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.
In this reading, we’ll explore what a rocker arm is, its diagram, types, and how it works. We’ll also learn it signs of failure and its replacement cost.
Let’s get started!
What Is A Rocker Arm?
A rocker arm is a part of the valvetrain, whose 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 contact 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.
Like most vehicle components, rocker arms are made with materials and specifications that are recommended by international engineering standards. Typically, high-quality alloy steels are used. This helps to ensure optimized strength and a longer engine lifespan.
How A Rocker Arm Works
In an engine, the rocker arm serves as a critical link between the camshaft and valves. It helps with valve operation timing and control. As the camshaft rotates, its lobes press against certain places on the rocker arm, causing it to pivot. The engine valves of the car receive this pivoting motion and open and close in time with the combustion cycle.
The camshaft’s lobe also presses up against the rocker arm during the intake stroke. It causes it to pivot and push down on the valve. Consequently, the air-fuel mixture can enter the combustion chamber when the valve opens. Another camshaft lobe presses up against a different spot on the rocker arm during the exhaust stroke.
It makes it pivot in the other way. The combustion chamber is sealed and the exhaust gases are released when this movement shuts the valve. In an automobile engine, the camshaft, valves, and rocker arms work together to maximize performance. Any change in timing or motion may cause ineffective combustion, power outages, or even damage to the engine.
Related: What Is A Cam Phaser? Its Function, Diagram, & How it Works
Diagram Of A Rocker Arm
Types Of Rocker Arms
Automotive engines frequently use a variety of rocker arm types, each with a unique design and purpose. Some of the common types include:
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. A shaft runs through the rocker arms and connects them together. 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.
Signs Of A Bad Rocker Arm
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 problem could be caused by another faulty component. Whatever the cause, the problem must be resolved either by you or a mechanic before the car can be driven again. The most common symptoms include:
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.
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, may be a 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 is 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?
Rocker arms are commonly made of stamped steel, which is essentially flat sheet metal that has been formed by a die after passing through a stamping press. 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.
FAQs
Where is the rocker arm located?
Typically, rocker arms are located between the pushrod and the intake and exhaust valves.
What are rocker arms also known as?
Valve rockers, 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?
Faulty rocker arms can cause loud ticking sounds inside your engine, which can lead to engine misfire. Replace your worn-out rocker arms before they break to avoid having misfires destroy your engine.