Camshaft vs Crankshaft: A Clear Guide for Mechanics and Parts Dealers

Auto parts dealers, wholesalers, and retailers often deal with clients who don’t understand how a car engine works, especially the difference between the camshaft and the crankshaft. These two components stand out when it comes to the heart of an internal combustion engine. Each of them serves a distinct purpose that impacts the performance of your engine.

However, some motorists, beginner mechanics, car enthusiasts, and DIYers don’t understand how the two shafts are different from each other, regulating the working of the exhaust stroke and the intake stroke.

So, the purpose of this blog is to settle the “camshaft vs crankshaft” debate forever.

Understanding their difference isn’t just for mechanics; it’s crucial knowledge for someone who wants to know how engines work and diagnose engine problems. So, this detailed blog will help auto parts dealers, wholesalers, and retailers inform their clients about which part is at fault.

Let’s break down the function of these shafts to explain why they’re vital for a healthy engine.

What is a Camshaft?

You may wonder what the cam in block camshafts stands for. Well, today’s internal combustion engines have these cams or lobes that give this component its name. The engine camshaft function is very critical in controlling the valve train system.

Its main job is to manage the timing and movement of the intake and exhaust valves. This way, you can easily get air and fuel inside the combustion chamber, meanwhile exhaust gases exit the system after combustion.

How does it work?

• The camshaft moves, driven by the crankshaft via a timing belt, chain, or gears.
• A modern internal combustion engine can have up to four camshafts for pushrod engines.
• A camshaft is easily recognizable with egg-shaped cam lobes protruding from the engine.
• Along the shaft are specially shaped lobes (cams) that push against the valves (either directly or through lifters/rockers), opening them at precise moments.
• The size and shape of these lobes determine how long and how far the valves open, which directly affects engine performance, power, and efficiency.

Key facts

• You can find the camshaft located at the top of the engine (in overhead cam designs); it is very close to the valve it operates.
• The camshaft is made from forged alloy steel for strength and durability.
• Overhead Cam (OHC), Double Overhead Cam (DOHC), and older engines with camshafts in the engine block (OHV) are some common types of engine configurations.

Analogy: You can think of the camshaft as the conductor of an orchestra, ensuring that each valve opens and closes at the perfect time for smoother engine “music.”

What is a Crankshaft?

You can describe the engine crankshaft function as the heart of the engine. That’s because the crankshaft turns the linear (up-and-down) motion of the engine’s pistons into rotary motion. It will turn the wheels, and that’s how the cookie crumbles!

You can see, basically, that a crankshaft’s job is to rotate the engine by turning piston motion into rotary movements. We can also say that the camshaft transfers motion, which is necessary for proper combustion, especially when we’re talking about a four-stroke combustion cycle intake & compression and combustion strokes.

How does it work?

• Certain rods connect the shaft to your engine’s pistons.
• As the pistons move up and down during combustion, the crankshaft spins, creating the rotational force needed to drive the vehicle.
• The crankshaft’s position & speed are monitored by a crankshaft position sensor, which is crucial for the engine control unit (ECU) to manage ignition and fuel injection timing.

Key facts

• It runs through the bottom of the engine block, beneath the cylinders.
• The crankshaft is forged from high-strength alloy steel to withstand immense forces.
• This shaft features counterweights and journals to balance engine operation and reduce vibrations.

Analogy: If the camshaft is the conductor, you can think of the crankshaft as the main axle of a car’s engine, turning the power of combustion into forward motion.

Camshaft vs Crankshaft: Key Differences

Understanding the difference between cam and crankshaft is fundamental to grasping how an engine operates. A camshaft is very different from a crankshaft. Mainly composed of mandrel, cam, and bearing location, a camshaft plays a different role in the combustion chamber than a crankshaft does.

Both camshaft and crankshaft gears play a key role in making your vehicle move, while one controls the motion of the pistons (i.e., the crankshaft converts the movement of pistons into a rotary movement), and the camshaft turns the valves open or closed.

Any problem with the camshaft/crankshaft can render your entire engine performance obsolete. So, repairing a bad camshaft or crankshaft is very important.

Below is a clear side-by-side comparison to help you quickly grasp the main distinctions:

This table highlights the engine parts differences that make shafts unique but complementary.

How Do Camshaft and Crankshaft Work Together?

Even though these two components are different from each other, they work together, playing a vital role in the combustion process. The crankshaft vs camshaft relationship is a perfect example of mechanical synchronization.

It’s vital for these two shafts to operate in perfect harmony for the engine to run efficiently. This fine and delicate synchronization happens through a timing system, which consists of a belt, chain, and gears, that connects the shafts (both cam and crank).

Why is timing crucial?

If the crankshaft and camshaft fall out of sync, your car valves will open & close at the wrong time. It’ll lead to poor combustion and even loss of power. Ultimately, all of this will cause major engine damage, such as valves colliding with pistons.

How does the timing system work?

The timing belt or chain will keep the camshaft rotating at 50% of the speed of the “crank.” one in a 4-stroke engine (one that works via compression and combustion strokes). This precise ratio is essential for proper valve and piston coordination.

Common Issues and Symptoms

Camshaft-Related Problems

• Timing Issues: Worn or stretched timing belts/chains can cause the camshaft to fall out of sync.
• Wear: Cam lobes can wear down, so it’ll affect the timing and lift of your engine’s valves.
• Noise: If you hear ticking or tapping noises, it indicates camshaft or valvetrain problems.

Crankshaft-Related Problem

• Bearing Failures: Worn crankshaft bearings will emit knocking noises, and you’ll find oil pressure has decreased.
• Cracks or Bends: Physical damage can easily lead to imbalance, vibration, or sorts of catastrophic failure.
• Imbalance: You may find the shaft vibrating excessively. It’ll damage other components of your car’s engine.

Impact: Both camshaft and crankshaft issues sometimes lead to rough running, loss of power, increased fuel consumption, and, in severe cases, complete engine failure.

Maintenance and Repair

You should look for maintenance issues in your engine’s shafts. Diagnosing the problems that we have mentioned above will prevent expensive repairs. Timely maintenance can even extend engine life.

Spotting early signs of failure will prevent the need to replace the cylinder head (or worse, replace the entire engine!). Here are some tips for you to remember:

• You should inspect the timing belt or chain attached regularly and replace it when recommended by the manufacturer (if required, make the replacement to manufacturer specifications).
• Select your camshaft after looking into different factors, such as its price, type, make, manufacturer, and other important elements.
• Make sure an ASE-certified master technician is checking your engine’s shafts.
• Clean oil reduces wear on both crankshaft and camshaft surfaces.
• Look for debris in the engine and clean it properly.
• learn the signs and symptoms of a bad camshaft.
• Don’t leave the valve cover off exposing your engine to engine performance issues, especially fires.

Keep in mind that replacing the camshaft can cost you $500 to $1,500, while a new crankshaft will set you back by $1,500 to $3,000 (almost 2x the price of camshaft replacement!).

Basically, the camshaft replacement cost is more affordable than the cost of getting new crankshaft gears. New crankshaft gears will cost you twice as much (and also a new cylinder head).

Conclusion

The fact of the matter is that both the camshaft and crankshaft play a key role in a car engine’s operation. Each shaft serves a unique and vital function. While the camshaft manages the exact timing of air and fuel flow, the crankshaft turns the combustion energy into the rotational force to bring your four-wheeler into motion.

Whether you have an inline six-cylinder engine or one that uses a stroke combustion cycle intake compression, combustion, and exhaust valves, while the crankshaft moves the pistons, understanding the difference between a crankshaft’s working and also why a camshaft opens and closes the valves per cylinder varies is necessary.

So, understanding the engine parts differences between the two shafts can help you easily diagnose engine issues and maintain your engine properly.

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FAQs

What causes a camshaft to fail?

Common causes include poor lubrication, excessive wear, manufacturing defects, or broken timing belts/chains.

What happens if the crankshaft fails?

A failed crankshaft can cause total engine failure, as it is essential for converting piston motion to rotational power. The engine may seize, and major internal damage can occur.

Can you replace the crankshaft and camshaft separately?

Yes, but both are major repairs. Camshaft replacement tends to be less invasive than crankshaft replacement, which often requires a full engine teardown.