CÂU HỎI PHỎNG VẤN THUYỀN VIÊN MÁY(QUESTIONS ANSWERS FROM MOL TRAINING CENTER)

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DIESEL ENGINE
1.

What happens when too much cylinder oil is injected in the
working cylinder?
Ans.
. Color of exhaust gas is bluish.
. Formation of carbon deposits on piston ring and ring grooves
. Increase in cylinder oil consumption

2.

Is the unit and normal value fuel ratio of an average diesel
engine?
Ans.
G/psh
20 - 130g/psh

3.

What is the formula for 1 HP of a two-cycle engine?
Ans.
IHP =

PLAN c
33000 ft-LB/min

4.

Name the indicator diagram.
Ans.

5.

-

Power diagram

-

Compression diagram

-

Out of phase diagram/draw card

-

Light spring diagram

What are the 3 parts in indicator diagram?
Ans.
Maximum compression pressure, maximum combustion pressure,
means effective pressure.

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6.

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What are the causes of damage of diesel engine exhaust Valve?
Ans.

7.

-

Fuel contaminants ( Sulphur, Sodium, Vanadium)

-

Exhaust valve leakage

-

Erosion and Corrosion

What are the causes of LO. high temperature in a diesel engine?
Ans.

8.

-

Insufficient flow of cooling medium

-

Clogged up cooling tubes

-

Incorrect opening of temperature control valve

What trouble could result if the main engine is using a low
grade of fuel?
Ans.
Inefficient combustion takes place-causing cylinder liner wear,
exhaust valve wear, trouble with fuel injectors and prone to carbon
build-up In the exhaust system.

9.

What are the causes of liner high temperature?
Ans.
Engine is overloaded; insufficient lubrication

10.

What happen when too much cylinder oil is injected in the

working cylinder?
Ans.
Color of exhaust gas will be bluish. Excessive carbon deposit

11.

How many lubricating holes are there in cylinder?
Ans.
Approximately 8.

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12.

Trainees Reviewer

What are the defects in exhaust valves?
Ans.

13.

-

Exhaust valve seat pitting/wear

-

Excessive carbon residue at spindle

-

Erosion and corrosion

How do you control cylinder liner wear?
Ans.

14.

-

Sufficient lubrication

-

Correct liner and piston ring clearances

-

Well maintained and timed fuel injectors

-

Proper fuel and LO treatment process

-

Usage of LO. with properties ( Total Base Number)

-

Correct scavenging air temperatures

-

Correct Cooling water and lubricating oil temperatures

How much is the specific fuel consumption of an average diesel
engine?
Ans.
120-130 G/PS-Hr

15.

Purpose of lubricator in a large diesel engine.
Ans.
To pump oil into the cylinder passing a number of lubricating orifice
during the upward stroke.

16.

Explain how the cylinder lubrication on main engine is done?
Ans.
lubricators are usually supplied with oil from a day tank, The through
a gravity, which equipped with a built in float, strainers and stop
valves. The oil Is pumped into the cylinder by lubricator pump via

non-return valve, passing a number of lubricating orifice during the

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upward stroke. The oil feed rate or dosage should be in accordance
with the engine builder's recommendation and should be increased
during starting, maneuvering and large changes in engine load.

17.

Explain the function of cooling water expansion tank.
Ans.
To maintain sufficient cooling water in the F.W.C. system by gravity.
To reduce air or steam pockets Allow changes of the cooling water
volume due to heating and cooling Maintains a constant head in the
system

18.

Explain the causes of the exhaust valve leakage.
Ans.
Corrosion/Wear of exhaust valve seat

19.

What is the purpose of l.O. circulation before and after starting
of engine?
Ans.
The purpose of l.O. circulation before starting of engine is to prevent
seizure of metal parts especially the cylinder and the piston. While
after stafting of engine and continuos running, is to prevent metal to
metal contact and reduce friction and wear at a moving parts. It also
serves a cooling medium between metal parts.

20.

Names of valve connected in cylinder head of the engine.
Ans.
1. Relief valve
2. Fuel injector valve
3. Indicator valve
4. Starting air valve
5. Exhaust valve

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21.

Trainees Reviewer

Name the safety devices of diesel engine?
Ans.
1. Relief valves fitted to the chamber to warn of excessive
in combustion pressure.

increase

2. Relief valves fitted to the crankcase to act, as safety valves should
oil vapor ignite due, for instance, to a hot bearing.
3. Relief valves fitted to scavenge spaces to protect the chamber
against high pressure,
4. Relief valves for fuel pumps and fuel system to prevent line from
bursting.
5. Relief valves for starting air system to prevent excessive pressure
and flame traps or bursting disc at each starting air valve.
6. Interlocks fitted to turning gears to ensure that the engine- cannot
be started whilst the turning gear is engaged.
7. Automatic shut down of the engine due to low pressure in the
lubricating or cooling system.
8. Automatic shut down of the engine due to high/low temperature in
various systems.
9. Shut down the engine from the bridge should the communication
with the engine room fail when the vessel is in hazardous
posItion.

22.

10.

Over-speed trip which cuts the fuel supply to the engine should
the main governor fail and the engine RPM increases.

11.

Oil mist detector fitted in the crankcase to give warning of hot
running parts.

12.

A temperature probe system fitted to bearing to give alarm of
excessive temperature.

13.

A temperature probe system fitted in the scavenge air space to
indicate scavenge fires.

What is injection lag?

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Ans.
After compression fuel is injected and comes in contact with hot
compressed air, total combustion of fuel does not occur instantly
(time delay of ignition) due to the quality of IFO.

23.

Explain how to measure crank web deflection?
Ans.
Crankshaft alignment can be checked by taking deflections. A Strain
gage arrange horizontally between the crank webs opposite the crank
pin and ideally at the circumference of the main journal will give
horizontal deflection, when the crank is rotated through one
revolution, that is directly proportional to the vertical deflection.
Vertical and horizontal misalignment can be checked against the
permissible values supplied by the engine builder.

24.

In a 4cycle engine the intake valve begins to open at ?
Ans.
Intake stroke

25.

What causes cylinder liner - wear down?
Ans.
a. insufficient lubrication

b. excessive load
c. poor combustion
d. incorrect L.O. properties used
e. poor quality of fuel oil used

26.

What causes diesel engine to automatically stop?
Ans.
a. Over speed
b. Low L.O. pressure of System. Crosshead and cylinder L.O.
c. Low pressure and high temperature of cooling water

27.

What causes crankcase explosion?

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Ans.
a. blowpast of hot gases inside the underpiston?
b. Formation of flammable vapor inside the crankcase

c. Presence of hot spot inside the crankcase (Main Bearing)
d. Excessive crankcase pressure

28.

What do you
combustion?

call

the

clearing

of

air

inside

cylinder

after

Ans.
Scavenging method ( Uniflow , Loop and Cross scavenging)

29.

What is the circulation of l.O. pump to diesel engine?

Ans.
Sump tank.. ~ Suction strainer ~L.O. pump ~ L.O. cooler ~ Auto
backwash filter L.O. ~ M/E
2

30.

What causes diesel engine trouble when using heavy oil?
Ans.
a. poor combustion
b. excessive formation of carbon deposits
c. excessive corrosion and wear of engine parts
d. high thermal load

31.

What causes turbocharger surging?
Ans.
a. fouling of turbocharger
b. rough sea condition
c. contamination of exhaust and scavenging ducting ports and filters
d. variation in gas supply to turbo charger due to unbalanced output.
e. Mechanical damage in turbo charger

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32.

Trainees Reviewer

What pressure is highest L.O. Gravity Head or S.W. of the stern
tube circulation
Ans.
Pressure of L. O. gravity tank

33.

What is fuel catalytic cracking
Ans.
Method of
catalyst.

34.

separating

fuel

into

different

grades

by

the

use

of

a

Contaminants of fuel oil
Ans.
1. Sodium - is contaminant which may be present due to seawater in
the fuel.
2. Vanadium and Sulfur - are dissolved in the fuel and not removed by
the purifier. The effect of the sulfur can be neutralized by alkali
additives in diesel engine cylinder lubricants.
3. Silicon and aluminum - catalytic fines are remove in the purifier or
clarifier I but slow throughout is essential for optimum results.

35.

Crankcase oil mist detector
Ans.
it uses photoelectric cells to measure small increases in 011 mist
density which is harmful and may lead to crankcase explosion.

36.

Inspection for intermediate shaft bearing.
Ans.

Shaft bearings are of two types, the aftermost tunnel bearing and all
others. The aftermost tunnel bearing has a top and a bottom bearing
shell because It must counter act the propeller mass and take a
vertical upward thrust at the forward end of the tailshaft. The
intermediate shaft bearing only support the shaft weight and thus
have only lower half bearing shell. lubrication is from a bath in the
lower half of the casing and should be inspected. Also the cooling

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process by water circulating through a tube cooler in the bottom of
the casing.

37.

What are the causes of main engine black smoke?
Ans.
1. Poor atomization of fuel
2. Damaged fuel injectors
3. Insufficient air (Restricted air Intake system)
4. Damaged piston rings and exhaust valve
5. low fuel oil pressure and temperature

6. Fouled Exhaust gas Economizer

38.

Causes of emergency trip of diesel engine
Ans.
1. low lube oil pressure
2. Shut down of the engine from the bridge should the communication
fail while the vessel is in hazardous position.
3. Over speeding, governor failure
4. Control air failure
5. Jacket cooling water high temperature

39.

What are the causes if one cylinder In a diesel engine has a
high temperature?
Ans.
1. Damaged exhaust valves.
2. Poor jacket cooling in a single cylinder due to scale formation.
3. Damaged fuel injector nozzles.
4. Damage exhaust valve
5.

Clogged scavenging port

6. Excessive cylinder and piston ring wear

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40.

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Explain how the lubricating oil circulates in a diesel engine.
Ans.
Lubricating for an engine is stored in the bottom of the crankcase,
known as the pump, or in a drain tank located beneath the engine.
The oil is drawn from the tank through a strainer, one of a pair of
pumps, into one of a pair of fine filters. It is then passed to a cooler
before entering the engine and being distributed to the various branch
pipes. The branch pipes for a particular cylinder may feed the main
bearing, for instance. Some of this oil my pass along a drilled passage
in the connecting rod to the gudgeon pin or crosshead bearing. An
alarm at the end of the distribution pipes ensures that adequate
pressure is maintained by the pump. Pumps and fine filters are
arranged in a duplicate with one standby. The fine filters will be
arranged so that one can clean while the other is operating. After
used in the engine the oil drains back to a sump tank or a drain tank
for reuse. A level gauge gives a local read-out of the drain tank
contents. A centrifuge is arranged for cleaning the lubricating oil in
the system and clean oil can be provided from a storage tank.
The oil cooler is circulated by seawater, which is at a lower pressure
than the oil. As a result any leak in the cooler will mean a loss of oil
and not contamination of the oil by seawater.

41.

What are the causes of damage to propellers?
Ans.
~ Cavitation - the forming and bursting of vapour filled cavities or
bubbles, can occur as result of pressure variation at the back of
a propeller blade.
~ Corrosion
~ Small Cracks - due to loads and wears.
~ Grounding - this causes bents and worn out propellers.

42.

What causes friction in the cylinder?
Ans.
1. Inadequate or incorrect lubrication.
2. Faulty combustion.

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3. Used of incorrect cylinder oil.

4. Overloading of the engine.

43.

What causes damage to impellers?
Ans.
1. Over speeding
2. Vibrations
3. Corrosion
4. Wears

44.

In a four-stroke diesel engine, in what stroke exhaust valve
will open?
Ans.
Exhaust Stroke

45.

How is propeller fitted in shaft?
Ans.
The propeller is fitted unto a taper on the tailshaft and a key maybe
inserted between the two; alternatively a keyless arrangement maybe
used. A large nut is fastened and locked in place on the end of the
taishaft; a cone is then bolted over the end of the tailshaft to provide
a smooth flow of water from the propeller.

46.

What valves are fitted in a four-stroke diesel engine?
Ans.
Exhaust valves and intake valves.

47.

What are the automatic tripping devices of diesel generator?
Ans.
1. Automatic shutdown of the engine due to high or low temperature
in various systems.

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2. Automatic shutdown of the engine
lubricating or cooling system.

due

to

low

pressure

in

the

3. Over speed trip

48.

What is the purpose of thrust bearing?
Ans.
Its

purpose is
prevent

to

transmit

thrust

of

the

propeller

to

the

hull

to

the main engine from being forced out alignment.

49.

What is fuel oil viscosity, specific gravity?
Ans.
Viscosity is the resistance to flow specified by Redwood Viscosity in
Seconds being replaced by Kinematic Viscosity in Centistokes.
The specific gravity or relative density is the weight of a given
volume of fuel compared to the weight of the same volume of water
expressed as a ratio and measured at a fixed temperature.

50.

What are the causes of low compression in the main engine?
Ans.
1. Worn out piston rings.
2. Damaged valves
3. Leaking cylinder head
4. Cam not in proper position
5. Restricted air passages
6. Back pressure of exhaust due to fouled Economizer
7. High scavenging air temperature

51.

What do you measure in the banana and mountain diagram?
Ans.
The relations of pressure and volume are measured in this indicator
diagram.

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The compression, power and expansion curves are shown.

52.

What is a brake horse power?
Ans.
The power developed by an engine as measured by the force applied
to a friction brake or by an absorption dynamometer applied to the
shaft or flywheel.

53.

What are the requirements of a good fuel?
Ans.
The fuel oil must have a good viscosity at specific gravity. The
ignition quality should have of higher value for better ignition. The
flash point must be also obtained for maximum safe storage. The pour
point and cloud point must be good. Low sulphur content to minimize
engine wear. No water content and free from dirt and solid particles
such as sand and small metal chips.

54.

What is the purpose of a settling tank?
Ans.
The purpose of a settling tank is for fuel oil to settle down before it
is drawn by purifiers and delivers it to the service tank.

55.

What is the purpose of the turning gear?
Ans.
The purpose of the turning gear is to revolve the crankshaft of the
engine while in stop position. This is done for the purpose of
inspection and maintenance work.

56.

What is the purpose of starting air?
Ans.
Starting
auxiliary

air

is

used

to

initially

turn

the

main

engine

and

other

engine during starting by the use of pressurize air.

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57.

Trainees Reviewer

What is the purpose of engine preheating?
Ans.
The engine must be preheated to warm up the engine and reach the
temperature at which it will be easier to start. This is done to avoid
sudden rise of temperature during combustion which may result to
thermal cracking and stress to the metals.

58.

What is the purpose of air blow?
Ans.
Air blow is done to clear and check the combustion chamber from any
leaks of jacket water and accumulation of moisture present before
starting the engine to prevent for hydraulic knock.

59.

What is the purpose of stern tube? ,
Ans.
Stern tubes are constructed to
prevent seawater from entering.

60.

secure

an

hold

the

tailshaft

and

Where can you find thermometers in diesel engines?
Ans.
Thermometers can be found on exhaust ports, jacket cooling lines,
fuel oil lines and lubricating oil lines.

61.

What would happen if there is air in fuel oil?
Ans.
a. Poor combustion fuel.
b. Injection valve will not function properly.
c. Air pocket.
d. Damage to engine parts.
e. Pulsation of fuel oil lines
e. Stop or operate with reduced power
f.

Failed to start

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62.

Trainees Reviewer

What type of pump is lubricator pump?
Ans.
Positive displacement

63.

What is the purpose of piston rings?
Ans.
The piston is so attached to the piston to prevent combustion gases
to leak between the cylinder and piston during combustion. To provide
a gas tight sealing.

64.

The advantage of a controllable pitch propeller?
Ans.

1.

It allows the main engine a single direction rotation.

2. Fast action on reversing.

65.

Explain the fresh water cooling systems.
Ans.
The high temperature of the working cycle would quickly heat up the
metal forming the cylinders, cylinder covers and pistons if steps were
not taken to prevent this happening. It is necessary to keep the
piston rings at temperatures sufficiently low for the lubricating oil
surrounding them to survive and mechanisms such as fuel valves,
exhaust valves and starting air valves must be kept at temperatures
at which they will work satisfactorily and remain lubricated. Also the
metal of parts forming the combustion spaces must be kept at a
temperature low enough to avoid losing mechanical strength. The
necessary control of temperature is carried out by the surrounding the
cylinders with a jacket and by providing cylinder covers and pistons
with passages through which the cooling fluids maybe passed. The
coolant is fresh water in the case of the cylinder covers. Pistons are
cooled by fresh water in some designs and by lubricating oil in others.
The heat picked up by these cooling fluids is transferred to seawater
in heat exchangers and thus rejected to the sea, the cooling fluids

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becoming cooled and ready to circulate the jacket spaces again. Sea
water cannot be used readily in the cooling spaces of modern engines
as it Is both corrosive and liable to leave deposits. OPEN AND CLOSED
FRESH WATER SYSTEM
A fresh water system may be open or closed. In the open system
water is drawn from a tank at atmospheric pressure, it is pumped
through a heat exchanger (often termed the jacket water cooler) and
then upwards through the engine emerging from the top of the
engine. There are usually a number of outlets; one for each cylinder
or cylinder cover and one for each piston if the pistons are water
cooled. The cooling water spaces of turbochargers are usually
included in the circuit also and will each have a water outlet. The
water from these outlets is led to a hopper or tun dish which serves
as a visual flow indicator. At this point the water reaches atmospheric
pressure again. Each tun dish is usually encased and viewed through a
glass window in tne interests of safety and cleanliness. From here the
water descends by gravity to the drain tank, the individual outlets
usually being gathered together at a convenient point en-route.
In the closed system there is no collecting tank. The engine jackets,
the heat exchanger and the pump form a continuous circuit which is
not open to the atmosphere. However, provision has to be made for
the expansion of the water due to the increase in temperature and
due to small amounts of air which may enter the system and become

entrained. These eventualities are met by a small header tank. The
header tank is open to the atmosphere and place at a higher level
than any other point in the system changes in volume can be
accommodated by changing the level of the free surface of the water
in the tank. The header tank is generally connected into the system at
the pump suction, as this minimizes the chance of air being drawn
into the system at the pump. With closed systems it is customary for
the pump to circulate the water first to the engine jackets and then to
the heat exchanger. The minimum height of the header tank may be
based on maintaining pressure of fresh water in the heat exchanger
above that of the sea water to ensure that in the event of a small
internal leak developing sea water cannot enter the fresh water
system. Alternatively, it may be based on the for a minimum pressure
to be maintained within the jacKets to avoid cavitation effects. The
maximum height of the header tank is determined by the pressure
which joints and seals in the fresh water system can withstand.
Open systems are self-venting but closed systems usually need vents
if steam pockets or air locks are not to cause trouble. Vent pipes of

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small bore tube are lead from any local high point in the system to

the top of the header tank so that the steam or air does not collect in
these local high places. The temperature of the water entering the
engine jackets is regulated by means of a by-pass across the heat
exchanger. The proportion of water passing through the cooler, or bypassing it are controlled by a three way valve arranged either as a
diverting valve if upstream of the heat exchanger, or as a mixing
valve if downstream. The temperature is usually adjusted to maintain
a constant outlet water temperature from the engine regardless of the
load or speed or the temperature of the sea water. Almost always this
is done automatically by using temperature sensitive controls for the
valves.
Fuel Injector valves require precise control of the temperature at the
tip of the nozzles; too high a temperature leading to the formation of
carbon trumpets, too Iowa temperature causing corrosion. They are
generally provided with a cooling water system which is either a
branch of the jacket water system or an entirely separate circuit. In
either case there will be a separate heat exchanger or a cooling tank
and some means of adjusting, or at least setting, the rate of flow to
the injector which is independent of that flow to the engine cylinder
jackets.

66.

What are the typical indicator diagrams?
Ans.
The power and draw cards should be closely studied. Diagrams given
are for compression ignition engines of the 2 and 4 stroke types.
Pressures and temperatures are shown on the sketches where
appropriate. The draw card is an extended scale picture of the of the
combustion process. In early marine practice the indicator card was
drawn by the hand-hence the name. In modern practIce an 'out of

phase' (90 degrees) cam would be provided adjacent to the general
indicator com. In correct combustion details show readily on the draw
card. There is no real marked difference between the diagrams for 2
stroke or 4 stroke. In general the compression point on the draw card
is more difficult to detect on the 2 stroke as the line is fairly
continuous. There is no induction - exhaust loop for the 4 stroke as
the spring used in the indicator is too strong to discriminate on a
pressure difference of say 1/3 bar only. With the fuel shut off
expansion and compression should appear as one line. Errors would be
due to a time lag in the drive or a faulty Indicator com setting or

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relative phase difference between camshaft and crankshaft. Normally
such diagrams would only be necessary on initial engine trials unless
loss of compression or cam shift on the engine was suspected.

67.

What is the trunk type and crosshead type piston
Ans.
Trunk type - work done in the piston is directly transmitted to the

crankshaft
Crosshead type - the piston is connected to a vertical member, the
lower end of which is attached to a sliding member called a
crosshead. It moves up and down in guides and is connected on the
lower end of the connecting rod.

68.

What is higher IHP or BHP
Ans.
IHP is always higher than BHP

69.

What is the sensitive part of the liner
Ans.
The upper most portion of the liner is the most sensitive part. It is
where high pressure and temperature occurs.

70.

Discuss how to prepare the M/E in standby condition
Ans.
I.

Before a large diesel is started it must be warmed through by
circulating hot water through the jackets, etc. This will enable
the various engine parts to expand in relation to one another.

2.

The various supply tanks, filters, valves and drains are all to be
checked.

3.

The lubricating oil pumps and circulating water pumps
started and all the visible returns should be observed.

4.

All control equipment and alarms should be examined for correct
operation.

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5.

The indicator cocks are opened, the turning gear engaged and
the engine turned through several complete revolutions. In this

way any. water which may have collected in the cylinders will
be forced out.

6.

The fuel oil system is checked and circulated with hot oil.

7.

Auxiliary
started.

8.

The turning gear is removed and if possible the engine should
be turned over on air before closing the indicator cocks.

9.

The engine is now available for standby.

scavenge

blowers,

if

manually

operated,

should

be

The length of time involved in these preparations will depend
upon the size of the engine.

71.

Explain now to clean LO
Ans.
L.O. requires treatment before passing to the engine, This will involve
storage and heating to allow separation of water present, coarse and
fine filtering to remove solid particles and also centrifuging.

72.

Explain the principle of Sulzer Fuel oil injection pump
Ans.
Sulzer engines are provided with a fuel pump of timed double valve
type, driven by the camshaft. Each pump consists of a plunger and
guide bush and a driving piston. The roller is kept in contact with the
cam by a powerful spring. A fuel pump can be taken out of service by
a mechanical cut-out lever, which lifts the driving piston and roller
clear of the cam. This lever can also be used for priming the injection
system.
The fuel pump delivery is controlled by suction and spill valves. As
the suction valve remains off its seat no fuel is delivered. When the
fuel pump plunger is raised, the suction valve is lowered on to its

seat. As soon as the suction valve closes, fuel is delivered. Normally
the start of delivery is constant and the effective stroke is controlled
by adjusting the spill valve. Retarding the spill valve increases the
effective delivery stroke, while advancing reduces the effective
stroke. These adjustments must be made when the engine is stopped
and never when running. Ignition pressures are equalised only by

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turning the cams and not by altering the length of the pushrod. The
fuel charge for individual cylinders can be temporarily reduced, for
instance when running in a spare part such as a liner or piston, etc.
by fitting a spacer between the pushrod and the regulating rod.
This raises the suction valve by 2.4 mm. When adjusting the fuel
pump control valves no spacers should be fitted.

73.

What is the volume develop by the piston from BDC to TDC
Ans.
Swept volume is volume swept by the piston from BDC to TDC

74.

Enumerate some trouble of fuel injection valve
Ans.
-

leaking F.O. injection valve

-

stuck-up needle

-

clogged up atomizer

75.

Causes of M/E high exhaust valve temperature
Ans.

76.

-

leaking hot combustion gas

-

Incomplete combustion leading to high exhaust temperature I

-

Insufficient cooling of valve seat

.

What is the purpose of scrapper ring

Ans.
Scrapper ring distributes the cylinder oil injected in the surface of the
cylinder.

77.

What are the items to inspect after cylinder liner is pulled
out
Ans.
-

corrosion of the flange

-

circumferential crack of the fillet shoulder

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-

wear down and corrosion of sliding surface

-

longitudinal crack of the inside of liner

-

crack on corner of the oil hole and oil groove

-

crack and corrosion of cooling surface

-

condition of liner surface

-

condition of lubrication

-

cylinder liner wear

78.

What resistance the ship encounter when the vessel is at sea
Ans.
-

Wave resistance

-

Hull resistance due to marine growth

-

Weather (rough wind and sea condition)

79.

What will you do in case of scavenging fire
Ans.
-

When alarm has been given, the speed of the engine should be
reduced to slow and fuel cut off to the particular cylinder. The
cylinder oil supply should be maintained or even increased.

-

The bridge must be informed and permission to stop requested.
Cut out fuel priming pump. Personnel must keep clear from
doors and relief valves. Where fire-fighting equipment is fitted
to the air receiver this should be brought into operation as soon
as possible. If no equipment is available the fire will generally
subside in about five to fifteen minutes.

-

Do not open scavenge space doors or crankcase doors before
the site of the fire has cooled down. When opening up care
must be taken to keep cleat of any flame.

-

After

opening

up

all

scavenge

spaces

must

be

thoroughly

cleaned and all debris removed.
-

The

piston

rods

and

cylinder

liner

should

be

examined

for

surface blemishes, straightness etc., and the diaphragm glands
examined to ensure that they are operational and not damaged.

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MOL Training Center Cavite
Oral Test Questions

Trainees Reviewer

If possible the piston head in question should be renewed at the

-

earliest possible moment and the damaged unit overhauled.
On engines fitted with tie bolts it may be necessary to re-

-

tighten the bolts adjacent to the fire.
The flat surfaces of the scavenge space should be examined for

-

distortion as alignment of the camshaft
cylinder liners etc may be affected.
When

-

starting

the

engine

again

care

bearings

must

be

and

taken

the
after

switching on the fuel to the cylinder in question that the
cylinder lubricating oil quantities are reduced to normal. Due to
the large volume of air being blown through the receiver the
formation of an explosive gas/air mixture Is extremely
improbable.
Conscientious maintenance of the engine and regular inspection

-

and cleaning of the scavenge air spaces will help to eliminate
scavenge fires.

80.

.
Draw the flow of F.O. diagram from service tank to main
engine?
Ans.

81.

.
What are the types of cleaning main engine Turbo charger
blower side?
Ans.
~ Water washing

82.

What are the causes of main engine Turbo Charger blower
side dirty?
Ans.
~ Poor combustion due to low grade fuel
~ Damaged air filter

83.

.

Sketch the jacket coling system.

Ans.

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MOL Training Center Cavite
Oral Test Questions

84.

What will
continuously?

Trainees Reviewer

cause

if

you

run

your

engine in

critical

RPM

Ans.
It affects the torsional load resulting to torsional vibration.
The first mode of torsional vibration in the shafting system will have
to noode and the highest torsional alternating stresses occur immediately
aft of propulsion of the engine, for vessels with fairly long runs shafting,
the first mode frequency usually occurs at a low shaft rpm.

85. What are the properties of fuel oil?
Ans.
~ Sulfur - is present in most crude oils to varying degrees and is chemically
bound in the fuel, the higher viscosity residual fractions tend to have higher
sulfur contents.
~ Carbon residue - is the percentage of coked material remaining the
sample of fuel oil has been exposed to high temperatures. Carbon reach
fuels are more difficult to burn and therefore, have poor combustion
characteristics which lead to the formation of soot and carbon deposits.
Since carbon deposits can be major source of abrasive wear, the fuel carbon
residue value may be an important parameter in the operation of a diesel
engine.
~ Asphaltenes - are those components of asphalt that are insoluble in
petroleum
~ Naphtha but are soluble in carbon disulfide. They can be hard and brittle,

are made up largely of high molecular weight, polynuclear hydrocarbon
derivatives containing carbon, hydrogen, nitrogen, oxygen, and usually one
or more of the three heavy metals- nickel, iron, and vanadium as well as
sulfur.
~ Compatibility - is very important fuel quality, as a residual oils become
more intensely refined, the resulting fuel is blended with cutter stocks of
light distillate to produce usable handling characteristics. When light
fractions with predominance of aliphatic hydrocarbon are mixed with a
heavy fuel, the collidal dispersion of high molecular weight substances is
disturbed. Due to this loss of equilibrium, the heavier constituents tent to

Japanese Licensure Examination

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MOL Training Center Cavite
Oral Test Questions
precipitate, This is usually seen as sludge
strainers and fouled filters and purifiers.

Trainees Reviewer
formation,

causing

clogged

~ Vanadium - is a metallic element that is chemically bound in oil in the
form of a soluble organometallic compound. The vanadium levels in residual

fuels vary widely, depending the origin of crude oil, when present in critical
amounts which vary with temperature involved, it forms adherent slag on
high temperature surface, which include the super heater tubes in
steam plant boilers and the exhaust valve and seats in valved diesel
engines, as well as piston crowns, causing localized hotspot and eventual
burning of high temperature surfaces.
~ Nickel - is another metallic element that is found in heavy crude oils, but
in smaller amounts than vanadium. When compared to vanadium the
combustion problems associated with nickel are minor.
~ Sodium - is an alkaline, metallic element that is found only in combined
form, one of which is common salt, sodium salt (NaCI). Most sodium
compounds are water
soluble. Sodium found in fuel can come several
sources but most of it is a direct result of storing and handling procedures
from the time fuel leaves the refinery until it is delivered to bunkers. Salt
water contamination in barges used to transport fuel is not uncommon, to
some extent even salt air condensation in fuel tanks contributes to a fuel
overall sodium content. Regardless of the manner of contamination, sodium
in fuel is usually water soluble and can therefore, be removed with the
water by a centrifugal separator.
~ Ash content - The ash content of a fuel oil is a measure of the metallic
content and the noncombustible inorganic solid contamination in the fuel.
The ash content specially of heavy fuels, provides a method of assessing the
quality of fuel oil and takes into account characteristics such as solid
foreign materials and the dispersed and dissolved compounds of metals such
as vanadium, sodium, iron and nickel.
~ Oxidation products - Residual fuels may have a poor storage stability,
especially when maintained in a heated condition for extended periods of
time. As fuel ages it becomes oxidize by air and begins to polymerize,
forming sludge, gums, and resins that can foul filters and heaters and can

sometimes cause fouling of the injectors, combustion chambers, and exhaust
system. Oxidation products can remain soluble in the fuel or become
insoluble and precipitate out, forming an organic sediment.
~ Sediment - in fuels consists of insoluble matter, which may include sand,
rust, and catalytic fines such as tar like polymerized hydrocarbons and
precipitated asphaltenes, both of which break down under the heat of
combustion and form lacquer and tarry deposits that impair the movement

Japanese Licensure Examination

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MOL Training Center Cavite
Oral Test Questions

Trainees Reviewer

of parts and sometimes interfere with fuel nozzle spray patterns. Sediments
containing abrasive materials or large amount organic materials can damage
high pressure fuel pumps and fuel nozzles. Sediments are removed by
centrifuges and filters.

86. What will you check if one cylinder of your engine is not like the
others?
Ans.
~ Exhaust temperature
~ Jacket cooling water outlet temperature
~ Fuel pump rack scale
~ Fuel injection timing

~ Fuel injector atomization and opening pressure
~ Check Pmax and Pcom

87. What do you do when in your duty, ME alarm oil mist detect high
density?
Ans.
~ Reduce speed to slow down level
~ Ask the bridge for permission to stop
~ When engine stop order is received, stop the engine and close the
fuel oil supply
~ Switch off the auxiliary blowers
~ Open the skylights and/or store hatch
~ Leave the engine room
~ Lock the casing doors and keep away from them
~ Prepare the fire fighting equipment

MEASURES TO BE TAKEN WHEN OIL MIST HAS OCCURRED :
~ Don't stand near crankcase doors or relief valves nor in the corridors
in the engine room casings.
~ Don't open crankcase until 30 min. after stopping the engine.

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