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Haryana BSEH Secondary NSQF Automotive study materials
Haryana BSEH Secondary NSQF Automotive study resources

Haryana BSEH Secondary NSQF Automotive practice questions

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Question 1Automotive Workshop Safety, Tools and Equipment

While working under a vehicle on a two-post hoist, which practice best protects a technician from a falling load?

  1. Standing under the raised vehicle while a helper operates the controls
  2. Relying on the hydraulic pressure alone to hold the arms
  3. Leaving the hoist slightly below full height so the arms rest on the floor
  4. Placing the lift arms at the manufacturer's recommended pick-up points and locking the mechanical safety Correct answer.

Explanation

A vehicle hoist must be loaded at the pick-up points specified by the vehicle maker and the mechanical safety lock must be engaged before anyone goes underneath. Hydraulic pressure can bleed off, so it is never a substitute for the mechanical lock. Correct arm placement also prevents the vehicle from tipping on the lift.

Question 2Automotive Workshop Safety, Tools and Equipment

What is the correct first action when a grinding wheel on a bench grinder is found to have a visible crack?

  1. Run it at low speed to check whether the crack spreads
  2. Remove the wheel from service and replace it Correct answer.
  3. Reduce the tool rest gap and continue using the wheel
  4. Dress the wheel with a dressing tool to remove the crack

Explanation

A cracked abrasive wheel can burst at operating speed and throw fragments, so it must be taken out of service immediately and replaced. Cracks cannot be repaired by dressing or by running the wheel. Only an undamaged wheel that passes the ring test should be mounted.

Question 3Automotive Workshop Safety, Tools and Equipment

Which personal protective equipment is essential when using a pneumatic impact wrench to remove wheel nuts?

  1. Safety goggles and hearing protection Correct answer.
  2. A full-face welding shield
  3. A rubber apron and acid-resistant gloves
  4. An organic-vapour respirator

Explanation

Impact wrenches generate flying debris and high noise levels, so eye protection and hearing protection are the primary requirements. Impact sockets can shatter and sockets can slip, which is why eye protection matters. Welding shields, chemical aprons and respirators address hazards that are not present in this task.

Question 4Automotive Workshop Safety, Tools and Equipment

A technician must raise a vehicle using a trolley jack for a brake inspection. Where should the axle stands be placed?

  1. Under the manufacturer's specified jacking and support points on the chassis or axle Correct answer.
  2. Under the sill panel at any convenient point
  3. Under the plastic underbody trim
  4. Under the brake disc or drum being inspected

Explanation

Axle stands must sit under strong structural points named by the vehicle manufacturer, such as the chassis rails or axle tubes. Sills, brake components and plastic trim cannot carry the vehicle's weight and will deform or collapse. The jack is only a lifting device; the stands carry the load.

Question 5Automotive Workshop Safety, Tools and Equipment

Which fire extinguisher class is appropriate for a small petrol fire in the workshop?

  1. Class D dry powder extinguisher
  2. Class B foam or dry powder extinguisher Correct answer.
  3. Class A water extinguisher
  4. Carbon dioxide only for deep-seated petrol fires

Explanation

Petrol is a flammable liquid, which places it in Class B, so foam or dry powder extinguishers are suitable. Water must never be used because it spreads the burning liquid. Class D agents are for combustible metals such as magnesium.

Question 6Automotive Workshop Safety, Tools and Equipment

What is the main purpose of a torque wrench in automotive assembly?

  1. To check battery voltage during charging
  2. To tighten fasteners to a specified clamping force without over-stressing them Correct answer.
  3. To measure the length of a bolt before fitting
  4. To loosen seized nuts quickly using a long extension

Explanation

A torque wrench applies a controlled turning moment so that a fastener is clamped to the value specified by the manufacturer. Correct torque prevents joint failure from under-tightening and thread or gasket damage from over-tightening. It is a tightening instrument, not a loosening or measuring tool for other quantities.

Question 7Automotive Workshop Safety, Tools and Equipment

Why should compressed air never be directed at a person's skin during cleaning?

  1. It is too cold and causes frostbite on contact
  2. It removes protective oils and can force air into the bloodstream through a small cut Correct answer.
  3. It wastes electricity in the compressor
  4. It damages the nozzle of the blow gun

Explanation

Compressed air at workshop pressure can penetrate skin through a tiny break and cause an air embolism, which is a serious medical emergency. It also strips lubricants and drives debris into eyes. Cleaning should be done with a brush, vacuum or approved low-pressure nozzle.

Question 8Automotive Workshop Safety, Tools and Equipment

A technician is about to arc weld a patch onto a vehicle body. Which precaution protects the vehicle's electronic control units?

  1. Welding with the ignition switched on to keep sensors active
  2. Leaving the battery connected so the ECU stays powered
  3. Disconnecting the battery and unplugging the ECU connectors, and earthing the welder close to the weld Correct answer.
  4. Earthing the welder to the rear bumper to keep the cable short

Explanation

Welding current can travel through the vehicle's wiring and destroy electronic modules, so the battery should be disconnected and ECUs protected. The welder earth clamp must be placed close to the work so current does not pass through the vehicle body. Keeping systems powered or earthing far away increases the risk of damage.

Question 9Automotive Workshop Safety, Tools and Equipment

What does the ring test on a vitrified grinding wheel check?

  1. Whether the wheel has internal cracks or defects Correct answer.
  2. Whether the wheel is balanced on its spindle
  3. Whether the wheel guard clearance is adequate
  4. Whether the wheel's abrasive grade is correct

Explanation

A sound wheel tapped lightly with a non-metallic object gives a clear ring, while a cracked wheel gives a dull thud. The test screens for internal damage before mounting. Balance, grade and guard clearance are checked by other means.

Question 10Automotive Workshop Safety, Tools and Equipment

A hydraulic trolley jack slowly sinks after lifting a vehicle. What is the most likely cause?

  1. The axle stands are set too high
  2. The jack handle is too short
  3. The release valve is not fully closed or the seals are leaking Correct answer.
  4. The vehicle is too light for the jack

Explanation

A jack that sinks under load usually has a release valve that is partly open or worn seals that allow hydraulic fluid to bypass. Both prevent the ram from holding pressure. Jack handle length, vehicle mass and stand height do not cause internal sinking.

Question 11Automotive Workshop Safety, Tools and Equipment

Which tool is the correct choice for removing a rusted exhaust manifold nut without rounding it?

  1. An open-ended spanner one size too large
  2. A six-point flank-drive socket of the exact size Correct answer.
  3. An adjustable wrench tightened as far as possible
  4. A pair of long-nose pliers

Explanation

A six-point socket that grips the flats of the nut transmits force to the strongest part and reduces rounding. The correct size ensures full engagement on a corroded fastener. Oversized, adjustable or plier-type tools contact only corners or edges and slip under high torque.

Question 12Automotive Workshop Safety, Tools and Equipment

A vehicle on a two-post hoist is found to be nose-heavy and the rear wheels lift off the arms. What should the technician do?

  1. Loosen the rear arm pads to let the vehicle settle
  2. Stand on the rear bumper to weigh the vehicle down
  3. Lower the vehicle and reposition it or the arms to achieve a balanced centre of gravity Correct answer.
  4. Raise the hoist fully and continue working

Explanation

An unbalanced load on a hoist can tip and fall, so the vehicle must be lowered and repositioned until its centre of gravity sits correctly between the arms. Adding body weight or continuing to raise the vehicle does not correct the instability. Arm pads must stay properly engaged and locked.

Question 13Automotive Workshop Safety, Tools and Equipment

What is the purpose of the dead-man handle or self-closing valve on a compressed air blow gun?

  1. To filter oil and water from the air line
  2. To reduce the noise of the compressor
  3. To increase the air pressure at the nozzle
  4. To stop the air flow automatically when the operator releases the trigger Correct answer.

Explanation

A self-closing valve shuts off air as soon as the operator lets go, so a dropped or unattended gun cannot keep blowing debris. This limits injury and workshop contamination. Pressure regulation, filtration and noise control are handled by other components.

Question 14Automotive Workshop Safety, Tools and Equipment

Which statement correctly describes the use of a micrometer for measuring a brake disc thickness?

  1. It should be read after zeroing and used squarely across the disc with light friction on the thimble Correct answer.
  2. It should be tightened firmly until the spindle stops turning
  3. It should be held at an angle to reach the worn area
  4. It should be used with the lock nut tightened during measurement

Explanation

A micrometer is zeroed first, then applied square to the measuring faces with the friction thimble so consistent light pressure is used. Forcing the spindle distorts the frame and gives a false reading. The lock nut is used to hold a reading, not while adjusting.

Question 15Automotive Workshop Safety, Tools and Equipment

A workshop stores oxygen and acetylene cylinders together in a corner. What is the correct practice?

  1. Lay both cylinders horizontally to save space
  2. Keep them next to the paint store to save walking distance
  3. Store acetylene below oxygen on the same trolley without restraints
  4. Store them upright, separated by a fire-resistant barrier or minimum distance, with caps fitted and away from ignition sources Correct answer.

Explanation

Fuel gas and oxygen cylinders must be stored upright, secured, valve-capped and separated so a leak in one cannot feed the other. Keeping them away from ignition sources and flammable stores reduces fire risk. Laying cylinders down or storing them near paint is unsafe.

Question 16Automotive Workshop Safety, Tools and Equipment

What is the main reason for using a torque wrench within its calibrated range rather than at the extremes?

  1. Fasteners below the range cannot be threaded
  2. The ratchet reverses direction at low settings
  3. Accuracy is specified as a percentage of full scale and is poorest near the bottom of the range Correct answer.
  4. The wrench becomes physically longer at low settings

Explanation

Torque wrench accuracy is quoted as a percentage of full scale, so very low settings fall outside the reliable band. Using the tool in the middle of its range keeps error small. Physical size, threadability and ratchet direction are unrelated to calibration accuracy.

Question 17Automotive Workshop Safety, Tools and Equipment

A technician notices the insulation on a portable inspection lamp lead is cut and the conductor is exposed. What is the correct action?

  1. Hold the lead away from the metal work while using the lamp
  2. Plug it into a socket protected by a residual current device and carry on
  3. Take the lamp out of service and report it for repair or replacement Correct answer.
  4. Wrap the cut with insulating tape and continue using the lamp

Explanation

Damaged insulation on portable electrical equipment is a shock hazard and the item must be withdrawn from use until repaired. Taping over damage hides a defect that may worsen and is not an approved repair. An RCD reduces but does not remove the risk from a known fault.

Question 18Automotive Workshop Safety, Tools and Equipment

Which practice correctly applies the principle of correct lifting technique when removing a gearbox from a bench?

  1. Holding the gearbox at arm's length to keep it clear of the body
  2. Lifting with a jerking motion to overcome the initial weight
  3. Keeping the load close, bending the knees and avoiding twisting while lifting Correct answer.
  4. Bending at the waist with straight legs and twisting to place the gearbox

Explanation

Safe manual handling keeps the load close to the body, uses the leg muscles by bending the knees and avoids twisting the spine under load. These measures reduce strain on the lower back. Bending at the waist, reaching out or jerking the load all increase injury risk.

Question 19Automotive Workshop Safety, Tools and Equipment

A four-gas detector is used before entering a workshop inspection pit where exhaust gases may collect. Which reading combination requires immediate evacuation?

  1. Oxygen 20.0 percent, LEL 2 percent, carbon monoxide 10 ppm
  2. Oxygen 19.5 percent, LEL 5 percent, carbon monoxide 35 ppm Correct answer.
  3. Oxygen 20.5 percent, LEL 0 percent, carbon monoxide 5 ppm
  4. Oxygen 20.9 percent, LEL 0 percent, carbon monoxide 0 ppm

Explanation

Carbon monoxide at 35 ppm exceeds typical occupational exposure limits, and a falling oxygen level plus a measurable LEL indicate a hazardous atmosphere in the pit. Confined spaces must be tested and ventilated before entry. The other readings stay within normal or acceptable limits.

Question 20Automotive Workshop Safety, Tools and Equipment

During a road test a technician hears a rhythmic scraping from one wheel that changes with vehicle speed but not with engine speed. Which diagnostic step is most appropriate before dismantling?

  1. Inspect that wheel for a foreign object or worn brake pad and check for a bent dust shield Correct answer.
  2. Replace the gearbox oil and retest
  3. Rev the engine in neutral to see whether the noise changes
  4. Adjust the idle speed and retest

Explanation

A speed-related noise that does not follow engine speed points to rotating running gear such as brakes, wheel bearings or a trapped stone. A visual inspection of the affected wheel is the logical first step. Engine-related tests or gearbox oil changes do not address a wheel-speed noise.

Question 21Automotive Workshop Safety, Tools and Equipment

A torque wrench was dropped onto the workshop floor the previous week and is now used daily. What is the correct quality-control response?

  1. Have it recalibrated or verified against a reference before further use Correct answer.
  2. Continue using it because a drop does not affect a mechanical tool
  3. Set it to its maximum setting to reset the internal spring
  4. Oil the ratchet mechanism and return it to the toolbox

Explanation

A drop can disturb the calibration mechanism and cause readings to drift, so the wrench must be verified or recalibrated before use on safety-critical fasteners. Storing at maximum setting or oiling does not restore accuracy. Records of calibration also support workshop quality systems.

Question 22Automotive Workshop Safety, Tools and Equipment

A vehicle is to be raised on a scissor lift in a bay with a low ceiling. Which combination of checks is most important before lifting?

  1. Checking the lift's rated capacity against the vehicle weight and confirming overhead clearance Correct answer.
  2. Checking only that the lift platform is clean
  3. Checking the tyre pressures and the radio setting
  4. Checking that the bay lights are switched off

Explanation

The lift must be rated for the vehicle's weight with a margin, and the raised height plus the vehicle must clear overhead obstructions such as ducts and lamps. Exceeding capacity or striking the ceiling can cause structural failure or a dropped load. Cleanliness and tyre pressure are useful but do not address the primary risks.

Question 23Automotive Workshop Safety, Tools and Equipment

An apprentice reports a mild electric shock from a hand-held drill that still runs normally. What is the correct technical interpretation?

  1. The socket's voltage is too low and should be increased
  2. The shock is harmless because the drill still works
  3. The shock indicates the drill is too powerful for the socket
  4. A fault in insulation or earthing is present and the drill must be withdrawn and tested Correct answer.

Explanation

Even a mild shock indicates that current reached the operator through a fault such as degraded insulation or a broken earth connection. The equipment must be taken out of service and tested by a competent person. Continued operation risks a fatal shock, and the drill running normally does not prove it is safe.

Question 24Automotive Workshop Safety, Tools and Equipment

A workshop uses a hydraulic press to fit a bearing. Which precaution most directly prevents a sudden release of stored energy?

  1. Using a correctly rated press, centring the work and fitting a guard or shield around the work area Correct answer.
  2. Increasing the pump speed to finish the job faster
  3. Holding the bearing by hand to feel when it seats
  4. Placing the work off-centre so the ram has more leverage

Explanation

Hydraulic presses store large amounts of energy, and a bearing that shatters or slips can eject fragments. Correct capacity, centred loading and a guard contain that energy. Faster pumping, hand-holding or off-centre loading increases the chance of a sudden failure.

Question 25Automotive Engine Systems and Components

In a four-stroke spark-ignition engine, during which stroke does the intake valve remain open while the piston moves from top dead centre to bottom dead centre?

  1. Intake stroke Correct answer.
  2. Compression stroke
  3. Exhaust stroke
  4. Power stroke

Explanation

The intake stroke is the first stroke of the four-stroke cycle, when the piston travels downward from TDC to BDC and the descending piston creates a low-pressure region that draws the air-fuel mixture through the open intake valve. The other three strokes occur after the intake valve has closed and the charge is compressed, ignited and expelled.

Question 26Automotive Engine Systems and Components

Which component in a spark-ignition engine converts the reciprocating motion of the piston into rotary motion?

  1. Connecting rod and crankshaft assembly Correct answer.
  2. Flywheel
  3. Push rod
  4. Camshaft

Explanation

The connecting rod links the piston to the crankshaft, and as the piston reciprocates the rod swings and turns the crankshaft, producing rotary output. The crankshaft is the part that actually delivers the rotational motion to the flywheel and transmission.

Question 27Automotive Engine Systems and Components

The clearance volume of a cylinder is 50 cc and the swept volume is 450 cc. What is the compression ratio of the engine?

  1. 8:1
  2. 9:1
  3. 10:1 Correct answer.
  4. 11:1

Explanation

Compression ratio equals total cylinder volume divided by clearance volume. Total volume is swept volume plus clearance volume, that is 450 + 50 = 500 cc, and 500 divided by 50 gives 10:1.

Question 28Automotive Engine Systems and Components

What is the primary function of the flywheel in an engine?

  1. To open the exhaust valve at the correct time
  2. To filter the engine oil before it reaches the bearings
  3. To increase the compression ratio during the power stroke
  4. To store rotational energy and smooth out cyclic speed fluctuations Correct answer.

Explanation

Because only one power stroke occurs in every two revolutions of a four-stroke engine, the crankshaft speed tends to fluctuate. The flywheel's inertia absorbs energy during the power stroke and releases it during the other strokes, giving smoother running and helping the engine idle steadily.

Question 29Automotive Engine Systems and Components

In a diesel engine, how is the air-fuel mixture ignited?

  1. By a spark plug fired by the ignition coil
  2. By a pilot flame from the intake manifold
  3. By a glow plug that fires on every cycle
  4. By the heat of highly compressed air Correct answer.

Explanation

In a compression-ignition diesel engine, air is compressed to a high pressure and temperature, and fuel injected at the end of compression ignites spontaneously because of that heat. No spark is needed for normal running.

Question 30Automotive Engine Systems and Components

Which type of lubrication system uses a pump to force oil under pressure to the main bearings and connecting rod bearings?

  1. Splash lubrication system
  2. Grease-pack system
  3. Pressure lubrication system Correct answer.
  4. Petrol-oil premix system

Explanation

In a pressure (forced-feed) lubrication system, an oil pump delivers oil under pressure through galleries to the main bearings, big-end bearings and other moving parts before it drains back to the sump. Splash systems rely on dippers or slingers to throw oil instead of pumping it.

Question 31Automotive Engine Systems and Components

What is the main purpose of the radiator in a liquid-cooled engine?

  1. To pressurise the fuel line
  2. To transfer heat from the coolant to the surrounding air Correct answer.
  3. To increase the octane rating of the fuel
  4. To store extra coolant for the engine

Explanation

Hot coolant from the engine flows through the radiator core, where air passing over the fins absorbs heat and the coolant is cooled before returning to the engine. This maintains the engine within its designed operating temperature range.

Question 32Automotive Engine Systems and Components

A thermostat in the engine cooling system remains stuck in the closed position. What is the most likely result?

  1. The coolant freezes in the radiator
  2. The engine overheats because coolant cannot circulate to the radiator Correct answer.
  3. The engine runs colder than normal
  4. The radiator fan stops turning

Explanation

A closed thermostat blocks the path from the engine to the radiator, so the coolant cannot release heat and the engine temperature rises above normal. This can lead to overheating and possible gasket or head damage if not corrected.

Question 33Automotive Engine Systems and Components

Which part of the valve train directly opens the valve against spring pressure?

  1. Valve seat
  2. Valve guide
  3. Rocker arm Correct answer.
  4. Valve stem seal

Explanation

The rocker arm pivots and pushes down on the valve stem, overcoming the valve spring and opening the valve. The camshaft lobe drives the rocker arm, directly or through a push rod.

Question 34Automotive Engine Systems and Components

What is the effect of excessive valve clearance (tappet gap) in an overhead-valve engine?

  1. The compression ratio increases
  2. The valve opens earlier and stays open longer
  3. The valve opens later and closes earlier, reducing lift and causing noise Correct answer.
  4. The valve spring becomes stronger

Explanation

Excessive clearance means the rocker arm must travel further before contacting the valve stem, so the valve opens later, closes earlier and lifts less than designed. This reduces breathing efficiency and produces a loud tapping noise.

Question 35Automotive Engine Systems and Components

Which component supplies the spark in a conventional spark-ignition engine ignition system?

  1. Glow plug
  2. Spark plug Correct answer.
  3. Injector nozzle
  4. Fuel injector

Explanation

The spark plug is fitted into the combustion chamber and produces an electric arc across its electrodes when high voltage is applied. This arc ignites the compressed air-fuel mixture at the correct moment.

Question 36Automotive Engine Systems and Components

What is the function of the ignition coil?

  1. To step up battery voltage to a high voltage for the spark plug Correct answer.
  2. To filter electrical noise from the radio
  3. To store fuel before injection
  4. To regulate the alternator output

Explanation

The ignition coil uses mutual induction between its primary and secondary windings to transform the low battery voltage into the high voltage needed to jump the spark plug gap. When the primary circuit is interrupted, the collapsing magnetic field induces a high voltage in the secondary winding.

Question 37Automotive Engine Systems and Components

A technician finds that the engine cranks but does not start, and a spark test shows no spark at any plug. Which is the most logical first area to check?

  1. The fuel filter
  2. The ignition primary circuit and coil supply Correct answer.
  3. The radiator cap
  4. The exhaust muffler

Explanation

If no spark is present at any plug, the fault lies in the ignition system rather than in fuel or cooling. Checking the supply to the coil and the primary circuit confirms whether the coil is receiving power and switching signals.

Question 38Automotive Engine Systems and Components

What is the purpose of the air filter in the intake system?

  1. To remove dust and abrasive particles from the air entering the engine Correct answer.
  2. To silence the exhaust note
  3. To cool the intake air
  4. To mix fuel with air

Explanation

The air filter traps dust, grit and other particles so that they do not enter the cylinder and cause abrasive wear of the piston rings, cylinder bore and valves. Clean filtered air is essential for long engine life.

Question 39Automotive Engine Systems and Components

In a multi-point fuel injection system, where is fuel injected?

  1. Into the air cleaner housing
  2. Into the intake port near each cylinder's intake valve Correct answer.
  3. Into the throttle body above the throttle plate
  4. Directly into the exhaust manifold

Explanation

Multi-point (port) fuel injection uses one injector per cylinder mounted in the intake manifold runner close to the intake valve. This gives more accurate fuel metering per cylinder than a single central injector.

Question 40Automotive Engine Systems and Components

A petrol engine is said to be 'running rich'. What does this mean?

  1. The air-fuel mixture contains too much fuel for the air present Correct answer.
  2. The coolant contains too much antifreeze
  3. The air-fuel mixture contains too much air for the fuel present
  4. The engine oil level is too high

Explanation

A rich mixture has a lower air-fuel ratio than the stoichiometric value, meaning excess fuel remains after combustion. This causes black exhaust smoke, fouled plugs and higher fuel consumption.

Question 41Automotive Engine Systems and Components

Which of the following best describes the function of the catalytic converter?

  1. It cools the exhaust gases before release
  2. It converts harmful exhaust gases into less harmful substances Correct answer.
  3. It increases engine power by supercharging the intake
  4. It removes carbon dioxide from the exhaust completely

Explanation

The catalytic converter uses a catalyst to promote chemical reactions that oxidise carbon monoxide and hydrocarbons and reduce oxides of nitrogen into less harmful gases. It does not eliminate all emissions or add power.

Question 42Automotive Engine Systems and Components

In a turbocharger, what drives the turbine wheel?

  1. The engine's camshaft through a belt
  2. An electric motor powered by the battery
  3. The flow of exhaust gases leaving the engine Correct answer.
  4. The crankshaft through a gear train

Explanation

Exhaust gas energy spins the turbine wheel, which is connected by a shaft to the compressor wheel. The compressor then forces more air into the intake, increasing the charge density and engine power.

Question 43Automotive Engine Systems and Components

What is valve overlap in a four-stroke engine?

  1. The distance the valve travels from its seat
  2. The period when both intake and exhaust valves are open together near top dead centre Correct answer.
  3. The time taken for the valve spring to close the valve
  4. The gap between the valve stem and rocker arm

Explanation

Valve overlap occurs near the end of the exhaust stroke and the start of the intake stroke, when the intake valve has opened slightly before the exhaust valve fully closes. It uses the scavenging effect of exhaust flow to help draw in the fresh charge.

Question 44Automotive Engine Systems and Components

An engine has a bore of 80 mm and a stroke of 90 mm. Using the swept volume formula, what is the swept volume of one cylinder approximately?

  1. 720 cc
  2. 362 cc
  3. 452 cc Correct answer.
  4. 576 cc

Explanation

Swept volume equals the cross-sectional area of the bore multiplied by the stroke. The area is pi times 40 mm squared, about 5027 mm squared, and multiplying by 90 mm gives about 452,000 cubic millimetres, or roughly 452 cc.

Question 45Automotive Engine Systems and Components

Why is a pressurised cooling system with a radiator cap rated at a higher pressure beneficial?

  1. It reduces the freezing point of the coolant
  2. It eliminates the need for a thermostat
  3. It increases the flow rate of the coolant pump
  4. It raises the boiling point of the coolant, allowing higher operating temperatures without boiling Correct answer.

Explanation

Increasing the pressure in the cooling system raises the boiling point of the coolant, so the engine can run hotter without the coolant boiling and forming vapour pockets. This improves heat transfer and reduces coolant loss.

Question 46Automotive Engine Systems and Components

Which statement correctly describes the operation of a two-stroke engine?

  1. It completes one power stroke in every two revolutions of the crankshaft
  2. It completes one power stroke in every revolution of the crankshaft Correct answer.
  3. It has no crankcase compression
  4. It uses only intake and exhaust strokes

Explanation

In a two-stroke engine, the piston performs the intake, compression, power and exhaust functions in a single up-and-down movement, so one power stroke occurs per crankshaft revolution. This gives a higher power-to-weight ratio than a four-stroke of similar size.

Question 47Automotive Engine Systems and Components

A knocking or pinging sound is heard from a spark-ignition engine under load. Which factor most directly causes this?

  1. Premature detonation of the end gas in the cylinder Correct answer.
  2. A clogged air filter element
  3. A loose radiator hose clamp
  4. Too low an engine oil level

Explanation

Knock occurs when the unburnt end gas ahead of the flame front ignites spontaneously because of high pressure and temperature, producing a sharp pressure pulse. Causes include over-advanced ignition timing, low-octane fuel and excessive compression.

Question 48Automotive Engine Systems and Components

What is the function of a piston ring, specifically the compression ring?

  1. To transfer heat from the piston crown to the cylinder wall only
  2. To connect the piston to the connecting rod
  3. To wipe excess oil from the cylinder wall
  4. To seal the combustion chamber and prevent gas leakage past the piston Correct answer.

Explanation

The top compression rings press against the cylinder wall to seal the combustion chamber, preventing high-pressure gases from escaping past the piston into the crankcase. The oil control ring, by contrast, regulates the oil film.

Question 49Automotive Engine Systems and Components

A vehicle's engine oil pressure warning lamp comes on while driving. Which action is most appropriate?

  1. Stop the engine safely as soon as possible and check the oil level and pressure Correct answer.
  2. Turn off the air conditioning and continue
  3. Increase engine speed to raise oil pressure
  4. Continue driving until the next scheduled service

Explanation

Low oil pressure means bearings and other moving parts may be starved of lubrication, which can cause rapid and severe damage. The safe action is to stop the engine promptly, check the oil level and investigate the cause before running it again.

Question 50Automotive Engine Systems and Components

In a four-stroke spark-ignition engine, which component transmits the upward and downward motion of the piston to the crankshaft while allowing the connecting rod to swing as the crank rotates?

  1. The gudgeon pin, which joins the piston to the small end of the connecting rod Correct answer.
  2. The camshaft lobe, which actuates the follower
  3. The crankshaft counterweight, which balances the rotating assembly
  4. The flywheel ring gear, which meshes with the starter pinion

Explanation

The gudgeon pin (piston pin) is the hollow pin that passes through the piston boss and the small end of the connecting rod, forming a pivot so the rod can swing while the piston stays aligned in the bore. It must withstand combustion load and reciprocating inertia while transferring force from the piston crown to the rod. Counterweights, cam lobes and the ring gear perform entirely different duties in the engine.