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MEK exit exam questions and answers — Set 2

Set 2 of the Marine Engineering Knowledge (MEK) exit exam bank — 30 of 195 questions, with the correct option marked and a one-line explanation for every one. Read it end to end, jump to a single set, or search it — then sit the same bank as a timed paper. The real DG Shipping exit exam is 30 marks with 15 to pass.

These are the bank's original groupings. Practising deals the whole bank out again every time you reshuffle, so a practice “Set 3” is a different 30 questions each time — the set numbers below are the source file's, and are only used here so the key stays navigable. Options are listed in their original order with fixed letters; when you practise, those move too.

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Set 2 — 30 MEK exit exam questions with answers

1. What safety device prevents starting air from entering an engine cylinder when the piston is in motion?

  • A. Cylinder relief valve
  • B. Fuel injector needle
  • C. Starting air distributor / control valve
  • D. Exhaust valve rotator
Answer: C — Starting air distributor / control valve
Air distributors time air delivery strictly during the starting stroke sequence.

2. What is the function of an oily water separator (OWS) bilge alarm (15 ppm monitor)?

  • A. Measure fuel viscosity
  • B. Check bilge well level
  • C. Continuously monitor discharge water purity and stop overboard valve if oil exceeds 15 ppm
  • D. Pump bilge water out faster
Answer: C — Continuously monitor discharge water purity and stop overboard valve if oil exceeds 15 ppm
The 15 ppm monitor ensures compliance with MARPOL Annex I by auto-stopping illegal discharge.

3. What causes thermal surging in a marine engine turbocharger?

  • A. Excessive cooling water temperature
  • B. High fuel viscosity
  • C. Low engine lube oil pressure
  • D. Breakdown of smooth airflow through compressor due to sudden engine load changes or fouled grid
Answer: D — Breakdown of smooth airflow through compressor due to sudden engine load changes or fouled grid
Surging occurs when compressor backpressure exceeds aerodynamic delivery pressure.

4. What is the main advantage of using a variable pitch propeller (CPP) on merchant vessels?

  • A. Allows continuous engine operation at optimal RPM while controlling vessel speed via blade pitch
  • B. Requires no hydraulic oil
  • C. Reduces hull resistance to zero
  • D. Eliminates need for stern tube bearings
Answer: A — Allows continuous engine operation at optimal RPM while controlling vessel speed via blade pitch
CPP allows rapid maneuvering without reversing main engine rotation direction.

5. What type of valve is installed on cylinder heads to protect against excessive combustion pressure?

  • A. Starting air valve
  • B. Fuel injection valve
  • C. Cylinder Safety Relief Valve
  • D. Indicator cock
Answer: C — Cylinder Safety Relief Valve
Relief valves lift automatically if cylinder firing pressure exceeds safe limits.

6. What is the primary function of the stern tube seal assembly?

  • A. Measure shaft RPM
  • B. Cool the propeller shaft tail
  • C. Support propeller weight only
  • D. Prevent seawater from entering the engine room and prevent lube oil from leaking into sea
Answer: D — Prevent seawater from entering the engine room and prevent lube oil from leaking into sea
Stern tube seals maintain watertight integrity around the rotating shafting.

7. Why must auxiliary diesel engines be warmed up before applying heavy electrical load?

  • A. To increase generator frequency to 100 Hz
  • B. To ensure uniform thermal expansion of engine components and proper lube oil circulation
  • C. To burn off carbon in exhaust pipe
  • D. To test overspeed governor
Answer: B — To ensure uniform thermal expansion of engine components and proper lube oil circulation
Warming up prevents thermal stress, piston scuffing, and bearing damage.

8. What is the purpose of an air compressor intercooler?

  • A. Increase air pressure directly
  • B. Lubricate compressor valves
  • C. Cool compressed air between stages to reduce volume, increase air density, and remove moisture
  • D. Heat air before entering receiver
Answer: C — Cool compressed air between stages to reduce volume, increase air density, and remove moisture
Intercooling improves volumetric efficiency and prevents moisture carryover to air bottles.

9. What condition causes high exhaust gas temperature across all cylinders of a diesel engine?

  • A. High cooling water temperature
  • B. Engine overload, fouled turbocharger compressor/turbine, or restricted air intake filter
  • C. Excessive lube oil level
  • D. Low fuel temperature
Answer: B — Engine overload, fouled turbocharger compressor/turbine, or restricted air intake filter
Air starvation or thermal overload increases exhaust temperatures uniformly.

10. What is the function of a governor on a marine diesel engine?

  • A. Control cooling water valve
  • B. Regulate lube oil pressure
  • C. Start the engine on air
  • D. Automatically adjust fuel rack position to maintain set engine speed under varying loads
Answer: D — Automatically adjust fuel rack position to maintain set engine speed under varying loads
Governors maintain speed stability and prevent overspeeding in rough seas.

11. What is the function of an indicator cock fitted on a engine cylinder head?

  • A. Vent air from cooling jacket
  • B. Sample exhaust gases
  • C. Inject fuel into cylinder
  • D. Allow attachment of engine indicator gear to measure cylinder pressure diagrams and blow out water
Answer: D — Allow attachment of engine indicator gear to measure cylinder pressure diagrams and blow out water
Indicator cocks allow taking combustion cards and venting moisture prior to engine start.

12. What type of pump is self-priming and commonly used for positive displacement lube oil transfer?

  • A. Centrifugal Pump
  • B. Ejector Pump
  • C. Gear Pump or Screw Pump
  • D. Axial Flow Pump
Answer: C — Gear Pump or Screw Pump
Positive displacement gear/screw pumps generate suction lift without external priming.

13. What is cavitation in a centrifugal pump and how does it affect performance?

  • A. Overheating of electric motor bearings
  • B. High pressure at suction flange
  • C. Air trapped in discharge pipe
  • D. Formation and collapse of vapor bubbles near impeller causing noise, vibration, and metal erosion
Answer: D — Formation and collapse of vapor bubbles near impeller causing noise, vibration, and metal erosion
Cavitation occurs when fluid pressure drops below vapor pressure, eroding impeller blades.

14. What is the function of an automatic voltage regulator (AVR) on a marine alternator?

  • A. Control engine governor speed
  • B. Maintain constant generator terminal voltage despite changes in electrical load
  • C. Trip main circuit breaker
  • D. Synchronize frequency
Answer: B — Maintain constant generator terminal voltage despite changes in electrical load
AVR adjusts alternator field excitation current to keep output voltage steady.

15. What safety precaution must be taken before opening an engine crankcase after a hot spot alarm?

  • A. Open doors immediately to vent smoke
  • B. Spray cold water inside crankcase
  • C. Start lube oil pump at max pressure
  • D. Wait at least 30 minutes to allow hot spots to cool down before opening doors
Answer: D — Wait at least 30 minutes to allow hot spots to cool down before opening doors
Opening crankcase doors immediately introduces oxygen, triggering explosive oil mist ignition.

16. What is the purpose of thermostatic control valves in engine cooling water systems?

  • A. Shut off water when engine stops
  • B. Increase pump discharge pressure
  • C. Maintain constant engine cooling water temperature by modulating bypass flow to heat exchanger
  • D. Filter dirt from fresh water
Answer: C — Maintain constant engine cooling water temperature by modulating bypass flow to heat exchanger
Thermostatic valves regulate coolant temperature for optimal engine thermal balance.

17. What is the function of a emergency generator automatic main failure (AMF) panel?

  • A. Supply power to main engine lube pump
  • B. Step down voltage from 440V to 220V
  • C. Charge radio batteries only
  • D. Detect loss of main switchboard power and auto-start the emergency generator within 45 seconds
Answer: D — Detect loss of main switchboard power and auto-start the emergency generator within 45 seconds
AMF panels restore essential lighting and safety loads during blackouts.

18. Which of this is not a moving part of a diesel engine

  • A. piston
  • B. crankshaft
  • C. connecting rod
  • D. crankcase
Answer: D — crankcase
The crankcase is the housing for the crankshaft and part of the engine block; it is a stationary component. The piston, crankshaft, and connecting rod are all essential moving parts within the diesel engine's power cycle.

19. Generator engine on board ship is started using

  • A. hydraulic oil motors/pressure
  • B. compressed air
  • C. air compressor
  • D. turbo generator
Answer: B — compressed air
Generator engines on ships are typically started using compressed air stored in receiver tanks, which engages the engine's starting mechanism. Hydraulic systems or air compressors are used to supply this air, but the immediate starting medium is the compressed air itself.

20. Purpose of fresh water circulation through diesel engine cylinder is to

  • A. prevent corrosion
  • B. remove heat of combustion
  • C. clean exhaust gases
  • D. lubricate moving part
Answer: B — remove heat of combustion
The primary purpose of circulating fresh water through a diesel engine's cooling system is to absorb and remove the immense heat generated by combustion, thereby maintaining optimal operating temperatures. It does not primarily prevent corrosion or clean exhaust gases.

21. Turning gear on main engine is provided for

  • A. remove exhaus gases from cylinder
  • B. turning the engine during overhaul
  • C. releasing parts if jammed
  • D. ensure turning of propeller
Answer: B — turning the engine during overhaul
The turning gear is provided on the main engine to allow slow rotation of the crankshaft during maintenance, overhaul, or pre-starting checks. This ensures even cooling, allows access to components, and prevents seizure.

22. Exhaust gas economiser produces

  • A. steam
  • B. fresh water
  • C. inert gas
  • D. electricity
Answer: A — steam
An exhaust gas economizer is a heat exchanger that recovers waste heat from the exhaust gases of the main engine or auxiliary boilers to generate steam or preheat feedwater. It is not involved in producing fresh water, inert gas, or electricity directly.

23. Turbo chargers on diesel engine

  • A. increases pressure of intake air
  • B. acts as fuel charger
  • C. increases RPM
  • D. decreases the pressure of intake air
Answer: A — increases pressure of intake air
Turbochargers are used to increase the power output of diesel engines by compressing and forcing more intake air into the cylinders. This results in higher volumetric efficiency and improved combustion, not a decrease in air pressure.

24. Exhaust gases from the main engine go to the atmosphere through

  • A. oil fired boiler
  • B. inert gasgenerator
  • C. exhaust fan
  • D. exhaust gas boiler
Answer: D — exhaust gas boiler
Exhaust gases from the main engine, after potentially passing through an exhaust gas boiler (economizer) for heat recovery, are released to the atmosphere through the ship's exhaust uptake or funnel. An inert gas generator or exhaust fan serves different purposes.

25. Relief valves are provided on main engine cylinders for protection against high

  • A. level of water
  • B. pressure
  • C. exhaust temperature
  • D. speed
Answer: B — pressure
Cylinder head relief valves are safety devices designed to protect the engine from potentially catastrophic over-pressurization within the combustion chamber. This can occur due to excessive fuel injection or other abnormal combustion events, not high exhaust temperature or speed.

26. Function of a cylinder head relief valve is to

  • A. reduce the speed of engine
  • B. prevent crankcase explosion
  • C. stop the engine
  • D. release excessive pressure
Answer: D — release excessive pressure
A cylinder head relief valve is a safety device that opens automatically to release excessive pressure from within the cylinder during operation. This prevents damage to the engine components and potential hazards from over-pressurization.

27. Function of crankcase relief door is to

  • A. detect the mist inside the crankcase
  • B. release pressure from crankcase
  • C. stop the engine
  • D. reduce the speed of engine
Answer: B — release pressure from crankcase
Crankcase relief doors are designed as safety vents to rapidly release any abnormal pressure build-up within the crankcase, which can be caused by a crankcase explosion. This prevents damage to the engine casing and potential injury.

28. If cooling water becomes less in a diesel engine the engine will

  • A. not start
  • B. cool down too much
  • C. make more noise
  • D. get overheated
Answer: D — get overheated
Insufficient cooling water in a diesel engine leads to inadequate heat removal from the combustion process, causing the engine's temperature to rise beyond its safe operating limits, resulting in overheating. Proper cooling is essential for engine longevity and performance.

29. Diesel engine bearing will get damaged if supply of ___________ is not enough

  • A. lubricating oil
  • B. fuel
  • C. air
  • D. water
Answer: A — lubricating oil
Bearings in a diesel engine rely on a continuous supply of lubricating oil to create a film that separates moving surfaces, reducing friction and wear. A lack of lubricating oil will lead to metal-to-metal contact, overheating, and eventual bearing seizure or damage.

30. Speed of diesel engine is adjusted by changing the supply of

  • A. lubricating oil
  • B. air
  • C. fuel
  • D. water
Answer: C — fuel
The speed of a diesel engine is primarily regulated by controlling the amount of fuel injected into the cylinders. Increasing fuel supply increases power and speed, while decreasing it reduces them. Air supply is also important but fuel is the primary control.

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