The Big List of Auto Parts Everyone Who Drives a Car Should Know

When you pop the hood of your car, do you immediately feel overwhelmed? If so, you’re not alone. Motor vehicles are more complex than ever before. But there’s no need to be intimidated.

Welcome to the Big List of Auto Parts. You’ll learn everything you need to know about what’s inside your vehicle. Understanding what each component does, and where to find it in your car, helps diagnose, prevent and repair a variety of major vehicle problems.

Ready to get started? Here’s an in-depth look under the hood (and everywhere else):

The Basics

Auto parts fit together in intricate, carefully balanced ways. All the electrical and mechanical systems working together is nothing short of amazing. While it certainly is complicated, the basics are fairly straightforward.

Before diving into the details, let’s take a brief look at the major auto parts and how they work together:

It all starts with powerful, but small explosions created by the interaction of fuel and spark plugs. These explosions move pistons up and down inside cylinders.

Pistons connect to the camshaft, which controls intake and outtake valves. Opening and closing these values controls airflow, which regulates the timing of the explosions.

The pistons also connect to the crankshaft. As they move up and down, the crankshaft rotates. Rotational energy is created which moves the wheels.

If the power goes to the front wheels, the vehicle is front-wheel drive. FWD vehicles have good fuel economy and traction. Plus, they’re usually cheaper than rear-wheel drive vehicles.

Rear-wheel drive vehicles are, naturally, ones where the power goes to the rear wheels. They’re durable and have good handling.

Now that you understand the basics, let’s dive into deeper detail:

Major Components

You’ve probably heard of most of these parts. Here’s a closer look at what they do:

Car Battery

A car battery is a physical reserve of energy for a vehicle. It provides the initial power needed to start the car during ignition. Plus, it also powers the car’s electronics when the engine is off. When running, the engine charges the battery.

Batteries are necessary for gasoline engines. When you turn the ignition, the battery ignites the fuel. Diesel engines don’t need a battery. Electric vehicles require a battery to provide traction energy.

There are a few different types of car batteries:

• Flooded
• Sealed
• VRLA
• Glass

Flooded batteries are very common. They consist of lead plates floating in sulfuric acid. During normal operations, water will evaporate. Flooded batteries must be topped off with distilled water on a semi-regular basis.

Sealed batteries are also common. They’re basically the same as flooded batteries except they’re sealed, so they don’t need water replenishment. If you’ve never topped off your car’s battery with distilled water, it most likely has a sealed battery.

VRLA batteries are valve regulated lead acid batteries. They have two types. The more common type of VRLA has a safety valve which dispenses hydrogen and oxygen. The other type uses a special surface instead of a valve to release harmful gases.

Finally, glass batteries are quite different from all other types. They use recombinant technology to prevent the loss of hydrogen and oxygen. Plus, they hold a charge longer than any other battery, losing just one to three percent each month.

Alternator

The alternator is the main power supply for your car. It supplies electricity to all auto systems. Plus, the alternator keeps the battery charged at appropriate levels.

A red battery warning light should appear on your dashboard if the alternator develops problems. Take this light seriously. The time between when the light appears and when the alternator fails is unpredictable.

If the alternator fails, your car will stall and die. You’ll either need to replace the alternator wherever you are, or you’ll need a tow. Most alternator failures are due to any combination of excessive wear, poor maintenance, age, and prolonged harsh driving conditions.

However, sometimes alternators fail due to bearing failure. A problem with the bearings is actually one of the better alternator problems to have. Bearing failure causes a loud whining noise which, while irritating to listen to, is a clear warning sign of alternator problems.

Spark Plugs

Spark plugs ignite a mixture of fuel and air to create combustion which powers the engine. They’re made from copper, iridium or platinum. Check out our 2019 Guide to the Best Spark Plugs to learn which type is best for your car.

Spark plugs are small and simple but also mighty. If they’re not working, your car won’t start at all.

Before your car starts, the fuel pump sends fuel to the fuel injectors. This fuel mixes with cold air, and the mixture is then injected into the cylinder. Inside the cylinder, the spark plug ignites, which creates a small explosion to move a piston. The entire process repeats several times each minute.

Spark plug problems can be somewhat difficult to diagnose when driving because the symptoms mirror those of many other engine issues. Common signs of faulty spark plugs include:

• The car is jittery and rough when idling
• The car is slow to start, especially on cold days
• The engine briefly halts when driving
• Acceleration is poor
• Fuel consumption increases

Replacing spark plugs is usually a simple task even non-mechanics can perform at home.

Head Gasket

Your engine depends on three vital fluids: oil, coolant and a mixture of fuel and air. They each perform critical functions in making the engine run. However, these fluids don’t get along. If they accidentally touch in any combination, serious problems can result.

The head gasket coordinates the movements of these fluids throughout the engine block. It seals up the combustion chambers. Plus, it creates seals to keep oil and coolant in their respective galleries.

Ever heard the phrase “blown a gasket”? Well, that phrase exists for a reason. Damaged head gaskets can cause catastrophic problems. The specifics depend on which liquid leaked and what it touched, but head gasket problems can result in engine fires, melted parts, and even explosions!

Short-term repairs are possible. You can spray a special liquid solution on a damaged gasket. It’ll seal up any leaks. However, this should only be for a short drive to your mechanic. Replacement is the only long-term solution to a damaged gasket.

Not sure what type of head gasket you need? Our 2019 Guide to the Best Head Gaskets is a helpful resource you’ll want to check out.

Fuel Pump

Also called the electronic fuel injection system, a fuel pump delivers fuel to the engine’s combustion chambers. The fuel pump is a sophisticated piece of equipment. It calculates exactly how much fuel to deliver at any given times based on the position of the throttle, the current air-fuel ration and the contents of the exhaust.

Fuel pumps are found in a variety of locations depending on the make and model of your car. They’re commonly bolted into the fuel tank or else located somewhere between the tank and engine.

Diagnosing fuel pump problems is humorously old school. Using a rubber mallet, tap the fuel pump lightly while trying to start the car. If the problem is the pump, tapping it will cause the car to stutter and start. Keep in mind you need to replace your fuel pump right away. This method usually only works once or twice.

Gas Cap

Now, I don’t mean to insult your intelligence. Everyone knows what a gas cap is. The problem is that a gas cap is so common, and so simple, that many people forget it exists.

A loose gas cap is an extremely common reason for a “Check Engine Light” to appear. You can drive yourself crazy searching deep inside your engine for a problem when all you needed was a new gas cap.

Over time, the seal on the gas cap can wear down or dissolve. Even a small gap in the seal will activate a warning light.

Replacing your gas cap is usually easier than repairing it. However, prevention is the easiest. Clean around your gas cap with a clean cloth. Regular cleanings help reduce debris buildup.

Camshafts

The camshaft opens and closes the engine’s valves. It allows air and fuel inside the engine while allowing exhaust gas to escape. Generally, camshafts are durable. Problems are rare. If your camshaft fails, other parts of your engine are likely also having serious problems. Typically, camshaft failures result after a prolonged period without oil.

Camshaft Position Sensor

This is the brains of the camshaft. As the engine runs, the cam rotates 360 degrees. The position sensor continually monitors the direction the camshaft faces. It uses this information to control when fuel sprays into the intake manifold.

There are two ways to recognize a faulty position sensor. First, the “check engine” light will appear on the dash. You might also notice your car taking longer to start. If the sensor is off, the camshaft will spray more fuel than necessary, which slows down the ignition process.

Timing Chain

Also called a timing belt or a cam belt, the timing chain synchronizes the crankshaft and camshaft. It ensures both of those components rotate at the same speed. Synchronization ensures the valves open and close at the correct times during intake and exhaust.

Although “timing belt” and “timing chain” are used interchangeably, there is an important technical difference. A timing chain is made of metal links. It’s like a souped-up version of a bicycle chain. The chain links move sprockets on the crankshaft and camshaft. Moving these sprockets opens and closes valves.

All timing chains wear down with time. Rougher, faster driving conditions will wear the chain down sooner than taking it easy on the road. If the chain fails, the car won’t run. The Check Engine Light will also light up your dash.

If the chain is worn and about to fail, you’ll likely hear engine rattling. It’ll be especially noticeable when the car is idling. Also, watch for metal shavings in the car’s oil.

Replace a damaged timing chain right away, even if you have to pay a mechanic to do so. A faulty timing chain can set off a, well, chain reaction of damage extending to your crankshaft and camshaft. Repairs can cost thousands of dollars.

Mass Air Sensor

As you’ve probably noticed by now, the air/fuel mixture plays an important role in engine operation. The mass air sensor helps regulate this mixture. It detects the air volume entering your car’s intake.

The sensor needs to monitor the air flowing into the car. But this means the sensor is also easily contaminated by dirt, dust and other road debris. Too much build-up can damage the accuracy of the readings.

Hoses

All vehicles are packed with hoses. Common types of hoses include:

• Radiator Hoses
• Fuel Hoses
• Oil Hoses
• Transmission Hoses

Hoses inevitably leak. Their rubber material will dry out and crack over time. Keep tabs on your parking space. If you notice spills, drops, and stains, it’s time to crawl underneath your car and hunt leaks.

Most leaks aren’t a big deal once identified. You simply need to replace the worn-out hose. However, you want to replace any leaking hoses as soon as possible.

Oil leaks are especially destructive. Oil will eat through rubber fairly fast. You want to fix all leaks quickly but be extra-fast about attending to oil leaks.

Ignition Switches

If the term sounds familiar, it’s likely because ignition switches were prominently featured in the news just a few years ago. Faulty ignition switches in General Motors vehicles results in 19 deaths.

An ignition switch is basically an on/off switch for your car. It acts like a light switch; it’s either on or off. If you ever notice your car is slow to turn off even when you turn the key to the off position, stop driving and contact a mechanic. Ignition switch failure on the road can be deadly, so you don’t want to take any chances.

Braking-Related Auto Parts

Driving fast is fun, but your vehicle’s ability to slow and stop is far more important. Here’s a look at auto parts related to the brake system:

ABS Control Unit

Anti-lock braking systems prevent the wheels from locking up when braking. They reduce the chances of skids and increase your overall control over the vehicle, even when braking suddenly. Almost all cars made after 1978 have ABS brakes.

The ABS Control Unit monitors brake pressure and wheel speed to adjust the stopping power as needed in real time. If the Control Unit develops a potential problem, a yellow or orange ABS warning light will appear on the dash.

The warning light could have three potential causes. The Control Unit itself could be damaged. Unfortunately, this is a fairly expensive and labor-intensive repair. However, the warning light could also activate due to a failure of either the wheel-speed sensor or brake-pressure sensor. Both of those are significantly easier to replace.

Brake Caliper

The brake caliper physically stops the car by clamping the brake pads onto the brake rotor. They’re a relatively simple part but vital to overall safety.

Typically, brake caliper failure doesn’t mean you can’t stop the car. Instead, it means the brakes stay applied at all times. Seized rotors can cause the car to pull to one side. The brake pads will burn away quickly. Additionally, brake caliper problems can cause brake fluid leaks.

Caliper repair kits are available. But new calipers are inexpensive. Buying new ones is usually an easier and longer-lasting solution.

Brake Rotor

These large, silver discs are a major brake component. The calipers clamp the brakes pads down onto the rotor, which then stops the vehicle. Normal vehicles operation places lots of friction and heat on the rotors.

Poor stopping ability is a sign a vehicle’s brake rotors are worn. Another sign is when the brake pedal pulsates when pressed. Worn rotors are a safety hazard and should be replaced immediately. Always replace rotors in pairs to ensure even wear.

Brake Light Switch

If your brake lights are out, check the lightbulb. Most likely it just needs to be replaced. But if that doesn’t get the brakes lights working again, the brake light switch is probably faulty. The brake light switch is a small connector which activates the lights whenever you apply the brakes.

License Plate Bulbs

As long as you’re checking out your brake lights, don’t forget about the lights around your license plate. Most states require that the rear license plate remain visible at all times. Unfortunately, these bulbs are the most forgotten bulbs in the entire car. Don’t risk a ticket over a lightbulb that costs less than a buck.

Check your bulbs frequently. If they go out, you probably won’t get a dashboard warning. Toss an extra pack of bulbs in your glove box just in case.

Air Conditioning System Parts

Stay cool behind the wheel no matter where you drive with a working A/C system. Aside from keeping you comfortable, your A/C system acts as a barometer for the health of your vehicle. Here’s a rundown of what parts help maintain safe temps inside the cabin and engine:

AC Compressor

The AC Compressor is the main component of the vehicle’s air conditioning system. It keeps the system pressurized and allows refrigerant to flow properly.

Two potential problems can occur with an AC compressor. A clutch might fail to engage with a pulley on the end of the unit, which causes the system to lose pressure. Not every type of compressor has this clutch.

All compressors have internal seals. The main source of compressor problems is internal seal failure. When seals leak or become dislodged, system pressurization plummets. Repairing a damaged AC compressor usually isn’t possible. Instead, replacement is the only option.

Leaks are the most common cause of A/C problems. If you’re not able to keep your car cool, or if the airflow is weak, first check all hosing and connections. But if the system is leak-free, a faulty compressor is the likely culprit.

Blower Motor

This device, which resembles a hamster wheel, blows air from the engine into the cabin. It sits behind the glove compartment. When you adjust the fan speed, you’re actually adjusting the blower motor.

If the fan in your car produces no air whatsoever, the blower motor has likely failed. You’ll likely need to install a new unit. However, the motor might only need repair if the fan is noisy or creates a weak air stream. Partial function often means the blower motor resistor needs replacement.

Heater Core

You don’t always need to keep the passenger cabin cool. During winter months, you’ll want to crank up the heat. The heater core is used to increase the temperature inside the car.

A heater core is basically a tiny radiator. It’s behind the dashboard near the blower motor. Adjusting the fan regulates the temperature.

Heat systems have two common problems. They can leak coolant into the interior. You’ll be able to notice that directly. They can also become clogged. You’ll notice that issue indirectly. The heat will be weak or non-existent.

Steering System Parts

Turning the steering wheels changes the direction of the tires. Steering sounds simple, right? As it turns out, quite a few different parts are involved. Here’s a closer look:

Steering Wheel

Turning the steering wheel moves the car. But that’s not all it does. The steering wheel is also home to the horn, cruise control, audio system controls and more. The more you can do by pressing buttons on the steering wheel, the less you have to take your eyes off the road while driving.

Most modern cars have some type of steering assistance system. Hydraulic Power Steering and Electric Power Steering are the two most common forms of steering assistance.

Behind the wheel, you’ll find the steering column. Original steering columns were non-collapsible. Unfortunately, a non-collapsible steering column was practically guaranteed to impale the driver in an accident. In 1968, the U.S. adopted new standards in crash prevention which mandated collapsible steering columns.

Certain cars use “rack and pinion” steering. It consists of a circular gear called a pinion. The pinion has teeth which engage with the linear “rack” to transform the rotational motion of the steering wheel into linear motion to guide the vehicle.

Differential

The differential regulates engine torque to either the front or back wheels. It performs three key functions:

• Directs engine power to the wheels
• Slows rotational speed of the transmission as needed
• Splits power levels between wheels

The last function is arguably the most important. The differential independently adjusts the power directed to each wheel.

The differential directs power to the driving wheels on your car. For example, if your car is front wheel drive, the power is sent to the front wheels. But – and this is the key part — that power isn’t sent equally.

Picture a vehicle making a gentle turn. The front left wheel and front right wheel are moving different distances at different speeds. If engine power was sent equally to both wheels, they’d be forced to move at the same speed – and that’s no good. It would make turning difficult while also putting needless strain wheels, axel, and other components.

Aside from FWD and RWD vehicles, differentials are found in all-wheel-drive vehicles. Also known as full-time four-wheel-drive vehicles, all-wheel drive vehicles need a set of differentials. One differential powers the front wheels while another powers the back.

Axle Shafts

Also called CV shafts, these thin rods connect the differential to either the front or rear wheels (depending on your drivetrain). They allow power created by the engine to reach the wheels and create forward momentum. Problems with these shafts affect steering and drive.

CV shafts have a rubber boot on each end which protects a joint. These two boots are the most vulnerable areas. If either becomes loose or torn, the joints underneath can be damaged by dirt and debris.

When the boots are worn, you’ll hear a clicking sound when driving. It’ll be especially noticeable when turning. When caught early, you can replace just the rubber boots. However, make sure the shaft itself is free from damage. Otherwise, it’ll have to be replaced, too, as driving with a damaged axle shaft is dangerous.

Ball Joint

The ball joint plays a major role in keeping your ride smooth when driving. It acts as a pivot point for the suspension and steering linkage.

Problems with the ball joint are usually obvious to diagnose. A failing ball joint makes an obnoxious rattling noise whenever the shocks are engaged. The noises are especially pronounced whenever the vehicle passes over any bump.

Damaged ball joints must be replaced. Generally, the quality of the construction determines the lifespan of the ball joint. While you can find cheap ball joints, they’re unlikely to last for a long time. Always buy the highest quality you can afford – you’ll save in the long run.

Control Arm

Control arms connect the wheels to the body of the vehicle. The shape and size of the arms vary by vehicles type. Control arms consist of ball joints and bushing.

If control arms become worn, you’ll hear a knocking, banging sound underneath your car, especially when driving over uneven terrain. Additionally, the alignment might feel loose. Sometimes the ball joints can be replaced individually. Otherwise, you’ll need to replace the entire arm.

Tires

The tires are where the rubber meets the road. They’re arguably the most important part of your vehicle. Every other component in your car could be in perfect working order, but a problem with the tires can still put you at risk of an accident. Always make sure your tires stay in great working condition and check out any potential problems right away.

Only use tires specifically recommended by the manufacturer. You’ll find the appropriate size listed in your owner’s manual. Many cars also display tire information on the inside frame of either the driver or passenger door. Tire size is also printed directly on the tire. It’s a long string of letters and numbers.

Aside from size, you’ll also want to know the tire’s load index and speed rating.

Also known as the load carrying capacity, a tire’s load index is the amount of weight the tire can support. For example, an 88-load index can carry 1,235 pounds. Keep in mind that’s the weight limit per tire. Four tires with an 88-load index can support 4,940 pounds total.

The load index is a two-digit number found after the tire size. On the tire, you’ll see the long alphanumeric string. That’s the tire size. To the right will be two numbers and a letter. Those two numbers are the load index.

The letter next to those two numbers is the speed rating. The most common ratings are L, M, N, P, Q, R, S, T, U, H, Y and (Y). Without getting into too much detail, the order listed roughly corresponds to higher speeds. An L rating can safely handle speeds of 75 mph while a (Y) can handle 180 mph.

In Conclusion

Cars are getting more complicated by the day. But don’t be intimidated. When you understand the basics, it’s easy to figure out the rest as you go along.

Every part of your vehicle, even the tiniest screw, has a distinct purpose. Identifying what various components do is a great way to diagnose problems. Plus, understanding the basic functions of major auto parts makes maintenance easier, too.

When you encounter an unfamiliar part, try to connect it to a part you are familiar with. Try to understand how the part fits in with larger systems within the car. Before you know it, you’ll be an auto part expert!