Auto & Shop Information · Practice test 4

Correct answer: cut threads on the outside of a rod or bolt

A die is a hardened ring with cutting teeth that is turned down over a rod to form an external thread. It is the mirror image of the tap, which cuts the internal thread it will screw into.

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Correct answer: Intake, compression, power, exhaust

The cycle draws the mixture in, squeezes it, burns it to drive the piston down, then pushes the spent gas out. Only the power stroke produces work; the other three consume it, which is why an engine needs a flywheel.

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Correct answer: directs high voltage to each spark plug wire in firing order

As the rotor spins inside the cap, its tip passes close to each terminal in turn, sending the coil's spark to the correct cylinder at the correct moment.

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Correct answer: damp the springs so the vehicle stops bouncing

The springs carry the weight and absorb the bump; the shock absorber controls how fast the spring returns, stopping it from oscillating. Worn shocks show up as a car that keeps bouncing after a dip.

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Correct answer: does not melt the base metals being joined

Solder melts and flows between the parts while the parts themselves stay solid, so the bond is adhesion rather than fusion and is much weaker than a weld. Brazing works the same way at a higher temperature and is stronger than soldering.

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Correct answer: let air enter the tank as fuel is drawn out

As fuel leaves the tank, the space it vacates must be filled with air or the tank would form a vacuum and starve the pump; the vented cap allows that air in.

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Correct answer: give the concrete strength against pulling forces

Concrete is very strong in compression but weak in tension, so it cracks when pulled or bent. Embedded steel carries that tension, and the combination is what makes reinforced concrete work.

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Correct answer: valves that never fully close and eventually burn

Metal expands as it heats, so a clearance set too tight disappears entirely and holds the valve slightly open. The valve then loses its contact with the seat, which is how it sheds heat, and it burns. Too much clearance gives the tapping noise instead, which is noisy but far less damaging.

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Correct answer: axle shafts

Axle shafts connect the differential's side gears to the wheel hubs, transmitting the final drive torque to turn the wheels.

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Correct answer: shoes, which press outward against the drum

A wheel cylinder pushes the curved shoes outward until their linings meet the inside of the rotating drum. Pads belong to disc brakes, which shed heat better and are now standard at the front.

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Correct answer: locking a pawl into a gear on the output shaft to prevent the wheels from turning

Selecting Park drops a small pawl into notches on a park gear fixed to the output shaft, mechanically preventing the drive wheels from rotating.

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Correct answer: the camshaft and crankshaft rotating in the correct relationship

Valves must open and close at the exact right moment in the piston's travel, so the belt or chain links camshaft rotation to crankshaft rotation at the correct ratio.

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Correct answer: measure the gap with a gauge and adjust it to specification before fitting the plug

The gap must be set to the manufacturer's specification with a feeler or wire gauge before the plug goes in, since it cannot be adjusted once threaded into the head.

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Correct answer: a thermostat stuck closed

A thermostat stuck shut blocks coolant from ever reaching the radiator, so heat has nowhere to go and the temperature climbs rapidly even before the car moves.

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Correct answer: has deteriorated internally and should be replaced

A healthy hose should feel firm; softness usually means the internal reinforcement has broken down, and the hose can collapse or burst under pressure and heat.

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Correct answer: battery

The battery supplies the large burst of current the starter needs to crank the engine and powers the electrics whenever the engine is off.

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Correct answer: fewer threads per inch and a deeper thread profile

Coarse threads are spaced further apart, giving fewer threads per inch and a deeper cut, which generally assembles faster and resists cross-threading better than a fine thread.

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Correct answer: worn main or rod bearings

As bearing clearance grows from wear, the crankshaft slaps inside the bearing under load, producing a deep knock that gets worse with engine speed and load.

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Correct answer: become out of round or unbalanced

An uneven wheel surface strikes the work unevenly each rotation, producing a chattering vibration that a properly dressed, balanced wheel would not show.

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Correct answer: hold two pieces of material firmly together while work is done on them

Shaped like the letter C, this clamp's screw tightens down to squeeze pieces together, holding them steady for gluing, welding, or other work.

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Correct answer: bring the piston in that cylinder to top dead center on its compression stroke

Valve clearance is only checked with the lobe pointing away from the follower, which happens reliably at top dead center of the compression stroke for that cylinder.

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Correct answer: stores the engine's supply of oil

The pan is a reservoir beneath the crankshaft that holds the oil the pump draws from. It is also called the sump.

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Correct answer: box-end wrench

The closed ring of a box-end wrench grips all six or twelve points of a fastener at once, giving a stronger hold than an open-end wrench that only touches two sides.

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Correct answer: a fault in the charging system

The light means the system is no longer charging, usually a failed alternator or a broken drive belt. The vehicle will run on battery alone for a short time and then stop, so the fault is urgent even though the battery itself may be fine.

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Correct answer: lubricate moving parts and reduce friction

Oil keeps a film between metal surfaces so they slide rather than grind. It also carries away heat and suspends contaminants, which is why it darkens and must be changed.

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