The Engine Quiz for Dummies


By: Dave Davis

7 Min Quiz

Image: Jetta Productions Inc

About This Quiz

While you don't need to know how to build a clock to know what time it is, you do need to be able to tell time to make sense of the hands' positions. The same goes for automobiles. You don't have to be a mechanical genius or know the intimate details of the internal combustion engine, but drivers should know a bit about the machine they're entrusting with their day — and in some cases — their lives. Do you know your OBD port from your dipstick? This quiz will put your knowledge to the test! 

Major repairs should be left to the professionals, but a car owner who knows how to perform the basic functions of vehicle maintenance will be able to skip some of the more expensive trips to the mechanic. And, when it does come time for a major repair, you'll be a more informed consumer, rather than just handing over the keys and saying, "My car is broke." Reputable mechanics would like a little more information; disreputable mechanics will see a payday. Either way, you're not helping your case by not understanding at least the broad strokes of what's going on under the hood.

So, are you up on your knowledge of your car's engine or could you use a refresher course? What does it mean when white smoke is coming out of your tailpipe. What exactly is the oxygen sensor sensing and why? At the end of this quiz, you'll either be more confident in your skills or will have learned some valuable lessons, so c'mon in and show us what you've got!

What does the alternator do in a vehicle?

While the car's battery provides the initial spark that gets the vehicle running, the alternator takes over the electrical charging duties from there. The alternator, so named because it generates alternating current (AC), provides power to the starter, ignition coil and all the vehicle's electric systems, such as the headlights, stereo, dashboard lights and other items.


The temperature needle on your dash is edging toward the red zone — what's going on?

The engine produces a lot of heat when it's running, and when the system that draws that heat away fails at some point, your temp needle is going to start moving (or, less helpfully, your light is going to come on). It's time to visit the garage and see what's going on under the hood.


What's the dipstick's function in your car?

The humble dipstick is one of the best ways to check on the health of your car by making sure your engine has enough oil and that the oil is clean. Every driver should be able to use the dipstick because it's an easy process; pull it out and wipe it clean, put it back into its pipe, take it back out and check the level and the color of the oil. Done!


Smoke Break! What does black smoke coming out of your tailpipe mean?

If your car is running too rich — meaning there is too much fuel in your fuel/air mix — black smoke will start to appear in your exhaust (and also might be putting off a "rotten egg" smell). Common causes for this could be a leaking fuel injector, a faulty engine sensor or a bad fuel pressure regulator.


You go to start your car and nothing happens — what's the first thing you should do?

The clamps that attach the battery terminals to the electrical system need to be in full contact to complete the circuit and get your car started. When you turn the key and nothing happens — no lights and no sound — pop the hood and check to make sure things are attached correctly. The fix could be easier than you think!


In the automotive world, what is a gasket?

Gaskets are mechanically simple but vital parts of your car's engine. Usually consisting of a steel center coated in a rubberized material, gaskets not only provide a cushion between metal parts of the engine but provide a seal that keeps oil and other fluids from going where they should not go. The head gasket is probably the most famous member of the gasket family.


The solenoid, brush gears and field coil are all part of the ...?

When you turn the key to start the car, you are activating the starter motor, which gets the internal combustion process started until the engine can take it from there. The starter motor is a complex machine in its own right and while you only use it at the very beginning of your journey, you're not going anywhere without it.


What ultimately happens when you run your engine without oil?

When a car's engine runs, there are a LOT of moving parts involved, and some of these parts come into contact with others. Without oil to lubricate the works while the engine is running, those parts start to grind together. While this will cause excess heat and noise, the engine will eventually just stop working and seize. Check your oil!


Which of these best describes a car's radiator?

The car's engine puts out a lot of heat, and the radiator is one of the most critical parts in getting that heat away from the motor. Coolant is pumped through the car's engine and this hot liquid eventually makes its way through the thin tubes in the radiator which cools it by transferring the heat to the outside air.


Where does oil go when the car is not running?

Oil is circulated throughout the engine when the motor is running to keep all the pieces nice and lubricated. When the engine is shut off, it is stored in the oil pan, located under the engine. If the pan gets damaged through the wear and tear of an active life, attentive owners will start to notice puddles of oil forming under the car.


What is the heaviest part of the engine called?

The engine block is, basically, a big hunk of shaped metal that has precision holes drilled into it. The engine block, which is sometimes called a cylinder block, is the bottom part of the motor and contains the cylinder bores, along with passages for oil for lubrication and coolant passages to keep the heat down.


What does the serpentine belt do in an automobile?

The serpentine belt snakes around (giving it its name) and connects the alternator, air conditioning compressor, power steering pump and other components to the crankshaft pulley, and provides power to keep them running. Older cars had many belts to perform all the functions this one belt now pulls off.


What's the function of an oxygen sensor in your car?

The oxygen (O2) sensor measures how much unburned oxygen is left after the engine's combustion process. The car's onboard computer can take this information and change the ratio to make sure the most efficient mix is being used. Symptoms of a bad O2 sensor are a rough idle and difficulty in starting.


What do connecting rods actually connect?

Connecting rods are what connect the piston to the crankshaft. Because they can rotate at both ends, they allow the up-and-down motion of the pistons to be converted into the rotational motion of the crankshaft that goes to spin the wheels. When you hear of someone "throwing a rod," these are the rods in question.


In automotive technology, what does "OBD2" mean?

On-board diagnostics is the way a car can report to its mechanic or owner what's going on with it. Through the use of a scanner that plugs into the vehicle's OBD port — usually located under the dashboard near the steering column — the user can read codes that tell the health or status of the various sensors within the car.


Smoke Break! What does bluish-gray smoke coming out of your tailpipe mean?

Blue-gray (or sometimes white-gray) smoke is a symptom of your car's engine burning oil. This could mean that you've got too much oil in the engine (which is important to remedy but easy to fix), or your engine's piston rings are worn or you've got worn valve seals (not as easy to fix — you're going to need a professional).


What type of engine is found in the typical car on the road today?

Although electric engines are becoming much more common, the standard car is powered by an internal combustion engine. With these, the fuel/air mix is injected into the cylinder where it is combusted (think of it as a cylinder-sized explosion), which moves the pistons, the wheels and you down the street.


What's the function of your car's harmonic balancer?

The harmonic balancer has a new-age name, but it's all about mechanical practicality. Since the internal combustion engine fires in succession and not continuously, the engine would vibrate terribly with this "on/off" power generation. The harmonic balancer, connected to the crankshaft, evens this out by spinning smoothly and providing stability.


What control function can the car's ECU perform?

The engine control unit, or ECU, of the modern car is the computer that maintains engine performance of the vehicle. Using an array of sensors, the ECU keeps a check on how your engine is operating and can make changes to the fuel/air mix, the idle speed, the timing of the valves and more to get optimal performance from the beast under your hood.


The engines of most cars today are powered by...?

Most cars today use gasoline as fuel for the combustion that makes the wheels go round. Although inventors experimented with other fuel sources, gasoline — which was actually a byproduct from the process of making kerosene — eventually got the nod because of its high-energy potential and the fact that it mixes well with air for the combustion process.


Where is the cylinder head located?

The cylinder head is bolted to the top of the engine block — separated by the head gasket — and forms the upper part of the cylinder's combustion chamber. Made of aluminum alloys in modern cars, symptoms of a cracked cylinder head can include oil and coolant loss, smoke and overall cruddy performance. The cylinder head shown here is from a 1987 Honda CRX Si and includes a single cam, rocker arms, valve springs and other components.


When your mechanic says your car has a vacuum leak, what's that mean?

Your engine runs most effectively when airflow is carefully maintained and monitored. When you have a cracked hose, a leaking gasket or seal or another way air is being let into the system where it shouldn't, your car may idle roughly or too high, the engine may stall or you may hear a squealing sound.


In your engine, fuel injectors are ...?

Fuel injectors are small nozzles used to bring fuel into the cylinder that, when mixed with air, is ignited in the internal combustion process. Most modern cars — those from the 1980s onward — use fuel injection systems, which replaced carburetors because of their better performance and increased fuel efficiency.


What does the spark from the spark plug actually do?

In a gasoline engine, the fuel/air mix does nothing until it receives a spark generated by the spark plug. When the spark hits, the mixture ignites and moves the pistons. Spark plugs can be made up of different materials — copper, platinum or iridium can make up the electrode, while the insulator (the white part) is a shell usually made of an aluminum oxide ceramics.


When you look at your car's RPM — revolutions per minute — what are you really measuring?

The crankshaft changes the up-and-down motion of the pistons in the engine into rotational energy that ultimately drives the wheels. RPMs measure how fast the crankshaft is spinning. When the car is idle (not moving), the RPMs are somewhere around 1,000. The faster the engine runs, the higher the RPMs.


What's the difference between a timing belt and a timing chain?

The timing belt synchronizes the camshaft's and crankshaft's rotation and maintains the engine's timing or, more simply, it keeps all the players in the dance of internal combustion playing nice with each other. In older cars, this critical function was performed by a metal timing chain; newer cars have timing belts, which are quieter and less complicated.


Smoke Break! What does white smoke coming out of your tailpipe mean?

Some white smoke when first starting the car, especially on cold days, is a normal result of condensation. When it doesn't stop, however, it most likely means that you've got coolant leaking into the engine's cylinders. This could mean a cracked cylinder head, a leaking head gasket or a cracked engine block. Time to go to the mechanic!


How often should you have the oil filter changed?

Oil is critical to your engine's well being, but dirty oil can start to damage its inner workings. The humble oil filter doesn't cost much but can add years to the life of your engine by keeping dirt, debris and other impurities out of the lubrication system. When you have the oil changed, they'll always change out the filter, as well.


An engine's air filter...?

The air filter is designed to clean the air coming into the throttle and keep dust, dirt, debris, pollen and other contaminants out of the engine where they can do damage over time. This part does need to be changed out regularly (every 15,000 and 30,000 miles, depending on conditions), but it's usually a very easy thing to do.


What should you do when the "check engine" light comes on?

This mysterious light could mean anything from your gas cap is loose to oxygen sensor needs to be replaced to your catalytic converter has gone bad. The on-board diagnostic (OBD) will let you know which one it is. When the light is flashing, however, that's a signal to visit your mechanic because there's serious trouble going on under the hood.


What does a manifold do in a modern vehicle's engine?

The internal combustion engine in a modern car has two manifolds — one for intake and the other for exhaust. The intake manifold brings air to the engine's cylinders which are mixed with fuel and then combusted. The exhaust manifold (shown here) takes these spent gasses and moves them along to make way for a fresh mix.


How does a turbocharger work?

Turbochargers work by forcing more compressed air into the engine's cylinders, which allows for more fuel to be injected as well for a bigger explosion and more power. The turbine that makes all this possible is powered by the engine's exhaust gases. Although they perform similar functions, a turbocharger and a supercharger are mechanically very different.


What is a "Hemi" engine?

Normally associated with powerful, fast vehicles, a "Hemi" engine is one that has a hemispherical (or domed) cylinder head, rather than a flattened one seen in most vehicles. It provides more power but does have design drawbacks. Chrysler is perhaps the best-known manufacturer of this type of engine, but several other companies offer this as an option.


What does the crankshaft do?

Without the crankshaft, the car's engine would run just fine but it would go nowhere. When the fuel/air mix is combusted, it drives the pistons up and down — a motion that is no good for getting the wheels to roll. The crankshaft is connected to the pistons by rods and is designed to convert that lateral motion into rotational energy.


The engine, transmission, driveshaft and axles make up what system in your car?

The powertrain is made up of all the parts that generate power in your car and transfer it to the wheels. When you buy or are given a "powertrain" warranty, this is the system covered. The drivetrain — the parts that connect the transmission to the drive axles — is part of the powertrain.


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