Understanding rocker arm

Many drivers may operate their cars for years without having a clear understanding of the essential components required for the proper functioning of their vehicle, such as tappets, piston rings, and valves. Even individuals who work in workshops occasionally run into components whose purpose is unclear or hard to recall. This is the rocker arm case for the engine.

rocker arms

Well, in this article, we’ll get into detail about the rocker arm. Nonetheless, the following questions will be addressed:

  • What is a rocker arm?
  • How does it work?
  • What are the types of rocker arms?
  • What are the symptoms of a bad one?
  • How much is the rocker arm replacement cost?
  • What type of rocker arm should you buy?

So, let’s get started!


What is a rocker arm?

A rocker arm is a part of the valvetrain, which function is to transmit the motion of a pushrod to the corresponding intake or exhaust valve in the context of an internal combustion engine. Automobile rocker arms are often constructed of stamped steel or, in higher-revving applications, aluminum. To lessen wear and friction at the contact point, certain rocker arms (also known as roller rockers) have a bearing there.

At one of its ends, the tappet is in direct touch with the rocker arms, but its other end is connected to the intake and exhaust valves. This indicates that the rocker’s arm lowers one of its sides in response to the camshaft cam, opening the valve and allowing the mixture of fuel and air to enter the combustion chamber.

Both intake and exhaust valves move in this manner. A spring is used to maintain the displacement, which in turn pushes the valves back to their starting positions. Given that the operation happens at extremely high speeds and maintains continual contact with the rocker arms, the springs must be strong enough to survive fast engine revolutions.

Rocker arms are created using materials and specifications advised by international engineering standards, typically using high-quality alloy steels, just like the majority of vehicle components. This helps to ensure optimized strength and a longer engine lifespan.

This video explains more about what rocker arms do:

How does it work?

The camshaft at the base of the engine pushes the pushrod upward in the typical application of an overhead valve (pushrod) engine. The rocker arm, which is located at the top of the engine, positioned between the pushrod and the intake and exhaust valves, rotates as a result of the top of the pushrod pressing upward on one side of it. As a result of this movement, the rocker arm’s other end presses against the top of the valve and moves it downward, opening the valve.

In place of metal moving over metal at the point where the rocker and valve make contact, the roller rocker arm employs needle bearings (or a single-bearing ball in older engines). The valve guide’s “bell-mouthing” and uneven wear are decreased as a result of less friction.

Overhead cam engines can also use roller rockers. The roller on these, however, is often located where the cam lobe meets the rocker rather than where the rocker meets the valve stem. A roller tip may be able to reduce friction where it comes into contact with the valve stem.

A similar setup transmits the action to a second rocker arm through a different roller tip. This revolves around the rocker shaft and transmits motion to the valve through a tappet. Short rocker arms, commonly referred to as “fingers,” are used in some overhead camshaft engines where the cam lobe pushes down (as opposed to up) on the rocker arm to open the valve.

On this kind of rocker arm, the cam acts on the middle of the arm whereas the fulcrum is at the end rather than the middle. The valve is opened by the opposing end. These rocker arms are frequently employed in place of direct tappets on overhead camshaft engines, where they are especially prevalent. Ford 5.4 L 3v and Ford Zetec RoCam SOHC engines use rocker arms in this form.

What are the types of rocker arms?

rocker arms

Here are the major types of rocker arms available:

  • Stamped Steel Rocker Arms
  • Roller-Tipped Rocker Arms
  • Full Roller Rocker Arms
  • Shaft Rocker Arms

Stamped Steel Rocker Arms

The most popular type of production rocker arm is most likely made of stamped steel. Because they are stamped from a single piece of metal, they are the simplest and least expensive to produce. The rocker is held in place by a trunnion pivot and a nut with a rounded bottom. This is an incredibly easy way to secure the rocker while enabling it to move up and down.

Roller-Tipped Rocker Arms

The Roller Tipped Rocker Arm is exactly what it says on the tin. They add a roller to the tip of the rocker arm’s valve end, making them similar to stamped steel rockers. As a result, there is less friction, a little bit more power, and less valve tip wear. To keep things simple, the Roller Tipped Rocker Arm continues to employ the trunnion pivot nut and stud.  They can also be made of cast, machined, aluminum, or steel.

Full Roller Rocker Arms

It’s not a stamped steel rocker; it’s a whole roller rocker arm. They are made of either aluminum or machined steel. Bearings are used in place of the trunion pivot. They do not use the nut, but they do continue to use the stud from the trunnion pivot. They have a very small shaft that is bolted securely into place and has bearings on either end (within the rocker) that allow the rocker to pivot.

Shaft Rocker Arms

The Full Roller Rocker Arms serve as the foundation for the Shaft Rocker Arms. The rocker arms are connected by a shaft that runs through them. Depending on how the head was made, the shaft may pass through 2 rocker arms only in some cases and all the rocker arms in other cases. The use of a shaft is necessary for stiffness. It is significantly more rigid to insert a shaft through the rocker arms rather than just utilizing a stud from the head. The less the valve train deflects and the less likely it is to move in an uncontrolled manner at higher RPMs, the stiffer the valve train.

What are the symptoms of a bad one?

If one or more rocker arms in your engine are deteriorating, your engine may display one or more of the symptoms listed below. However, the issue can be brought on by another faulty component. No matter what the source, the issue needs to be fixed either by you or a mechanic before the car can be driven again. The most common symptoms include:

  • Noises such as clicking or ticking
  • Check Engine Light Is On
  • Stalling or poor engine performance
  • Physical Impairment

Noises such as clicking or ticking

Valve-related strange noises frequently have a fast clicking or ticking sound, like a sewing machine. If you hear this noise when the engine is operating, you should check the rocker arms and surrounding components. Ineffective rocker arms might cause the valves to stick open or close ineffectively.

Other potential reasons for unusual noises in the combustion chamber and related components include worn camshaft lobes, deformed valves, and a lack of lubrication between moving parts. If a visual inspection reveals that the rocker arms are operating properly, more investigation by you or a professional is required to identify the issue.

Check Engine Light Is On

Weak engine performance will also be detected by the vehicle, and it will alert the driver by turning on the check engine light. You should never ignore this indication. A diagnostic scanner should be used to look for any stored codes. P2646 (A rocker arm actuator system performance or stuck off bank 1), P2647 (rocker arm oil pressure switch), and P2662 (B rocker arm actuator sys stuck on bank 2) are a few examples of rocker arm-related DTC codes.

Stalling or poor engine performance

A functioning internal combustion engine depends on precise timing. The precise timing of valve opening and closing is essential for maximum efficiency. You’ll notice less power and poor acceleration if the car’s broken rocker arm is interfering with this procedure. In extreme circumstances, the engine can even stall out while being driven. When the broken part is not replaced, the car eventually won’t even start.

Physical Impairment

Any wear or cracks in the rocker arms can also be seen by visual inspection. Search beneath the rocker arms for any metal fragments after removing the valve cover since worn-out rocker arms can grind against the pivot point and valves. Even if there are no other signs, worn-out rocker arms should be replaced since issues will inevitably arise.

Here is how you can check if your rocker arms have worned out:

How much is the rocker arm replacement cost?

Depending on the vehicle and whether it is an intake or exhaust rocker arm, a single rocker arm can cost anywhere from $15 to $60. If you are confident that you can complete the replacement task yourself, purchasing a rocker arm kit, which normally costs between $100 and $500, maybe the better option. These kits contain other important components like pushrods and guide plates.

It would be a good idea to replace all of the rocker arms at once because they frequently all break down at the same time. As a result, the whole kits are the most popular choice for purchases. It can take a lot of time and effort to repair a rocker arm, so hiring a dealership or auto mechanic to complete the work is not inexpensive.

Depending on the car, expect it to cost anywhere between $500 and $1,500 (parts + labor). Due to the lengthy access times for the required parts, labor accounts for a sizable portion of the cost. The final amount could go up due to taxes and fees.

What type of rocker arm should you buy?

Stamped steel, which is essentially flat sheet metal that has been put through a stamping press and then formed by a die, is frequently used to make rocker arms. Steel is a good material for economy cars since it is affordable, sturdy, and relatively light. Aluminum rocker arms are typically used in high-performance vehicles because of how much lighter they are.

Even stronger rocker arms composed of cast iron or forged carbon steel are frequently needed for truck engines. To choose the right rocker arm if you’re performing the work yourself, some research is required. Automotive parts retailers might have the kit you need in stock or be able to purchase it on special.

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Where is rocker arm located?

Typically, rocker arms are located between the pushrod and the intake and exhaust valves.

What are rocker arms or cam?

They enable the pushrods to push up on the rocker arms, which in turn causes the valves to push down. In contrast, the Cam will ride directly on the Rocker Arm in Over Head Cam setups.

What are rocker arms also known as?

Valve rocker or simply rockers.

What causes rocker arm failure?

And if a rocker arm fails, it’s not unusual for the engine to frequently stall or cease running altogether until the broken rocker arm is replaced. Because of incorrect heating treatment and poor production, rockers frequently fail due to brittleness, cracks, and strains.

How do you know if a rocker arm is bad?

You should inspect the rocker arm or its surrounding components if you notice clicking or ticking noises when you start the engine. While the engine is running, visually inspect the rocker arm. If you hear a noise, a damaged rocker arm may become trapped and fail to properly open and close the valves.

Can rocker arms cause a misfire?

The loud ticking sounds inside your engine caused by faulty rocker arms might cause engine misfires. Replace your worn-out rocker arms before they break to avoid having misfires destroy your engine.

What is a rocker arm sensor?

The rocker arm control solenoid gives hydraulic pressure to the variable timing and lift mechanism in automobiles with VTEC systems. As a result, the ECM uses the rocker arm oil pressure switch to monitor and confirm the oil pressure, and the VTEC system is able to modify valve timing and lift as necessary.

Wrapping up

As we’ve already seen, most internal combustion engines feature an engine rocker arm, which is a part of the mechanical distribution system on the valve assembly. However, did you know that there are two different kinds of rocker arms available right now? Along with the flat, conventional ones, roller rocker arms are gaining popularity with customers.

Through the use of rollers between the rocker arms and the cam, the new roller technology used in some engines enables simultaneous communication between the camshaft, hydraulic tappets, and valves. As a result, there is a reduction in friction, which has an immediate influence on performance.

All of this is made possible by the use of cutting-edge technology in the micro fusion process using a particular alloy and by the roller rocker arm’s meticulously monitored heat treatments, which produce a unique tempered and ground steel.

It goes without saying that one of the most crucial factors in ensuring the lifetime and good performance of the rocker arm components is the efficiency of the lubrication. Due to this, it is also advised to regularly check the lubrication hole on this component for any obstructions.

So, has it gotten any simpler to comprehend how this crucial part of a car’s engine works? And that’s it for this article. Hope it was helpful. If so, kindly share it with others. Thanks for reading; see you around!

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