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Assam ASSEB HSLC NSQF Automotive study materials
Assam ASSEB HSLC NSQF Automotive study resources

Assam ASSEB HSLC NSQF Automotive practice questions

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Question 1Automotive Workshop Safety, Tools and Equipment

A trainee in an HSLC automotive workshop must lift a heavy gearbox. Which practice best protects the spine during the lift?

  1. Twist the trunk while lifting to gain momentum
  2. Keep the back straight, bend the knees and hold the load close to the body Correct answer.
  3. Bend at the waist and keep the arms straight
  4. Lift with outstretched arms to keep the load away from the body

Explanation

Safe manual handling keeps the natural curve of the spine, uses the strong leg muscles, and holds the load close so the load moment on the lower back is small. Twisting or reaching away from the body greatly increases spinal stress.

Question 2Automotive Workshop Safety, Tools and Equipment

In an automotive workshop, which PPE is specifically intended to protect the eyes while using a bench grinder?

  1. Leather hand gloves
  2. Close-fitting safety goggles Correct answer.
  3. A cotton dust mask
  4. Steel-toe safety boots

Explanation

Grinding throws high-speed metal particles and sparks, so impact-rated close-fitting goggles are needed to seal around the eyes. Gloves, masks and boots protect other body parts and do not shield the eyes.

Question 3Automotive Workshop Safety, Tools and Equipment

A carbon dioxide fire extinguisher is most appropriate for which workshop situation?

  1. A fire in a timber storage rack
  2. An electrical fire in a battery charger panel Correct answer.
  3. A fire in a magnesium alloy component
  4. A deep-seated fire in a waste-oil soaked rag bin

Explanation

Carbon dioxide is a clean, non-conducting agent that leaves no residue, so it suits live electrical equipment such as a charger panel. It has poor cooling and penetration, so deep-seated or metal fires are not its application.

Question 4Automotive Workshop Safety, Tools and Equipment

Why must a vehicle be supported on axle stands rather than on a hydraulic trolley jack alone before working underneath it?

  1. Axle stands make the suspension easier to inspect
  2. Axle stands allow the wheels to be removed more quickly
  3. A trolley jack can lose pressure and lower the vehicle unexpectedly Correct answer.
  4. A trolley jack cannot reach the recommended lifting points

Explanation

A hydraulic jack is a lifting device, not a support device; seals can fail or the release valve can creep, allowing sudden descent. Rigid axle stands provide a positive mechanical support before anyone goes under the vehicle.

Question 5Automotive Workshop Safety, Tools and Equipment

Before using a pneumatic impact wrench on a wheel nut, what is the correct sequence of checks?

  1. Inspect the socket and impact-rated hose, confirm the correct pressure, and check the socket is fully seated Correct answer.
  2. Increase pressure above the rated value to break the nut quickly
  3. Fit the socket, start the tool, then check the hose pressure
  4. Remove the safety clip so the socket fits more easily

Explanation

Impact work requires impact-rated sockets and hoses, correct regulated pressure, and full socket engagement on the nut. This prevents socket shatter, hose whip and rounded fasteners.

Question 6Automotive Workshop Safety, Tools and Equipment

A ring spanner is preferred over an open-ended spanner for loosening a tight bolt because it:

  1. Fits several bolt sizes at once
  2. Can be used with a hammer to shock the bolt
  3. Grips all six flats of the fastener and resists slipping Correct answer.
  4. Has a thinner head for tight spaces

Explanation

A ring spanner contacts all six corners of the hexagon, spreading the load and reducing the risk of rounding the fastener or slipping. An open-ended spanner contacts only two flats and is more likely to slip under high torque.

Question 7Automotive Workshop Safety, Tools and Equipment

Which torque wrench handling practice preserves measurement accuracy?

  1. Using it as a breaker bar for loosening seized nuts
  2. Returning it to its lowest setting after use and calibrating it periodically Correct answer.
  3. Storing it set at its maximum scale value
  4. Leaving it in a hot workshop cabinet for long periods

Explanation

A torque wrench is a measuring instrument; its spring should be unloaded to the lowest setting after use and the tool should be calibrated at intervals. Using it to loosen fasteners or storing it at high setting causes drift.

Question 8Automotive Workshop Safety, Tools and Equipment

What is the main reason for wearing a face shield in addition to goggles when using a compressed-air blow gun for cleaning parts?

  1. The shield filters solvent vapour
  2. The shield keeps the hair tidy
  3. The shield protects the whole face from flying debris and fluid mist Correct answer.
  4. The shield improves visibility of small parts

Explanation

Compressed air can drive chips, rust and solvent mist back towards the operator, and a face shield adds full-face coverage over the eyes. It is not a respiratory filter and does not replace ventilation.

Question 9Automotive Workshop Safety, Tools and Equipment

Which class of fire involves flammable liquids such as petrol and diesel in a workshop?

  1. Class B Correct answer.
  2. Class D
  3. Class A
  4. Class C

Explanation

Class B fires are those of flammable and combustible liquids such as petrol, diesel and solvents. Class A is solid combustibles, Class C involves flammable gases and Class D combustible metals.

Question 10Automotive Workshop Safety, Tools and Equipment

A bench grinder in the workshop must have the wheel guard and tool rest correctly set. What is the recommended maximum gap between the tool rest and the wheel face?

  1. About 20 mm
  2. About 10 mm
  3. About 3 mm Correct answer.
  4. About 30 mm

Explanation

The tool rest should be set close to the wheel, typically within about 3 mm, so that a workpiece cannot be drawn into the gap and jam or shatter the wheel. Larger gaps create a nip point and increase the risk of wheel burst injury.

Question 11Automotive Workshop Safety, Tools and Equipment

Why is it unsafe to use a screwdriver as a chisel or a pry bar?

  1. The blade is hardened for torsion and may snap and fly off Correct answer.
  2. The handle may be a different colour
  3. The tip is always magnetic
  4. The screwdriver is too short for any lever work

Explanation

Screwdriver blades are hardened and tempered for twisting loads, not for impact or bending, so they can crack and eject sharp fragments. The correct tool for striking or prying must be used instead.

Question 12Automotive Workshop Safety, Tools and Equipment

What is the correct action when a hydraulic floor jack begins to sink slowly while holding a raised vehicle?

  1. Place axle stands and lower the vehicle onto them, then take the jack out of service Correct answer.
  2. Add oil to the reservoir while the load is held
  3. Pump the handle rapidly to keep it up
  4. Continue working quickly before it sinks further

Explanation

Slow sinking indicates a leaking seal or valve, so the jack must not be trusted as a support. The vehicle should be set on axle stands and the faulty jack tagged and withdrawn from service for repair.

Question 13Automotive Workshop Safety, Tools and Equipment

Which property makes a micrometer more suitable than a steel rule for measuring valve stem diameter?

  1. It reads to 0.01 mm with a controlled measuring force Correct answer.
  2. It has a longer measuring range
  3. It can measure while the engine is hot
  4. It does not need zeroing

Explanation

A micrometer uses a calibrated screw and a friction or ratchet thimble to give a repeatable reading to 0.01 mm at a controlled force. A steel rule has coarse graduations and depends on the operator's eye and touch.

Question 14Automotive Workshop Safety, Tools and Equipment

A vernier caliper reads 0 on the main scale when closed, but the vernier zero is slightly past the main-scale zero. What does this indicate?

  1. The depth rod is fully extended
  2. The jaws are too sharp
  3. The caliper is correctly adjusted
  4. There is a zero error that must be allowed for or the tool reset Correct answer.

Explanation

When the jaws are closed the two zeros must coincide; if they do not, the instrument has a zero error. The error is either corrected by adjustment or added to or subtracted from every reading.

Question 15Automotive Workshop Safety, Tools and Equipment

Which statement correctly describes the safe use of an angle grinder with a cutting disc?

  1. Fit the guard, use the correct disc for the material, and let the disc cut at its rated speed Correct answer.
  2. Remove the side handle to reach awkward areas
  3. Use the disc without the guard to see the cut line clearly
  4. Apply side pressure to speed up cutting through thick metal

Explanation

The guard contains fragments if the disc bursts, the disc must match the material and the machine's rated speed, and the side handle gives control against kickback. Side loading and guard removal are common causes of disc failure.

Question 16Automotive Workshop Safety, Tools and Equipment

In a workshop using oxy-acetylene equipment, why must the cylinder valves be opened slowly and the regulator adjusted before the torch valve?

  1. To save gas during the working day
  2. To avoid a sudden pressure surge that can damage the regulator and cause a flashback risk Correct answer.
  3. To make the flame hotter
  4. To keep the cylinder cool

Explanation

Opening a cylinder valve quickly sends a high-pressure surge into the regulator, which can damage the diaphragm and seat and create unsafe pressure. Slow opening and correct regulator setting give controlled delivery to the torch.

Question 17Automotive Workshop Safety, Tools and Equipment

What is the main purpose of a fume extraction system in an automotive paint booth?

  1. To cool the booth for the painter's comfort
  2. To speed up the drying of the paint film
  3. To remove solvent vapour and overspray from the breathing zone Correct answer.
  4. To increase the gloss of the finish

Explanation

Solvent-based paints and thinners release harmful vapours, so extraction removes them from the operator's breathing zone and keeps concentrations below exposure limits. Comfort, drying speed and finish gloss are secondary effects, not the safety purpose.

Question 18Automotive Workshop Safety, Tools and Equipment

A socket is marked 12-point and is used on a badly corroded hex nut. Why is a 6-point socket usually the better choice?

  1. It fits any size of nut
  2. It is always shorter
  3. It can be used without a ratchet
  4. It grips the flats rather than the corners and reduces rounding Correct answer.

Explanation

A 6-point socket contacts the flat sides of the hexagon, so the load is spread and the corners of a corroded nut are less likely to round off. A 12-point socket contacts nearer the corners and is better suited to undamaged fasteners in tight swing arcs.

Question 19Automotive Workshop Safety, Tools and Equipment

Which statement best explains why a torque wrench should not be used to check the torque of a fastener that was just tightened with an impact wrench?

  1. The torque wrench cannot fit on an impact-tightened nut
  2. Impact wrenches leave no torque on the fastener
  3. The torque wrench will damage the impact socket
  4. The torque wrench will read higher than the true tightening torque because of friction and relaxation effects Correct answer.

Explanation

Impact tightening leaves the joint in a different friction and relaxation state, so a static torque check does not reproduce the original tightening torque. Torque should be applied with the torque wrench itself, in a controlled sequence.

Question 20Automotive Workshop Safety, Tools and Equipment

Which practice is correct for storing hand tools at the end of a workshop session?

  1. Leave them on the floor beside the vehicle for the next shift
  2. Oil every tool heavily and stack them in a drawer
  3. Clean them, check for damage and return them to the designated rack or toolbox Correct answer.
  4. Store cutting tools with the edge exposed for quick access

Explanation

Tools should be cleaned, inspected for damage and returned to their designated place, which prevents loss, corrosion and injuries from tools left on the floor. Damaged tools are tagged for repair rather than returned to service.

Question 21Automotive Workshop Safety, Tools and Equipment

A workshop air line is fitted with a filter-regulator-lubricator unit. What is the function of the lubricator in this unit?

  1. To regulate the line pressure
  2. To add a fine oil mist to lubricate air tools Correct answer.
  3. To filter solid particles from the air
  4. To remove water from the compressed air

Explanation

The lubricator injects a controlled oil mist into the air stream so that pneumatic tools receive internal lubrication. Water removal and particle filtering are done by the filter, and pressure is set by the regulator.

Question 22Automotive Workshop Safety, Tools and Equipment

What is the correct first action when a small petrol fire starts in the workshop fuel bay?

  1. Fan the flames with a rag to disperse the vapour
  2. Cover the fire with a plastic sheet
  3. Raise the alarm, cut off the fuel and electricity if safe, and use a suitable extinguisher from a safe distance Correct answer.
  4. Throw water on the flames

Explanation

The priority is to alert others, remove the fuel and ignition sources where it is safe to do so, and attack the fire with a foam, dry powder or CO2 extinguisher from a safe position with an escape route. Water spreads burning petrol.

Question 23Automotive Workshop Safety, Tools and Equipment

Which inspection point is most critical before using a two-post vehicle lift in an HSLC workshop?

  1. The vehicle has a full fuel tank
  2. The lifting pads and arm locks are correctly positioned at the manufacturer's lift points Correct answer.
  3. The colour of the lift arms
  4. The workshop clock shows the correct time

Explanation

A two-post lift must have its arms and pads located at the vehicle manufacturer's designated lift points and the arm locks engaged, otherwise the vehicle can slip or the body can deform. Colour, time and fuel level have no bearing on lift safety.

Question 24Automotive Workshop Safety, Tools and Equipment

Why is a hacksaw blade fitted with the teeth pointing forward, away from the handle, in normal workshop use?

  1. It makes the frame lighter
  2. It prevents the blade from rusting
  3. The cutting action occurs on the forward stroke, which gives better control and blade life Correct answer.
  4. It allows the saw to cut on the back stroke only

Explanation

With teeth pointing forward, the saw cuts on the push stroke, which is the stronger and more controllable action for the operator. The return stroke is light, so the blade is loaded mainly in the intended direction.

Question 25Automotive Engine Systems and Components

In a four-stroke petrol engine, which component opens and closes the intake and exhaust ports in a side-valve (L-head) design?

  1. The crankshaft counterweights
  2. The flywheel ring gear
  3. The piston skirt uncovering the ports
  4. The camshaft acting through lifters and valves Correct answer.

Explanation

In a side-valve engine the camshaft lobes push lifters that open the valves, and springs close them, so valve timing is controlled by the camshaft. The piston does not uncover the ports in this design; that happens only in two-stroke and sleeve-valve arrangements.

Question 26Automotive Engine Systems and Components

What is the main function of the flywheel in an automotive engine?

  1. To cool the exhaust gases before they leave the manifold
  2. To store rotational energy and smooth out power pulses between firing strokes Correct answer.
  3. To filter engine oil before it reaches the bearings
  4. To increase the compression ratio during high load

Explanation

The flywheel's inertia keeps the crankshaft turning between power strokes and absorbs cyclic speed fluctuations, giving smoother running. It also provides a mounting face for the clutch and a ring gear for the starter.

Question 27Automotive Engine Systems and Components

A technician drains engine oil and finds it thin, dark and smelling strongly of petrol. Which component is the most likely cause?

  1. A blocked radiator core
  2. A faulty thermostat stuck open
  3. A worn fuel pump diaphragm or leaking injector diluting the oil Correct answer.
  4. A slipping clutch disc

Explanation

Fuel dilution occurs when unburnt petrol enters the sump, typically through a leaking fuel pump diaphragm or a dripping injector. The fuel thins the oil and lowers its lubricating film strength, so the fault must be corrected before the oil is changed again.

Question 28Automotive Engine Systems and Components

Which sequence correctly describes the four strokes of a four-stroke diesel engine?

  1. Power, exhaust, intake, compression
  2. Compression, intake, exhaust, power
  3. Intake, power, compression, exhaust
  4. Intake, compression, power, exhaust Correct answer.

Explanation

The standard order is intake of air, compression of that air to a high pressure and temperature, power from fuel injected and ignited, then exhaust of burnt gases. Only air is drawn in on the intake stroke in a diesel; fuel is injected near the end of compression.

Question 29Automotive Engine Systems and Components

A compression-ignition engine has a measured compression pressure well below specification on all cylinders, and the engine is hard to start when cold. Which cause best fits these symptoms?

  1. A clogged fuel filter only
  2. Worn piston rings and cylinder bores causing blow-by Correct answer.
  3. A weak ignition coil
  4. An incorrectly adjusted clutch pedal

Explanation

Uniformly low compression across all cylinders points to a common mechanical cause such as worn rings, glazed bores or leaking valves. In a diesel, low compression means the air does not reach ignition temperature, so cold starting becomes difficult.

Question 30Automotive Engine Systems and Components

What is the purpose of the thermostat in an engine cooling system?

  1. To remove air bubbles from the radiator
  2. To drive the water pump impeller
  3. To regulate coolant flow so the engine reaches and holds its design operating temperature Correct answer.
  4. To increase the boiling point of the coolant

Explanation

The thermostat is a temperature-sensitive valve that stays closed during warm-up and then opens to route coolant through the radiator. This keeps the engine within its design temperature band for efficient combustion and lubrication.

Question 31Automotive Engine Systems and Components

In a simple carburettor, what happens to the air-fuel mixture as the throttle butterfly is opened further at constant engine speed?

  1. Mixture strength stays exactly constant regardless of throttle position
  2. Less air flows and fuel delivery is reduced
  3. The float chamber empties completely
  4. More air flows and the venturi depression increases, drawing more fuel Correct answer.

Explanation

Opening the throttle reduces the restriction, so airflow rises and the venturi vacuum signal strengthens, pulling additional fuel through the main jet. The result is a richer and larger charge to meet increased load demand.

Question 32Automotive Engine Systems and Components

Which component converts the reciprocating motion of the piston into rotary motion of the crankshaft?

  1. The connecting rod Correct answer.
  2. The camshaft
  3. The rocker arm
  4. The pushrod

Explanation

The connecting rod links the piston pin to the crankpin and swings through an arc as the piston moves, converting linear piston travel into crankshaft rotation. The other listed parts belong to the valve train.

Question 33Automotive Engine Systems and Components

An engine shows blue-grey smoke from the exhaust that persists after warm-up. Which condition is the most probable cause?

  1. A restricted exhaust silencer
  2. Coolant leaking into the intake manifold
  3. Excessively lean air-fuel mixture
  4. Engine oil entering the combustion chamber past worn valve guides or rings Correct answer.

Explanation

Blue-grey smoke indicates oil being burnt in the cylinder, usually from worn valve stem seals, valve guides or piston rings. Lean mixture and coolant leakage produce different symptoms, so the oil path must be checked.

Question 34Automotive Engine Systems and Components

What does the term valve overlap mean in an engine valve-timing diagram?

  1. The period when both intake and exhaust valves are open around top dead centre Correct answer.
  2. The angle by which the camshaft lags the crankshaft
  3. The lift of the valve at maximum cam peak
  4. The clearance between valve stem and rocker arm

Explanation

Valve overlap is the crank-angle interval during which the intake valve has opened before the exhaust valve fully closes, near the end of the exhaust stroke. It uses gas flow inertia to improve scavenging and cylinder filling.

Question 35Automotive Engine Systems and Components

A vehicle with a turbocharged diesel engine loses power and the turbocharger makes a whistling noise, with oil mist found in the intake duct. Which fault best explains this?

  1. A clogged air filter element only
  2. A worn clutch release bearing
  3. A leaking compressor seal allowing oil into the intake Correct answer.
  4. An over-tightened drive belt

Explanation

Oil mist in the intake duct together with a whistling noise suggests the compressor-side seal is leaking, letting lubricating oil pass into the airstream. This reduces boost efficiency and can cause smoke, so the turbocharger should be inspected.

Question 36Automotive Engine Systems and Components

Which type of bearing is normally used for the main and big-end bearings of a modern automotive engine crankshaft?

  1. Deep groove ball bearings packed with grease
  2. Taper roller bearings running dry
  3. Precision thin-wall shell bearings with a lubricating oil film Correct answer.
  4. Bronze bushings without oil supply

Explanation

Crankshaft main and big-end bearings are split thin-wall shells with a soft overlay, relying on a pressurised hydrodynamic oil film rather than rolling elements. This design allows high load capacity, easy replacement and precise clearance control.

Question 37Automotive Engine Systems and Components

What is the effect of excessively advanced ignition timing on a spark-ignition engine?

  1. Fuel consumption falls sharply with no risk of detonation
  2. The starter motor turns more slowly
  3. The engine runs cooler and produces more torque at all speeds
  4. Peak cylinder pressure occurs too early, causing knock and possible piston damage Correct answer.

Explanation

Advancing ignition makes the mixture burn earlier so peak pressure arrives before top dead centre, opposing piston motion. This raises peak temperature and pressure, producing knock and possible piston or head gasket damage.

Question 38Automotive Engine Systems and Components

Which statement correctly describes the function of the radiator pressure cap?

  1. It filters rust particles from the coolant
  2. It controls the speed of the cooling fan
  3. It raises the coolant boiling point by maintaining system pressure and allows coolant to return from the expansion tank Correct answer.
  4. It prevents coolant from circulating when the engine is hot

Explanation

By holding pressure in a sealed cooling system, the cap raises the boiling point of the coolant, allowing higher operating temperatures without boil-over. Its vacuum valve also lets coolant return from the overflow bottle as the system cools.

Question 39Automotive Engine Systems and Components

During a cylinder leakage test, air escapes continuously from the oil filler neck. What does this indicate?

  1. A leaking intake valve
  2. A blown head gasket between two adjacent cylinders
  3. A leaking exhaust valve
  4. Leakage past the piston rings or a holed piston into the crankcase Correct answer.

Explanation

Air heard at the oil filler neck has travelled from the combustion chamber into the crankcase, which points to worn rings, a scored bore or a damaged piston. Listening at the intake, exhaust and radiator helps separate valve and gasket faults.

Question 40Automotive Engine Systems and Components

Which component in a common-rail diesel injection system stores high-pressure fuel and supplies it to the injectors?

  1. The fuel filter housing
  2. The high-pressure accumulator rail Correct answer.
  3. The lift pump in the tank
  4. The EGR cooler

Explanation

The rail is a common high-pressure accumulator fed by the high-pressure pump; it delivers fuel to all injectors at the pressure set by the control valve. Injection timing and quantity are then controlled electronically at each injector.

Question 41Automotive Engine Systems and Components

A mechanic measures the valve clearance of an overhead-valve engine and finds it smaller than specification. What is the likely consequence?

  1. The engine oil pressure will increase
  2. The valve will open later than designed and reduce lift
  3. The valve may not seat fully, causing compression loss and possible burning Correct answer.
  4. The camshaft will rotate at half speed

Explanation

Too little clearance means the valve is held slightly off its seat when the engine is hot, so compression leaks and the valve face can overheat and burn. Clearance must be reset to the manufacturer's specification.

Question 42Automotive Engine Systems and Components

Which of the following best describes the purpose of a PCV (positive crankcase ventilation) system?

  1. To supply extra fuel during cold starting
  2. To cool the engine oil during high-speed running
  3. To draw blow-by gases from the crankcase back into the intake for burning Correct answer.
  4. To increase the compression ratio of the engine

Explanation

The PCV valve meters crankcase blow-by gases into the intake manifold so they are burnt rather than released to atmosphere. This also prevents pressure build-up that could force oil past seals.

Question 43Automotive Engine Systems and Components

An engine starts and runs but overheats rapidly, and the top radiator hose stays cool while the bottom hose is hot. What is the most likely fault?

  1. A leaking radiator cap
  2. A blocked heater matrix only
  3. A thermostat stuck closed Correct answer.
  4. A faulty water pump drive belt

Explanation

If the thermostat stays closed, coolant cannot circulate through the radiator, so the upper hose remains cool while the engine block overheats. Replacing or testing the thermostat in hot water confirms the diagnosis.

Question 44Automotive Engine Systems and Components

Which of these is a correct description of the firing order of a four-cylinder in-line engine?

  1. It gives the order in which valves are adjusted
  2. It specifies the tightening sequence of cylinder head bolts
  3. It defines the sequence in which cylinders receive their power strokes Correct answer.
  4. It lists the order in which spark plugs are removed

Explanation

Firing order is the crankshaft-angle sequence in which the cylinders reach top dead centre on the power stroke, chosen to balance loads on the crankshaft. It is not a service sequence such as bolt tightening.

Question 45Automotive Engine Systems and Components

A vehicle is emitting black smoke under acceleration and the exhaust smells strongly of unburnt fuel. Which fault is most consistent with these symptoms?

  1. A blocked crankcase breather
  2. Over-fuelling from a leaking injector or incorrect air-fuel ratio Correct answer.
  3. A weak battery
  4. A worn wheel bearing

Explanation

Black smoke indicates excessive fuel in the mixture, so the air-fuel ratio is too rich, often from a leaking injector or a faulty sensor. The excess fuel cannot burn completely and leaves soot in the exhaust.

Question 46Automotive Engine Systems and Components

Which statement about the function of the camshaft in a four-stroke engine is correct?

  1. It rotates at twice crankshaft speed and drives the distributor only
  2. It rotates at half crankshaft speed and operates the valves at the correct time Correct answer.
  3. It regulates the pressure of the lubricating oil
  4. It converts reciprocating motion into rotary motion

Explanation

Because each valve opens once per two crankshaft revolutions, the camshaft must turn at half engine speed. Its lobes are ground with the correct profile to give the required lift and timing.

Question 47Automotive Engine Systems and Components

What is the primary reason for using a multi-grade engine oil such as 15W-40 instead of a single-grade oil?

  1. It eliminates the need for an oil filter
  2. It maintains a suitable viscosity over a wide temperature range from cold start to hot running Correct answer.
  3. It increases the compression ratio
  4. It has a higher calorific value than single-grade oil

Explanation

The W rating describes low-temperature flow behaviour, while the second number describes viscosity at operating temperature. A multi-grade oil therefore flows easily when cold yet still protects when hot.

Question 48Automotive Engine Systems and Components

A compression test on a four-cylinder petrol engine gives 11.5, 11.8, 7.2 and 11.6 bar. What is the correct interpretation?

  1. The engine has a uniform fault affecting all cylinders
  2. The gauge is definitely faulty and the test must be repeated
  3. One cylinder has a compression fault and should be investigated further Correct answer.
  4. The engine is in good condition with normal variation

Explanation

Three cylinders are close together while one is far below the others, which indicates a localised fault such as a burnt valve, broken ring or head gasket leak on that cylinder. A wet test and leakage test would help pinpoint the cause.

Question 49Transmission, Clutch, Gearbox and Driveline

In a vehicle clutch, which component is pressed against the rotating flywheel by the pressure plate to transmit engine torque to the gearbox input shaft?

  1. The pilot bushing
  2. The throw-out fork
  3. The release bearing
  4. The clutch disc (friction plate) Correct answer.

Explanation

The clutch disc carries friction lining on both faces and is clamped between the flywheel and the pressure plate. Friction at these two surfaces locks the disc to the engine so torque flows into the gearbox input shaft. The release bearing and fork only act to disengage the clamp load.

Question 50Transmission, Clutch, Gearbox and Driveline

A driver notices the clutch pedal must be pressed almost to the floor before the gears can be selected with the engine running. Which condition best explains this?

  1. The gearbox is overfilled with oil
  2. The clutch friction disc is worn thin
  3. The differential backlash is excessive
  4. The clutch is dragging because release travel is insufficient Correct answer.

Explanation

When the pedal must travel very far before disengagement, the release mechanism is not fully separating the disc from the flywheel. The clutch therefore drags and keeps applying torque to the input shaft, making gear selection difficult. Worn hydraulics, air in the line, or a misadjusted cable are typical causes.