NZ Certificate in Heavy Automotive Engineering (Level 4) Theory Assessment

Under New Zealand HSWA 2015, what is a Level 4 heavy automotive technician's duty when monitoring workshop safety?

• AIdentify hazards, report risks to the PCBU, and ensure controls are followed by supervise…
• BIgnore minor hazards if a truck must leave the workshop by end of shift
• CDelegate all safety monitoring solely to NZTA inspectors
• DRely on drivers to report workshop hazards before servicing begins

Before demounting a split-rim (multi-piece) wheel on a heavy truck in New Zealand, what is mandatory?

• ADeflate fully, use a split-rim cage, stand clear of the trajectory zone, and follow manuf…
• BLoosen nuts while the tyre remains fully inflated to check bead seating
• CUse a hammer on the sidewall to break the bead without deflation
• DDemount inside the cab to protect the tyre from weather

What minimum tread depth at principal grooves is required for heavy vehicle tyres at NZ Certificate of Fitness inspection?

• A3.0 mm
• B1.5 mm
• C5.0 mm
• D0.5 mm

When must a New Zealand heavy automotive workshop conduct a risk assessment under HSWA principles?

• AWhen introducing new equipment, processes, or high-risk tasks such as tank cleaning or sp…
• BOnly after a serious harm notification to WorkSafe
• COnce every ten years regardless of process changes
• DOnly when requested by a fleet customer in writing

A Level 4 technician notices an apprentice working under a raised heavy truck without axle stands. What is the correct response?

• AStop the task, lower or support the vehicle on rated stands, and reinforce the workshop s…
• BAllow it if the hoist safety latch is engaged
• CReport the apprentice to NZTA instead of the workshop supervisor
• DIgnore it if the apprentice has completed Level 3 theory

Which document must be available before using a new diesel exhaust fluid (AdBlue) additive in a NZ heavy vehicle workshop?

• ACurrent Safety Data Sheet (SDS) with hazard controls and PPE requirements
• BThe truck owner's insurance policy
• CA CoF inspection checklist only
• DThe apprentice's school report

What is the primary hazard when opening a common-rail diesel fuel line on a running heavy truck engine?

• AHigh-pressure fluid injection through skin (hydraulic injection injury)
• BLow-voltage shock from the fuel temperature sensor only
• CCarbon monoxide from the workshop floor only
• DStatic discharge from the fuel tank cap

Under NZ CoF requirements, who is responsible for ensuring a heavy vehicle is maintained in a safe condition for road use?

• AThe vehicle operator (owner/operator) with the technician supporting compliant repair sta…
• BOnly the CoF inspector at annual inspection
• COnly MITO apprentices during training
• DThe tyre supplier exclusively

What PPE is minimum when grinding rust from a heavy truck chassis rail in a NZ workshop?

• AEye protection, hearing protection, and respiratory protection suitable for metal dust
• BOpen-toe sandals and cotton gloves only
• CNo PPE if the task takes less than five minutes
• DSunscreen only because the workshop has windows

When supervising hot work (welding) near a heavy vehicle fuel tank, what control is essential in a NZ workshop?

• ARemove or isolate fuel sources, purge vapours where required, fire watch, and hot-work pe…
• BWeld immediately if the tank looks empty from outside
• CUse a household fan only without checking for flammable vapours
• DHot work is exempt from HSWA on heavy vehicles

In a four-stroke heavy-duty diesel engine, during which stroke is fuel injected and combustion initiated?

• ACompression stroke near top dead centre
• BIntake stroke while the inlet valve opens
• CExhaust stroke while the exhaust valve opens
• DPower stroke after the exhaust valve closes

A heavy truck diesel shows white smoke at cold start that clears when warm. The most likely cause is:

• ADelayed injection timing or weak compression causing incomplete cold combustion
• BOverfilled engine oil only
• CExcessive turbo boost at all times
• DA fully blocked air dryer

Black smoke under heavy load on a turbocharged diesel truck most commonly indicates:

• AOver-fuelling or insufficient air supply for the injected fuel quantity
• BNormal complete combustion with no fault
• CLow coolant temperature only
• DExcessive engine oil viscosity when cold

What is the typical compression ratio range for a heavy-duty diesel engine?

• A14:1 to 22:1
• B8:1 to 10:1
• C4:1 to 6:1
• D25:1 to 35:1

On a common-rail diesel, what component maintains rail pressure independently of engine speed?

• AHigh-pressure pump with pressure control valve and ECU regulation
• BThe mechanical fuel lift pump only
• CThe air compressor governor
• DThe radiator pressure cap

A cylinder compression test on a warm heavy diesel reads 320 kPa on all cylinders except one at 210 kPa. What is the best next step?

• APerform a leak-down test on the low cylinder to locate valve, ring, or gasket leakage
• BReplace the turbocharger immediately
• CAdjust the air brake slack adjusters
• DFlush the fuel tank without further testing

Blue exhaust smoke from a heavy diesel engine usually indicates:

• ABurning engine oil entering the combustion chamber
• BExcess diesel fuel from over-injection only
• CWater in the fuel filter only
• DCorrect combustion with no fault

What is the purpose of a diesel particulate filter (DPF) on a modern heavy truck?

• ATrap soot particles and regenerate periodically to reduce PM emissions
• BIncrease fuel rail pressure for common-rail injection
• CCool compressed air before the intake manifold
• DReplace the engine oil filter during service

Selective Catalytic Reduction (SCR) on a heavy diesel reduces NOx using:

• ADiesel exhaust fluid (AdBlue/urea) injected into the exhaust stream
• BExtra diesel fuel injected directly into the exhaust pipe only
• CEngine oil additives mixed with coolant
• DCompressed air from the brake system only

An EGR valve stuck open on a heavy diesel will most likely cause:

• ARough idle, reduced power, and possible black smoke from recirculated exhaust displacing…
• BHigher rail pressure and engine overspeed
• CImmediate air brake failure
• DIncreased turbo boost pressure at all times

What does a turbocharger intercooler do on a heavy diesel engine?

• ACools compressed intake air to increase air density and reduce combustion temperature
• BCools exhaust gases before the DPF only
• CLubricates turbocharger bearings with engine oil
• DRegulates fuel injection timing electronically

Low power and whistling from the intake on a turbocharged truck often indicates:

• ABoost leak in intercooler piping or damaged hose clamps
• BWorn brake linings on all axles
• CLow engine oil level only
• DOverfilled AdBlue tank

Glow plugs on a heavy diesel primarily assist:

• ACold starting by heating the combustion chamber air
• BHigh-speed cruising at motorway load
• CAir brake compressor warm-up
• DDPF regeneration at highway speed only

What causes cavitation damage in a heavy diesel cooling system?

• ALow coolant level, air ingestion, or inadequate pressurisation causing vapour bubbles tha…
• BUsing the correct OEM coolant mix only
• CNormal thermostat opening at 85 °C
• DClean radiator fins with no obstruction

Injector return flow significantly higher than specification on one cylinder suggests:

• AInternal injector wear or stuck nozzle allowing excess fuel return to the tank line
• BPerfect injector sealing with no fault
• CLow air filter restriction
• DCorrect turbo VGT position only

Crankcase pressure excessive on a heavy diesel with oil seeping from breathers indicates:

• APiston ring blow-by or worn cylinders pressurising the crankcase
• BNormal operation at all engine speeds
• CLow fuel rail pressure only
• DAir brake governor cut-out set too high

What is the function of a diesel engine's lift pump?

• ASupply low-pressure fuel from the tank to the high-pressure injection pump
• BInject fuel directly into the cylinder at 2,000 bar
• CCompress intake air before the turbocharger
• DDrive the air brake compressor exclusively

Water contamination in heavy diesel fuel most commonly causes:

• ARough running, white smoke, and possible injector damage if not drained from the water se…
• BIncreased turbo boost automatically
• CHigher compression ratio in all cylinders
• DImproved cold-start performance

A failed turbocharger on a heavy diesel typically produces which symptom combination?

• ALoss of power, possible black smoke, and abnormal exhaust or intake noise
• BInstant engine seizure at idle only
• CAir brakes locking on all axles
• DAutomatic increase in CoF validity period

What does retarded injection timing on all cylinders of a heavy diesel cause?

• AHard starting, low power, high exhaust temperature, and possible white smoke
• BImmediate engine overspeed on idle
• CExcessive air brake pressure
• DReduced engine oil pressure at all times regardless of speed

The primary lubrication function of engine oil in a heavy diesel is to:

• ASeparate moving surfaces, carry heat away, and suspend contaminants for filter removal
• BIncrease fuel rail pressure during acceleration
• CReplace coolant in the radiator during summer
• DPressurise the air brake service circuit

A DPF differential pressure sensor reading high with frequent forced regeneration suggests:

• AExcessive soot loading from faulty injectors, oil consumption, or failed regeneration cyc…
• BNormal clean filter operation
• CLow air brake reservoir pressure
• DCorrect kingpin alignment

What is the purpose of a diesel engine thermostat?

• ARegulate coolant flow to maintain optimal operating temperature for efficiency and emissi…
• BControl fuel injection quantity at idle
• CAdjust air brake cut-in pressure
• DSet turbo wastegate opening point

High-pressure common-rail injector solenoid or piezo failure typically causes:

• ACylinder misfire, rough running, and related DTC for cylinder balance or injection fault
• BImmediate loss of all braking on the truck
• CAir suspension bag over-inflation on all axles
• DAutomatic transmission upshift without driver input only

When replacing a heavy diesel fuel filter, what procedure prevents air lock in the fuel system?

• APrime the system using the manual primer pump or specified scan-tool routine until firm r…
• BStart the engine immediately without priming and drive at full load
• CFill the filter with petrol for easier flow
• DDisconnect the air dryer before filter change

What is the primary function of a twin-plate clutch on a heavy truck?

• AIncrease torque capacity and heat dissipation for high engine torque applications
• BReduce the number of gearbox ratios required
• CReplace the need for a propshaft on rigid trucks
• DPressurise the air brake supply circuit

Clutch slip under load in top gear on a loaded truck most often indicates:

• AWorn friction material, weak diaphragm springs, or incorrect free-play adjustment
• BCorrect clutch operation at all times
• CLow air brake reservoir pressure only
• DOverfilled power steering reservoir

In a heavy truck range-change gearbox, what does the range splitter control?

• ASelection between low and high range ratios within each main gear
• BEngine fuel injection timing only
• CAir brake application force at the rear axle
• DSteering kingpin preload adjustment

Double-clutching on an unsynchronised heavy truck gearbox is used to:

• AMatch input shaft and gear wheel speeds for smooth engagement without grinding
• BIncrease turbo boost during upshifts
• CBleed air from the brake chambers
• DAdjust rear axle alignment angles

A heavy truck propshaft universal joint phasing error causes:

• AVibration at specific road speeds due to unequal angular velocity between joints
• BPermanent air brake lockup on all axles
• CEngine oil dilution from fuel only
• DAutomatic DPF regeneration disable

What is the acceptable propshaft working angle limit on many heavy truck applications?

• ATypically 3° or less per joint; excessive angle causes vibration and U-joint wear
• B45° minimum for all operating conditions
• CAngles are irrelevant if tyres are inflated correctly
• D90° is standard at the differential pinion

A clunk when engaging drive on a heavy rigid truck after gear selection often indicates:

• AExcessive driveline backlash from worn U-joints, slip yoke splines, or differential gears
• BCorrect soft-shift calibration only
• CLow AdBlue level
• DClean air filter condition

What does a Power Take-Off (PTO) on a heavy truck transmission drive?

• AAuxiliary equipment such as tipper pumps, winches, or hydraulic packs from gearbox power
• BThe air brake compressor exclusively on all models
• CThe steering box directly without hydraulic assist
• DThe radiator fan only on electric vehicles

Hypoid final drive gears in a heavy truck differential are lubricated with:

• ASpecified hypoid gear oil with EP additives — not standard engine oil
• BBrake fluid DOT 4
• CCompressed air from the wet tank
• DEngine coolant 50/50 mix

Inter-axle differential lock on a tandem drive truck is used to:

• ALock the differential between drive axles so both axles share torque equally in low tract…
• BIncrease fuel rail pressure during hill starts
• CDisable ABS on all wheels permanently
• DReduce air suspension ride height automatically

Whining noise from a heavy truck differential that increases with road speed suggests:

• AWorn ring and pinion gear teeth or incorrect mesh pattern from improper setup
• BNormal tyre tread on all dual wheels
• CCorrect air brake adjustment on S-cams
• DFull AdBlue tank level

An automated manual transmission (AMT) on a heavy truck differs from a full automatic because:

• AIt uses a manual gearbox with computer-controlled clutch and shift actuators
• BIt has no clutch and uses a torque converter exclusively like a car automatic
• CIt eliminates the need for any lubricating oil in the gearbox
• DIt cannot be driven in manual mode under any circumstances