7 Signs & Symptoms of a Blown Head Gasket

From the time of the engine’s invention, it has gone through several design changes and improvements. In the present time, several modern engines follow the four-stroke design, which makes use of three kinds of liquids. These liquids are motor oil, water coolant, and combustible air-fuel. Although a four-stroke design utilizes all three, they should never mix. If they did, it would cause a major problem with your engine, which eventually leads to failure. The head gasket guides the liquids so that they don’t mix.

What is it and what does it do?

Vehicles are very common, and we understand what they do. However, we do not know much about its internal parts and what each does. Several people may know a thing or two about the engine and what it does, but nothing more than that. Several equally important parts make up a vehicle, such as the head gasket. It prevents fluids that should not mix from mixing. In physical appearance, the it looks like a rectangular panel with big circular holes in it.

To have a deeper understanding of what it does, we need to know a little history behind the engine. In layman’s terms, it is like an air pump. It pulls in intake air charge and pushes out exhaust gases. It mixes the intake air charge with fuel, compresses it, and ignites it with the spark plug. During the ignition process, it creates heat and other gases, which pushes the piston down. This power allows the motor to turn and the vehicle to start moving. You may think that it is that simple, but there is a catch. For it to run efficiently, the cylinder that encloses the piston needs to be fully sealed. The valves that direct intake air needs to close and open at the right time while keeping the combustion gasses from escaping. Don’t let excess fuel go to waste. Use a waste oil heater to turn used fuel into something useful.

head gasket

If manufacturers create the entire thing in a single unit, it would be difficult and expensive. It would also be costly to maintain because you will have to consider the entire unit. Manufacturers came up with a modular approach to the problem by creating an engine with separate pieces. In most cases, the cylinder head is a different piece from the engine block. These two pieces are bolt together. In between these two is the head gasket, which acts as a seal. On the topic of fusing two or more parts, you may want to check on some of the best engine-driven welders in the market.

It prevents combustion gasses from escaping during ignition. While doing this, it has to keep with the constant fluctuation of temperatures. It also prevents cooling water from entering the cylinder walls.

What causes it to blow?

The head gasket goes through a lot of tough jobs. It deals with high and low pressures and a wide range of temperatures. Any object that is subject to varying conditions will degrade over time. It is a common issue for it to blow up over time, but it is important to know the exact cause.

The primary culprit for the head gasket to blow is exposure to varying high engine temperatures. A leak in the coolant and inadequate coolant in the radiator are the two common causes of high temperatures. We know the common causes for it to blow up, but we do not know what exact temperature or coolant level it will happen.

There are several types as well. Manufacturers use steel, cork, fiberglass, rubber, silicone, or even Teflon to manufacture these products. Aluminum steel is the least preferred because it is likely to expand faster than other steel types when heated. If the thermal expansion rate of metal is high, then the chances of expansion are high. It would mean the one made of aluminum steel will no longer have a tight fit when it is subject to high temperatures. On the other hand, manufacturers prefer using fiberglass when making them because it can handle high pressure.

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How can I prevent a blown one?

Having a blown one is one of the many things you do not want to happen to your vehicle. In the event yours blows up, you might need to rebuild the entire engine. The worst case is buying a new one or even an entirely new car. 

The problems a blown one can bring are big. It is important to know what measures to take to prevent it in the first place. With proper maintenance of your vehicle, you might save yourself from spending a huge amount to repair or replace your engine.

The head gasket is such an important component of the engine because it blocks the coolant from entering the engine block. During the combustion process, the block gets hot. The job of the coolant is to remove the heat from the block by passing over it. With that said, it goes through a wide range of temperature and pressure, which leads to it wearing out in time.

Its failure often happens when the engine frequently overheats. It is a sign that the system is not in excellent condition. To address this issue, you will have to ensure that the coolant levels are at the right levels.

The first thing you need to do is to check for any leaking in the system. Any leaking will cause the coolant to escape from the system, which leads to low levels and overheating of the engine block. When the block overheats frequently, it may lead to the failure of the head gasket. The second thing you need to check is if the radiator is working efficiently. If you experience frequent vehicle overheating, leaking coolant, discolored, or frequent low coolant levels, your radiator may have some issues. Call for professional help right away if you are experiencing at least one of these signs. The third thing you need to check is the coolant level. Is it at the correct level? If it is not, refill the it until it reaches the right level. If it frequently goes below the normal level, this may be a sign of leaking somewhere in the system. Immediately call professional help and have it checked as soon as possible.

If you think you have one that is blown, you can check if carbon dioxide is present in the cooling system. Do note that this test will only tell if it has blown but will not tell if there are other problems with it. So, not having carbon dioxide in the cooling system does not necessarily mean there are zero issues with it.

What are the symptoms of a leaking one?

An engine that frequently overheats is the most common reason they experience issues. Knowing the symptoms of a leaking one is important. Here is a list of how to tell if it is leaking.

Overheating Oil contamination
Loss of power Odd smoke
External leaks Bubbles in the radiator

1. Is your engine overheating?

An overheating engine could be the cause for it to fail. It overheats for many reasons, such as a faulty fan, a clogged radiator, or a low coolant level. When it does so frequently, it could affect the durability of it as well When it frequently comes in contact with high temperatures, it could wear off faster than it should, which causes it to blow up.

An exhaust gas that leaks into the cooling system can cause the vehicle’s engine to overheat. A coolant that leaks into the cylinders also causes it to overheat. There are several causes for the engine to overheat, so it is important to maintain your vehicle regularly. 

As soon as you experience an overheating engine, immediately call for professional help to avoid further issues from occurring. Every time you allow the engine to overheat, you let the alloy cylinder to warp its form. You also let the it burn too much steam, which can add significant damage to the catalytic converter.

2. Are you experiencing a loss of power?

Compression in a vehicle’s engine is what gives power to the vehicle. If it has blown up, it allows compressed fuel and air to escape from the chamber, which causes the compression in the cylinder to reduce. As a result, you may experience a loss in power.

If you experience this, immediately call for professional help. You may experience loss of power anytime and could be the reason for an accident to occur. 

3. Is there oil contamination?

A good indicator of a failed head gasket is when a mayonnaise-like substance appears on the oil filler cap’s underside. Although there is no solid proof that it indicates a failure, it is a good indicator that there is an issue with the engine, and a professional needs to look at it as soon as possible.

A faulty one does not cause the oil to leak, but it does let the coolant mix with the oil. Contaminated oil causes damage to the bearings, which may lead to more severe issues.

To fix oil contamination, you will need to flush out the oil and replace the oil filter. Doing this ensures that all traces of contaminated oil are no longer present. Once you have done those, you can now add the new oil to the system.

man fixing car

4. Is the smoke coming from the exhaust odd?

The smoke that goes off a vehicle is usually colorless. A blue smoke that goes off your vehicle’s exhaust indicates the head gasket is faulty. When leaking oil gets through and into the cylinders, it gets burnt during combustion, which causes the exhaust smoke to turn blue.

A faulty one can also let exhaust gasses enter the oilways, which causes a problem with the lubrication.

5. Are there any external leaks?

If you see a coolant leak or oil leak, the failure is somewhere in the oilway or waterway area. By itself, an external leak does not imply a severe issue. However, it can lead to one if left unattended. If you allow it to leak continuously, your engine might reach high temperatures and overheat.

6. Are there bubbles in the radiator?

If the internal head gasket is faulty, it may allow exhaust gasses to mix with the coolant. When this happens, bubbles will start appearing in the coolant reservoir or radiator. It will make it look like it is boiling even when it is cold. The bubbles you see are the gasses that got into the cooling system during combustion.

There is a way to know if the bubbles are the result of a faulty one. You can do a chemical test on the coolant to check if exhaust gasses are present. If the test shows exhaust gasses are present in the coolant, it means you have a faulty head gasket. Otherwise, there might be a different issue.

7. Is your spark plug working correctly?

During the combustion process, the coolant that is burning will leave small particles on the spark plug. You can usually find these small particles near the electrode and ground strap.

A faulty spark plug is not a direct indication of a blown head gasket, but it could mean there are some problems with the system that could lead to a problem.

Can you drive with a blown one?

man repairing a car

The answer is that you can no longer drive with a blown head gasket due to a significant loss of power. It is also not safe to continue driving with one that’s not working properly. When it has failed, the pistons can no longer produce the required amount of force that powers the vehicle’s engine.

Due to the faulty head gasket, the combustion chamber cannot hold enough pressure, which results in oil and coolant leakage in different areas. Coolant might mix with other liquids in the engine, such as the motor oil. If this happens, it will reduce its ability to apply lubrication to the parts that need it, such as the crank bearings. When there is not enough lubrication to these parts, it could lead to more serious problems and damage in the long run. Another issue you might encounter when the coolant is leaking is that your engine might not be able to lower its temperature as intended. A leak would bring the coolant level below its normal level, which affects its ability to cool down the engine. When there is insufficient coolant, it will easily overheat as you keep driving. It will lead to further damage.

It is also important to know that if you decide to keep driving with a faulty one, you will only introduce more damage to your engine. Leaving a faulty part unattended will only make the repair more costly. 

From the moment it blows up, you will not be able to drive far in most cases. If you think you are experiencing a blown one while on the road, slowly position your vehicle at the side of the road. Make a stop as soon as possible and call for professional help. 

Is it worth fixing? 

It is worth fixing it. After all, your vehicle will not work as expected if the part is faulty. One can’t ignore a faulty head gasket and expect his car to run smoothly. It needs repairing as soon as possible to avoid further damage to your vehicle’s engine. It could result in damage to the fuel injection system, exhaust system, and ignition system. The worst case is replacing the entire engine with a new one.

If you would like to fix it on your own, you can give it a try. The cheapest temporary solution is applying a gasket sealer to the leak. There are several brands you can choose from when looking for a gasket sealer. When looking for one, be sure the formula contains sodium silicate sealing liquid and gasket sealing particles.

To apply the gasket sealer, you need to pour it into your vehicle’s radiator. Depending on the instructions in the sealer’s label, you might need to rev your car in 20 to 30-minute cycles. It is important to do these steps correctly because it lets the formula circulate the engine thoroughly. When the formula takes effect, a seal will form in the leaking areas, stopping any leaking. Picking a gasket sealer from a reputable brand is recommended to ensure you get the best results.

The gasket sealer solution is temporary and is usually not recommended. It is not a permanent solution to the problem as it only delays the leak from getting worse. The seal could fall off anytime, which could cause major problems when it happens at the most unexpected time. 

If the leak is too big for a gasket sealer to handle, you might need to replace it with a new one. You will have to talk with a professional mechanic to repair or replace it.

How much does it cost to replace?


The head gasket is not an expensive part. You can find this part in-store or online for as low as $20, depending on the brand and model. What makes a replacement or repair expensive is the labor cost. Because replacing it is such a time-consuming and intensive job, it costs a lot. When replacing it with a new one, the mechanic needs to pull the engine apart. It is typically in between the block and cylinder head. Depending on how busy the mechanic’s schedule is, this procedure could take a few days to perform.

Taking  it apart requires the utmost care and precision because a wrong move might make things worse. Disassembling it to gain access to the necessary component takes time, and so is installing the new one and assembling it back together. One with overhead cams increases the complexity of removing the chain and timing belt. It makes the entire replacement process more challenging and expensive. Moreover, the cylinders will have to fire in the right order. Calibrating it is something you cannot guess.

With that said, you need to consider if the cost of repair is worth the spend. If your vehicle is old, you might want to compute the cost of repair versus selling it and buying a new car. For example, if you need to spend $3,000 to repair it, do you think it is worth it? If not, you may want to consider selling the car to a junk shop and add cash to buy a new car. The final decision is up to you.

However, if selling your car and buying a new one is not what you want, it is important to know other parts that might need replacing. Aside from the head gasket, there might be a need to replace the seals, belts, and water pump. These add up to the overall cost of repairing your vehicle.

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