What Do You Know About Car Engines?


By: J. Reinoehl

6 Min Quiz

Image: shutterstock

About This Quiz

How well do you know your way around a car's engine? You might be as skilled as a NASCAR pit crew chief, but you're going to have to prove it on this quiz. Your level of automotive knowledge will be put up on the rack for inspection!

If your car started making a loud, squealing noise every time you turned the wheel to the right, would you be able to diagnose it? Or would you need to have your mechanic take a look? Some of us are mechanically inclined, and some of us really shouldn't peek under the hood. Car engines are complex machines with dozens of parts working together. Only a trained automotive mechanic will be able to speed through this quiz with ease, but we're sure you will surprise us with your knowledge!

Put your pedal to the metal, and put yourself to the test! Tell us if you know your camshafts from your axles, and we'll be able to accurately determine how much of a car whiz you are. Have you got what it takes to change your own head gaskets, or do you have a tow truck on speed dial? Let's find out how much you know!

Cars with fuel injection no longer need which device?

Because the injector atomizes fuel into the air stream, it does not require the suction of the carburetor to draw the fuel into it. However, fuel filters that clean impurities from the fuel, valves that allow fuel into the engine, and catalytic converters that reduce air pollution are all still necessary components.


What is the usual order of a four-stroke engine cycle?

Intake is the first downward stroke that brings the fuel-air mixture into the chamber. The second stroke moves upward, compressing the mixture. At that point, a spark ignites the mixture and drives the piston downward in the power stroke. The final stroke moves upward and expels the exhaust from the chamber.


What is the purpose of a catalytic converter?

The catalytic converter contains a catalyst to interact with engine exhaust. This reaction changes the harmful gasses created during combustion into less harmful ones.


What is a design difference between gasoline and Diesel engines?

Diesel engines use compression heat to ignite the fuel instead of using an actual spark like gasoline engines. Diesel engines need a heating element, or glow plug, to help start the process on a cold day.


The connecting rod does what?

The piston head connects to the crankshaft by the connecting rod. The purpose of the rod is to convert the up-and-down motion of the piston into the rotating motion of the crankshaft.


Thick white smoke coming out the exhaust usually means what?

A thick cloud of white smoke indicates that radiator fluid is leaking into the exhaust. The only way for this to happen is if either the head gasket or engine block is damaged.


A four-stroke engine with which of the following number of valves would not be considered a multi-valve engine?

A four-stroke engine must have at least two valves. Therefore, two valves are "standard." Three or more valves increase the efficiency of the engine and give it the “multi-valve” designation.


Which component initially cranks the engine so people no longer have to stand next to it and turn a crank to start their cars?

The solenoid starter cranks the engine when the key is turned. Not only was cranking a car by hand difficult, but it was also dangerous.


Which three are the most common engine configurations for vehicles?

The I-engine is an inline or straight engine. A variation of this would be the flat (boxer or horizontal) engine. The V-engine has the pistons angled out, and the W is a combination of the I and V.


What is the most likely reason you would notice spark plugs coated in oil when you are changing them?

If oil coats the spark plug, it is usually because the piston rings or valves are leaking. This situation can cause the engine to misfire or only spark weakly.


If the engine is overheating, which of the following is most likely the reason?

When a car is overheating, the most likely cause is a bad thermostat out of all the options offered. Another reason a car engine might overheat is if there is an internal or external leak. The best thing to do with an overheating engine is to turn the engine off immediately because permanent damage can occur.


Which of the following is NOT an advantage of multi-valve engines?

The more valves an engine has, the more it increases the area through which air, fuel, and exhaust travels. It improves the air-exchange efficiency and allows the engine to create more power and operate at higher RPMs. However, it increases the manufacturing cost and can also consume more oil.


Which of the following is not an advantage of firing order in an engine?

Firing order has no effect on fuel efficiency. It is essential for maintaining balance and reducing engine vibration. Proper firing also allows the power output of an engine to flow evenly.


What is the purpose of a torque wrench?

Torque wrenches are designed to tighten bolts to a specific pressure. Beam style torque wrenches are less reliable than the dial or digital ones. A torque wrench should never be used to loosen a bolt—break bars are designed for that task.


What should you do if your car begins to overheat?

Pulling the cap off the radiator when the engine is hot (whether it is running or not) can cause severe burns. The air conditioning may cool the inside of the car, but it will make the engine run hotter and cause more damage. As soon as you shut an overheating car off, it will begin to cool down. You should wait until it is completely cool before attempting to service it.


What attaches the piston head to the connecting rod?

The gudgeon pin allows the connecting rod to pivot around it in a ratcheting fashion. If the connecting rod does not move freely, it is usually due to rust on the pin.


Which of the following is an advantage of poppet valves over sliding valves?

They have almost no leakage. Poppet valves work when cams press against the valve stem and compress the spring. Although their response times are consistent, desmodromic valves are sometimes used in engines that will run at high speeds because of valve float.


What is the purpose of a flywheel?

The flywheel is a heavy disk that spins and stores rotational energy. Because the power stroke of the piston is the only one providing energy to the system, the flywheel allows speeds to remain constant and smooth, even during the other three strokes.


The starter relay (or solenoid starter) starts the car using which principle?

The starter is a coil of wires that uses electromagnetic principles to start the engine when a current passes through it. It spins the drive pinion, which then moves the flywheel to start the engine.


What is the usual firing order for a standard 4-cylindar engine?

Although technically any firing order could be designed into the engine, 1-3-4-2 is the standard. Another acceptable but less frequently used order is 1-2-4-3.


What device opens and closes engine valves?

The camshaft operates the valves with protruding lobes. The lobes press different valves open as they rotate.


If blue smoke is coming out the exhaust, which of the following is most likely the cause?

Blue smoke indicates oil is burning in the combustion chamber. Worn piston rings or worn valve seals could cause this problem.


Engine cylinders fire in the correct order because of what?

At one time, cars only used a distributor spinning a rotor to create an electrical current that would flow through the leads to the right spark plug and fire each cylinder in the correct order. However, many modern cars use a more direct system where the computer fires each coil in the correct order.


The Wankel engine is unique because of what?

The center of a Wankel engine contains an internal elliptical rotor instead of reciprocating pistons. Because of its simpler design, it tends to be lighter than piston engines with similar power output.


Which of the following is not an electric car?

Although Honda has experimented with hybrids, its Civic remains powered by a gasoline engine (or hybrid) instead of being fully electric. The Honda Fit EV is the company's pure electric model.


What is a ring compressor used for?

A ring compressor fits around the piston rings and compresses them so that the piston will fit into the cylinder. There are adjustable and fixed models, each with benefits and drawbacks.


An OHV engine has a camshaft located where?

The abbreviation OHV stands for OverHead Valve. It is used to describe a camshaft located directly over the crankshaft in the engine block (as opposed to being over the valves).


What is the purpose of a fuel injector?

Fuel injectors atomize fuel into a spray and inject it either into the air stream or directly into the combustion chamber. It is cheaper to use for controlling emissions than the complex carburetors required to do the same job.


What is the purpose of honing?

Honing is a process of putting small cross-hatches in the metal, which helps it retain oil across its surface. It cannot be too rough, or it will cause excess wear.


What are some disadvantages gasoline engines have as compared to Diesel engines?

Because Diesel engines use compression heat to help create the explosion, they are more efficient and produce less carbon monoxide than gasoline engines. Diesel engines are louder, more expensive, and have a higher power-to-weight ratio.


Which of the following tools would be used to clean debris from threaded holes?

Thread cleaning taps clean threaded holes to keep debris out of the engine and torque measurements correct. Thread-cutting taps are sometimes used for this purpose, but they can damage the threads if they are not used correctly.


When the radiator thermostat is hot, what does it do?

As the temperature of the engine rises, the thermostat opens, allowing coolant from the radiator to flow more freely into the engine and cool it. The thermostat is made out of metal that expands at the necessary temperatures.


What does DOHC stand for?

When the camshaft is over the valves, it is called an OverHead Cam. When there are two camshafts, one for intake and one for exhaust, it is called a double camshaft. When a camshaft is over the valves, it is considered an overhead camshaft or cam. DOHC is a double overhead camshaft.


Which part of the engine do you need a harmonic balancer tool to install and remove properly?

A harmonic balancer tool prevents damage to the crankshaft when pulling the crankshaft out or installing it. It enables you to safely remove and install the harmonic balancer that connects the engine to the drive belts, as well as reducing vibration.


In what way can you "tune" the exhaust system to increase engine power?

Installing headers separates the gas flow from each cylinder, to keep them from interfering with each other. It also maintains the ideal speed of the exhaust and allows cylinders to assist each other.


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