Rocker Arms: Everything You Should Know

Rocker arm is a part of your automobile's combustion engine that you will find between the exhaust and intake valves and the pushrods. It prevents excess friction and premature combustion. The role it plays in the function of your vehicle cannot be overstated. Rocker arms help your internal combustion engine to safely and efficiently run.

Rocker Arms Mechanism: How It Works?

Rocker Arms Mechanism

The rotation on the camshaft causes an end of the rocker arm to move up and down. This movement happens due to the tappet or the camshaft. The tapper helps in transmitting energy between forwarding and side-to-side progress. In doing so, the tapper which is a lifter itself conveys the rotational motion into a linear motion.

You can read about the causes of a tappet engine and how to fix it here. The second end of the rocker arm is not made to move up and down. It works as the valve stem. It allows gas into the chamber by opening up and then closes to keep the gas in the chamber.

This alternation helps keep the chamber’s pressure at the right level. The valve system allows for the correct timing of combustion and ignition by keeping fuel mixture and the right air within the engine. Have a look at our exhaust gaskets guide just to make sure that everything is fine there in your car.

Types of Rocker Arms

Types of rocker arms

There is more than a single rocker arm. A single type of it cannot be suited for different types of vehicles, hence the variety. The types of rocker arms include:

Center Pivot Rocker Arms

Although they look alike, there is a difference between the traditional rocker arm and the center pivot rocker arm. Instead of the rocker arm being on the pushrod, the camshaft is one on end and the pivot is located at the center of the rocker arm. To force the valve down, the camshaft is moved into the head and pushes up directly on the lifter. This happens in the place of the pushrod pushing up on the lifter.

End Pivot Rocker Arms

Here, the location of the rocker arm must be at the middle of the rocker arm. This is to enable the camshaft push on the rocker arm. End pivot is also referred to as the "finger-follower". It puts the pivot point right at the end of the rocker arm.

Full Roller Rocker Arms

There are stamped steel rockers and the full roller rocker arm is not one of them. The full roller rocker arms are a replacement for the trunion pivot with bearings. It is either they are aluminum or machine steel. Although they do not utilize the nut from the trunnion pivot, they still make use of the stud. There are bearings inside the rocker of their short shaft. The shaft is tightly secured with bolts while the bearings make sure that the rocker pivots.

Roller-Tipped Rocker Arms

Just as its name sounds, the roller-tipped rocker arm adds a roller to the tip of the valve terminals of the rocker arm. Quite similar to the stamped steel rocker, the roller-tipped rocker arms reduce friction. This results in more power and a reduction in wear and tear on the tip of the valve.

Shaft-Rocker Arms

One of the arms built from full roller rocker arms is the shaft-rocker arms. Their rocker arms have shafts that go through it. Depending on the way that the head was produced, the shaft may go through all of the rocker arms or just 2 rocker arms.

The main function of the shaft is to provide rigidity to the arms. It is more rigid having a shaft through the rocker arms than just making use of a stud from the head. The valve train will deflect less if it is more rigid. The chance of not being able to control the valve train motion at a higher revolution per minute (RPM) is less.

Stamped Steel Rocker Arms

The most common style of the manufactured rocker arm is probably the stamped steel rocker arm.  Just like the full roller rocker arm, they use a trunnion pivot. With the help of a rounded bottom nut, the trunnion pivot helps hold the rocker in position. This allows the rocker to easily pivot up and down. Because they are stamped from one piece of metal, the stamped steel rocker arms are the cheapest and easiest to produce.

Which Are the Functions of the Rocker Arms?

Functions Rocker Arms

In an internal combustion engine, the rocker arm changes radial motion into linear motion. A device that does this is often referred to as a reciprocating lever. For the valve to open and close, the arm is raised by the camshaft. To make sure of this at the right time, the inside of the arm exerts pressure on the stem of the valve.

This allows gas and pressure in or out of the system. The regulation of the gas is needed to make the arm of the rocker keep the levels of the internal combustion engines at the right levels. This prevents premature combustion. Rocker arms are made of steel, giving them the much-needed strength to go with their weight. The leverage they can exert is great as well.

Common Symptoms of a Faulty Rocker Arm

faulty rocket arm symptoms

The rocker arm performs an important function in your vehicle. It must function to make sure the exhaust and intake valve close and open at the appropriate time. You won't be able to run your vehicle properly without the rocker arm. There are symptoms you’ll observe if your rocker arm is faulty.

The faulty rocker arm needs to be replaced immediately to avoid any irreversible damage to the engine of your vehicle. When other parts of your vehicle are defective, they may also cause you problems. However, if it is your rocker arm that is faulty, you will observe the following symptoms.

Clicking or ticking noises

It is unusual to hear loud and strange noises come out of your vehicle. These sounds often involve valves. If you hear such sound, carry out an instant inspection of the rocker arms and other parts surrounding it. Do this while the engine is running. During rotation, a faulty rocker arm can get stuck, causing unusual noise.

You can read on diagnosing valve train noise and other symptoms of a bad valve train here. Other parts of the vehicle can also be the cause of the clicking noises in the internal combustion engine of your vehicle. Other causes may include improper lubrication of other moving parts, worn camshaft lobes, and warped valves.

If after inspection you find the rocker arm still working fine, the next line of action is troubleshooting the vehicle. You or your mechanic can do this to find out the cause of the noise. This will allow you to fix the issue on time before it turns into something much bigger.

Engine stall

A rocker arm that has been allowed to get too bad may cause your engine to stall on the road while you drive. The stalling might be irregular until it shuts down completely and unable to start. If you notice this sign, then the rocker arm of your vehicle needs to be fixed on time.

Engine warning light on

Engine warning light on

The Artificial intelligence (AI) installed in modern vehicles will indicate engine performance. The AI is a diagnostic tech that puts the engine lights on if senses any problem. Whenever this alarming light comes on, do not ignore it. To check for any stored codes related to the rocker arm, you can make use of a diagnostic scanner. P2646, P2647, and P2662 are examples of rocker arm-related issues. Immediately take your vehicle for repair if you find any of these codes.

Physical deterioration

Visual inspection can be carried out on the rocker arms to check for any wear and tear. Do this if you hear any clicking or strange sound. In inspecting the rocker arm visually, firstly remove the valve. Check below the rocker arm to see if you will find any kind of metal.

This is necessary because rocker arm grind together with the valve tip, thereby damaging the surface of the rocker arm. Replace the degraded rocker arm. Remember to do this to avoid a worse problem because physical deterioration is an indicator that a bigger issue may follow soon.

Weak engine performance

The exhaust and intake valves in the internal combustion engine of your vehicle must close at the right time for your engine to function properly. This is essential for your vehicle to work efficiently and save fuel. The power and performance of the car’s engine will be poor if the rocker arm is faulty. If the case is severe, your vehicle may begin to stall while you drive. If you don't replace the rocker arm immediately, the engine of your vehicle may not start.

Causes of a Faulty Rocker Arm

faulty rocker arm

There are many reasons why your vehicle’s rocker arms are damaged. The most common causes are:

Bent valve

A bent valve can cause a valve to remain open. This will make your rocker arm fail. Issues during engine rebuild, not servicing your engine at regular intervals and the over-revving engine can make the valve bend. If the space left during an engine rebuild between the valves and piston is not enough, the exhaust and intake valves may end up being misaligned with the valve. The valve guides may stick and rub against the pistons if it is no serviced regularly.

Debris in oil

Your rocker arm may be damaged if the fuel you use is contaminated. You will be alerted of this problem before it affects your engine. If the fuel is dirty, you will notice black and smoky exhaust, perceive oil smell and hear loud sounds from your engine.

Poor fuel

Poor fuel

Using poor fuel can damage the rocker arm of your vehicle. The use of an incorrect toy of fuel may keep the valve in an open position. A dirty fuel injector can result in poor fuel.

Valve seat dislodging

The rocker arm can be damaged if the valve moves out of its normal position. Check if your engine has a lot of fluids and oil, or if the rocker arm is broken to see if the seat is dislodged. By the way, the problem might not be with your rocker arms but with your rocker panels. Check out our other blog post to learn more about that.

Rocker Arm Replacement Kits

Rocker arms replacement kit

Replacing a single damaged rocker arm will cost you between $15 and $60. This of course depends on the type of vehicle you are using. You may need to replace more than one rocker arm as they tend to be faulty at the same time. Moreover, you can purchase a rocker arm kit for about $100 to $500. You will find pushrods, guide plates, rocker arm, and important components in the kit. You can get a good rocker arm kit from Amazon such as this one:

Type of Rocker Arm to Buy

Rocker arms consist of a flat sheet of metal that has been put through a stamping press. For economy cars, steel is a good option. It is lightweight, strong, and inexpensive. Lighter options such as aluminum are good for high-performance vehicles.

Rocker arms that are produced from cast iron or forged carbon steel are the best options for the engines of trucks. If you want to get the rocker arm yourself, do some thorough research. Check out this rocker arm from Ford: Speaking of Ford, check out our other blog post here to discover how much a Ford Ranger weigh.

Final Thoughts

Often overlooked, the rocker arm is very important in the operation of the internal combustion engine. It is that part that raises the performance of the vehicle. Inspect your vehicle if you notice any unusual sound. A faulty rocker arm may be the cause of this sound.

Other symptoms of a faulty rocker arm are stalling of the vehicle's engine, physical deterioration, weak engine performance, and engine lights being on. To avoid severe damage to your car's engine, the rocker arm must be replaced if you notice any of the above symptoms.

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