101) The expansion tank for a diesel engine
closed cooling system is designed to maintain a constant head on the system and
a)reduce water temperature
b)reduce water turbulence
c)provide an air cushion
d)allow
for an increase in water volume as the engine warms up
102) To minimize corrosion, fuel oil strainer
disks, spacers and scraper blades are made of
a)brass
b)copper
c)iron
d)monel
metal or stainless steel
103)
Which of the following statements describes the function of an expansion
tank in a diesel engine cooling system?
a)Maintains a constant head on the
system
b)Reduces the air cock when fires
are lighted
c)Provides a low pressure point for
the addition of makeup cooling water
d)All
of the above
104) On a large diesel engine installation,
crankshaft axial alignment is maintained by the
a)piston rod guides
b)engine
thrust bearing
c)crosshead bearing
d)main shaft flexible coupling
105) Scavenging in a four-stroke/cycle diesel
engine occurs during the
a)last
part of the exhaust stroke, and the first part of the intake stroke
b)last part of the intake stroke
only
c)early part of the injection stroke
only
d)early part of the power stroke
106)
In a large, slow-speed, main propulsion diesel engine, which of the
parts listed is under tension when the engine is running?
a)Bed plate
b)Column
c)Entablature
d)Tie
rod
107)
The lube oil cooler is located after the lube oil filter in order for
a)the
filter to operate more efficiently
b)the lube oil cooler to be bypassed
c)positive lube oil pump suction to
be assured
d)galvanic action in the cooler to
be minimized
108) In two-stroke/cycle diesel engine, the
process of scavenging begins as the
a)piston nears and passes TDC
b)early
part of the upstroke
c)piston passes BDC
d)early part of the downstroke
109 W res. to
flow of lubricating oil through a diesel engine, the lube oil coolers
are located after filters in order to
a)allow filtration of less viscous
oil
b)decrease the pressure drop across
the filter
c)improve overall filtration
d)all
of the above
110)
Passages are drilled in the crankshafts of diesel engines to provide
lubricating oil to the
a)main bearings
b)connecting rod bearings
c)piston pin bushings
d)All
of the above
111)
The outlet from an expansion tank of a closed freshwater cooling system
should be piped to the-
a)cylinder head water outlet header
b)cylinder jacket inlet main
c)heat exchanger inlet connection
d)jacket
water pump suction line
112)
The intake valves in diesel engine are reseated by
a)cam followers
b)push rods
c)combustion gases
d)valve
springs
113)
Small amounts of moisture are necessary to trigger the growth of
microbiological organisms found in some marine fuels. Some sources of water
contamination are
a)tank surface leakage
b)humidity and condensation
c)improper tank washing procedures
d)All of the above
114)
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
115) On most modern diesel engines,the main and
connecting rod bearings receive their lubricating oil by –
a)banjo feed
b)splash feed
c)gravity feed
d)pressure
feed
116) A
unit type fuel injector is used on a diesel engine to
a)meter the fuel
b)produce the proper fuel oil
pressure
c)atomize the fuel
d)all
of the above
117) Lubricating system for diesel engines are
usually designed to initially provide lube oil to the engine-
a)camshaft bearings
b)main
bearings
c)piston crowns
d)cylinder walls
118)
Mechanical lubricators for diesel engine cylinders are usually small
reciprocating pumps which are-
a)operated manually once each hour
b)operated until the engine has
started
c)placed into operation only at
maximum load
d)adjustable
to meet lubrication requirements
119)
Shacker, circulation, and spray are the three general methods used in
a)pre-injection fuel oil treatment
b)lube oil filtration
c)fuel oil purification
d)piston
cooling
120)
Fuel injector nozzles are usually of the multi-orifice type with the
number and placement of the holes arranged according to the
a)type of piston rings
b)pressure of the fuel system
c)size of the pump plunger spring
d)design
of the combustion chamber
121)
What is the crank angle between any two crank throws in the firing order
of a four-stroke/cycle, in line, eight cylinder diesel engine?
a)45° b)60° c)90° d)100°
122) The main reason counterweights are added to
crankshafts is to
a)reduce piston side thrust
b)reduce crankshaft end thrust
c)provide
uniform loading and wear of main bearings
d)increase the strength of the crank
webs
123) A viscous damper, as used on a marine
diesel, is a sealed precision built device which dampens the torsional
vibrations in the
a)camshaft
b)flywheel
c)crankshaft
d)thrust shaft
124) A
crankshaft whose center of gravity coincides with its center line is said to be
a)dynamically balanced
b)statically
balanced
c)counter balanced
d)resonantly balanced
125)
The possibility of damage from operating a diesel engine at critical
speeds is reduced by the use of
a)an isochronous governor
b)elastic engine mounts
c)a
vibration damper
d)a cast iron bed plate with good
flexible qualities
126). In a diesel engine lube oil system, which of
the following parts should be lubricated first?
a)Camshaft bearings
b)Main
bearings
c)Piston crowns
d)Cylinder walls
127)
When fuel oil heaters are required for engine operation,
a)each heater shall have the
capacity to supply the main engine at full power
b)at
least two heaters of approximately equal size are to be installed
c)the system shall be designed to
permit series or parallel operation
d)none of the above
128)
An advantage of aluminium pistons compared to cast iron pistons is:
a)greater high temperature strength
b)better
heat conductivity
c)greater weight per cubic cm
d)increased resistance to wear
129) Which engine component increases air density
and helps to improve engine operating efficiency?-
a)impeller
b)compressor
c)aftercooler
d)exhaust diffuser
130) An electric heater built into the cylinder
water jacket would be used to
a)raise lube oil viscosity for
easier starting in cold weather
b)increase air inlet temperature
c)increase compression ratio
d)increase
water temperature for easier starting in cold weather
131)
Which is found with both mechanical and hydraulic governors?
a)direct linkage between the ball
head and fuel rack
b)a servomotor
c)a compensating device
d)flyweights
132)
Which of the following design features will reduce the possibility of
overheating the top compression rings of a cast iron piston?
a)The top ring is located as close
to the piston as possible
b)The inside surface of the piston
head is rounded into the ring belt
c)A nickel-bearing insert is cast
into the top ring groove
d)A
heat dam design is sometimes used in the piston head
133)
The purpose of heat dam used in some diesel engine cast iron pistons is
to
a)concentrate all heat in the piston
crown
b)increase
the distance of travel for heat from the crown to the top ring groove
c)ensure that all heat in the piston
crowns is conducted to the top ring
d)provide a short direct path for
heat to flow from the crown to the top ring
134)
Valves used in diesel engine fuel oil pressure piping are to be
a)
installed to close against flow
or so constructed as to permit
packing under pressure.
b)solenoid released upon the failure
of engine lubrication
c)either of the gate or globe valve
type
d)forge constructed under the
approval of the Marine Inspector
135). Cast iron pistons used in large propulsion
engines are constructed with
a)no taper whatsoever
b)the skirt being tapered and
smaller than the crown
c)the skirt being tapered and larger
than the crown
d)the
crown being tapered and smaller than the skirt
136)
The diameter of a piston is usually less at the crown than at the skirt,
in order to
a)facilitate the installation of
piston rings
b)allow
for the expansion of the piston during operation
c)prevent crankcase vapors from
entering the combustion chamber
d)reduce wearing of the upper
cylinder liner
137). Which of the following manufacturing methods
is recommended for diesel engine fuel injection line piping?-
a)Cold rolled
b)Electric resistance welded
c)Seamless
drawn
d)Straight seam
138)
Exhaust pipes of multiple engine installations are not to be
interconnected, but are to be run separately to the atmosphere
a)unless
arranged to prevent the return of gases to an idle engine
b)to a point not lower than the
highest load line
c)at a location segregated from
other ventilation systems
d)and shall be protected by a rain
guard or similar device
139)
Which of the bearing types listed is most commonly used in smaller
vessel main propulsion reduction gears as thrust bearings?
a)ball bearings
b)poured bearings
c)sleeved bearings
d)tapered
roller bearings
140)
The main reason for using bimetallic piston rings is to
a)increase engine thermal efficiency
b)reduce specific fuel consumption
c)reduce
the probability of ring fracture
d)allow for ring expansion
141) A spring-loaded centrifugal flyweight
governor responds to reduced engine load with an immediate increase in
A) Pilot valve oil pressure
b) Speeder spring force
c) compensation needle valve
clearance
D)centrifugal
force on the flyweights
142) The reason why the pneumatic
reversible roller guide of fuel pump could oscillate is
a)incorrect clearance in the air
cylinder guideway/ reverse arm bushing
b)too large air pressure drop
c)insufficient air supply
d)all
of above
143) Reasons for exhaust valve
hammering could be-
a)deficiency in oil supply
b)errors in air spring
c)excessive leakage in the HP oil
system
d)all
of above
144) error in the air spring system
causing exhaust valve hammer can be due to—
a)air pressure too high
b)maladjusted safety/ drain valve
c)supply pressure not corresponding
with safety valve opening pressure
d)all
of above
145)deficiency in oil supply causing
exhaust valve hammering can be due to-
a)foaming oil due to air leak at
pump suction
b)too low oil supply pressure
c)too high oil temperature (MECC )
causing low viscocity
d)all
of above
146) excessive difference between
combustion pressure and compression pressure in a ME cylinder can be due to-
a)low scavenge air pressure
b)change in exhaust valve timing
c)burnt exhaust valves
d)all
of above
147)the difference between water
washing and dry cleaning the TC turbine is
a)there is no difference one is wet,
the other is dry
b)wet
washing requires reduced load
c)dry cleaning requires reduced load
d)none of the above
148) oscillations of pneumatic
reversible roller guide for fuel pump can cause-
a)mechanical damage to air cylinder
b)leakages on maneuvering air
c)loss of engine maneuverability
d)all
of above
149) During maneuvering the MECYL
feed rate is usually
a)125%
of service feed rate
b)50%
c)200%
d)300%
150)The difference between the max
combustion pressure and compression pressure in a 2 stroke engine cylinder unit
is
a)40
bars
b)10 bars
c)70 bars
d)65 bars
151) The air spring pressure to
prevent ME exhaust valve hammer is in the region of—
a)2 kg
b)7kg
c)12 kg
d)14 kg
152. 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?
A
Check fuel injector valve, fuel injection timing, fuel pump suction valve and
fuel pump lead
B Clean air cooler and turbocharger
air cooler
C Adjust fuel pump lead only during
operation
D Increase fuel pump setting.
153.Your indicator diagram is as
shown. What kind of steps do you think are necessary to rectify the failure? Pc
normal pm high
A
Check if fuel injection is too early or fuel pump lead too large
B Check if fuel injection valve is
correctly by adjusted.
C Check that you have correctly
viscosity/fuel preheating.
D Replace the fuel valve.
154.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
A
Overhaul the unit to determine faults such as: piston ring blow-by, exhaust
valve malfunction, clogged scavenging ports, delayed ignition etc.
B Adjust fuel pump lead to inject
more fuel so as to maintain power balance
C Change fuel injection valve
D Check fuel pump safety valve.
155.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:
A
Increase cylinder oil consumption, determine fuel quality and readjust the fuel
oil purifiers
B Increase cylinder oil consumption
C Replace all piston rings
D Run engine at lower load.
156.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
A Decrease jacket cooling water
temperature to avoid heat stress
B
Increase the jacket cooling water temperature to avoid the sulphur dew point
C Increase cylinder oil consumption
to neutralize the sulphur
D Contact engine maker for advice.
157.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:
A Operate the engine with slightly
open drain cocks, scavenging to get rid of the water
B Reduce speed.
C Decrease the air temperature so
proper draining can be achieved from the air cooler
D
Increase scavenging air temperature to above dew point
158.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?
A Dirt in the lubricating oil
B Wrong casting of bearing shell
C
Water in the lubricating oil during service
D Bearing shell service time
exceeded.
159.When carrying out piston
overhaul, it is important to clean the ring grooves properly. Why?
A
To make sure gas pressure can enter freely on top of and behind the piston ring
B To make the rings fit in the
groove
C All rings must be changed to
maintain a perfect sealing
D That piston rings can move freely
in the grooves.
160.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?
A High back pressure in the exhaust
system
B) Turbocharger failure
C Fuel valve stick in open position.
D
Scavenge box fire
161.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?
A Reduce speed.
B No action necessary.
C
Reduce speed temporarily and increase cylinder oil consumption.
D Increase cylinder oil consumption.
162.You have installed a new bearing
in the main engine. What is the
necessary action to take in the running-in period?
A Stop after 30 min. running to hand
feel the bearing.
B
Allowance must be made for a running-in period with reduced speed and careful
temperature monitoring.
C No necessary steps to be taken.
D Allow for 1 hr. running with appropriate temperature monitoring of
the bearing.
163.You are experiencing large
hunting on the fresh water cooling system.
What is the reason?
A The fresh water circulating pump
is worn out.
B The cooling water temperature is
too low.
C
You have a cracked liner, or cover.
D The expansion tank is empty.
164.Why is it important to check the
timing on the cylinder oil lubricators?
A To avoid high temperature in the
combustion chamber.
B To get the right amount of oil
into the cylinder.
C
To get the oil into the cylinder when the piston is in the right position
D To avoid excess lubrication.
165.Why do we use cylinder oil?
A
To neutralize the sulphur and get a lubricating oil film between piston rings
and liner.
B To get a lubricating oil film
between piston rings and liner.
C To neutralize the sulphur in the
fuel.
D To avoid blowby.
166.How large a deviation in opening
pressure can be accepted in a diesel engine injection valve?
A 15 kg/cm2
B 40 kg
C
50 kg
D 70 kg
167.What will the effect be, if you
have a fuel injector valve that is dripping after the injection is finished ?
A Less carbonizing.
B
Damage to piston and liner.
C Greater output of the engine.
D Better combustion.
168.How is the quantity of fuel oil,
in HP fuel oil pump adjusted when the engine is running ?
A By adjustment of the pressure
valve in the pump.
B By adjusting the length of the
pump stroke.
C
Turning the plunger piston according to
engine load
D Adjusting oil flow to the HP fuel
oil pump.
169.When a changeover from HFO to
diesel oil is going to take place, we want this to be carried out as follows
A as fast as possible to save HFO.
B as fast as possible to save steam.
C as quick as possible, to obtain a
fast temperature reduction to cool the HP fuelpumps.
D
slow to get slow cooling.
170.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 ?
A
Engage the turning gear on the engine.
B Close absolutely all valves on the
starting air bottle.
C Close the instrument air supply.
D Keep a man posted in the control
room to watch that nobody tries to start the engine
171.If you get a heavy scavenging
air fire, which one of the following part is likely to take the most serious
damage ?
A
Stuffing box.
B Exhaust valve.
C Piston.
D Crosshead bearing.
172.Why are we blowing the engine
before start (slow turning on air) ?
A
To be sure that we do not have water collected in the cylinders.
B To be sure that no parts are
loose, or that the engine is blocked from rotation.
C To get fresh air into cylinders
ensuring a safe start of the engine.
D To be sure that all indicator
cocks are closed, and no passage into the combustion chamber.
173.The cylinder oil for FO with
high sulphur content is supposed to be:
A acidic.
B Alkaline
C neutral.
D does not matter.
174.A 2 stroke engine is usually
equipped with an auxiliary blower fan, which is supposed to be used:-
A continuously, together with the
turbochargers to ensure enough air to the engine during full speed running.
B during continuously reduced speed
under a longer sea voyage.
C
during manoeuvre and manoeuvre speed condition (arrival and departure)
D during a scavenging fire, to help
put out the fire.
175.What do you consider as the most
important task after a piston job ?
A
A search inside the crankcase for tools and rags.
B Starting the auxillary blower to
ventilate the scavenging belt, and the cylinder liners, to ensure that the
engine has sufficient fresh air for starting.
C Patch up destroyed paint work on
the crankcase doors.
D Starting the engine to see that it
rotates
176.Why is it so important to keep
the lub oil viscosity within safe limits?
A
To keep the oil protective film between moving metal surfaces .
B The luboil viscosity has no
influence on the oil's lubrication ability.
C To keep the additives in good
condition.
D It is not important
177.Total Base Number ( TBN ) is
important as a measure of neutralizing ability against strong Acids. What will You do if this TBN base
number is reduced to a low level?-
A
Renew lub oil in the system.
B Send one lub oil sample to new analysis.
C Nothing.
D Purify the oil system.
178.What can happen with a lub. oil
cooled piston if you stop the lub. oil pump immediately after You stop the
engine?
A Nothing happens.
B The oil flashpoint will be
changed.
C
Overheating of the piston, and oil coke deposits in the cooling chambers
D You save the oil sealings in the
piston.
179.You have checked the oil
viscosity in an auxiliary engine with the viscosity test kit. The result shows
that the viscosity is high. What will you do?
A Decrease the cooling water
temperature for the oil.
B
Clean the system and change the oil
C Increase the cooling water
temperature for the oil.
D Increase the lub oil pressure.
180.You have checked the oil
viscosity in an auxiliary engine with the viscosity test kit. The result shows
that the viscosity is low. What will you do?
A
Clean the system and change the oil.
B Increase the oil temperature.
C Start to purify the oil.
D Decrease the oil temperature.
181.What could be the reason if the
lub oil viscosity increase?
A
Heavy fuel oil leakage to the lub oil system.
B The lub oil viscosity will not
increase.
C.Water-leakage to the lub oil
system
D High lub oil temperature.
182.What could be the reason if the
lub oil viscosity decrease?
A Heavy fuel oil leakage to the lub
oil system.
B
Diesel oil leakage to the lub oil system
C Low lub oil temperature.
D Wrong lub oil pressure
183.A water content greater than 2 %
is detected in a lub oil system. What is the best action to do?
A Continuous purifying the system
with the lub oil pumps running.
B Boil out the water by increasing
the temperature.
C
Segregate the oil in a seperate tank for continuous purifying.
D It is no danger before the water
level reach 6-8%.
184.What long term effect will
excessively high temperature have on lubricating oil quality?
A Cause oxidation which reduce
viscosity.
B Evaporates the oil giving high
consumption.
C The oil flashpoint will be
changed.
D
Cause oxidation which increase viscosity.
185.Which would be the most suitable
place to obtain an oil sample for analysis?
A From the lub. oil pump suction
line.
B
From the system pipeline
C From the oil cooler drain.
D From the filter drain.
186.If water contamination occurs in
the crankcase oil of an auxiliary engine the oil viscosity will:-
A
Increase.
B Nothing happens.
C Stay at the same.
D Decrease.
187.What type of lubricating oils
are generally used in auxiliary engines?
A
Detergent.
B Alkaline.
C Synthetic.
D It is not important.
188.In a Burmeister & Wain main
engine, at what point is cylinder oil injected?
A Just before "Top Dead
Centre".
B As the piston passes "The
Lubrication Points" in a downward direction
C
As the piston passes "The Lubrication Points" in an upward direction
D Just before "Bottom Dead
Centre"
189.What differential pressure would
you expect to find across an engine lub.oil filter?
A 1.2 Bar
B 3.0 Bar
C Zero
D
0.2 Bar
190.You notice the sump level in an
engine has increased and no new oil has been added. What action would you take?
A Drain some oil from the engine.
B
Stop the engine and look for a fuel or water leak.
C Reduced the load, and look after
fuel or water leak.
D Leave it the same.
191.Oil analysis results show a high
level of tin. What could be the cause of this?
A
Bearing damage.
B Water contamination.
C Fuel contamination
D Too high lub.oil temperature.
192.We have two kinds of
turbocharging systems: constant pressure and impulse. The difference between
these two can be found in:
A The exhaust gas receiver.
B Scavenging air coolers.
C The blades on the exhaust gas
turbine.
D The scavenging valves of the
engine.
193.We have a problem with surging
in the turbocharger. Which of the following could be the cause?
A Worn out bearings on the
turbocharger.
B The lubrication oil pump is
malfunctioning.
C Dirty rotor blades.
D
Dirty scavenging air cooler on the air side.
194.The revolutions on the
turbocharger have increased during the night with unmanned engine. Could this
be caused by:
A The viscosity of the fuel is to
high .
B We have favourable winds and
current.
C
The current and wind are holding the vessel back
D Poor combustion due to malfunction
of fuel valves
195. The turbocharger (constant
pressure) is making "whoofing" noises. What might be the cause?
A
Heavy seas from behind.
B A faulty turbocharger bearing.
C One or more leaking
exhaust-valve(s).
D Strong current against
196.After how many hours would you
consider changing the turbocharger bearings, even though all appears to be
normal?
12.000
hours.
B 4.000 hours.
C 25.000 hours.
D 30.000 hours.
197.The timing of the engine is
delayed. The exhaust temperatures are high. How would you expect this to affect
the turbocharger?
A Decreased turbocharger
revolutions.
B Surging of the turbocharger.
C
Increased turbocharger revolutions
D Higher air and gas temperature
after turbocharger.
198.We have a problem with vibration
in the turbocharger. What might be the cause?
A Dirty air inlet filter.
B
The turbine rotor is not balanced
C The lubricating oil needs to be
changed.
D Worn out turbocharger bearings.
199.With full load on the main
engine, the RPM for the turbocharger is too low. What may cause this?
A
The diffuser ring is damaged.
B Exhaust temperatures on the main
engine are too high.
C Dirty nozzle ring.
D The lubricating oil pump is
malfunctioning.
200. with full load on the main
engine, the turbocharger tachometer reads: Too low RPM. Why?
A Damaged connection between pick-up
and tachometer unit
B Pick up is not connected to
turbocharger.
C Turbocharger need to be
cleaned/overhauled.
D
Pick up for tachometer is wrongly adjusted.
201.The lubricating oil on the
exhaust side of the turbine blower gets very dirty after only a few hours in
service. What can the reason be?
A
Exhaust gas leaking into the oil chamber
B Wrong type of oil used.
C Lubricating oil is mixed with salt
water
D Worn out bearing turbine side
202. After water-washing the
turbocharger exhaust side, the blower starts to vibrate. What has happened?-
A Water drain for washing system is
clogged.
B Foundation bolts for the blower
unit are loose
C
The rotor blades are damaged or the blades are not properly cleaned
D Inlet filter partly clogged.
203.The blower's air delivery is not
sufficient. What is the cause?
A Air temperature in engine room too
high.
B Dirty scavenge duct.
C
Clogged air inlet filter.
D Cooling water temperature too high
204.Why is it important to slow down
the main engine RPM while water-washing the turbocharger?
A To protect the bearings .
B To protect the exhaust gas
economizer.
C To protect the blower side .
D
Not to damage the rotor blades.
205.Some engine manufacturers
recommend that washing of the compressor side is not carried out. Is this due
to:
A
Greasy sludge from the compressor sticking between the fins in the air coolers,
necessitating extra cleaning of these.
B Large volumes of water being
carried over into the cylinders of the engine.
C The nozzle ring becoming corroded
D The thermal shock exhibited by the
vanes.
206.What is the meaning of the term
"valve clearance"?
A
The clearance between the rocker arm and valve pushrod.
B The clearance between valve
spindle disc and seat.
C The clearance between the rocker
arm and camshaft pushrod.
D The clearance between the rocker
arm and valve pushrod in either warm or cold state.
207.The meaning of lapping a valve
and valve seat is:.
A Adjust the overlapping of the
inlet and exhaust valves.
B
Grind the valve against the valve seat to obtain a uniform sealing surface.
C Machining the valve in a lathe
machine.
D Repair by welding.
208.Some 4-stroke engines are fitted
with a rotorcap on the cylinder head valves. For what reason?
A Rotate the inlet valve during
operation.
B Distribute the exhaust gas or the
air inlet better to improve combustion.
C
Improve the scaling surface function, increase the service time of the exhaust
valve in the engine
D To prevent the valve spindle from
sticking..
209.When overhauling the cylinder
covers on a modern 4-stroke engine, is it important not to interchange inlet
and exhaust valves?
A Not so important.
B
Important due to different material and working conditions.
C Can be changed if same size.
D Important due to different type
size valve guide.
210.What is the purpose of the
cylinder head safety valve?
A
To relieve excessive high pressure in the cylinder to protect the engine from
being damaged.
B To adjust the cylinder pressure to
a safe working pressure.
C A valve for safety stop
(emergency) of the engine.
D For indication of engine being
overloaded.
211.Most of the engine makers
recommend to change the cylinder head gaskets each time a piston overhaul is
carried out. Why?
A
To obtain a proper sealing and correct distance between piston and cover in TDC
position.
B To increase the consumption of
parts so they can make more money.
C To avoid heat transfer to the
cylinder head.
D To be granted a proper sealing with
a new gasket.
212.Some 4-stroke engines are
equipped with cooled fuel valves. Why is it so important to keep the coolant's
temperature correct?
A For cooling only.
B For preheating only
C To avoid overheating the fuel
nozzle
D
For cooling and to maintain correct viscosity on the fuel when injected
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