As drivers, we know what some car parts are for. The tires connect with the road. The steering wheel allows us to navigate turns and corners. Motor oil keeps the engine running smoothly. 

But other parts are a little more obscure. Like the valvetrain. It sounds important. But what exactly is a valvetrain, and how does it work?

What is a valvetrain?

In today’s modern cars, the valvetrain is integral to the engine’s functionality. It comprises various parts, such as valves, rocker arms, pushrods, camshafts, and lifters, that control the intake and exhaust of air and fuel in the engine. 

The valves open and close at specific intervals, allowing gasoline to enter the combustion chamber while expelling exhaust fumes. A well-maintained valvetrain ensures optimal engine performance, improving fuel efficiency, reducing emissions, and extending engine life. Therefore, it’s crucial to have a basic understanding of what a valvetrain is and how it contributes to your car’s overall performance.

How a valvetrain functions

To understand how a valvetrain functions, let’s begin with the basics of how an engine works. The engine’s pistons move up and down, creating pressure that drives a crankshaft, which powers the car’s motion. The valvetrain controls the air and fuel entering and leaving the combustion chamber, where the pistons move.

Each cylinder typically has two or more valves – an intake valve and an exhaust valve – both controlled by the valvetrain. The camshaft is a crucial part of the valvetrain and controls the timing of when the valves open and close. The camshaft rotates with the crankshaft, and its lobes push against the rocker arms attached to the valve stems, causing the valves to open and close.

The process of opening and closing valves is precisely timed to ensure that the right amount of fuel and air enters the combustion chamber while the correct amount of exhaust gasses are expelled, producing the desired power output.

Valvetrain components and what they do

A car is constructed from thousands of moving parts. The valvetrain is an intricate component with many parts coming together to keep your car operational. Parts include:

Camshaft

The camshaft is the heart of the valvetrain. It’s a rotating shaft with a series of cam lobes that control the opening and closing of the engine’s valves. As the camshaft rotates, the lobes push on the pushrods or rocker arms, causing them to move the valves up and down.

Pushrods

Pushrods are long, thin rods that connect the camshaft to the rocker arms. They transmit the motion of the cam lobe to the rocker arm, which then opens or closes the valve.

Rocker arms

Rocker arms are the pivoting levers that transfer the motion of the pushrod to the valve. They pivot on a shaft mounted on the cylinder head. The rocker arms come in various configurations, including stamped steel, cast aluminum, and roller tip designs.

Rocker shafts

Rocker shafts support the rocker arms and allow them to pivot smoothly. They are typically made of steel or aluminum and are mounted on the cylinder head.

Valve bridges

Valve bridges are small metal pieces that connect the intake and exhaust valves. They ensure that the valves open and close together, preventing interference between the valves.

Valves

The valves are the components that control the flow of air and fuel into the combustion chamber and the exhaust gasses out of the engine. There are typically two valves per cylinder, an intake valve, and an exhaust valve. The valves are opened and closed by the camshaft, pushrods, and rocker arms.

Valve springs

Valve springs are the coil springs that keep the valves closed when the engine is not running. They ensure that the valves close tightly against the valve seats, preventing any leakage of air or fuel.

Timing belt

The timing belt is a toothed belt that connects the camshaft to the crankshaft. It ensures that the camshaft rotates at the correct speed and in time with the crankshaft. The timing belt must be replaced periodically to prevent it from breaking and causing damage to the engine.

Belt tensioner

The belt tensioner is a component that maintains the proper tension on the timing belt. It ensures that the timing belt does not slip or jump teeth, which can cause the engine to run poorly or not at all.

Regular maintenance to keep the valvetrain at peak performance

One of the most important things you can do to keep your car’s valvetrain in peak performance is to change the oil regularly. Oil is the lifeblood of the valvetrain, and without proper lubrication, the valves can stick, causing damage to the engine. Additionally, the oil contains detergents and other additives that keep the valvetrain clean and prevent the buildup of carbon deposits.

Another essential maintenance task is to check the valve clearances regularly. Valve clearances, also known as valve lash, are the distance between the rocker arm and the valve stem when the valve is closed. Too much or too little clearance can lead to poor engine performance or damage. This is where it helps to have a mechanic you can rely on for regular maintenance. When they know a car well, they can help you maintain it over time. 

It’s also important to keep the air filter clean and replace it when necessary. A dirty air filter can reduce engine performance, causing the valves to work harder than they need to, wearing them out faster.

Is your car’s valvetrain in good working condition?

The valvetrain is a vital component of your car’s engine, and it’s essential to understand how it works to keep it well-maintained. Regular oil changes, checking valve clearances, and replacing air filters are just a few of the vital tasks required for proper valvetrain maintenance. 

By taking care of your car’s valvetrain, you can ensure optimal engine performance, prolong engine life, and save on fuel costs. So, the next time you’re behind the wheel, take a moment to appreciate the intricacies of your car’s valvetrain and give it the care it deserves.