Diesel Mechanic Interview Questions & Answers

  • Question 1. What Is Automatic Valve?

    Answer :

    A valve assisted by a spring,’which is opened by a difference of pressure acting in one direction and closed by a difference in pressure acting in the opposite direction.

  • Question 2. What Is Case-harden?

    Answer :

    To harden the outer surface of metal to a given case or shell depth, while leaving the inner portion soft to absorb shocks and allow bending.

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  • Question 3. What Is Analog Sensor?

    Answer :

    A sensor which sends a range of voltages in DC to the ECM to describe, for example, coolant temperature, engine oil pressure, or atmospheric pressure.

  • Question 4. What Is Air Signal Attenuator?

    Answer :

    A device that reduces both exhaust smoke and noise by slowing engine acceleration slightly until adequate turbocharger boost pressure is present.

  • Question 5. What Is Critical Speeds?

    Answer :

    Speeds at which the frequency of the power strokes synchronize with the crankshaft’s natural frequency. If the engine is operated at one of its critical speeds for any length of time, a broken crankshaft may result.

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  • Question 6. What Is Brake Thermal Efficiency?

    Answer :

    Ratio of power output in the form of brake horsepower to equivalent power input in the form of heat from fuel. Typical brake thermal effidency ranges from thirty to forty-two percent.

  • Question 7. Tell Me What Are Different Types Of Vehicles Based On Diesel Engines?

    Answer :

    Automobiles, trucks, buses, marines, and construction areas are popular types that are based on diesel engines.

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  • Question 8. Do You Know What Is Cam?

    Answer :

    A rotating component of irregular shape. It is used to change the direction of the motion of another part moving against it, e.g., rotary into reciprocating or variable motion.

  • Question 9. What Is Dead Center?

    Answer :

    Either of the two positions when the crank and connecting rod are in a straight line at the end of the stroke. The total piston travel is the distance between the two dead center positions.

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  • Question 10. What Is Relay?

    Answer :

    Normally used in control circuits, relay is a switch driven by electricity and rules over contactor by virtue of low amperage contacts.

  • Question 11. What Is Compression Release?

    Answer :

    A device which holds open the intake or exhaust valve, thereby permitting the engine to be turned over without compression. This is one method of engine braking where by the power stroke is cancelled.

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  • Question 12. What Is Chamfer (taper Lead)?

    Answer :

    The taper at the thread end of a tap or the throat of a die, made by cutting away the crests of the first few threads. This distributes the work of cutting over several threads and acts as a guide in starting the tap or die. The chamfer is relieved to facilitate cutting.

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  • Question 13. What Is Constant-pressure Combustion?

    Answer :

    Combustion which occurs without change in pressure. In an engine, this is obtained by a slower rate of burning than with constant volume combustion.

  • Question 14. What Is Bimetal Arm?

    Answer :

    A thin sandwich strip of two metals with very dif- ferent heat expansion rates that bends to the left or the right due to heat caused by resistance to voltage.

  • Question 15. Explain Me Diesel Mechanic Duties For In This Matter?

    Answer :

    Diesel mechanic is typically responsible to operate, handle, maintain and repair diesel engines that are used to run any machinery including vehicles, generators and other machinery.

  • Question 16. What Is Brush?

    Answer :

    This graphite or copper made conducting element maintains sliding electrical contact between static and moving element.

  • Question 17. What Is Condenser?

    Answer :

    Also called a capaciator, this electronic component CI stores up electric charge until a set svoltage is reached; then a high but rapidly decaying current flows through the circuit until finally the voltage difference between the two leads reaches zero.

  • Question 18. What Is Atmospheric Pressure (barometric Pressure)?

    Answer :

    The pressure exerted by the atmosphere, averaging 14.7 psi at sea level with a decrease of approximately 1/4 lb per 1,000 ft of altitude gained.

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  • Question 19. Please Explain What A Diesel Mechanic Is Responsible For?

    Answer :

    Diesel mechanics are basically responsible for the troubleshooting, upkeep, maintenance, and repair of diesel engines. This may include vehicle engines, generators and plant machinery that requires diesel to make it run.

  • Question 20. What Is Generator?

    Answer :

    A utility device that converts mechanical energy into electrical energy, available either in the form of direct or alternating current.

  • Question 21. What Is Displacement?

    Answer :

    In a single acting engine, the volume swept by all pistons in making one stroke each. The displacement on one cylinder in cubic inches is the circular area (in square inches) times the stroke (in inches).

  • Question 22. What Is Critical Compression Ratio?

    Answer :

    Lowest compression ratio at which any particular fuel will ignite by compression. The lower the critical compression ratio the better ignition qualities the fuel has. (Gasoline engine, 4:1; oil engine, 7:1; diesel engine, 12.5:1.)

  • Question 23. What Is Brinen Hardness?

    Answer :

    The surface hardness of a metal, alloy, or similar material according to l.A. Brinell’s method of measurement. A metal’s surface is struck at a given force by a rigid steel ball of a given diameter, and the indentation is measured.

  • Question 24. Do You Know What Are Two Most Essential Skills That A Diesel Mechanic Should Own?

    Answer :

    A diesel mechanic must employ two important skills. First is analytical mind to be able to evaluate any issue occurred in the engine. Second is ability to read and perceive instructions manuals and blueprints of the engines since each engine has different design and small engine routes can end up in complex issues.

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  • Question 25. What Is Dynamo?

    Answer :

    A mechanical device that converts mechanical energy into electrical energy through electromagnetic induction process.

  • Question 26. What Is Battery Charge Rectifier?

    Answer :

    This component changes AC voltage from the battery charge windings to DC voltage for charging a battery.

  • Question 27. Tell Me What Is Alternating Current (ac)?

    Answer :

    Current flowing from zero to a positive maximum and then back to zero, flows down again to a negative maximum to return back to zero.

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  • Question 28. What Is Load?

    Answer :

    Load is that the amount of electric power used by devices associated to electricity generating system.

  • Question 29. What Is Brake Mean Effective Pressure (bmep)?

    Answer :

    Mean effective pressure acting on the piston which would result in the given brake horsepower output, if there were no losses due to friction, cooling, and exhaustion. Equal to mean indicated pressure times mechanical effidency.

  • Question 30. As You Know Diesel Mechanics Are Typically Assigned Based On Their Personal Skills In Specific Fields. What Fields Are You Most Adaptable Working In?

    Answer :

    Whilst I am an experienced and skilled mechanic with comprehension in diesel engine handling with their wholeness, I am sure my interest is about maintaining electrical and system of brake related to vehicular engines.

  • Question 31. What Is Ampere-hour Capacity (ah)?

    Answer :

    A measurement of the battery’s capacity to deliver a specified current over a spec.ified length of time.

  • Question 32. Tell Me What Relevant Skills Do You Possess?

    Answer :

    Apart from technical aptitude and in-depth knowledge of working on complex and varied diesel engines, I also possess strong leadership skills, especially where crew management is concerned. Moreover, I can use modern technologies and hand tools to manage maintenance and repair work.

  • Question 33. What Is Rated Voltage?

    Answer :

    The specific voltage measurement at which an engine generator set can start functioning.

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  • Question 34. What Is Winding?

    Answer :

    Winding comprises all the coils of a generator.

  • Question 35. What Is Off-peak Rate?

    Answer :

    This is the rate of cost for power used during Off-Peak periods.

  • Question 36. What Is Stator?

    Answer :

    Stator is the static or unmovable element of a generator.

  • Question 37. Tell Me What Does A Typical Diesel Engine Reconditioning Procedure Consist Of?

    Answer :

    The reconditioning process includes repairing or replacing pistons, bearings, gears, valves, and bushings. The use of engine lathes and boring machines is an important part of the reconditioning procedure.

  • Question 38. What Is Cradle?

    Answer :

    Covering a generator or engine, this metal frame provides extra protection from outer disturbances.

  • Question 39. What Is Gensets?

    Answer :

    A handy power generator, converting fuel into electrical power through mechanical ways. Clip-on gensets and Underslung gensets are most popular.

  • Question 40. What Is Electronic Engine Control (eec)?

    Answer :

    Microcomputer coupled with sensors and controls for fuel, coolant, and other on board systems, as well as self diagnostic ability.

  • Question 41. What Is Air Pollution?

    Answer :

    Contamination of the earth’s atmosphere by pollutants such as smoke, harmful gases, etc.

  • Question 42. What Is Ignition Coil?

    Answer :

    Ignition coil supplies DC voltage to the spark plugs.

  • Question 43. What Is Motor Generator?

    Answer :

    Normally used either to regulate or condition power from a raw power source like electric utility grid.

  • Question 44. Tell Us What Do You Believe Are The Two Most Important Skills That A Diesel Mechanic Should Have?

    Answer :

    While working as a diesel mechanic is skilled work entirely, the 2 most important things are to have an analytic mind and the ability to read and understand blueprints and instruction manuals. That is is because each engine is different and it is the small intricacies in their make-up that end up in complicated problems or maintenance issues.

  • Question 45. What Is Rotor?

    Answer :

    Rotor is the element that on, which the rotating of a generator depends.

  • Question 46. What Is Off-peak?

    Answer :

    A specific period when power demand of a system is comparatively low. Counted from 10 p.m. until 6 a.m., from Monday through Saturday and during the whole day on Sunday by NERC.

  • Question 47. What Is Flywheel?

    Answer :

    Storing energy in a rotating mass form, Flywheel is a very active substitution of chemical batteries.

  • Question 48. What Is Diesel Generator?

    Answer :

    Starts up and generates power automatically during power cut.

  • Question 49. What Is Current?

    Answer :

    The flow of particles charged by electricity.

  • Question 50. Explain Me What Additional Qualifications Do You Have That You Feel Have Made You A Successful Diesel Mechanic?

    Answer :

    I have deep knowledge of tooling, supply management, and inspection tools. These along with an exceptional attention to detail and thoroughness of nature make it possible for me to work for extended hours especially when detailed troubleshooting or maintenance is needed.

  • Question 51. Do You Know What Is Phase?

    Answer :

    Phase measures the uniform periodic change in amplitude or magnitude of an alternating current.

  • Question 52. What Is Rectifier?

    Answer :

    Rectifier is used for converting alternating current (AC) to direct current (DC).

  • Question 53. What Is Standby Generator?

    Answer :

    Used for power backup in home, Standby Generator is driven by gasoline or LP gas.

  • Question 54. What Is Engine Generator?

    Answer :

    Generates electric power with the help of natural gas or diesel reciprocating engine.

  • Question 55. What Is Distribution?

    Answer :

    Supply of lower voltage electric power from a centralized substation to the point of end use.

  • Question 56. What Is Contactor?

    Answer :

    It is used in control circuits.

  • Question 57. Please Explain What Three Duties Do You Consider “all In A Day’s Work” For Someone Working In A Diesel Mechanic Position?

    Answer :

    The first most important duty of a diesel mechanic is performing routine maintenance on diesel engines. Secondly, diesel mechanics replace and repair damaged or malfunctioning parts in engines, followed by fixing brake and electrical systems.

  • Question 58. What Is Stator Winding?

    Answer :

    Comprises of stator coils with their interconnections.

  • Question 59. What Is Core?

    Answer :

    Core is the magnetic structure built lamination in the generator.

  • Question 60. What Is Electric Generator?

    Answer :

    Generates electricity from a source of mechanical energy.

  • Question 61. Do You Know What Is Direct Current (dc)?

    Answer :

    Current produced by storage battery or electromagnetic induction, with a unidirectional flow.

  • Question 62. What Is Blackout?

    Answer :

    Sudden disruption of electrical power.

  • Question 63. What Is Cylinder Head?

    Answer :

    The replaceable portion of the engine that seals the cylinder at the top. It often contains the valves, and in some cases, it is part of the combustion chamber.

  • Question 64. What Is Bendix Type Starter Drive (inertia Starter Drive)?

    Answer :

    A type of starter drive that causes the gear to engage when the armature starts rotating and to automatically disengage when it stops.

  • Question 65. Tell Us What Abilities Do You Own That You Feel You Can Be Good Diesel Mechanic?

    Answer :

    I have comprehensive knowledge of equipment, supply handling and inspection instruments. These together with an attentive to detail and meticulousness make it likely for me to work overtime specifically when sharp maintenance or troubleshooting is necessary.

  • Question 66. What Is Peak?

    Answer :

    Measurement of the maximum load that is consumed within a specified time period.

  • Question 67. What Is Magneto?

    Answer :

    Built with permanent magnets, Magneto is a special kind of alternator that generates current for ignition in an internal combustion engine.

  • Question 68. What Is Turbine Generator?

    Answer :

    Running on gas or steam turbine, turbine generator generates electricity through electromagnetic forces caused by steam, water or wind etc.

  • Question 69. What Is Backup Generators?

    Answer :

    Used for fulfilling emergency load requirement during sudden shortage of power.

  • Question 70. What Is An American Public Power Association (appa)?

    Answer :

    A national service organization that represents 2000 municipal and other state or local publicly owned electric utilities spread across the United States.

  • Question 71. What Is Combustion Cycle?

    Answer :

    A series of thermodynamic processes throughwhich the working gas passes to produce one power stroke. The full cycle is: intake, compression, power, exhaust.

  • Question 72. What Is Digital Sensor?

    Answer :

    A sensor which uses duty cycles of two voltages in timed pulses of AC to relay such information as speed, throttle position, and engine timing.

  • Question 73. What Is Cam-ground Piston?

    Answer :

    Oval shaped piston head design used by most large-diameter aluminum pistons, which expands in a nonuniform manner when hot to attain a round shape.

  • Question 74. What Is Absolute Temperature?

    Answer :

    The temperature measured using absolute zero as a reference. Absolute zero is -469.69° F (-273.16° C) and is the lowest point of temperature known.

  • Question 75. As You Know Diesel Mechanics Are Usually Hired Depending On Their Expertise In Specific Areas. What Areas Are You Most Comfortable Working In?

    Answer :

    While I am an experienced diesel mechanic and have experience in handling diesel engines in their entirety, I believe my interest lies in handling electrical systems and overhauling pertaining to vehicular diesel engines.

  • Question 76. What Is Kva?

    Answer :

    KVA is kilovolt-ampere an
    d is the unit of apparent power. KVA is used for measuring the power consumption of non-resistive equipment such as motors, computers, and most non-incandescent lighting.

  • Question 77. What Is Voltage Regulator?

    Answer :

    By modulating the flow of DC to the rotor, Voltage regulator maintains optimum generator voltage, automatically.

  • Question 78. What Is Non-utility Generator?

    Answer :

    Connected to an electric utility system, Non-utility Generator generates electricity specifically for those not owned by an electric utility.

  • Question 79. What Is Diesel Engine?

    Answer :

    An internal combustion engine in which fuel oil is burnt by heat produced from air compression. The most commonly bought Industrial Diesel Engines are either Rebuilt Diesel Engine or Used Diesel Engine.