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Spark Plug Blowout: Possible Causes and How to Prevent It!

Spark Plug Blowout

A spark plug blowout can happen when the spark plug is loose or when it is fastened too tightly to the engine plug. It can be dangerous especially if it occurs while you are driving. If your spark plug gets loose on a coil over plug or COP, it could sound like someone shot a gun. The spark plug might shoot out like a bullet and can potentially break your ignition coil and your engine.  According to the experts, a spark plug blowout can also be caused by improper torque when the plugs are installed, cross threaded plugs, damaged threads, excessive pressures developed on intake leak that enables water to enter in the cylinder, or valve train mechanical issues that causes it to not allow the exhaust valve to open adequately. 

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Spark Plug Blowout: What does a spark plug do?


The spark plug of a vehicle might be small but the task it has to do is very crucial. Without a good, working spark plug, you won’t be able to start your car. It releases a spark of electricity across the small gap that makes the needed ignition for the combustion to start the vehicle. It enables the pistons of the engine to be in motion so the vehicle can have power, will continue to have power, and to create the compressed air and fuel mixture a smooth burn. 


The spark plug is made to be sturdy, it is designed to withstand extreme heat and pressure within the cylinders of the engine. It is made to eliminate deposits from fuel additives and other contaminants.  


Spark plugs need to be in a good, working condition since it can directly affect the performance of the engine. A weak or bad spark plugs can cause a lot of problems. It is for this reason why car owners are encouraged to follow the manufacturer’s recommended spark plug service or replacement schedule. Failing to do so can cause problems such as misfiring, cold starting, or a spark plug blowout. 


Spark Plug Blowout: What causes your spark plug to blow out?


It is said that back in the olden days, spark plug blowouts didn't usually happen because cylinder heads were built from cast iron and that the threads were very difficult to remove. WIth the modern cars, the cylinders are now usually made of aluminum composites. With spark plugs designed and engineered to become more sturdy, it tends to strip the cylinder head threads or perhaps blow out the top plug shell or its ceramic body. 


But what exactly causes a spark plug blowout? 

  • Cross threaded plug


One of the common causes of a spark blowout is a cross threaded plug. It can occur when you install a spark plug and it has started to be crooked in the hole and instead of removing it and correcting it, you proceed to tighten it with a socket. This is called cross threading and it can cause damages to the threads that can result in the plug not held securely. When this happens, a spark plug blowout can take place as the combustion pressure blows the plug out. 


To avoid spark plug cross threading, you need to install the plug using only your hand force since it ensures that the installation will be straight. In the event where you can’t reach the plug with your hand, you can use an extension on a spark plug wrench. Avoid using any tools that can add leverage like a breaker bar or a ratchet. 

  • Damaged threads


Another thing that can trigger a spark plug blowout is a plug that is installed on damaged threads. Cross threading can damage the threads but overtightening can also damage it as well. Damaged threads won’t be able to hold the plug securely and a spark plug blowout can happen when the combustion pressure blows out the plug. If you can avoid damaging your threads, you can also avoid a spark plug blowout. 

  • Loose spark plugs


Plugs that are loose and not tightened securely can also cause a spark plug blowout. If it is loose, it tends to move around in the threads. When this happens, it can cause fatigue in the threads making them break loose over time. While plugs that are not tightened securely can be blamed on human error, there are instances where some engines are actually prone to loosening spark plugs. If you have an engine that is prone to this, it is always a good habit to retorque them regularly.  

  • Mismanufactured plugs


There are a few instances where the spark plug blowout is caused by a mismanufactured plug. This can happen when the plug’s threaded plug is slightly too small. When you install it, it might not blow out immediately but it may give space and allow the hot exhaust gases to erode the threads over time until all the threads have been damaged. 

  • Design flaw


If you have remembered the Ford Triton engine in the early 2000s, you might have heard about its design flaw in the heads. It has been reported that there were very few threads that held the spark plugs in place. Many people were reporting that their spark plugs have blown out and that the threads in the aluminum head have been stripped or destroyed. It is said that the problem is caused by the plugs design flaw. It only uses four threads and it uses aluminum that is known to be weaker.   


Spark Plug Blowout: How can you tell if you have a blown spark plug?


A spark plug blowout usually happens without a warning but a lot of people have reported that they have heard a ticking sound while driving and a few minutes later, their spark plugs have blown out. There are also some reports about a spark plug that got loose on a coil over plug or COP can cause a blowout that can sound like there is someone shooting at you. 


Some have also reported  that when a spark is about to blow out, you will hear a sound exactly like an exhaust leak. It is advised that when you hear your vehicle making strange noises while you are driving, it is always a good idea to pull over, get it off the road and check it. Although a spark plug blowout can’t really damage your engine, when a part of a chunk of the blown spark plug falls inside the cylinder, it’s another story. Serious damages can happen because of it. 


While we’re at it, since a good, working spark is necessary to power up and start your car, you need to be aware of the early signs of a bad spark plug. You need to know if your spark is already due for a replacement so you can prevent other problems from occurring. These are some of the symptoms of a faulty spark plug. 


  • Engine misfiring.


A misfiring engine is one of the most common symptoms of a faulty spark plug. An engine misfire can lead to an engine that is running rough at idle or during accelerations. A faulty spark plug makes the engine hesitate and not run smoothly like it’s supposed to. 


A bad ignition coil plug cap or using a poor-quality fuel can also cause the engine to misfire but a faulty spark plug is the most common reason for it. You need to have your vehicle checked immediately to get the right diagnosis since a misfire can send raw fuel into the exhaust that can lead to a damaged catalytic converter. 


  • It is difficult to start the vehicle. 


We have already pointed out how important the spark plug is in starting a vehicle. But when the vehicle is hard to start, most people blame the battery for it or maybe an empty gasoline tank. Spark plugs that can’t create the needed spark to start the combustion process means that they are faulty and that you won’t be able to go anywhere unless you fix the problem. 


A faulty spark plug can cause this to happen since the engine will have to compensate for the faulty spark plugs by working twice as much. If the weather conditions are extreme, it will be more difficult to start the vehicle. 


  • Poor fuel economy.


Engine misfires and the engine having to work harder because of a faulty spark plug can take a toll on your fuel economy. The fuel won’t be effectively burned in the combustion chamber because of it. The misfires can also cause problems to the air/fuel mixture that can affect your vehicle’s fuel economy. If you notice that you have been filling up your fuel tank more frequently than usual as well as any of the bad spark plug symptoms,  you should check your plugs since they might be the one causing it.


Spark Plug Blowout: How can you prevent a spark plug blowout? 


A spark plug blowout can be a hassle and can cause a lot of problems, but how can you prevent it? Here are some of the ways you can prevent a spark plug blowout. 

  • If you need to install new plugs, install them correctly. 


It was mentioned earlier that a loose or overtightened plug can cause a spark plug blowout. To prevent this from happening, you need to install your spark plugs properly. You can do so by allowing your engine to cool down first. It is not only dangerous to install plugs with a hot engine, but the changes in the engine temperature can also result in the plugs to become twisted and misaligned as it cools down. 


It is also advised that when you install new spark plugs, you should only use hand force and not any tools that add leverage. You also have to make sure that it is installed securely and not loose. 

  • When replacing spark plugs, make sure that you replace it with the right one. 


Keep in mind that there are different standard thread lengths for the spark plugs. If ever you need to replace yours, make sure that you pick the right one. You can’t use a spark plug with a  ½” thread length in an engine that is designed for a ⅞” one. The engine might be able to run but the extra threads will be subjected to carbon build ups and can become damaged. 


Although the spark plug wire’s length does not matter, a spark plug with no proper thread reach can hinder the engine to operate properly. Installing a spark plug with the wrong length of thread may cause a spark plug blowout that can damage the engine since the piston or the valve can strike it.

  • Pay attention to the strange sounds when driving.


Many drivers have reported that they have heard a ticking sound before a spark plug blowout. If you hear a ticking sound when you are driving or as you try to start your vehicle, it could be a warning that your spark plug is about to be blown out.  


You need to pay close attention to the soft and repeating clicks that can happen when you try to start your vehicle or when you are revving your engine in idle. These ticking, repetitive clicks are usually being produced by the spark plugs themselves. 


It can be dangerous. It can compromise your safety and can cause damage to your engine. It is important to stop your car immediately when you hear the ticking sound and check the spark plugs. Allow your engine to cool down completely and adjust your spark plugs so they are properly held in place and make sure that their torque levels are correct. If needed, you can replace them with new ones. 


A spark plug blowout is something that you can’t take lightly. It can cause severe damage on your engine that can become too expensive to fix. Although a spark plug blowout can cause severe damages, preventing it from happening can be very simple. You just need to be really careful and thorough when you install a new one and make sure that you use the right spark plug for your vehicle. 









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