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RBSE Sec Voc Automotive study materials
RBSE Sec Voc Automotive study resources

RBSE Sec Voc Automotive practice questions

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Question 1Automotive Workshop Safety and Tools

When should wheel chocks be placed around a vehicle before any work begins underneath it in an automotive workshop?

  1. Only after the vehicle has been fully raised on the hoist
  2. After the wheels have been removed for brake service
  3. Only when the handbrake is known to be faulty
  4. Before the vehicle is raised, on the wheel that stays on the ground opposite the lifting point Correct answer.

Explanation

Chocking prevents rolling before and during lifting, so it must be done while the vehicle is still on the ground, on the wheels that remain in contact with the floor. Waiting until the vehicle is raised defeats the purpose because movement can already have started.

Question 2Automotive Workshop Safety and Tools

A trolley jack is being used to raise a car for a tyre change. What is the correct practice regarding the hydraulic jack once the car is at height?

  1. Keep the engine running to maintain hydraulic pressure
  2. Leave the car resting on the jack alone while the wheel is swapped
  3. Place a second trolley jack under the same jacking point for support
  4. Lower the car onto axle stands before removing the wheel Correct answer.

Explanation

A hydraulic jack is a lifting device, not a support device; it can bleed down or tip. The raised vehicle must be transferred onto rated axle stands placed at the manufacturer's support points before any work is done beneath or around it.

Question 3Automotive Workshop Safety and Tools

Which glove material is appropriate when handling brake fluid and cleaning solvents during a brake overhaul?

  1. Woollen liner gloves
  2. Leather welding gauntlets
  3. Cotton work gloves
  4. Nitrile disposable gloves Correct answer.

Explanation

Nitrile gloves resist brake fluid and common workshop solvents while allowing dexterity for small components. Cotton, wool and leather absorb liquids and hold them against the skin, so they offer no chemical protection.

Question 4Automotive Workshop Safety and Tools

What is the primary purpose of a vehicle exhaust extraction hose connected to a tailpipe in a workshop?

  1. To cool the exhaust gases before they reach the silencer
  2. To increase engine power by reducing back pressure
  3. To measure exhaust gas temperature during tuning
  4. To route carbon monoxide and other exhaust gases outdoors Correct answer.

Explanation

Running an engine indoors produces carbon monoxide, which is odourless and potentially fatal. Extraction hoses capture the exhaust at the tailpipe and discharge it outside the building, protecting everyone in the workshop.

Question 5Automotive Workshop Safety and Tools

Before using a hydraulic press or a two-post hoist for the first time in a shift, what check should the technician perform?

  1. Inspect the equipment for damage, leaks and correct operation before loading it Correct answer.
  2. Disconnect the safety lock to allow faster operation
  3. Ask a colleague to stand under the load as a spotter
  4. Load the heaviest vehicle first to test the capacity

Explanation

Pre-use inspection of lifting and pressing equipment is a basic safety duty: look for hydraulic leaks, frayed cables, damaged locks and correct function before any load is applied. Faults found at this stage prevent failures under load.

Question 6Automotive Workshop Safety and Tools

Which fire extinguisher type is suitable for a small fuel fire on the workshop floor?

  1. Carbon dioxide or dry powder extinguisher Correct answer.
  2. Wet chemical extinguisher
  3. Water stored-pressure extinguisher
  4. Pressurised foam extinguisher

Explanation

Petrol and diesel are class B flammable liquid fires, which are extinguished with carbon dioxide or dry powder. Water spreads fuel fires, wet chemical agents are formulated for cooking oils, and foam is intended mainly for class B liquid spills but is not the standard choice for fuel on a floor.

Question 7Automotive Workshop Safety and Tools

A technician must loosen a stubborn crankshaft pulley bolt while the engine is in the vehicle. Which approach best controls the reaction force?

  1. Hold the socket with one hand while pulling the breaker bar with the other
  2. Apply the force with a hammer on the breaker bar
  3. Ask an apprentice to hold the pulley by hand
  4. Use a dedicated holding tool or locking pin to restrain the pulley Correct answer.

Explanation

High-torque fasteners generate an equal and opposite reaction that can spin the engine or slip the tool. A dedicated holding tool or locking pin restrains the pulley safely and keeps hands clear of pinch points.

Question 8Automotive Workshop Safety and Tools

Why should a torque wrench be returned to its lowest setting before being stored?

  1. To reset the digital display to zero
  2. To prevent the internal spring from taking a permanent set and losing calibration Correct answer.
  3. To allow the ratchet head to drain oil
  4. To make the scale easier to read next time

Explanation

A torque wrench relies on a calibrated spring; leaving it compressed at a high setting causes the spring to fatigue and the wrench to read inaccurately. Backing it off to the minimum setting after use preserves calibration.

Question 9Automotive Workshop Safety and Tools

A technician is about to use an angle grinder to remove a seized exhaust clamp. Which combination of controls is most appropriate?

  1. Face shield plus safety glasses, guard in place, and hearing protection Correct answer.
  2. Ear defenders and cotton gloves only
  3. Prescription spectacles worn alone
  4. Safety glasses only, with the guard removed for access

Explanation

Grinding throws sparks and fragments, so eye protection must include a face shield over safety glasses; the guard limits fragment ejection and hearing protection addresses high noise. Gloves near a rotating wheel add an entanglement risk and spectacles alone leave the sides of the face exposed.

Question 10Automotive Workshop Safety and Tools

What is the correct handling of a compressed gas cylinder used for welding in a workshop?

  1. Chain it to a trolley with the regulator left fitted during transport
  2. Store it loose near the roller door for quick access
  3. Lay it horizontally under the bench to save space
  4. Secure it upright with a chain or strap and fit the valve cap when moving it Correct answer.

Explanation

Compressed gas cylinders must be stored and used upright and restrained so they cannot fall and shear the valve. The valve protection cap should be fitted whenever a cylinder is moved without a regulator.

Question 11Automotive Workshop Safety and Tools

A vehicle battery is being disconnected before electrical repair work. Which sequence protects the technician and the vehicle electronics?

  1. Leave the battery connected and remove the ECU fuse instead
  2. Disconnect both terminals simultaneously with two spanners
  3. Disconnect the negative terminal first, then the positive Correct answer.
  4. Disconnect the positive terminal first, then the negative

Explanation

Removing the negative (earth) terminal first breaks the return path, so a spanner touching the bodywork cannot complete a circuit through the tool. The positive terminal is reconnected first on reassembly.

Question 12Automotive Workshop Safety and Tools

Why is it important to use the correct flare nut spanner rather than an open-ended spanner on brake pipe unions?

  1. It is the only tool that fits metric threads
  2. It allows higher torque to be applied without rounding the soft hex Correct answer.
  3. It prevents brake fluid from escaping during loosening
  4. It automatically bleeds air from the line

Explanation

Brake pipe unions are made of soft material and have limited hex flats; a flare nut spanner grips five or six flats and spreads the load, reducing the risk of rounding. An open-ended spanner contacts only two flats and can slip under torque.

Question 13Automotive Workshop Safety and Tools

A hydraulic vehicle lift is found to be drifting down slowly with a car raised on it. What is the correct immediate action?

  1. Lower the vehicle immediately, tag the lift out of service and report the fault Correct answer.
  2. Continue working and lower the vehicle at the end of the job
  3. Increase the hydraulic pressure at the pump to compensate
  4. Place a second vehicle on the lift to add weight and stabilise it

Explanation

Slow descent indicates a hydraulic or lock fault that could become a sudden drop. The load must be removed promptly, the equipment isolated and tagged, and the fault reported so it is repaired before further use.

Question 14Automotive Workshop Safety and Tools

When grinding metal, why should the tool rest on a bench grinder be set close to the wheel, no more than about 2 mm away?

  1. To allow the wheel to run at a higher surface speed
  2. To stop the workpiece being drawn into the gap between rest and wheel Correct answer.
  3. To make the grinding sparks travel further
  4. To reduce motor current draw during grinding

Explanation

A large gap between the tool rest and the wheel can trap the workpiece and pull the operator's fingers into the rotating wheel. Keeping the rest close minimises that nip point and gives better control.

Question 15Automotive Workshop Safety and Tools

A technician is working alone in the workshop when a solvent ignites in a parts washer. What is the most appropriate first action?

  1. Carry the burning parts washer outside
  2. Raise the alarm and evacuate, then call the fire service from a safe point Correct answer.
  3. Open the workshop doors wide to let oxygen in
  4. Try to smother the fire with a rag before doing anything else

Explanation

Life safety comes first: raise the alarm, evacuate to a safe assembly point and call the emergency services. Only trained personnel should attempt to fight a fire, and never with an escape route behind them.

Question 16Automotive Workshop Safety and Tools

Why is a residual current device (RCD) recommended on portable electrical tools used in a wet workshop area?

  1. It increases the motor speed under load
  2. It recharges the tool battery during use
  3. It disconnects the supply quickly when current leaks to earth Correct answer.
  4. It converts single-phase supply to three-phase

Explanation

An RCD monitors the difference between live and neutral current; a leak to earth through a person or wet floor trips it within milliseconds. This limits the duration of a shock and reduces the risk of fatal injury.

Question 17Automotive Workshop Safety and Tools

A technician needs to remove a rusted suspension bolt that has already rounded. Which sequence best reflects sound workshop practice?

  1. Force an undersized twelve-point socket onto the bolt with a hammer
  2. Apply penetrating oil and heat where safe, then use a six-point flank-drive socket or bolt extractor Correct answer.
  3. Cut the bolt head off immediately without trying other methods
  4. Use an impact gun at maximum torque on the rounded head

Explanation

Penetrating oil and controlled heat reduce friction and corrosion, and a flank-drive or extractor socket grips the remaining flats rather than the corners. This preserves the fastener and avoids excessive force.

Question 18Automotive Workshop Safety and Tools

Two technicians are lifting a gearbox out of a vehicle using a transmission jack. Which practice best manages the risk of the load tipping?

  1. One technician stands under the gearbox to guide it onto the bench
  2. The load is secured to the jack and the area is kept clear of hands and feet during movement Correct answer.
  3. The jack is raised quickly to reduce the time the load is airborne
  4. Each technician holds one side of the gearbox by hand while it is raised

Explanation

A gearbox is heavy and its centre of gravity shifts as it is lowered, so it must be secured to the jack and moved with hands and feet clear of the crush zone. Communication between the two technicians keeps the movement controlled.

Question 19Automotive Workshop Safety and Tools

A workshop uses a parts washer filled with a solvent that has a flash point of 40 degrees Celsius. A heater in the corner raises the ambient temperature. What is the key safety concern and control?

  1. The solvent may release vapour near its flash point, so keep ignition sources away and provide ventilation Correct answer.
  2. The solvent becomes non-flammable as it warms
  3. The heater improves solvent performance and needs no control
  4. The solvent will freeze, so the heater must be kept running

Explanation

A flash point of 40 degrees Celsius means the liquid gives off ignitable vapour at temperatures that a heated workshop can approach. The control is to eliminate ignition sources, ventilate the area and keep the solvent below its flash point.

Question 20Automotive Workshop Safety and Tools

A technician is asked to weld a repair patch on a fuel tank that was drained yesterday. What is the correct assessment before any heat is applied?

  1. Filling the tank with water permanently removes all risk
  2. Draining the tank is sufficient because liquid fuel has been removed
  3. Welding is safe if the tank cap is left open during the work
  4. Residual vapour remains explosive, so the tank must be purged and tested before hot work Correct answer.

Explanation

An empty fuel tank is more dangerous than a full one because the vapour space contains a flammable mixture. Purging with an inert gas or steam and verifying with a gas detector is required before any hot work, and specialist procedures apply.

Question 21Engine Systems and Overhaul

In a four-stroke diesel engine, which stroke immediately follows the power stroke in the cylinder cycle?

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

Explanation

The four-stroke cycle runs intake, compression, power, then exhaust. After the power stroke the piston rises on the exhaust stroke to push burned gas out through the open exhaust valve, so the exhaust stroke is the correct next phase.

Question 22Engine Systems and Overhaul

A technician measures cylinder taper with a bore gauge and finds the bore is 0.10 mm larger at the top than at the bottom of ring travel. What is the most appropriate service action?

  1. Hone lightly and reassemble
  2. Rebore and fit oversize pistons Correct answer.
  3. Increase ring end gap
  4. Replace only the piston rings

Explanation

Taper beyond the manufacturer's limit means the cylinder is no longer parallel, so a light hone cannot restore a true bore. The standard repair is to rebore to the next oversize and fit matching oversize pistons and rings.

Question 23Engine Systems and Overhaul

Which component in a pushrod engine directly converts camshaft rotation into linear motion of the pushrod?

  1. Valve guide
  2. Valve spring
  3. Tappet (lifter) Correct answer.
  4. Rocker arm

Explanation

The camshaft lobe lifts the tappet, which rides on the lobe and transfers the lift to the pushrod as linear motion. The rocker arm then redirects that motion to open the valve.

Question 24Engine Systems and Overhaul

During a compression test, one cylinder reads 30 percent below the others, but adding a small amount of oil to the cylinder raises the reading to normal. What does this indicate?

  1. Leaking intake valve
  2. Broken valve spring
  3. Blown head gasket
  4. Worn piston rings Correct answer.

Explanation

Wet-oil testing temporarily seals ring-to-wall gaps; if compression rises after oil is added, the loss is past the rings. Valve or gasket leakage does not improve because the oil does not seal those paths.

Question 25Engine Systems and Overhaul

What is the primary purpose of setting valve clearance (lash) on a mechanical valvetrain?

  1. To advance injection timing
  2. To increase valve lift
  3. To reduce oil pressure at idle
  4. To allow for thermal expansion of valvetrain parts Correct answer.

Explanation

Valvetrain components expand as the engine warms, so a specified cold clearance prevents the valve from being held off its seat when hot. Correct lash also preserves the designed valve timing and lift.

Question 26Engine Systems and Overhaul

An engine has low oil pressure at hot idle that rises to normal at higher speed, and the oil pressure warning lamp flickers at idle. Which cause is most consistent with these symptoms?

  1. Worn main and rod bearings Correct answer.
  2. Clogged air filter
  3. Faulty coolant thermostat
  4. Incorrect ignition timing

Explanation

Excessive bearing clearance lets oil escape too easily, so pressure is lowest when pump speed and flow are lowest, at hot idle. As speed and pump output rise, pressure recovers toward normal.

Question 27Engine Systems and Overhaul

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

  1. To limit boost pressure by bypassing exhaust gas around the turbine Correct answer.
  2. To meter fuel at high load
  3. To cool the intake charge
  4. To recirculate crankcase gases

Explanation

The wastegate opens to divert exhaust gas around the turbine once the target boost is reached, preventing overboost and protecting the engine. This regulates turbine speed and therefore compressor output.

Question 28Engine Systems and Overhaul

A cylinder head is being checked for warpage with a straightedge and feeler gauge. The measurement exceeds the maximum flatness limit specified by the manufacturer. What is the correct action?

  1. Install a thicker head gasket only
  2. Reuse the head as-is with sealant
  3. Torque the head bolts tighter
  4. Resurface the head within the allowable material removal limit Correct answer.

Explanation

Warpage beyond the flatness limit requires machining the deck flat, provided the amount removed stays within the manufacturer's minimum height limit. A thicker gasket does not correct a warped sealing surface.

Question 29Engine Systems and Overhaul

Which statement correctly describes the firing order purpose in a multi-cylinder engine?

  1. It determines the direction of coolant flow
  2. It determines the sequence in which cylinders produce power to balance loads on the crankshaft Correct answer.
  3. It sets the order in which valves are adjusted
  4. It controls the sequence of oil filter changes

Explanation

Firing order spreads power pulses evenly along the crankshaft to reduce vibration and torsional load. It is a design characteristic of the crank and cam arrangement, not a maintenance procedure.

Question 30Engine Systems and Overhaul

A diesel engine cranks but will not start, and the technician observes no fuel at the injector lines while cranking. Which area should be checked first?

  1. Spark plug gap
  2. Throttle position sensor calibration
  3. Exhaust gas recirculation valve
  4. Fuel supply and shutoff solenoid at the injection pump Correct answer.

Explanation

No fuel at the injector lines points to a delivery problem upstream, such as a closed shutoff solenoid, air in the supply, or a failed lift pump. Confirming supply and solenoid operation is the logical first step.

Question 31Engine Systems and Overhaul

What is the purpose of piston ring end gap?

  1. To hold the ring square in the bore
  2. To lock the ring to the piston land
  3. To allow for thermal expansion of the ring without butting ends Correct answer.
  4. To permit oil to pass into the combustion chamber

Explanation

Rings run hotter than the cylinder wall and expand, so a specified end gap prevents the ends from butting and scuffing the bore. Too small a gap causes breakage; too large a gap increases blowby.

Question 32Engine Systems and Overhaul

After an engine overhaul, a technician finds the engine uses excessive oil but shows normal compression and no external leaks. Which cause best fits these findings?

  1. Worn valve guides and stem seals Correct answer.
  2. Worn compression rings
  3. Restricted exhaust
  4. Leaking head gasket

Explanation

Oil can enter the cylinder past worn valve guides and seals, especially on the intake stroke when manifold vacuum is high, without affecting compression. Ring wear, by contrast, would lower compression readings.

Question 33Engine Systems and Overhaul

What does the term 'valve overlap' refer to in an engine?

  1. The distance the valve travels below the seat
  2. The clearance between valve stem and rocker
  3. The time between two successive injections
  4. The period when both intake and exhaust valves are open near top dead center Correct answer.

Explanation

Overlap occurs around top dead center when the intake valve has opened slightly before the exhaust valve fully closes. It helps scavenge exhaust gas and improve cylinder filling at speed.

Question 34Engine Systems and Overhaul

A technician is measuring crankshaft journal out-of-round with a micrometer at several points. The readings vary by 0.04 mm, exceeding the limit. What does this indicate and what is the remedy?

  1. Journal is tapered; replace the crankshaft
  2. Journal is out-of-round; regrind to the next undersize Correct answer.
  3. Bearing is too tight; add shims
  4. Oil clearance is excessive; use thicker oil

Explanation

Varying diameter readings around a journal indicate out-of-round (ovality), which prevents a proper oil film and bearing fit. The journal must be reground to the next undersize and matched with undersize bearings.

Question 35Engine Systems and Overhaul

In a cooling system, what is the function of the thermostat in engine warm-up?

  1. To drive the water pump
  2. To remove air from the radiator
  3. To regulate coolant flow so the engine reaches and holds operating temperature Correct answer.
  4. To pressurize the cooling system

Explanation

The thermostat stays closed during warm-up, limiting coolant flow to the radiator until the engine reaches design temperature. It then opens progressively to maintain stable operating temperature.

Question 36Engine Systems and Overhaul

An engine is diagnosed with a blown head gasket between two adjacent cylinders. Which test result most directly supports this diagnosis?

  1. One cylinder shows low compression that rises with added oil
  2. Both adjacent cylinders show equally low compression, and adding oil does not raise it Correct answer.
  3. Coolant temperature rises when the heater is on
  4. Oil pressure drops only at idle

Explanation

A gasket breach between two cylinders links them, so both lose compression and the loss is not sealed by adding oil. Ring-related loss would affect one cylinder and respond to oil.

Question 37Engine Systems and Overhaul

What is the purpose of deglazing (honing) cylinder walls before fitting new rings?

  1. To create a crosshatch pattern that helps rings seat and retain oil Correct answer.
  2. To harden the cylinder surface
  3. To remove taper and out-of-round
  4. To increase the bore diameter by 0.5 mm

Explanation

Honing produces a fine crosshatch that retains oil and helps new rings wear in to a proper seal. It is a surface-finish operation, not a dimensional correction.

Question 38Engine Systems and Overhaul

During disassembly, a technician notes that the main bearing caps are numbered. Why must they be reinstalled in their original positions and orientation?

  1. Because the bolts are torque-to-yield
  2. Because caps are line-bored to the block and are not interchangeable Correct answer.
  3. Because the caps are different colors
  4. Because the caps hold the oil pan

Explanation

Main bearing bores are machined with the caps in place, so each cap fits only its own location and direction. Swapping or reversing caps misaligns the bore and destroys bearing clearance.

Question 39Engine Systems and Overhaul

Which of the following best describes the function of a diesel engine's injection pump in a mechanical system?

  1. To pressurize and time fuel delivery to each injector Correct answer.
  2. To atomize fuel at the nozzle tip
  3. To ignite the fuel-air mixture
  4. To filter contaminants from the fuel

Explanation

The injection pump raises fuel to injection pressure and distributes it to each cylinder at the correct moment. Atomization happens at the injector nozzle, and ignition results from compression heat.

Question 40Engine Systems and Overhaul

A rebuilt engine shows blue-gray exhaust smoke that persists after warm-up. Which condition is the most likely cause?

  1. Retarded injection timing
  2. Excess fuel delivery
  3. Oil entering the combustion chamber Correct answer.
  4. Coolant entering the cylinder

Explanation

Persistent blue-gray smoke indicates oil burning in the cylinder, typically from worn rings, guides, or turbo seals. It does not clear after warm-up as normal cold-start smoke would.

Question 41Engine Systems and Overhaul

What is the correct procedure for measuring piston-to-bore clearance?

  1. Measure the piston skirt at the specified point and compare with the bore measurement at the same height Correct answer.
  2. Measure the ring end gap and subtract from bore
  3. Measure the piston crown diameter only
  4. Measure the wrist pin diameter

Explanation

Piston diameter is specified at a particular skirt location and height, so the bore must be measured at the corresponding position. The difference gives the true running clearance.

Question 42Engine Systems and Overhaul

In an overhead cam engine, what does the timing belt or chain synchronize?

  1. Water pump speed with fan speed
  2. Crankshaft rotation with camshaft rotation Correct answer.
  3. Alternator output with battery voltage
  4. Oil pump output with fuel delivery

Explanation

The timing belt or chain maintains the fixed relationship between crankshaft and camshaft positions so valves open at the correct point in the cycle. Incorrect timing causes poor running or valve-to-piston contact.

Question 43Engine Systems and Overhaul

A technician finds the valve stem tip height has changed after a valve seat was recut. Why is stem height important?

  1. It affects valve spring installed height and valvetrain geometry Correct answer.
  2. It changes the coolant flow rate
  3. It determines the oil grade required
  4. It sets the injection pump timing

Explanation

Recutting a seat can sink the valve, changing stem height and spring installed height. Correct geometry is needed to maintain spring pressure and proper rocker or tappet contact.

Question 44Engine Systems and Overhaul

What is the primary function of the connecting rod in an engine?

  1. To seal combustion gases
  2. To circulate lubricating oil
  3. To transfer force from the piston to the crankshaft Correct answer.
  4. To control valve opening

Explanation

The connecting rod links the reciprocating piston to the rotating crankshaft, converting linear force into rotary motion. Sealing is done by rings, and valve control by the valvetrain.

Question 45Engine Systems and Overhaul

An engine is being assembled and the technician applies assembly lubricant to bearing surfaces. Which statement best explains why?

  1. It sets the final torque of the cap bolts
  2. It provides lubrication during initial cranking before oil pressure builds Correct answer.
  3. It seals the oil passages
  4. It increases bearing crush for a tighter fit

Explanation

During the first start, oil pressure has not yet built, so assembly lubricant protects bearings from dry scuffing. It also helps components slide into place during assembly.

Question 46Engine Systems and Overhaul

In a four-stroke engine, which sequence of strokes occurs after the piston passes top dead centre at the start of the power stroke?

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

Explanation

The four-stroke cycle runs intake, compression, power, then exhaust, with the crankshaft making two revolutions per complete cycle. Once the power stroke finishes at bottom dead centre, the exhaust stroke begins, followed by intake and compression. The order is fixed by the camshaft lobes and cannot vary between cylinders.

Question 47Engine Systems and Overhaul

A technician is checking valve clearance on a cold engine and finds the clearance on one intake valve is below specification. What is the most likely effect if the engine is run in this condition?

  1. The valve will open too early and close too late
  2. The valve will not open fully, reducing cylinder filling
  3. The valve spring will lose tension permanently
  4. The valve will be held off its seat and may burn Correct answer.

Explanation

Too little clearance means the cam profile takes up the gap and holds the valve slightly open once the engine warms and parts expand. Hot combustion gas then escapes past the sealing face, which can overheat and burn the valve. Correct clearance allows the valve to seat fully when the lifter is on the base circle.

Question 48Engine Systems and Overhaul

During a wet compression test, oil is added to a cylinder and the compression reading rises noticeably compared with the dry test. What does this result indicate?

  1. A blown head gasket between cylinders
  2. Excessive carbon on the piston crown
  3. Worn piston rings or cylinder bore Correct answer.
  4. Leaking intake valve sealing

Explanation

Oil temporarily seals the gap between the rings and the cylinder wall, so a rise in reading points to ring or bore wear as the leak path. If the reading stays low after adding oil, the leakage is more likely past the valves or gasket. The test isolates the ring seal from other leak sources.

Question 49Engine Systems and Overhaul

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

  1. The harmonic balancer
  2. The camshaft
  3. The flywheel
  4. The connecting rod Correct answer.

Explanation

The connecting rod links the piston pin to the crankshaft journal, and its angular swing converts straight-line piston travel into rotation. The big and small ends carry the load through the bearing shells. No other listed part performs this kinematic conversion.

Question 50Engine Systems and Overhaul

A cylinder head bolt set is specified as torque-to-yield. Why must new bolts be fitted rather than reusing the old ones?

  1. The old bolts have stretched past their elastic limit and will not clamp reliably Correct answer.
  2. The old bolts are shorter and will bottom out in blind holes
  3. The old bolts have lost their thread coating and will seize in the block
  4. The old bolts have hardened and will snap at the specified torque

Explanation

Torque-to-yield bolts are tightened into their plastic range so the clamp load stays stable, which permanently stretches them. Once stretched, they cannot return to the original length and reuse risks insufficient or uneven clamping. Replacing them each time the head is removed is therefore required.