MEO CLASS IV exam is conducted by DG SHIPPING govt. of India. Below is the list of questions most frequently asked in meo class 4 motor exam.

Precaution is taken to give all correct answers at the same time author is not responsible for any mistakes whatsoever.

These class 4 motor questions and answers can be considered as a reference guide for your class 4 written exam.


Which standards govern the specifications for supply of Residual Marine Fuels and Distillate Marine Fuels onboard merchant ships?

A. ISO 3012:1999
B. ISO 3648:1996
C. ISO 8216-1:2010
D. ISO 8217:2010 *

Crank web deflection readings will give a positive indication of

A. worn main bearing journals *
B. torsional stress deformation
C. slack thrust bearings
D. bearing shells shim dimensions

ESD stands for which type of boiler

A. External superheater D-type * B. Emergency shutdown Boiler
C. Extreme Superheat type
D. External Superheat De-superheater type

The advantage of tie rods over an engine without tie rods is that:

A. The engine is very easily aligned after any misalignment has taken place between different components of the engine *
B. The engine doesnt require thrust pads for transmission of thrust to the ships hull as the same is being taken care of by the tie rods
C. The engine components are much lighter leading in overall reduction is engine weight with a high power generation with the elimination of fatigue stresses
D. There are no advantages of engines with tie rods, because tie rods require regular maintenance and replacement like connecting rods and overall engine becomes more expensive to operate

Which of the following is an example of a solid bearing?

A. Piston pin bushing *
B. Turbo-generator turbine bearing
C. Spring bearing
D. Thrust bearing

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In order for microbiological growths to thrive in a fuel tank, it is necessary for

A. high temperatures to exist
B. low temperatures to exist
C. small amounts of water to be present *
D. large amounts of water to be present

Marine boilers burning H.F.O. face a problem of cold corrosion due to high sulphur content. The minimum flue gas temperature within any boiler part is kept above due point of H2SO4. The actual dew point of H2SO4 in flue gases depends on the:

A. Boiler furnace temperature
B. Ambient air temperature
C. Boiler operating pressure
D. HFO sulphur content and moisture in combustion air *

The purpose of an air cooler in a supercharging system is to:

A. Reduce the temperature of supercharged air in order to condense and remove maximum possible moisture from the air prior to entry to the engine
B. Reduce the temperature of the supercharged air in order to increase the density & also to cool down below dew point to remove moisture from air prior to entry to the engine *
C. Cool supercharged air to increase its density such that the dew point is not reached to avoid entry of moisture into the engine
D. Cool supercharged air to increase it???s density and also to keep the peak temperature and exhaust gas temperature within limits

The use of Halon as a fire extinguishing medium has been discontinued because

A. It is highly toxic
B. It is expensive
C. It has high Ozone depleting potential *
D. It leads to acid rains


In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low-alloy steel because

A. the beveled edges of the intake valves provide forself-centering during seating
B. intake valves utilize stellite-coated valve seat insertswhich reduce wear
C. the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
D. intake valves are less affected to the corrosive action of exhaust gases *

Why is it essential to renew turbocharger bearings after a preset number of hours of running even if the bearings are in seemingly perfect condition?

A. Because they are prone to failure due to prolonged exposure to high-temperature conditions.
B. Because they are subject to cyclic loading and are prone to failure due to metal fatigue. *
C. It is not essential to renew if condition monitoring suggests perfect condition.
D. Lube oil contamination is bound to occur and affect the condition of the bearings.

Which of the following statements is true?

A. The rotary vane type steering gear generally operates at higher oil pressures than the ram type.
B. The ram type steering gear generally operates at higher oil pressures than the rotary vane type. *
C. Both ram type and rotary vane type steering gears generally operate at similar oil pressures
D. None of the above

Modern marine turbochargers use a ________type of compressor

A. Radial flow * B. Axial flow
C. Mixed flow
D. Turbulent flow

Which of the following is a disadvantage of water as a cooling medium for pistons, when compared to oil?

A. Chemical treatment is required
B. Higher thermal stresses in piston
C. Piston of more complicated design D. All of the above *

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How is the concentration of dissolved oxygen in the feed water of an auxiliary boiler maintained at acceptable limits?

A. Feed water is cycled through a DC heater.
B. Feed water is treated with phosphates.
C. Oxygen is liberated in the three-stages of feed water preheating.
D. Oxygen is liberated by maintaining the highest practical feed water temperature *

In a 2-stroke marine diesel engine if the o-ring for Jacket cooling water sealing is leaking then

A. The water will leak directly into the crankcase
B. The water will leak into the under piston space
C. The water will come out through tell-tale hole provided between the two o-rings *
D. The water will come out from the top of the cylinder jacket

The lube oil pump used in a diesel engine is a

A. volute pump
B. centrifugal pump
C. diaphragm pump D. gear pump *

Prior to lighting off a cold automatically fired auxiliary boiler, you should

A. check and regulate the water level *
B. close the air cock once fires are lit
C. blow down the gauge glass
D. crack the steam stop to assure protective steam flow

Steam temperature control for the ESD-II boiler is achieved by :

A. Fitting a de-superheater between 1st & 2nd passes of superheater
B. Fitting an attemperator between 1st & 2nd passes of superheater C. Gas dampers in boiler uptake *
D. Bypassing the superheater

The coating which is provided on the valve stem of exhaust valves of modern marine diesel engines is of:

A. Nickel B. Stellite *
C. Chromium
D. Nimonic

If the combustion control system of an automatically fired auxiliary boiler fails to sustain burner ignition after a normal shutdown, you should check for a/an

A. faulty photocell detector *
B. low steam pressure
C. high voltage on the ignition electrode
D. open-air damper


Which of the following statements is true, about slow-speed engines?

A. A scavenge fire can lead to a crankcase explosion
B. A scavenge fire can lead to deformation of the diaphragm plate
C. A scavenge fire can lead to damage to tie rods. D. All of the above. *

For a two-stroke engine two o-rings are provided on the liner. The function of the top o-ring is to __________and function of the lower o-ring is to___________

A. Seal jacket cooling water; act as secondary seal in case 1st o-ring leaks B. Seal jacket cooling water, Seal scavenge air *
C. Seal scavenge air, Seal Jacket cooling water
D. Seal combustion gases, Seal jacket cooling water

Even if there is an oil mist concentration inside a crankcase, and there is also a hot spot, crankcase explosion will only take place when

A. The hot spot provides the ignition temperature for the oil mist concentration
B. When the oil mist – air mixture is in the flammable range C. Both A and B *
D. None of the above

Which of the following conditions is responsible for the fuel oil to atomize when using a steam atomizer in an auxiliary boiler?

A. Expansion of the steam in the furnace. *
B. Expansion of the steam in the whirling chamber.
C. Expansion of the steam in the orifice plate.
D. All of the above.

Some 4-stroke engines are fitted with a rotor cap 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

Shaft tunnel requires

a) drain
b) escape trunk
c) watertight door d) all the above *

What do you mean by the surge limit of a turbocharger?

A. Characteristic curve of a turbocharger
B. Portion of compressor characteristic curve which lies on the left side of the point of maximum pressure
C. A line joining all the points of maximum pressure on compressor characteristic curves, drawn at various speeds of operation *
D. Maximum rpm limit of T/C above which surging will start

A large, low-speed, main propulsion diesel engine uses seawater to directly cool the

A. cylinder heads
B. exhaust valves C. scavenging air *
D. injectors

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Exhaust Grouping is required in case of______________ turbocharging in order to

A. Constant pressure prevents shockwave generation
B. Pulse pressure, prevent interference with scavenging of other cylinders *
C. Constant pressure, prevent interference with scavenging of other cylinders
D. Pulse pressure prevents shockwave generation

Function of a de-superheater is to.

A. Protect superheater from overheat
B. Control superheater steam outlet temperature
C. Increase the efficiency of the boiler
D. Reduce steam temperature for auxiliary uses after steam superheater

Which of the following statements is false?

A. Oxidation of lubricant leads to decrease in its viscosity *
B. Formation of oxidation acids, sulfuric acid leads to depletion of TBN of lubricant
C. Contamination with water will lead to decrease in the load carrying capacity of a lubricant .
D. Build up of insolubles will lead to increase in viscosity of a lubricant

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

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


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

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

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 to 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 an allowance for thermal expansion to minimize the thermal stresses

Which of these fuel oil impurities can cause maximum abrasive damage?

A. Water
B. Ash
C. Catalytic fines *
D. Sodium

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

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 *


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 is 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

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

If the boiler tubes are scaled on the waterside 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

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 *

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

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

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Hopefully, you like our guide on MEO CLASS 4 MOTOR QUESTIONS AND ANSWERS 1.0. In case of any query feel free to comment below.

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