Reduce speed.
2. No action necessary.     
3. Reduce speed temporarily and increase cylinder oil consumption.
4. Increase cylinder oil consumption.

ANS.: C

146.You have installed a new bearing in the main engine.  What is the necessary action to take in the running-in period?

1. Stop after 30 min. running to hand feel the bearing.
2. Allowance must be made for a running-in period with reduced speed and careful temperature monitoring.
3. No necessary steps  to be taken.
4. Allow for 1 hr. running  with appropriate temperature monitoring of the bearing.  

ANS.: B

147.You are experiencing large hunting on the fresh water cooling system.  What is the reason?

1. The fresh water circulating pump is worn out.
2. The cooling water temperature is too low.
3. You have a cracked liner, or cover.
4. The expansion tank is empty.

ANS.: C

148.Why is it important to check the timing on the cylinder oil  lubricators?

1. To avoid high temperature in the combustion chamber.
2. To get the right amount of oil into the cylinder.
3. To get the oil into the cylinder when the piston is in the right position
4. To avoid excess lubrication.

ANS.: C

149.Why do we use cylinder oil?

1. To neutralize the sulphur and get a lubricating oil film between piston rings and liner.
2. To get a lubricating oil film between piston rings and liner.
3. To neutralize the sulphur in the fuel.
4. To avoid blowby.

ANS.: A

150. How large a deviation in opening pressure can be accepted in a diesel engine injection valve?

1. 15 kg/cm2
2. 40 kg
3. 50 kg
4. 70 kg

ANS.: C

151.What will the effect be, if you have a fuel injector valve that is dripping after the injection is finished ?

1. Less carbonizing.
2. Damage to piston and liner.
3. Greater output of the engine.
4. Better combustion.

ANS.: B

152. How is the quantity of fuel oil, in HP fuel oil pump adjusted when the engine is running ?

1. By adjustment of the pressure valve in the pump.
2. By adjusting the length of the pump stroke.
3. Turning the plunger piston  according to engine load 
4. Adjusting oil flow to the HP fuel oil pump.

ANS.: C

153. When a changeover from HFO to diesel oil is going to take place, we want this to be carried out as follows

1. as fast as possible to save HFO.
2. as fast as possible to save steam.
3. as quick as possible, to obtain a fast temperature reduction to cool the HP fuel pumps.
4. slow to get slow cooling.

ANS.: D

154. If you are going to enter the engines crankcase (go inside), how will you secure the engine after you have closed the main starting air valve ?

1. Engage the turning gear on the engine.
2. Close absolutely all valves on the starting air bottle.
3. Close the instrument air supply.
4. Keep a man posted in the control room to watch that nobody tries to start the engine

ANS.: A