Your car is a finely tuned machine that should run like a dream – unless one of its key components starts to malfunction. Rocker arms are one of those.
If your rocker arms are going bad, you may notice a few symptoms. First, a tapping noise from the engine. Another is a loss of power. This can lead to a decrease in performance and may cause your vehicle to stall.
In this article, we’ll discuss what a rocker arm is and what can go wrong with it. Keep reading for more information!
Table of Contents
What is a Rocker Arm?
A rocker arm is an oscillating lever located under the valve cover that transfers linear motion from a cam to a valve in an internal combustion engine.
Rocker arms are used in pushrod engines, where they are mounted on the cylinder head above the valves and actuate the valves by direct contact. In overhead camshaft engines, the rocker arms are usually mounted directly to the engine block.
Rocker arms have been used in automotive engines since the earliest days of the internal combustion engine. Early engines used simple levers to transfer motion from the camshaft to the valves, but as engine speeds increased, it became apparent that these simple designs were not up to the task.
While the basic principle of operation remains, the same, rocker arms have undergone several evolutionary changes. Modern rocker arms are designed to minimize friction and maximize durability.
Many modern cars now use a hydraulic lifter instead of a rocker arm. The main disadvantage of the rocker arm is that it requires more frequent adjustment than a hydraulic lifter since the clearance between the valve and the rocker arm must be kept within a tight tolerance.
How Does a Rocker Arm Work?
A rocker arm is a lever that actuates the valves in an internal combustion engine. There are usually two rocker arms per cylinder, one for the exhaust valve and one for the intake valve, although some engines may only have one for the combustion chamber.
Rocker arms typically have a roller at the end that makes contact with the valve stem, and they are actuated by pushrods from the camshaft.
Rocker arms have adjustment screws that allow for fine-tuning of the valve clearance, which is the distance between the valve and the rocker arm. The clearance must be correct for the engine to run properly.
If the clearance is too small, the valves will not open far enough, and the engine will run poorly. If the clearance is too large, the valves will bounce off the rocker arms and cause noise.
When the engine is running, the camshaft lobe pushes on the pushrod, which in turn actuates the rocker arm. The roller at the end of the rocker arm then pushes on the valve stem, opening or closing it as needed.
Rocker arms are typically made from steel. But can also find aluminum rocker arms coated with a hard material such as chromium to reduce wear. Some performance engines have roller-rocker arms, which use rollers instead of contact pads to actuate the valves.
Roller-rocker arms can provide better performance because they reduce friction and allow for higher engine speeds.
Rocker arms are a key part of the valvetrain and play a vital role in an engine’s performance. Properly designed and manufactured rocker arms can help an engine to run more smoothly and efficiently, while poorly designed or made rocker arms can cause all sorts of problems.
It is important to choose the right rocker arm for your engine and ensure that it is properly installed and maintained.
Symptoms of Bad Rocker Arms
If you suspect that your rocker arms are going bad, there are several symptoms that you can look for.
- Check Engine Light
- Car Won’t Start
- Clicking or Ticking Noises
- Reduced Fuel Efficiency
- Poor Engine Performance
- Cracked Surface
For better understanding, each symptom is explained below:
1. Check Engine Light:
If the check engine light is illuminated on your dash, the vehicle’s computer has detected a problem somewhere in the engine. Many things can trigger the check engine light, and a bad rocker arm is one of them.
Bad rocker arms can cause misfires, which will trigger a trouble code and turn on the check engine light. Or there can be another issue like a leaking fuel injector causing misfires.
If you have a check engine light and you suspect that your rocker arms may be to blame, the best thing to do is to take it to a mechanic or dealership for diagnosis. They will hook up a scanner to read any trouble codes that may be stored in the computer.
2. Car Won’t Start:
If your car doesn’t start, it could be due to several different issues. It could be something as simple as a dead battery or a loose connection. Or it could be something more serious like a fuel delivery problem.
A broken rocker arm can also cause starting problems. If the rocker arms are not functioning properly, they can prevent the valves from opening and closing correctly. This can cause a loss of compression, making it difficult or impossible for the engine to start.
Moreover, when the rocker arm breaks, it can cause the pushrod to become disconnected from the valve. This will prevent the engine from getting enough air and fuel, making it difficult to start. In some cases, the engine may not start at all.
3. Clicking or Ticking Noises:
If you hear a clicking or ticking noises coming from the engine, it could be a sign of bad rocker arms. The noise is usually caused by the valves bouncing off the rocker arms or debris getting caught between the valve and the rocker arm.
Bad rocker arms can also cause lifter tick. Lifter tick is a condition where the pushrod does not make full contact with the rocker arm, causing it to make a ticking noise. This can be caused by worn-out parts, an incorrect installation, or improper adjustment.
In some cases, excessive valve clearance can also cause ticking. Valve clearance is the space between the top of the valve and the bottom of the rocker arm when the valve is fully closed. If this space becomes too large, it can cause the valves to tick or click as they open and close.
Clicking or ticking noises are often mistaken for lifter noise. Lifter noise is usually a tick that gets louder when you accelerate. This is caused by oil pressure problems and is not related to the rocker arms.
If you’re not sure what kind of noise you’re hearing, it’s best to take your car to a mechanic so they can diagnose the problem.
4. Reduced Fuel Efficiency:
Another symptom of bad rocker arms is reduced fuel efficiency. A bad rocker arm can cause decreased fuel efficiency in several ways. First, it can cause the engine to run less efficiently because it cannot properly control the intake and exhaust valves.
Opening and closing of valves are critical to proper engine operation. If this timing is not optimized, it can lead to issues like pre-ignition, knocking, and pinging. All of these conditions lead to reduced fuel efficiency as the engine has to work harder to overcome these issues.
Another way that a bad rocker arm can cause reduced fuel efficiency is by causing the engine to produce more emissions. This is because when the valves are not opening and closing at the proper times, it can lead to incomplete combustion of the fuel mixture.
Not only is this harmful to the environment, but it also reduces fuel efficiency as the engine produces less power per stroke.
5. Poor Engine Performance:
If you notice that your engine is not performing as well as it used to, bad rocker arms may be to blame. Several things can cause weak engine performance, but one common cause is improper valve timing.
Remember how we said that the intake and exhaust valves need to open and close at the proper times? Well, if they’re not, it can lead to all sorts of problems like reduced fuel efficiency, increased emissions, and poor engine performance.
Other causes of poor engine performance include loss of compression, misfires, and knocking. All of these issues can be caused by bad rocker arms.
If you notice any decrease in your engine’s performance, it’s best to take it to a mechanic.
6. Cracked Surface:
During visual inspection, you may notice that the surface of the rocker arm is cracked. This is usually caused by metal fatigue and is a sure sign that the rocker arm needs to be replaced.
In some cases, a crack on the surface of the rocker arm may not be visible to the naked eye. However, if you suspect that your rocker arm may be cracked, it’s best to take it to a mechanic so they can inspect it.
Keep in mind that even a small crack can cause a faulty rocker arm. So, if you think there’s even a possibility that your rocker arm is cracked, don’t take any chances and get it replaced as soon as possible.
What Causes Rocker Arms to go Bad?
Now that we’ve gone over some of the symptoms of bad rocker arms let’s talk about what causes them to go bad in the first place. The list is rather long, so bear with us:
Wear and Tear:
The most common cause of bad rocker arms is wear and tear. Over time, the parts of the rocker arm start to wear down and break. This is especially true for the bearings. The bearings allow the pushrod to rotate freely inside the rocker arm. However, over time they can become worn out and damaged.
Incorrect Installation:
Another common cause of bad rocker arms is incorrect installation. If the rocker arm is not installed correctly, it can cause several problems. For example, it may not be aligned perfectly, which can cause the pushrod to bind inside the rocker arm.
This can damage both the pushrod and the rocker arm. So, if you’re going to replace your rocker arms, make sure that you know what you’re doing.
Engine Misfires:
Engine misfires are a killer of rocker arms. When an engine misfires, it sends a shockwave through the entire engine. This can cause damage to many different parts, including the rocker arms.
Now, many things may cause an engine to misfire. However, one of the most common causes is a faulty spark plug. So, if you’re having problems with your rocker arms, it’s worth checking your spark plugs to see if they’re the problem.
Excessive Carbon Buildup:
Another common cause of bad rocker arms is excessive carbon buildup. Over time, the carbon deposits inside the engine can build up on the rocker arms. This can cause them to stick or bind, damaging the rocker arm and the pushrod.
To prevent this from happening, it’s important to regularly clean your engine and remove any carbon buildup that may have occurred.
Using Wrong Engine Oil:
One of the most common causes of bad rocker arms is using the wrong engine oil. The oil that you use in your engine needs to meet certain specifications. If it doesn’t, it can cause several problems, including damage to the rocker arms.
So, ensure that you’re using the correct oil in your engine. You can usually find this information in your owner’s manual.
Bent Pushrods:
Bent pushrods are another common cause of bad rocker arms. The pushrod is what connects the valve to the rocker arm. If it’s bent, it can cause the rocker arm to bind or stick. This can damage both the pushrod and the rocker arm.
When a pushrod bends, it can cause the rocker arm to contact the valve stem at an angle. This can lead to premature wear on the rocker arm and valve stem and eventually cause engine damage.
Lack of Lubrication:
One of the most common causes of bad rocker arms is a lack of lubrication. The bearings inside the rocker arm must be properly lubricated to function correctly.
If they’re not, it can cause the bearings to seize up and damage both the pushrod and the rocker arm. So, make sure that you’re regularly lubricating your rocker arms.
Overheated Engine:
Another common cause of bad rocker arms is an overheated engine. When the engine gets too hot, it can damage many parts, including the rocker arms.
The heat can cause the metal to expand and warp, which can bind or stick the pushrod inside the rocker arm. This can damage both the pushrod and the rocker arm. Now, there is a long list of things that can cause an engine to overheat.
So, if you’re having problems with your rocker arms, it’s worth checking your cooling system to see if that’s the problem.
Worn Valve Guides:
Another common cause of bad rocker arms is worn valve guides. The valve guide is what holds the valve stem in place. If it’s worn out, it can allow the valve stem to move around, damaging the rocker arm.
Wrong Valve Adjustment:
If the valves are not adjusted correctly, it can cause the rocker arms to go bad. This is because if the valves are not adjusted correctly, the clearance between the valve tip and the rocker arm will be too great.
This will allow the valve to bounce off the rocker arm when it opens, which will cause a loss of power and torque. Additionally, this can cause premature wear on the valves and the rocker arms.
Timing Chain Defects:
One of the most common causes of bad rocker arms is timing chain defects. The timing chain keeps the engine’s valves in sync with the pistons. If it’s defective, it can cause the valves to open and close at the wrong time and damage the rocker arms.
Manufacturing Defects:
Last but not least, manufacturing defects can also cause bad rocker arms. Although it’s not common, there have been instances where the rocker arms were not made correctly and ended up breaking or failing soon after they were installed.
Rocker Arm Replacement Cost
Replacing a rocker arm can be a fairly expensive repair. The cost of the parts is usually around $100-$250. However, the labor can be a bit more expensive.
It usually takes about three hours to replace a rocker arm, so that the labor cost can be anywhere from $300-$1,000. So, all in all, the cost to replace a rocker arm is usually around $400-$1,250.
This rocker arm repair cost will vary depending on your vehicle’s year, make, and model. It will also vary depending on where you have the repair done.
The reason behind such a high replacement cost is that it is a labor-intensive job requiring special tools to remove and install the rocker arms.
Moreover, you might need to replace engine oil and associated gaskets when you replace the rocker arms. This will also add significant costs.
Conclusion
Faulty rocker arms are a common cause of engine problems. If you’re experiencing any of the bad rocker arm symptoms mentioned above, it’s important to have your vehicle inspected by a qualified mechanic.
They will be able to diagnose the problem and recommend the best course of action. In most cases, replacing the rocker arms is the best way to fix the problem.
However, if the problem is caused by something else, such as an overheated engine or worn valve guides, then repairing or replacing those parts may be necessary.
No matter what, it’s important to get the problem fixed as soon as possible to avoid further damage to your engine.
We hope this article was helpful in explaining everything you need to know about bad rocker arms.
Frequently Asked Questions
What happens when a rocker arm goes bad?
When a rocker arm goes bad, it can cause several problems for the engine, including:
- Decreased performance
- Increased fuel consumption
- Loss of power
- Knocking or pinging sounds
- Rough idling
- Misfiring cylinders
How long can you drive with bad rocker arms?
The answer to this question depends on how severe the damage is. If the rocker arms are only slightly damaged, you may be able to drive for some distances ranging from 5,000-10,000 miles without any issues.
However, if the damage is more severe, it is best to have the problem fixed as soon as possible to avoid further damage to your engine. If you continue to drive with damaged rocker arms, it could cause other engine components to fail.
Should you replace all rocker arms together?
It is recommended that you replace all rocker arms simultaneously, even if only one is damaged. This is because all rocker arms wear out at the same rate. If one rocker arm is damaged, it’s likely that the others are not far behind.
Moreover, the labor cost to replace all rocker arms is usually only slightly more than the cost to replace one. Therefore, it is best to just replace them all at once.
What causes rocker arm failure?
Rocker arms can fail for several reasons, but the most common cause is wear and tear. However, rocker arms can also fail due to other factors such as poor lubrication, excessive heat, or even manufacturing defects. Whatever the cause, rocker arm failure can be extremely detrimental to the performance of your engine.
Why do you have a loose rocker arm?
One of the most common reasons for a loose rocker arm is that the retaining nut has come loose. This can happen over time as the engine vibrates, causing the nut to loosen.
Another reason for a loose rocker arm is that the pushrod may have become worn down, causing it to be not as tight as it once was.
What is the average lifespan of a rocker arm?
The answer to this question depends on a number of factors, including the quality of the materials used to make the rocker arm and the care taken in its manufacture. In general, however, most rocker arms have an average lifespan of between 80,000 to 100,000 (five and eight years).
However, it is not uncommon for some rockers to last much longer, provided they are properly maintained. Additionally, it should be noted that the lifespan of a rocker arm can be significantly reduced if it is subjected to excessive stress or wearing conditions.
