What a camshaft does and where to find it

A camshaft is a metal rod inside your engine that controls when your engine's intake and exhaust valves open and close. It does this by pushing on valve lifters or rocker arms as it spins. If you need to identify one, you're looking for a shaft with a series of egg-shaped or teardrop-shaped bumps running along its length — those bumps are called lobes, and each lobe controls one valve.

The camshaft sits inside the engine block or cylinder head, depending on your vehicle's design. In older engines, it's usually in the block itself, lower in the engine. In newer engines, it's often mounted directly on top of the cylinder head, which is why you might hear the term "overhead cam" or OHC. To see it, you'll need to remove the valve cover — the plastic or metal lid on top of the engine — or look into the engine bay after removing other components.

Most engines have at least one camshaft, but many modern engines have two per cylinder head: one for intake valves and one for exhaust valves. These are sometimes labeled or color-coded to tell them apart.

Key Takeaways

  • A camshaft is a shaft with egg-shaped lobes that control when your engine's valves open and close as it rotates.
  • You'll find it inside the engine block or on top of the cylinder head, and you may need to remove the valve cover to see it.
  • The lobes on the shaft are what physically push on valve lifters or rocker arms to operate the valves.
  • Newer engines often have two camshafts per cylinder head — one for intake and one for exhaust — and they may be marked with different colors or labels.

How to locate the camshaft in your engine

Start by opening your hood and looking at the top of the engine. If your vehicle has an overhead cam design, the camshaft housing or cover will be visible. Look for a long, cylindrical metal component running across the top of the cylinder head. It will be held in place by a timing chain or timing belt that connects it to the crankshaft, and it will have a sprocket or gear attached to one end.

If your engine has the camshaft mounted lower in the block, you'll need to remove the valve cover first. The valve cover is usually held down by bolts around its perimeter. Once removed, you'll see the camshaft running horizontally through the center of the cylinder head, with rocker arms or valve lifters sitting on top of it. The lobes of the camshaft will be clearly visible as you look down into the engine.

Consult your vehicle's service manual for the exact location and orientation in your specific model. The manual will also show you which bolts to remove and in what order, which prevents damage to gaskets and seals.

Recognizing the lobes and their purpose

The lobes are the most distinctive feature of a camshaft. Each lobe is a raised, asymmetrical bump that looks like an egg standing on its point. As the camshaft rotates, each lobe pushes down on a valve lifter or rocker arm, which in turn pushes down on a valve stem to open the valve. When the lobe rotates away, a spring pulls the valve closed again.

The shape and size of each lobe determine how far the valve opens and for how long it stays open. A larger lobe means the valve opens wider and stays open longer. This is why performance camshafts have different lobe profiles than stock camshafts — they're designed to keep valves open at different times to change how the engine breathes and performs.

Count the lobes on the shaft to understand how many valves the camshaft controls. If you see eight lobes on one camshaft, that camshaft operates eight valves. In a four-cylinder engine with two valves per cylinder, you'd expect four lobes per camshaft.

Camshaft position in single-cam versus dual-cam engines

A single overhead cam (SOHC) engine has one camshaft per cylinder head. This camshaft controls both the intake and exhaust valves through a system of rocker arms. You'll see one camshaft running down the center of the cylinder head, with rocker arms branching off on both sides.

A dual overhead cam (DOHC) engine has two camshafts per cylinder head — one for intake valves and one for exhaust valves. These sit side by side on top of the cylinder head. The intake camshaft is often positioned toward the front of the engine, and the exhaust camshaft toward the rear, though this varies by manufacturer. DOHC engines are more common in modern vehicles because they allow more precise control over valve timing and can improve engine efficiency and performance.

To tell them apart, look for labels or color-coded paint on the sprockets or the camshaft itself. Some manufacturers paint the intake camshaft blue and the exhaust camshaft red, or mark them with letters like "I" and "E". Your service manual will confirm which is which for your engine.

Timing chain or belt connection

The camshaft is always connected to the crankshaft by either a timing chain or a timing belt. This connection ensures the camshaft rotates in perfect synchronization with the crankshaft — the camshaft must open and close valves at exactly the right moment in the engine's cycle, or the engine won't run.

A timing chain is a metal chain similar to a bicycle chain, and it's more durable and longer-lasting. A timing belt is made of reinforced rubber with teeth on the inside, and it typically needs replacement every 60,000 to 100,000 miles, depending on the manufacturer. Both are attached to a sprocket on the camshaft and a larger sprocket on the crankshaft.

When you're looking at the camshaft, the sprocket or gear at the end of the shaft is your visual confirmation that you've found the right component. The sprocket will have teeth that mesh with the timing chain or belt.

Camshaft markings and identification numbers

Many camshafts have identification numbers or codes stamped or cast into the metal. These numbers tell you the camshaft's profile, which manufacturer made it, and sometimes the engine it's designed for. You might see a number like "E7OE-6015-B" on a Ford camshaft, for example.

If you need to order a replacement or verify you have the correct camshaft, write down this number and cross-reference it with your vehicle's service manual or a parts catalog. The number is usually found on the side of the camshaft shaft itself, near one end. You may need to clean away oil or debris to read it clearly.

Color coding is also common on newer engines. Intake camshafts might be painted blue, green, or have a stripe, while exhaust camshafts are painted red or a different color. This makes it easier to identify them at a glance during engine work.

What to do if you can't locate the camshaft

If you've removed the valve cover and still can't find the camshaft, your engine may have the camshaft mounted in the block rather than on top. This is common in older vehicles and some truck engines. In this case, you'll need to remove additional components like the timing cover or the front of the engine to access it.

Another possibility is that your engine is a pushrod design, where the camshaft is deep in the block and operates the valves through long pushrods and rocker arms. In this case, you won't see the camshaft itself without significant disassembly. The rocker arms and pushrods will be visible on top of the engine, but the camshaft itself remains hidden.

Your vehicle's service manual is the most reliable resource for determining your engine's exact layout and how to access the camshaft. If you're unsure, a mechanic can point you to the right location and explain your engine's specific design.

Frequently Asked Questions

How many lobes should a camshaft have?

The number of lobes equals the number of valves the camshaft controls. A four-cylinder engine with one camshaft controlling all eight valves will have eight lobes. A DOHC engine with two camshafts per head will have four lobes on each camshaft. Check your engine's specifications to know what to expect.

Can I identify a camshaft just by looking at it without removing anything?

In DOHC engines, yes — you can often see the camshaft and its sprocket on top of the cylinder head without removing the valve cover. In SOHC or block-mounted designs, you'll need to remove the valve cover or other components to see it clearly.

What's the difference between an intake and exhaust camshaft?

The lobes have different shapes and timing. The intake camshaft's lobes are designed to open the intake valves at the right moment to let the air-fuel mixture in. The exhaust camshaft's lobes open the exhaust valves to let burned gases out. They're often marked with different colors or labels so you can tell them apart.

Why would I need to identify a camshaft?

You might need to identify it to order a replacement, verify it's the correct part for your engine, diagnose a valve timing problem, or understand your engine's design. Mechanics also identify camshafts when performing timing chain or belt replacement, valve work, or engine rebuilds.

Is the camshaft the same as the crankshaft?

No. The crankshaft converts the up-and-down motion of the pistons into rotational motion that turns the wheels. The camshaft controls when the valves open and close. They're separate components connected by a timing chain or belt, and they rotate at different speeds.