270201 - Engines and Related Systems

Compared with a four-stroke spark-ignition engine, a two-stroke spark-ignition engine generally:

Requires two crankshaft revolutions to complete an operating cycle Completes a power cycle in one crankshaft revolution Has no need for lubrication Cannot be air cooled

A horizontally opposed engine layout is characterized by:

Cylinders arranged in-line above the crankshaft Cylinders set at 90° to each other on a common crankshaft Cylinders lying flat on each side of the crankcase with pistons moving in opposite directions Two crankshafts with opposed pistons sharing a common cylinder

The distance the piston travels from top dead centre (TDC) to bottom dead centre (BDC) is called the:

Bore Stroke Deck height Compression ratio

The main difference between diesel and gasoline engines is that diesels:

Use spark plugs for ignition Rely on high compression and injected fuel instead of a spark ignition system Cannot use turbochargers Operate on only two strokes

The term that describes mounting an engine sideways in a front-wheel-drive vehicle is:

Longitudinal Vertical Transverse Radial

In an opposed-piston engine (not horizontally opposed), the cylinders have:

One piston and two spark plugs Two pistons in each cylinder with no cylinder head Three pistons in a Y configuration One piston and one intake valve

A V-type engine is commonly used because it:

Is taller but narrower than an inline engine Reduces overall engine length and can improve balance Eliminates the need for a crankshaft Requires only one connecting rod per crank pin

A short block assembly normally includes:

Block, pistons and cylinder head Block, crankshaft, pistons, rings, rods, and often camshaft and timing components Block, intake and exhaust manifolds only Block, water pump and accessory drives only

The passages that allow coolant to circulate around the cylinders in an engine block are called:

Oil galleries Transfer ports Water jackets Deck slots

A dry cylinder liner differs from a wet liner in that a dry liner:

Is in direct contact with coolant along its full length Is fully supported by the block casting and does not directly contact coolant Can only be used in aluminum blocks Does not require any machining of the block

Most modern light-duty gasoline engines use which type of cylinder liner?

Wet removable liner Integral liner formed as part of the block casting Sleeveless design with no cylinder wall Threaded screw-in liners

A full-floating piston pin is retained in the piston by:

Press-fit in the small end of the connecting rod Circlips or snap rings in grooves in the piston Being welded to the con rod A tapered interference fit in the piston bosses

The ring end gap on a piston ring is required to:

Increase compression ratio Allow installation and thermal expansion of the ring Ensure the ring locks tightly against the piston land at all times Prevent oil control

A cam-ground piston is manufactured so that:

Its skirt is perfectly round at all temperatures It is slightly oval when cold and becomes round at operating temperature The crown is lower on one side It will not require piston rings

The small end, shank, big end and cap are all parts of a:

Crankshaft Piston Connecting rod Camshaft

Crankshafts are commonly manufactured by:

Casting or forging processes Extruding aluminum tubing Welding separate journals together Stamping sheet metal

Main and rod bearing journals are lubricated by:

Splash from the timing chain only Oil passages drilled through the crankshaft Coolant spray from the water jacket Vacuum created in the crankcase

Axial (end) movement of the crankshaft is controlled by:

Counterweights only Camshaft thrust plate Main bearings with thrust faces or separate thrust washers Piston rings

A harmonic balancer (vibration damper) on the front of the crankshaft is used to:

Increase oil pressure Absorb torsional vibrations and assist in balancing external-balance engines Cool the radiator Drive the starter motor

Camshaft bearings are normally located in the:

Oil pan Cam bore in the block or cylinder head Crankshaft counterweights Rocker covers

Which type of lifter generally has the lowest friction losses?

Flat tappet lifter Mechanical bucket lifter Roller lifter Hydraulic lash adjuster without a roller

Hydraulic valve lifters are designed primarily to:

Increase valve lash Eliminate the need for periodic valve clearance adjustment Reduce oil pressure Prevent camshaft rotation

A surface treatment applied to some camshafts to help retain initial lubricant and prevent scuffing is called:

Nitriding Parkerizing Chroming Anodizing

In an overhead valve (OHV) engine, the valves are located in the:

Engine block Cylinder head Intake manifold Crankcase

The primary purpose of a valve guide is to:

Increase combustion chamber volume Hold the valve in alignment so the face seats properly Provide spring tension Seal oil from entering the cylinder

A device fitted to some exhaust valves to help reduce carbon build-up by rotating the valve slightly each time it opens is a:

Valve spring shim Valve seal Valve rotator Valve keeper

A complete top-end gasket set for an engine would typically include:

Head gasket, rocker cover gasket, valve stem seals and intake/exhaust manifold gaskets Only the oil pan gasket Only spark plugs and plug wires Only rear main seal and front crank seal

One major function of an engine cooling system is to:

Keep the engine at ambient temperature at all times Bring the engine up to operating temperature quickly and then control excess heat Increase exhaust backpressure Cool only the intake manifold

The main purpose of the thermostat is to:

Pressurize the cooling system Control flow of coolant so the engine reaches and maintains proper temperature Lubricate the water pump Vent air from the fuel system

Installing a radiator cap with a higher pressure rating will:

Decrease the boiling point of the coolant Increase the boiling point of the coolant Have no effect on boiling point Stop coolant flow through the radiator

A spring inside the lower radiator hose is used primarily to:

Control thermostat opening Prevent hose collapse when the engine cools or at high pump suction Maintain electrical ground Provide vibration damping for the radiator

Ethylene glycol antifreeze is commonly used because it:

Has a lower boiling point than water Raises both the boiling point and lowers the freezing point of the coolant Is non-toxic Does not require corrosion inhibitors

Propylene glycol coolant is preferred for many diesel engines because it:

Provides better cavitation and corrosion protection with low silicate levels Is coloured blue Has no environmental concerns Cannot freeze

A cooling system that warms up too slowly may be caused by:

A thermostat stuck open A blocked heater core Low engine oil pressure A slipping fan belt only

One function of engine oil is to:

Remove spark from the cylinders Lubricate, seal, cool, clean and cushion moving parts Increase exhaust restriction Provide anti-freeze protection

The viscosity of engine oil is a measure of its:

Colour Resistance to flow Additive content only Pour point temperature only

The filtering media used in most modern spin-on oil filters is:

Loose cotton waste Pleated paper or synthetic non-woven fibres Activated charcoal granules Steel wool

A full-flow oil filtration system:

Filters only a small portion of oil all the time Routes all oil through the filter before it reaches the bearings Does not use a filter bypass valve Is no longer used on engines

Exhaust manifolds are typically manufactured from:

Cast iron or steel Brass Plastic Glass fibre

An oxygen (O₂) sensor can be located:

Only in the intake manifold In the exhaust manifold, ahead of the catalytic converter or both ahead of and behind it Only inside the fuel tank Inside the air cleaner housing only

A resonator installed in the exhaust system is primarily used to:

Increase engine power Reduce specific exhaust sound frequencies for noise control Filter particulates from diesel exhaust Control NOx emissions

Rubber exhaust hangers are used to:

Support only catalytic converters Isolate exhaust vibration from the vehicle body and allow thermal expansion Prevent corrosion Seal exhaust leaks at flanges

When selling a replacement muffler, related parts that should be considered include:

Hangers, clamps and adapters Spark plugs and wires Radiator hoses only Brake pads

A restriction in the exhaust system is most likely to cause:

High idle speed but no power loss Loss of power and excessive exhaust backpressure Cooler engine operation under load Increased charging system voltage

A leaking exhaust system ahead of the passenger compartment can:

Improve fuel economy Introduce exhaust gases into the cabin and create a safety hazard Reduce NOx emissions Prevent catalyst overheating

A pre-cleaner on an air cleaner assembly is designed to:

Cool the incoming air Remove larger debris such as straw and leaves before the main filter Measure intake air mass Control throttle opening

Vanes or fins in a heavy-duty air cleaner housing are used to:

Heat the incoming air Create a swirling motion so heavier dirt particles are thrown outward Support the air filter element only Act as a throttle plate

MAP sensor stands for:

Manifold Air Pressure Manifold Absolute Pressure Mass Airflow Pressure Measured Air Proportion

A turbocharger increases engine power by:

Restricting airflow into the engine Using exhaust energy to compress intake air Cooling the radiator Reducing fuel pressure

When shipping a turbocharger, it is important to:

Allow the turbine to spin freely Package it so the turbine and compressor wheels cannot rotate Remove all lubrication Store it upside down only

A dirty or restricted air filter is most likely to cause:

High boost pressure Reduced engine performance and increased fuel consumption Higher charging system voltage Improved fuel economy

On some agricultural equipment, a restriction indicator in the air induction system is used to:

Show coolant temperature Warn when air filter restriction exceeds a specified limit Control fuel pressure Measure engine speed

The octane rating of gasoline is a measure of its:

Density Ability to resist knock (pre-ignition and detonation) Colour Sulphur content

Which of the following fuels provides the highest heat energy per gallon?

Propane Gasoline Diesel fuel Natural gas

Components of an EVAP (evaporative emissions) system that prevent fuel vapours from escaping include:

Charcoal canister, purge valve, sealed fuel cap and vapour lines Radiator cap and overflow bottle PCV valve and breather filter only Exhaust manifold and muffler

A multi-point fuel injection (MPI) system typically uses what type of fuel pump?

Mechanical diaphragm pump on the engine Electric pump located inside the fuel tank Hand-operated priming pump only Vacuum-operated pump in the intake manifold

The fuel tank module (or fuel cluster) normally contains:

Only the fuel cap Fuel pump, pickup screen and sending unit Radiator fan and shroud Throttle body housing

In a gasoline fuel injection system, the component that atomizes the fuel is the:

Fuel pressure regulator Fuel injector nozzle Fuel filter Idle air control valve

The fuel pressure regulator in a return-style system is designed to:

Maintain constant pressure at the injector rail relative to manifold pressure Measure air mass Control ignition timing Filter fuel

The engine control module (ECM) varies the amount of fuel delivered by:

Changing injector pulse width (on-time) Changing injector colour Altering fuel tank size Adjusting spark plug gap

Closed-loop operation of a gasoline EFI system uses feedback primarily from which sensor?

Coolant temperature sensor Throttle position sensor Oxygen (O₂) sensor Vehicle speed sensor

Top-feed and bottom-feed are terms used to describe:

Types of fuel pumps Injector body designs and how fuel enters the injector Carburetor choke types Intake manifold layouts

Diesel fuel grades 1D and 2D mainly differ in:

Colour only Cold-weather performance and volatility Octane rating Lead content

Diesel fuel is rated by:

Octane number Cetane number Viscosity only SAE weight

In a typical diesel fuel system, the primary filter is located:

Between the tank and the transfer (lift) pump After the high-pressure pump Inside the combustion chamber In the return line only

The component that senses engine speed and controls fuel delivery to limit maximum diesel engine speed is the:

Turbocharger Governor MAP sensor Throttle position sensor

A common-rail diesel injector is normally held closed by:

Vacuum in the return line A spring and high pressure acting on a control valve until the ECU energizes the solenoid Mechanical linkage to the throttle pedal Lack of fuel in the rail

Direct injection diesel systems deliver fuel:

Into the intake manifold upstream of the valves Into a pre-combustion chamber only Directly into the cylinder combustion chamber Into the exhaust port

In many LPG systems, the fuel filter is located inside the:

Carburetor float bowl Fuel lock (lock-off) assembly Radiator Engine oil pan

A characteristic of LPG used in Alberta is that it is:

Heavier than air and stored as a liquid under pressure Lighter than air and stored only as a gas Coloured green and heavier than water Non-flammable in liquid form

LPG pressure is usually reduced from tank pressure to near-atmospheric pressure by:

A single-stage carburetor A two-stage regulator/vaporizer The fuel injectors The throttle body

CNG (compressed natural gas) is stored on-board at high pressure mainly because:

It must remain a liquid at all times High pressure allows enough fuel mass to be stored in a reasonable tank size Low pressure would damage the injectors It improves octane rating

Ideally, complete combustion of a hydrocarbon fuel produces mainly:

Carbon monoxide and nitrogen oxides Water vapour, carbon dioxide and nitrogen Unburned hydrocarbons and sulphur dioxide Lead oxides and soot

Oxides of nitrogen (NOx) are mainly formed when:

Combustion temperature is low Combustion temperature is very high and excess oxygen is present The fuel contains water The exhaust system leaks

The PCV (positive crankcase ventilation) system helps emission control by:

Venting crankcase vapours directly to atmosphere Routing blow-by gases back into the intake to be burned Adding fuel to the crankcase Increasing fuel pump pressure

An evaporative emissions system prevents fuel vapours from escaping by:

Using open vented caps Storing vapours in a charcoal canister until they can be purged and burned Routing all vapours to the exhaust manifold Condensing them to liquid in the muffler

Particulate emissions from diesel engines consist mainly of:

Unburned soot, ash and heavy hydrocarbons Water vapour only Lead and mercury Nitrogen and oxygen

A Diesel Particulate Filter (DPF) is designed to:

Increase fuel pressure Trap soot and periodically regenerate by burning it off Reduce coolant temperature Replace the turbocharger

Sulphur dioxide emissions are primarily a concern because they:

Cause acid rain when combined with water vapour in the atmosphere Improve octane rating Increase engine power Neutralize NOx

The oxidizing catalyst in a three-way catalytic converter typically contains:

Iron filings Platinum and palladium Lead and copper Nickel and chromium

The reducing catalyst in a three-way converter primarily helps reduce:

Carbon dioxide (CO₂) Nitrogen oxides (NOx) Water vapour Oxygen levels in intake air

The main function of the EGR (exhaust gas recirculation) system is to:

Increase engine power under wide open throttle Reduce NOx emissions by lowering combustion temperature Increase exhaust noise Filter particulate emissions

A plugged catalytic converter will usually cause:

Free-flowing exhaust and high power Loss of power and increased exhaust backpressure Higher charging system voltage Low coolant temperature

When diagnosing a suspected EGR valve stuck open at idle, the technician would most likely observe:

Smooth idle and high power Rough idle, stalling and low manifold vacuum High oil pressure No change in engine operation

A catalytic converter is most efficient once it has reached:

Ambient temperature Its designed light-off temperature (hot operating temperature) Oil boiling temperature Coolant freezing temperature

Using leaded fuel in a catalytic converter–equipped vehicle will:

Improve converter efficiency Contaminate and permanently damage the catalyst Have no effect on emissions Reduce octane rating

Latent heat of vaporization refers to the:

Heat added or removed to change a substance from solid to liquid Heat added or removed to change a substance from liquid to vapour without changing temperature Heat needed to raise 1 kg of water by 1°C Heat loss from engine coolant

R134a systems typically use which type of refrigerant oil?

Mineral oil only Polyalkylene glycol (PAG) or polyol ester (POE) oil Engine oil Automatic transmission fluid

In a system using a thermal expansion valve, the correct order of major components starting at the compressor discharge is:

Compressor, evaporator, receiver-drier, condenser Compressor, condenser, receiver-drier, expansion valve, evaporator Evaporator, condenser, compressor, expansion valve Receiver-drier, compressor, condenser, evaporator

In an orifice-tube system, the low-side accumulator is used to:

Store high-pressure liquid refrigerant Prevent liquid refrigerant from entering the compressor Replace the receiver-drier and condense refrigerant Control condenser fan speed

The compressor clutch assembly consists of:

A pulley, electromagnetic coil and hub/drive plate Only a belt and pulley Receiver-drier and sight glass Expansion valve and sensing bulb

When the A/C clutch coil is energized, the:

Pulley stops rotating Hub/drive plate is pulled against the pulley to drive the compressor System is placed in defrost mode Expansion valve closes

A/C refrigerant leaving the condenser and entering the receiver-drier is normally:

Low-pressure vapour High-pressure liquid Low-pressure liquid-vapour mixture Engine coolant

Common A/C hose fittings on R134a systems include:

Flange, spring-lock and standard O-ring fittings Threaded pipe plugs only Quick-connect fuel fittings only Banjo bolts only

A Schrader valve on an A/C service port is used to:

Control blower motor speed Allow the system to be charged or evacuated without losing refrigerant when the hose is removed Regulate engine coolant temperature Adjust compressor oil level

Blower motor speed in many HVAC systems is controlled by:

The compressor clutch A resistor pack or electronic blower control module The radiator fan switch The throttle position sensor

Vehicle electronics may temporarily disable A/C clutch engagement under which condition?

When headlights are on During wide open throttle (WOT) to improve acceleration Whenever the radio is turned off Only when coolant is below freezing

A high-pressure cut-out switch in an A/C system is designed to:

Cycle the blower motor on and off Open the circuit to the clutch if discharge pressure becomes excessive Control cabin temperature directly Operate the heater core

On modern vehicles, the A/C system may receive input signals from:

Only the headlight switch Ambient temperature sensor, evaporator temperature sensor and engine control module The fuel gauge only The horn relay

When an A/C system is set to "defrost" mode, the compressor is often engaged so that:

More heat is added to the windshield Moisture is removed from the air to clear the glass more quickly Coolant can bypass the heater core The radiator fan turns off