Burnt Valve Symptoms – Everything You Need To Know

Burnt Valve Symptoms – Everything You Need To Know

October 6, 2021 0 By CarGuy

Are you experiencing constant misfires from your engine, despite giving everything to keep the vehicle in proper working order? That’s really unfortunate because you are probably experiencing some burnt valve symptoms. But you shouldn’t panic because we are going to give everything to explain to you how you can tackle this issue in your car.

Troubleshooting is key in order to learn how to diagnose a burnt valve problem. The first thing you need to know is to learn all of the symptoms that are connected with this problem to have a better idea of what to expect and based on these symptoms to diagnose the problem quickly and effectively. And that’s what we are going to help you out with.

You need to learn how to troubleshoot in order not to get ripped off by scammy mechanics that are waiting for someone to shave off. That’s why troubleshooting is key in order to understand the problems that you have on your car and how to overcome them. That’s why we are going to teach you everything you need to know when it comes to understanding burnt valve symptoms.

In this article, we are going to cover what are engine valves and we are going to list all of the burnt valve symptoms. Then we will cover the procedure of how to diagnose a burnt valve and the cost to tackle this problem quickly and effectively. So, without further ado, let’s dive into the article.

What Are Engine Valves? – Burnt Valve Symptoms

Engine valves are mechanical components that are installed on the engine head and their primary goal is to regulate the intake and exhaust.

How they work is pretty simple to explain. The engine intake valves open when there should be inserted air into the combustion process and then the big boom happens and the air burns off.

Then the exhaust valves open to allow the exhaust gasses to escape. All this process is happening in a fraction of a second. The higher the RPM, the faster this process occurs. And the more chance for damage to the valves as well. This will result in bent or burnt valves. That’s why engines are recommended to run at lower RPM unless your engine is a high compression engine made for a performance application.

Bent Valve Symptoms

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In order for the valves to deliver proper combustion in the combustion chamber, it is mandatory to have the proper compression. If there is even a hair of play between the valve and the head, there will be a lack of compression and the valves will not seal. This will result in burnt valve symptoms as well as low compression symptoms.

That’s why you should take note that you should always notice when there is something wrong with the work of your engine and make sure that the problem does not exacerbate and become much worse. But which are the burnt valve symptoms? We will cover that in the next chapter.

Burnt Valve Symptoms

When the valves get damaged there are symptoms that appear. You should be aware of these symptoms in order to diagnose the issue quickly and effectively. Because that is the most important. Knowing the symptoms is going to save you a lot of time and money in the process because you will be able to tell if your valves are damaged and the engine doesn’t work properly. But which are there burnt valve symptoms? Let’s find out.

Engine Misfires

One of the first symptoms that you are going to notice when your engine valves are bad is the engine misfires. The engine misfires are usually a tell-tale sign when there is something wrong, either mechanically or something wrong with the ignition components.

But what is a misfire? A misfire in simple words is improper combustion. All of the bangs in the cylinders have to be perfectly timed and even across all of the cylinders.

If the explosions are not evenly disbursed, the engine will start to misfire. But how I can recognize a misfire in my engine? It is dead easy to know if you have an engine misfire.

Usually when the engine misfires are starting to produce some sounds that are not normal. And these sounds usually come from the head of the engine, precisely at the point where the valves open and close.

The valves have a key role when it comes to misfiring. Because when the engine is misfiring, there is either there is a problem with the spark, or there is a problem with the timing and the valves do not open and close when they should. This can also be caused by burnt valves. The burnt valve is the last thing that you should connect when it comes to engine misfires since valves do not burn that frequently and these issues are happening not that often. But they do happen.

That’s why if you experience engine misfires coming from the engine, then you know that there is something off in the engine and it needs checking. If the ignition and the timing are perfectly good, you should start inspecting the engine valve health to see if they seal properly and that is something that we are going to cover a bit later.

Engine Hesitation

Engine hesitation is another of the burnt valve symptoms that are very frequent when there is no ideal combustion and there are misfires in the engine caused by a burnt or damaged valve.

The engine hesitation will feel like the engine doesn’t have power and all of a sudden it gets enough power to move. It simply hesitates at the start and then it kicks in.

This is not good and it has to be addressed pronto. The problem can also be connected with ignition components like spark plugs and coils. That’s why you need to make sure that all of these components are checked before you go any further into disassembling the engine and removing the engine heads. Since the problem can be just one spark plug or damaged coil.

But if the problem with the engine hesitation keeps bothering you and all the ignition components are good. Then the next thing you need to consider are the mechanical components.

More specifically if the timing of the engine is right. Because of the valves are misaligned, they can start causing some problems like this.

If the timing is right then the next thing you should consider is inspecting the valves for carbon buildup and possibly burnt valves. This is the last resort and if the valves are damaged, then you need to fix that. And how you can fix this issue we are going to discuss a bit later after we finish all of the burnt valve symptoms.

Rough Idle – Burnt Valve Symptoms

Rough idle as well can be one of the burnt valve symptoms that you will experience if one or some of the valves are burnt.

You will notice the rough idle when you start your car. The needle of the tachometer will constantly shake and will go up and down all the time.

This symptom by itself can mean a lot of things, like fuel delivery issues, ignition problems, and the problems that you don’t want to occur, which are the burnt valve problems.

When the valves are not sealing properly you will notice these symptoms. The rough idle is one of them and this means that the engine needs checking. The quicker you go through all of the components and troubleshoot, the sooner you will discover the right problem that is causing the rough running of the engine.

As we said, fuel delivery and ignition issues are the most frequent and you should take a look at these systems first. If these checks do not result in discovering and solving the issue. Then you should take a look at the valves. But how to diagnose burnt valves? We are going to discuss this later. But first, let’s cover all of the burnt valve symptoms. Since you need to know all of the symptoms if you want to diagnose the issue quickly and effectively and end all of your troubles.

Jerking And Stalling

Other burnt valve symptoms that are very common are the jerking and the stalling of the engine. These symptoms are caused because the valves do not seal properly.

There is a lot of blowby and this blowby doesn’t do any good to the engine and the engine simply struggles to keep itself alive. The engine wants to keep working but these components have failed and are causing it to struggle.

The valve clearance should be always perfect and if there are burnt valves then there will be no compression in the cylinder. We are going to cover the loss of compression later in the article.

Nevertheless, these burnt valves are basically holes at the top of the cylinder. And when there are holes there is a lot of unmetered air into the engine. Resulting in jerking in the engine and the engine simply has trouble keeping itself alive and avoid stalling.

When the problems become so excessive the engine will simply shut itself down and you will ask yourself why is this happening? There are a few logical explanations on the table. The first are the ignition issues with bad components like the spark plugs and coils, then there will be the fuel delivery issues. Namely, problems with the fuel filter, injectors, or fuel pump.

In this case, you need to troubleshoot and find out if these components are good. By finding out that the components of the ignition and the fuel delivery system are pretty good and in proper working order then you can take a look at the mechanical issues and inspect the engine for damage.

How you can diagnose burnt valves we are going to explain later in this article. But first, let’s see which is the last of the burnt valve symptoms.

Low Compression

Low compression is the last and the worst symptom that you will experience when you have a burnt valve issue. Usually, when there is low compression, there are big problems with keeping the engine running and in working order.

The engine will be down on power and also will struggle to keep running. Issues like stalling or jerking will be common and you will scratch your head of what could go wrong. But you shouldn’t worry, if the valves are bad, then fixing this issue will not going to be a big problem to overcome and you will be able to tackle this issue without replacing the engine.

This is the case because all the issues are in the valves which are located at the engine head. While the block is down and doesn’t really suffer any damage from this problem with the burnt valves.

The main problem is that there is a compression leak that allows a ton of unmetered air to get inside of the combustion chamber and this air basically ruins the vehicle’s performance. The worse the valve damage, the more air would be sucked in, and the worse the engine will run. Resulting in as we mentioned, engine stalling, jerking, loss of power, and misfires.

In the worst-case scenario, the engine will simply stop working altogether and you will think that your engine has failed but that doesn’t have always to be the case. And in the next chapter, we are going to explain why when we are going to cover how to diagnose this problem simply and effectively.

How To Diagnose The Problem With Burnt Valves?

This is a good question because valves can be a bit tricky to diagnose since they are inside of the engine and you cannot see them from the outside. This makes them extremely complicated to inspect and tell if they are bad or not. But luckily there are a few ways how you can perform this job and diagnose the issue. And which are they? Let’s find out.

Compression Test

The compression test is probably one of the first things that will come to your mind when you are experiencing this issue with your car. Why compression test? Because when the valves are bad they allow a lot of unmetered air to enter the combustion. Ruining the compression rating of the engine in the process.

Compression testers are pretty affordable and can be found at almost every car parts store. They are basically hoses with a gauge.

You need to attach the hose where the spark plug is mounted and then crank the engine. The engine will crank and compression on the gauge will start to rise. The ideal compression for most of the engines is somewhere between 100 to 120. For higher compression engines it’s even more. You need to know the right compression for your block.

If you have a bad compression, then one of the probabilities is that your valves are burnt. In this case, the engine has to be opened and inspected in detail.

Camera Probe

Many mechanics are using camera probes to inspect for damage inside of the cylinder and engine heads. How these probes are working it’s pretty simple to explain.

In order to enter the probe and see the condition of the valves, the whole intake has to be removed from the head, and then the probe is inserted inside of the intake and exhaust ports.

If there is carbon buildup or damage to the valves the technician would see and will note that this cylinder is affected by this problem and the problem needs solving as soon as possible if you want to return the vehicle to factory condition.

Head Removal And Inspection

The simplest way besides the compression test is to remove the engine head altogether from the engine and inspect the valves manually. This procedure is usually done when the mechanics have already determined that there is damage to the cylinder, either by inserting a small camera inside of the intake or exhaust ports or by doing a simple compression test on the engine.

After the head is removed, the damage will be determined and also the costs to perform this work. And that is something that we are going to cover next.

Cost To Repair Burnt Valves – Burnt Valve Symptoms

We have covered the burnt valve symptoms and how you can diagnose the problem with the burnt valves. Now let’s see how much does it cost to fix this issue. Since this is the most important thing in all of the process in order to determine if the engine is repairable or not. If the repairs cost more than the actual engine then it’s not worth it. If the repair is lower than the value of the engine, then the repair is feasible. Either way, we are going to discuss the costs involved in this process.

In order to solve this problem, the head will require to be machined. A new valve stem, valve seal, valve, and valve seat have to be installed.

These parts are not that expensive and will cost you less than 50$ for a single valve. The problem is the price for the machining work which can be rather expensive. The more valves that you have damaged, the more work will be required. And the cost to solve this issue can vary from $400 up to $1,000.

If the cost goes beyond $1,000, the best thing is to look for a good used head or a new aftermarket head. This will be cheaper and by doing this you will save a lot of money in the long run. Since you will have a new properly working engine head.

Can I Continue Driving Like This?

Yes, you can continue driving like this, but it is worth taking note that the engine will be hugely underpowered and you will experience a lot of misfires along the way.

As the problem progresses, the engine will find it rather difficult to keep itself alive and work properly. This can result in complete damage to the engine head and the only way to overcome this problem would be to install a new head.

This solution can be rather expensive because a new head can cost more than $1,500, compared to a simple valve job that can cost only $400. But the choice is yours and if you think that you don’t need the work you can keep driving your car like this until eventually fails completely on the side of the road.

Conclusion – Burnt Valve Symptoms

In this article, we have covered a lot when it comes to valves, more specifically burnt valves. We learned what valves are and what is their role in the combustion system.

Then we have covered all of the burnt valve symptoms that you need to know in order to diagnose this problem properly without any hassles. The most notorious problems that will occur when you have burned valves are engine misfires and the loss of power.

This loss of power is caused by decreased engine compression. Since the valves are burned, there is a lot of unmetered air that is entering the combustion process. And this air simply ruins the engine’s ability to work.

The engine struggles to keep itself alive and has problems with stalling and rough idle. The only way to find what is the real issue is to diagnose the problem. The problem can be diagnosed in three ways.

The first was to do a compression test and see which of the valves is bad and needs replacement. This is the simplest method and we have a full article on how you can do a compression test.

The second way is to use a camera probe in the intake and exhaust ports of the head and see if there is damage to the valves.

The last way is to remove the head altogether and inspect the head for damage. If there is damage to the head, the problem should be further investigated and repaired.

And lastly, we have covered the cost to fix this issue. It is not cheap since it requires a lot of machining work that can be rather expensive to perform.

Either way, the problem has to be solved if you plan o drive your vehicle without any issues in the future.