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BTEB Automotive Mechanics study materials
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BTEB Automotive Mechanics practice questions

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Question 1Workshop Safety, Tools and Measuring Instruments

Which personal protective equipment is most important when using a bench grinder to sharpen a chisel?

  1. A leather apron
  2. Safety goggles or a face shield Correct answer.
  3. Steel-toed boots
  4. Anti-vibration gloves

Explanation

A bench grinder throws sparks and small metal particles at high speed toward the operator's face. Eye protection such as goggles or a face shield prevents permanent eye injury from these flying fragments. Other PPE helps but does not address the primary hazard of the task.

Question 2Workshop Safety, Tools and Measuring Instruments

What is the correct way to carry a single open-end wrench across the workshop?

  1. Gripped firmly with the jaw pointing down and close to the body Correct answer.
  2. Held with the jaw pointing forward
  3. Held loosely in one hand at your side
  4. Carried in a pocket of overalls

Explanation

A wrench should be gripped firmly with the heavy jaw end pointing downward so that a slip cannot swing the head into the body or another person. Keeping it close to the body also reduces the chance of striking equipment or passers-by.

Question 3Workshop Safety, Tools and Measuring Instruments

A vernier caliper main scale reads 24 mm and the vernier scale shows the 6th line coinciding with a main scale line. If the vernier has 50 divisions, what is the reading?

  1. 24.60 mm
  2. 30.00 mm
  3. 24.06 mm
  4. 24.12 mm Correct answer.

Explanation

With 50 vernier divisions the least count is 1 mm divided by 50, which is 0.02 mm. Multiplying the coinciding line number by the least count gives 6 x 0.02 = 0.12 mm, so the reading is 24.12 mm.

Question 4Workshop Safety, Tools and Measuring Instruments

Why is a micrometer screw gauge generally preferred over a vernier caliper for measuring the diameter of a fuel injector needle?

  1. It does not need to be zeroed before use
  2. It can measure inside diameters more easily
  3. It has a larger measuring range
  4. It applies a controlled measuring force and reads to 0.01 mm Correct answer.

Explanation

A micrometer uses a friction thimble or ratchet that limits and standardises the clamping force, so soft or precision parts are not squeezed and distorted. Its 0.01 mm resolution also suits small precision components better than a typical caliper.

Question 5Workshop Safety, Tools and Measuring Instruments

A feeler gauge is the correct instrument for which of the following tasks?

  1. Measuring the diameter of a piston pin
  2. Checking the torque of a cylinder head bolt
  3. Checking valve clearance or spark plug gap Correct answer.
  4. Measuring the depth of a cylinder bore

Explanation

A feeler gauge is a set of thin steel blades of known thickness used to check small gaps by trial fit. Valve clearances and spark plug gaps are set by finding the blade that just slides through the gap with slight drag.

Question 6Workshop Safety, Tools and Measuring Instruments

Before using a torque wrench to tighten a cylinder head, what practice gives the most reliable result?

  1. Setting the wrench to the highest scale value and tightening once
  2. Using an extension bar as long as possible to increase leverage
  3. Applying thread lubricant to every bolt regardless of specification
  4. Calibrating the wrench and following the specified tightening sequence and stages Correct answer.

Explanation

Torque accuracy depends on the wrench being calibrated and on the fastener being tightened in the sequence and stages specified by the manufacturer. Staged tightening distributes clamping load evenly and prevents head distortion.

Question 7Workshop Safety, Tools and Measuring Instruments

Which property makes a socket made of chrome vanadium steel suitable for general workshop use?

  1. It combines toughness with hardness so it resists shock without shattering Correct answer.
  2. It is very hard and brittle so it resists wear
  3. It is soft enough to deform and warn of overload
  4. It is non-magnetic so it will not hold swarf

Explanation

Chrome vanadium steel is heat treated to give a balance of hardness and toughness, so a socket can withstand repeated impact and torque without cracking. Purely hard steels are brittle and can shatter under shock loads.

Question 8Workshop Safety, Tools and Measuring Instruments

A spanner is being used to loosen a stubborn nut. Which practice is safest and most effective?

  1. Pulling the handle toward you with the spanner squarely seated Correct answer.
  2. Pushing the handle away from you with an extension pipe fitted
  3. Striking the spanner with a hammer while it is under load
  4. Using a spanner one size larger to gain extra leverage

Explanation

Pulling toward the body with the spanner fully seated on the nut keeps the load controlled and prevents the jaw from slipping off and the hand from striking a hard surface. The correct size ensures full contact on the flats.

Question 9Workshop Safety, Tools and Measuring Instruments

Which fire extinguisher class is appropriate for a burning petrol spill on the workshop floor?

  1. Class A water extinguisher
  2. Class C only, using carbon dioxide on the fuel surface
  3. Class D sodium chloride extinguisher
  4. Class B foam or dry powder extinguisher Correct answer.

Explanation

Petrol is a flammable liquid, which places it in Class B, and foam or dry powder smothers the vapour and cools the surface. Water must never be used because it spreads the burning liquid.

Question 10Workshop Safety, Tools and Measuring Instruments

A hydraulic jack is used to raise a vehicle before work underneath. What must be done before anyone goes below it?

  1. Chock only the front wheels and rely on the jack
  2. Place rated axle stands under the chassis and lower the weight onto them Correct answer.
  3. Keep the jack handle in place as a secondary support
  4. Lower the jack slightly to settle the load

Explanation

A hydraulic jack can lose pressure suddenly, so it is only a lifting device and never a support. Rated axle stands placed under strong chassis points carry the load mechanically and remove the danger of crushing.

Question 11Workshop Safety, Tools and Measuring Instruments

When grinding a twist drill on a pedestal grinder, the tool rest should be set so that the gap to the wheel is no more than about:

  1. 3 mm Correct answer.
  2. 50 mm
  3. 15 mm
  4. 25 mm

Explanation

Keeping the tool rest close to the wheel, about 3 mm, prevents the workpiece or the operator's fingers from being drawn into the gap between the rest and the rotating wheel. A large gap creates a trapping hazard.

Question 12Workshop Safety, Tools and Measuring Instruments

A steel rule is being used to check the length of a component. Which error most affects the accuracy of the result?

  1. Holding the rule at an angle to the surface Correct answer.
  2. Using the rule at room temperature
  3. Reading the scale in good lighting
  4. Placing the rule end flush with the datum face

Explanation

Parallax error arises when the eye, the scale and the measured edge are not aligned, and tilting the rule also makes the measured length appear longer than it is. The rule should be laid flat and viewed squarely.

Question 13Workshop Safety, Tools and Measuring Instruments

A dial test indicator reading fluctuates by 0.03 mm while a shaft is rotated. What does this most likely indicate?

  1. The indicator is out of calibration
  2. The shaft has runout or is mounted eccentrically Correct answer.
  3. The magnetic base is too strong
  4. The shaft is perfectly round

Explanation

A dial test indicator measures small displacements, so a repeating variation as the shaft turns shows that the surface is not concentric with the axis of rotation. This runout may come from a bent shaft, an eccentric mounting or an out-of-round journal.

Question 14Workshop Safety, Tools and Measuring Instruments

A micrometer reads 0.02 mm when its jaws are closed. How should this be handled when measuring a component?

  1. Re-grind the anvil faces before use
  2. Ignore it because the error is small
  3. Subtract 0.02 mm from every reading Correct answer.
  4. Add 0.02 mm to every reading

Explanation

A positive zero error means the instrument reads above true size when closed, so the error must be subtracted from each measurement. The zero should also be rechecked and the instrument recalibrated if possible.

Question 15Workshop Safety, Tools and Measuring Instruments

Which instrument is most suitable for measuring the depth of a blind hole in a cylinder head to an accuracy of 0.02 mm?

  1. A steel rule
  2. A feeler gauge
  3. An outside micrometer
  4. A depth micrometer or the depth rod of a vernier caliper Correct answer.

Explanation

Depth is measured with an instrument that has a reference face and a moving rod, such as a depth micrometer or the depth rod of a vernier caliper. These give the required resolution and a stable datum across the hole opening.

Question 16Workshop Safety, Tools and Measuring Instruments

What is the main purpose of a ring spanner compared with an open-end spanner of the same size?

  1. It grips all the flats of the nut and reduces the risk of rounding Correct answer.
  2. It allows the handle to be angled for access
  3. It can be struck with a hammer to loosen tight nuts
  4. It can be used on pipe fittings

Explanation

A ring spanner encircles the nut and contacts all six flats, spreading the load and reducing the chance of rounding the corners. It is also less likely to slip off under heavy torque.

Question 17Workshop Safety, Tools and Measuring Instruments

A compressed air blow gun is being used to clean a machine. Which precaution is essential?

  1. Directing the jet at the floor to blow dust away
  2. Pointing the nozzle at nearby workers to warn them
  3. Using the highest pressure to remove stubborn dirt
  4. Reducing pressure to a safe level and never directing air at skin or eyes Correct answer.

Explanation

Compressed air at high pressure can force debris into the eyes and can inject air through the skin, causing serious injury. Pressure should be regulated to a safe level and the jet never aimed at people or used to clean clothing.

Question 18Workshop Safety, Tools and Measuring Instruments

A 0 to 25 mm outside micrometer has a barrel scale with 0.5 mm graduations and a thimble with 50 divisions. What does one thimble division represent?

  1. 0.1 mm
  2. 0.5 mm
  3. 0.05 mm
  4. 0.01 mm Correct answer.

Explanation

One full turn of the thimble advances the spindle by 0.5 mm, and the thimble is divided into 50 equal parts. Dividing 0.5 mm by 50 gives 0.01 mm per thimble division.

Question 19Workshop Safety, Tools and Measuring Instruments

Which combination of instruments would best check that a cylinder bore is both correctly sized and not tapered?

  1. A bore gauge zeroed on a micrometer, read at several heights and directions Correct answer.
  2. An outside micrometer used across the outside of the block
  3. A steel rule and a feeler gauge
  4. A vernier caliper used at the top of the bore only

Explanation

A bore gauge set to the true size with an outside micrometer measures the internal diameter accurately at chosen points. Taking readings at several heights and in two perpendicular directions reveals taper and out-of-roundness.

Question 20Workshop Safety, Tools and Measuring Instruments

Why should a file be fitted with a securely attached handle before use?

  1. To prevent the tang from piercing the hand if the file is forced or jammed Correct answer.
  2. To keep the file clean of swarf
  3. To allow the file to be struck with a hammer
  4. To improve the cutting action of the teeth

Explanation

The tang of a file is a sharp spike that can penetrate the palm if the file jams or is pushed hard without a handle. A sound, well-seated handle gives a safe grip and absorbs the thrust of the hand.

Question 21Automotive Engine Systems and Overhauling

In a four-stroke engine, which stroke immediately follows the intake stroke?

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

Explanation

The four-stroke cycle runs intake, compression, power, then exhaust, repeating in that fixed order. After the piston has drawn in the air-fuel charge on the intake stroke, both valves close and the piston rises to compress the charge. Compression must precede ignition because the mixture must be squeezed to raise its pressure and temperature before it can burn effectively.

Question 22Automotive Engine Systems and Overhauling

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

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

Explanation

The connecting rod links the piston to the crankshaft offset, so as the piston moves up and down the crank pin is forced around a circle. This linkage is what transforms straight-line reciprocation into rotation. The crankshaft then carries that torque out of the engine to the flywheel and drivetrain.

Question 23Automotive Engine Systems and Overhauling

What is the main purpose of the cooling system in an internal combustion engine?

  1. To keep metal temperatures within a range that preserves clearances and lubricant film Correct answer.
  2. To reduce the engine's oil pressure
  3. To increase the compression ratio
  4. To raise the temperature of the intake charge

Explanation

Combustion raises metal temperatures far above what lubricants and bearing clearances can tolerate. The cooling system removes that heat so parts stay within design limits, oil keeps its film strength, and thermal expansion stays controlled. Overheating causes detonation, warped heads, and seized parts.

Question 24Automotive Engine Systems and Overhauling

Which valve opens to admit the air-fuel mixture into the cylinder of a four-stroke petrol engine?

  1. Relief valve
  2. Exhaust valve
  3. PCV valve
  4. Intake valve Correct answer.

Explanation

The intake valve is timed to open as the piston begins its downward intake stroke, allowing atmospheric or boosted pressure to fill the cylinder. The exhaust valve stays closed during this period so the incoming charge is not lost. Valve timing is controlled by the camshaft.

Question 25Automotive Engine Systems and Overhauling

What does the term 'engine displacement' describe?

  1. The volume of coolant in the block
  2. The volume of oil the sump holds
  3. The volume of the combustion chamber at top dead centre
  4. The total volume swept by all pistons in one complete stroke Correct answer.

Explanation

Displacement is calculated from bore area multiplied by stroke and the number of cylinders, giving the swept volume moved by all pistons in one stroke. It indicates the engine's airflow capacity and is usually quoted in litres or cubic centimetres. Clearance volume above the piston is excluded.

Question 26Automotive Engine Systems and Overhauling

A technician finds the engine oil level above the full mark and smelling of petrol. Which fault is most likely?

  1. A leaking fuel injector diluting the oil Correct answer.
  2. A faulty thermostat stuck open
  3. A blocked oil filter
  4. A worn valve guide seal

Explanation

Fuel that leaks past a stuck-open injector or from repeated flooding runs down the cylinder walls into the sump, raising the level and thinning the oil. Petrol dilution destroys lubricating film strength and can cause bearing damage. The injector and fuel pressure circuit should be tested before the oil is changed.

Question 27Automotive Engine Systems and Overhauling

Which tool is used to measure the internal diameter of a cylinder bore accurately?

  1. Torque wrench
  2. Bore gauge Correct answer.
  3. Feeler gauge
  4. Vernier caliper

Explanation

A bore gauge is set against a micrometer and then rocked inside the bore to read taper and out-of-round at several depths and directions. Its self-centring plunger gives repeatable readings that a caliper jaw cannot reach reliably. Measurements must be taken at multiple points to assess wear.

Question 28Automotive Engine Systems and Overhauling

What is the function of piston rings in an engine?

  1. To drive the oil pump
  2. To centre the crankshaft in the block
  3. To seal combustion gases and control oil on the cylinder wall Correct answer.
  4. To lock the piston to the connecting rod

Explanation

Compression rings seal the burning charge against blow-by into the crankcase, while the oil control ring scrapes excess oil from the bore back to the sump. The rings also conduct heat from the piston crown to the cylinder wall. Correct end gaps and wall tension are essential for both jobs.

Question 29Automotive Engine Systems and Overhauling

An engine cranks normally but will not start, and a spark tester shows no spark at any plug. Which item should be checked first?

  1. Engine coolant temperature sensor
  2. Ignition coil supply and trigger signal Correct answer.
  3. Compression on cylinder one
  4. Fuel pump delivery pressure

Explanation

A confirmed absence of spark on every cylinder points to a common ignition supply or trigger fault rather than a single plug or lead. Checking for battery voltage at the coil and a switching signal from the module or ECU isolates the circuit quickly. Compression and fuel checks come after spark is restored.

Question 30Automotive Engine Systems and Overhauling

During a compression test, one cylinder reads about 40 percent below the others, and adding a few drops of oil raises the reading only slightly. What does this indicate?

  1. Worn piston rings
  2. A restricted exhaust system
  3. Excessively advanced ignition timing
  4. Leaking intake valve or head gasket Correct answer.

Explanation

If oil added to the bore does not raise compression, the leak is not past the rings, because the oil film would have sealed them. The loss is therefore at a valve seat, valve face, or head gasket. A cylinder leakage test with air pressure confirms where the escape occurs.

Question 31Automotive Engine Systems and Overhauling

Which condition causes detonation (knock) in a spark-ignition engine?

  1. A coolant temperature below operating range
  2. An intake air leak downstream of the throttle
  3. Excessive ignition advance combined with high combustion pressure Correct answer.
  4. Fuel octane rating above the engine requirement

Explanation

Detonation occurs when end-gas in the cylinder self-ignites before the flame front reaches it, producing a sharp pressure spike. Too much spark advance, high compression, low-octane fuel, or overheating all promote this by raising pressure and temperature. The ECU retards timing when the knock sensor detects it.

Question 32Automotive Engine Systems and Overhauling

What is the purpose of setting valve clearance on an overhead-valve engine with mechanical lifters?

  1. To maintain the correct camshaft end float
  2. To set the ignition timing
  3. To adjust the compression ratio
  4. To ensure valves fully seat when hot and open fully when the engine is at operating temperature Correct answer.

Explanation

Metal expands as the engine warms, so a small cold clearance prevents the valve from being held off its seat when hot, which would burn it and lose compression. Too much clearance causes noise, reduced lift, and accelerated wear. The specification is given for a stated engine temperature.

Question 33Automotive Engine Systems and Overhauling

A cylinder head bolt torque sequence usually starts at the centre and works outward. Why?

  1. To reduce the torque wrench reading needed
  2. To allow the gasket to be reused
  3. To spread clamping force evenly and avoid distorting the head Correct answer.
  4. To speed up the tightening process

Explanation

Tightening from the centre outward progressively pushes the head down evenly, allowing the gasket to compress without trapping high spots. Uneven clamping can warp the head, cause gasket leaks, or crack the casting. Many engines also require torque-to-yield bolts and a final angle stage.

Question 34Automotive Engine Systems and Overhauling

In a turbocharged engine, what is the function of the wastegate?

  1. To recirculate blow-by gases
  2. To cool the intake charge
  3. To limit boost pressure by bypassing exhaust gas around the turbine Correct answer.
  4. To control idle speed

Explanation

The wastegate opens a bypass around the turbine so that once target boost is reached, excess exhaust energy is diverted instead of over-speeding the turbo. This protects the engine from overboost and detonation. It is controlled by a spring actuator and often an electronic solenoid.

Question 35Automotive Engine Systems and Overhauling

A wet cylinder liner in a heavy-duty diesel engine is described as 'wet' because:

  1. It is fitted after the block is filled with oil
  2. It is lubricated by coolant
  3. It uses water instead of oil for lubrication
  4. Its outer surface is in direct contact with engine coolant Correct answer.

Explanation

In a wet-liner design the liner's outer wall forms part of the cooling jacket, so coolant flows directly around it. This gives excellent heat transfer and allows liners to be replaced without reboring the block. Sealing rings at the top and bottom of the liner prevent coolant from entering the sump.

Question 36Automotive Engine Systems and Overhauling

Which symptom most strongly suggests a blown head gasket between two adjacent cylinders?

  1. Oil pressure slightly low at idle
  2. Two neighbouring cylinders both showing low compression and a misfire Correct answer.
  3. A noisy tappet on one cylinder
  4. A slow cranking speed when hot

Explanation

A breach in the gasket between two bores lets compression escape from one cylinder into the other, so both read low and misfire together. Bubbles in the coolant or a sweet exhaust smell may also appear. A cylinder leakage test shows air passing into the neighbouring bore.

Question 37Automotive Engine Systems and Overhauling

What is the correct action when a torque-to-yield cylinder head bolt has been loosened during a repair?

  1. Reuse it but reduce the final torque by ten percent
  2. Reuse it after cleaning the threads
  3. Reuse it only if it passes a visual inspection
  4. Replace it with a new bolt of the specified grade Correct answer.

Explanation

Torque-to-yield bolts are tightened past their elastic limit and permanently stretch, so their clamping force is no longer predictable once released. Reusing them risks insufficient clamp load and gasket failure. They are specified as single-use items in the service information.

Question 38Automotive Engine Systems and Overhauling

During a cylinder leakage test, air escapes continuously from the radiator filler neck. Which fault does this indicate?

  1. Failed head gasket or cracked head into the cooling jacket Correct answer.
  2. Broken piston ring land
  3. Leaking exhaust valve
  4. Leaking intake valve

Explanation

Air entering the cooling system during a leakage test shows a path from the combustion chamber into a water jacket, typically through the head gasket or a crack. Bubbles or a rising coolant level confirm it. Valve or ring leaks would instead show at the throttle body, exhaust, or dipstick tube.

Question 39Automotive Engine Systems and Overhauling

Which statement best explains why an engine's volumetric efficiency falls at very high speed?

  1. Fuel octane rating decreases with engine speed
  2. Valve open time becomes short relative to piston demand, so less charge is trapped Correct answer.
  3. Coolant flow increases excessively
  4. Oil pressure rises too quickly

Explanation

At high speed the intake valve is open for a shorter time in absolute terms, and flow losses through ports and valves rise with the square of velocity. Both effects reduce the mass of charge trapped per cycle. Camshaft duration, port size, and manifold tuning are chosen to place peak volumetric efficiency at the intended speed.

Question 40Automotive Engine Systems and Overhauling

An engine has excessive blow-by and oil consumption, but a wet compression test shows little improvement. Which cause should be investigated?

  1. A weak fuel pump
  2. Worn valve guides and seals Correct answer.
  3. Worn piston rings
  4. Incorrect ignition timing

Explanation

When added oil fails to raise compression, the rings and bore are sealing reasonably and the leakage is at the valves or guides. Worn guides allow oil to be drawn down into the cylinder on the intake stroke, producing blue smoke and consumption. Blow-by with good ring sealing can still occur through a damaged piston or breather fault and should be checked separately.

Question 41Automotive Engine Systems and Overhauling

Which factor determines the compression ratio of a reciprocating engine?

  1. Clearance volume divided by swept volume
  2. Swept volume divided by engine speed
  3. Swept volume plus clearance volume divided by clearance volume Correct answer.
  4. Bore multiplied by stroke

Explanation

Compression ratio compares total cylinder volume at bottom dead centre with the clearance volume remaining at top dead centre. It is therefore (swept volume plus clearance volume) divided by clearance volume. Reducing clearance volume, for example by skimming the head, raises the ratio.

Question 42Automotive Engine Systems and Overhauling

A diesel engine starts poorly when cold but runs well once warm. Which item most directly explains this pattern?

  1. Faulty glow plugs or an inoperative cold-start advance Correct answer.
  2. A worn clutch release bearing
  3. An overfilled cooling system
  4. A clogged crankcase breather filter

Explanation

Diesel ignition relies on compression heat, so a cold chamber needs glow plugs or extra injection advance to start reliably. Once the engine warms, residual heat masks the fault and running appears normal. Testing glow plug continuity and the cold-start circuit confirms the cause.

Question 43Automotive Engine Systems and Overhauling

After a rebore, new pistons are fitted and the ring end gap is measured at 0.25 mm in a bore where the specification is 0.40 to 0.55 mm. What is the correct interpretation?

  1. The gap should be ignored because it changes after break-in
  2. The gap is too large and the engine will burn oil
  3. The gap is too small and the rings may butt and break when hot Correct answer.
  4. The gap is acceptable because it is smaller than the maximum

Explanation

Ring end gap must fall within the specified range when measured in the actual bore at the correct position. If it is below the minimum, the ends can close completely as the ring expands with heat, seizing or snapping the ring and scoring the bore. The ring ends must be filed squarely to achieve the minimum specified gap.

Question 44Automotive Engine Systems and Overhauling

An engine with a correctly timed camshaft shows low manifold vacuum at idle, a rough idle, and backfiring through the intake. Which valve train fault best fits these symptoms?

  1. Excessive valve guide clearance on the exhaust side
  2. Intake valve not seating due to insufficient clearance or a bent stem Correct answer.
  3. A worn rocker cover gasket
  4. A loose alternator belt

Explanation

An intake valve held slightly open during compression lets charge escape back into the manifold, causing rough idle, low vacuum, and intake backfire. Insufficient clearance or a bent stem can produce this. A cylinder leakage test showing air at the throttle body confirms the diagnosis.

Question 45Automotive Engine Systems and Overhauling

Which statement correctly describes the effect of advancing camshaft timing on a fixed engine?

  1. Intake valve closes later, improving high-speed power
  2. Valve lift increases without changing duration
  3. Intake valve closes earlier, moving peak torque to lower engine speeds Correct answer.
  4. Exhaust valve opens later, reducing overlap to zero

Explanation

Advancing the cam opens and closes the intake valve earlier in the cycle, so the cylinder traps charge sooner and low-speed cylinder pressure rises. This shifts the torque peak toward lower speeds at the expense of top-end power. Duration and lift are ground into the lobe and do not change with timing.

Question 46Automotive Engine Systems and Overhauling

What is the primary function of the camshaft in a four-stroke engine?

  1. To convert reciprocating motion into rotary motion
  2. To open and close the valves at the correct time Correct answer.
  3. To supply fuel to the combustion chamber
  4. To ignite the air-fuel mixture

Explanation

The camshaft has lobes that actuate the valves, either directly or through pushrods and rockers, so that they open and close in sync with the piston position. Its shape and timing determine when gas exchange occurs. The other functions listed belong to different components.

Question 47Automotive Engine Systems and Overhauling

Which component is responsible for converting the reciprocating motion of the piston into rotary motion?

  1. Crankshaft Correct answer.
  2. Camshaft
  3. Flywheel
  4. Connecting rod

Explanation

The crankshaft has offset journals that, together with the connecting rods, transform the linear motion of the pistons into rotation. The flywheel smooths the rotation but does not perform the conversion. The camshaft controls valve motion, and the connecting rod links the piston to the crank.

Question 48Automotive Engine Systems and Overhauling

What is the main purpose of the flywheel in an engine?

  1. To smooth out power pulses and store rotational energy Correct answer.
  2. To drive the oil pump
  3. To regulate coolant flow
  4. To increase engine displacement

Explanation

The flywheel's inertia carries the crankshaft through the non-power strokes, reducing speed fluctuations and providing smoother operation. It also provides a mounting surface for the clutch or torque converter. It does not affect displacement or drive accessories directly.

Question 49Automotive Engine Systems and Overhauling

Which type of valve train uses a pushrod and rocker arm to operate the valves?

  1. Overhead cam (OHC)
  2. Free-valve
  3. Dual overhead cam (DOHC)
  4. Overhead valve (OHV) Correct answer.

Explanation

In an overhead valve (OHV) engine, the camshaft is located in the block and actuates the valves via lifters, pushrods, and rocker arms. OHC and DOHC designs place the camshaft in the cylinder head and usually act directly on the valves. Free-valve is not a standard automotive configuration.

Question 50Automotive Engine Systems and Overhauling

A technician is measuring the cylinder bore of an engine block and obtains readings that vary by 0.05 mm. Which instrument is most suitable for this measurement?

  1. Feeler gauge
  2. Vernier caliper
  3. Bore gauge Correct answer.
  4. Outside micrometer

Explanation

A bore gauge is designed to measure internal diameters and, when used with an outside micrometer for calibration, can detect taper and out-of-round accurately. Vernier calipers are less precise for this task. Outside micrometers measure external dimensions, and feeler gauges measure gaps.