How Can I Identify a Bad Rocker Arm? Common Symptoms Explained

Rocker arms, just like other engine parts, contribute to the overall functionality of the engine. If anything goes wrong with even one rocker arm, your car won’t run well. In some cases, it won’t run at all. You probably might not know something is wrong with them until you start hearing unusual noises.

So, if you start hearing weird noises from your valvetrain or engine, check it out. They are likely to be the symptoms of a bad rocker arm. Rocker arms can last for a very long time. But if not cared for, they wear off and affect the engine.

So, knowing when they are bad and getting them fixed is crucial.  In this article, I will walk you through what rocker arms are, what they do and how to know they are faulty. After which you will learn their repair and replacement cost. But first, what is a rocker arm?

Symptoms of Bad Rocker Arm

What Is Rocker Arm?

A Rocker arm is a small button in a car’s engine that helps turn radial movement into linear movement. Better explained, it helps in turning spin movement from the camshaft into an up-down movement. This movement further helps in opening and closing the valves.

It can be used in the internal combustion engine of motorcycles, automotive, and other flying machines. There are several rocker arms in a car’s engine. And they work in conjunction with each other. So most times, when one rocker arm is faulty, it affects the others.

Rocker arms are made of aluminum. So you will find them at the engine head that connects the camshaft to the valves. However, you may look and not see if you’re not careful. This is because you won’t find them in the same places in all cars.

While you will find overhead cams in some engines, others have the cams under the rocker arms. So the position of the cams will determine where the rocker arms will be located. In some cars, rocker arms are placed under the valve cap that is set directly on the engine’s head. While other cars have it placed between the engine’s pushrod and the valves.

Rocker arms function together with other parts, like the camshaft, pushrods, nuts, etc. This happens to ensures that the engine runs smoothly. They come in various designs. So, how they work or how long you can use them, depends on their designs.

what does a bad rocker arm look like

What Does Rocker Arm Do?

Rocker arms might seem like an insignificant engine part, but it’s very vital.

They help in lifting the valves for air to enter and leave the combustion chamber anytime. In other words, they help to transfer movement equivalently from the pushrods to the valves. Simply put, they are used in controlling engine valves and camshafts.

Now, if these valves do not work well, it will make gas consumption high. What does this mean? It simply means your gas will run out quickly and you will spend money to fill it again.

The rocker arms also keep engine pressure at the proper level and ensure that ignition happens at the right time. This helps to avoid engine misfire or overheat.

Does it seem like the functions of the rocker arms are not much? Then wait until they are faulty. Your car’s overall performance will not just be limited. But it might also cause permanent damage to your engine.

Again, continuous circulation of air is needed by the combustion chamber. So without the rocker arm, insufficient air will enter and leave the combustion chamber. Without sufficient air, this chamber will burn and cause the engine to overheat.

Because rocker arms are made of aluminum, they are strong. Hence, they have enough force needed to open and close engine valves.

Every car’s engine has a particular number of rocker arms it needs to function. For example, a V8 has 8 cylinders with two rockers attached to each making it a total of 16 rocker arms. So, how many rocker arms are in a V6? A V6 engine has 6 cylinders with two rocker arms on each cylinder. In a nutshell, a V6 has a total of 12 rocker arms.

So you see how important rocker arms are to the engine performance?

Symptoms Of Bad Rocker Arm

When your rocker arm is bad, you may start experiencing one or more of these signs.

Weird Noises

A tapping noise like that of a sewing machine is an indication that one or more rocker arm is bad. Bad rocker arm sound is heard mostly when you start the engine or while trying to stop your car. However, other factors could cause these noises. For example, a bad camshaft, bent valves, or inadequate lubrication of the engine can also cause such noises.

When a rocker arm is faulty, it gets stuck. So because of this, the valves do not open and close well.

First thing first, identify which part of the engine the noise is coming from. Then check it out yourself or have an expert mechanic do it. This will help diagnose if the problem is from your rocker arm or other engine parts. The earlier you identify a bad rocker arm, the better. This is because as one goes bad, it spreads to affect others. Trust me, you do not want to change several rocker arms, as replacing them might be very expensive depending on your engine.

Poor or Weak Engine Performance

The rocker arm and drivetrain are what generate and supply power to the wheels. If they are faulty, there will be a problem supplying this power. So with time, the engine becomes weak and would not function normally.

Again, the rocker arms push the valves at a specific time to allow the inflow and outflow of air. If they are faulty, the valves will not be able to open and close at the right time. This late action weakens the engine and makes it perform poorly.

Engine Misfiring or Stalling

If your rocker arms are faulty, your engine will keep jerking at intervals as you drive. With time, when the rocker arms can’t function anymore, it will lead to engine knocking out.

Additionally, the rocker arms control when the valves open and close. So if the valves do not open and close at appropriate times, it causes the engine to misfire.

Engine Check Light On

The engine check light is a malfunction indicator light. When it is on, it means that something is wrong. So, if your engine is performing poorly, you will get a warning from the engine check light. Other things like a bad oxygen sensor, bad gas cover, faulty spark plugs, etc, can cause it. But a bad rocker arm is among the many things that can cause this light to turn on.

Noticeable Rocker Arm Damage

If you see some of those symptoms above playing out, then it’s time to inspect. If you can’t, you can have a professional mechanic inspect it for you.

The only way to verify if the rocker arm is bad is to take off the valve caps and see what’s under. So what does a bad rocker arm look like? If the rocker arms are faulty, you should see metal particles under the rocker arms. Or in some cases, you will find broken rocker arms. Broken rocker arm causes may include

  • Worn valve springs
  • Loose springs.
  • Inadequate engine maintenance
  • Use of none standard engine parts
  • Broken of rocker arms that jammed under your cam lobe etc.

To be very sure that the rocker arms are bad, compare all the rocker arms. All of them should look the same. If you notice any arm having a tear or symptoms of tear, quickly replace them. In turn, these bad rocker arms affect the engine.

How to Fix A Rocker Arm

You can fix a rocker arm yourself or have a professional do it. To do this, first, remove the faulty rocker arm. Then, replace it with a new one. But before you start, ensure that your tools box and work light are close by.

To Remove

  • Open your car’s engine cavity; locate the negative battery cord and disconnect it.
  • Remove the cover from the assembly of the air cleaner and pop out the air
  • Get a socket and ratchet; use it to remove the nuts. Then raise the assembly from the engine
  • Tag each spark plug cable with a marker and masking tape. Please take note of each plug’s location.
  • Hold the spark plug cable at the end and remove each cable from the spark plug
  • Clear all wires from your workspace and path
  • Separate the throttle cords from the throttle body
  • Remove the wire stand from the input plenum and set it aside
  • Take out the bolts from the valve’s cap
  • Take out the valve’s cap from the head of the cylinder
  • Remove nuts from the damaged rocker arms.
  • Loosen the camshaft
  • Take off the rocker’s arms

To Replace

  • Place the new rocker arms and torque the nuts
  • Torque the camshaft
  • Place the valve’s cap over the new gasket
  • Install and tighten the bolts
  • Install the throttle cord stand to input space and tighten it
  • Attach the throttle wires to the body of the throttle.
  • Plug the spark cables to the right spark according to the tag you placed when taking them off.
  • Push each cable until they fall into the position
  • Attach the spark plug cables to the clips.
  • Put the air cleaner on the engine and tighten the nuts with a wrench. Attach the negative battery wires. Then, use a wrench to fix the nut.

To understand better, watch these YouTube videos.

Frequently Asked Questions(FAQs)

Q: What Causes Rock Arm Failure

Rocker’s arm gets bad, yes! But what causes rocker arm failure? 

  • Bad fuel injectors or fuel that isn’t compatible with your car. Fuel problems will always cause your engine to misfire.
  • Continuous use of contaminated oil or the wrong type of oil. This is why it is recommended to change oils at specific periods with the right types of oil.
  • Bent or broken valves cause the valves to stay open. Bent valves in turn are caused by bad engine timing.
  • Driving long miles especially when the engines are not maintained. However, servicing your car regularly and using the right types of oil can make the rocker arms last.
  • Engine overheating probably caused by faulty radiators or other factors.
  • Bad timing belt or chain. A faulty timing belt stops the engine from igniting and turning over. When this happens, the rocker arms, valves, and even the pushrods get damaged.
  • Fault from the manufacturing process can also cause rocker arm failure.

Q: What Does A Loose Rocker Arm mean?

Not only a bad rocker arm can limit an engine’s performance. A loosed rocker arm can do the same. When a rocker arm is loose, it means that the rocker arm bolts in your engine are not tightened well. But what causes a rocker arm to come off?

This could be from the manufacturer’s end or you trying to adjust rocker arms at certain times. Other causes could be a bad valve seat or faulty valve springs.

A loose rocker arm noise is also like a sewing machine ticking and clicking rapidly.  So whenever you hear that sound, it may be that you have a loose or a bad rocker arm.

Q: How Do You Tighten Rocker Arms?

To tighten your loosed rocker arms, simply do the following?

  • Start the engine
  • Remove nuts until your engine starts clicking
  • Slowly tighten the nuts until the clicking stops
  • Tighten again, but this time in a quarter(¼) turns
  • Do them one after the other until you tighten all the loosed rocker arms.

You may need to get new nuts because nuts tightened and loosened over and over would not be able to hold properly.

Q: What Are The Various Designs Of A Rocker Arm?

There are different types of rocker’s arms specially designed for specific vehicles. Their durability and friction levels make them different from each other. But what makes each special is the way they move a car’s camshaft. Please note that not all rocker arm fits all engines. So ensure you use the one recommended for your engine.

  • Roller-tipped rocker arms: Made with aluminum, these types of rocker arms have rollers on their tip. Thus, help to reduce friction and prevent valves from wearing out. This rocker arm also helps to increase horsepower.
  • Shaft rocker arms: This one has a shaft that passes through the rocker arm’s head that helps to generate rigidity. With rigidity in the valve train, you have more control over the car’s engine.
  • Stampede steel rocker arms: Fast and easy to produce, they are the most used rocker arms.
  • Center pivot rocker arms: This type does not use pushrods. Instead, they use a camshaft to push the rocker arms.
  • End Pivot Rocker arms: This rocker arm has a pivot point at its end. With the camshaft in the middle to push down on the end pivot region.

Q: How Long Can You Drive With A Bad Rocker Arm?

I have seen people drive with a bad rocker arm. But how long can you drive with a bad rocker arm? I won’t advise you to drive with a bad rocker arm. Not only will it limit your engine’s performance. It will cause the valves to malfunction and damage the cylinder connected to the bad rocker arm.

Q: How Much Does A Rocker Arm Repair Cost?

Rocker arms repair costs between $500 – $1500. And almost all the money mentioned here goes into labor. Normally, the price of a rocker arm is around $5 – $20. But that’s not the only thing needed to repair it

For example, there are some gaskets you will need to remove in other to access the faulty rocker arm. So you will end up replacing all the gaskets connected to it. In other cases, you may drain out oils which cause money to replace.

Rocker arms get worn out almost the same time. So to save labor cost, ensure the expert checks all. Because the labor cost to change one is the labor cost to change all. So you might only need to spend extra money on buying an extra rocker arm.

However, do not try doing it yourself because of the expensive labor cost. This process requires technical know-how. So give it to an expert to do.

Last words

The most common symptom of a bad rocker arm is the tapping sounds coming from the engine. However, try to take note of other symptoms like the engine check light. And ensure you replace the bad rocker arm immediately. A bad rocker arm would not just obstruct the functionality of the valves and lower the engine’s performance. But you may also experience engine starting problems.

The process of replacing a faulty rocker arm is technical. So using an expert to do it might be a wise thing to do. Making mistakes while fixing them yourself may rise to worse problems.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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