Are you suspecting a blown head gasket in your car that never had any overheating? Do you want to know if it is possible to blow a head gasket without overheating? You’ve come to the right place, for we have researched this question, and we have the answer for you.
Yes, it is possible. Overheating is the most common cause of having a blown head gasket. However, it is not the only one.
Let’s talk more about the different reasons why a head gasket blows in the succeeding sections. Learn about the different types of head gaskets in the sections below.
Read on!
What Is A Head Gasket?
Let’s demystify what a head gasket is before we talk about the different causes of having a blown head gasket. This is to make sure that we are talking about the same engine part when we proceed to the latter sections of this article.
An internal combustion engine is made of two major parts—the engine block and the cylinder head. Why cylinder “head?” We’ll get to that in a bit.
The engine block is the half of the engine that houses the cylinders of the combustion chamber. Its structure is riddled with small channels where the coolant and the engine oil pass. The bottom of the engine block is the crankcase, where you’ll find the crankshaft and then the oil pan under that.
The cylinder head (or simply “head”), on the other hand, houses the roof of the combustion chamber. It also houses the intake and exhaust channels, the camshafts, the fuel injectors, and the spark plugs. V-type engines like the V6 and V8 engines have more than one cylinder head—one for each bank of cylinders.
The head gasket is what creates a seal between these two major engine parts. It is responsible for keeping huge amounts of pressure inside the combustion chamber. It also needs to make sure that the coolant and oil never mix and never get into the combustion chamber or outside the engine.
For the internal combustion engine inside your car to work, the pressure inside the combustion chamber and the forces that keep the coolant and the engine oil moving around the engine must be kept inside the engine and must be kept separate from each other.
Different Types Of Head Gaskets
Different types of engines need to have different types of head gaskets to create the ideal seal between the engine block and the cylinder head.
Head gaskets are normally made of a flat sheet that is pressed between the engine block and the cylinder head.
The different head gaskets below all have the purpose of creating a seal between the engine block and the cylinder head, but they are not made the same.
Multi-Layer Steel (MLS)
This is the most common type of head gasket.
This type is made from two to five sheets of steel. Elastomers or adhesives keep the steel sheets together. The surface of the MLS that comes into contact with the engine block or the cylinder head has a gasket coating.
MLS head gaskets are the most popular because they are proven to withstand higher pressures than other types of head gaskets.
Copper Head Gasket
Instead of multiple layers of steel, some engines use a solid sheet of copper as their head gasket. Solid copper is a stronger head gasket because it is made from solid metal. It is also able to provide better protection against leaks.
However, the installation of a copper head gasket requires a special machine, tools, and experience.
Composite Head Gasket
A composite head gasket is common in cars from the 80s. This type is made from graphite. Graphite is a strong material. However, a head gasket made from graphite doesn’t provide the level of leak protection that most engines need.
Thus, car manufacturers had to move away from using composite head gaskets in their newer engines.
Elastomeric Head Gasket
An elastomeric head gasket is made from a single sheet of steel. Elastomeric beads cover the surface of the steel core. The elastomeric beads—a silicone-based material—are rubber-like in elasticity and sealing properties.
Silicone elastomers are synthetic rubber materials that are the core component for most gaskets—not just head gaskets.
Unfortunately, elastomeric head gaskets are not as durable as MLS or copper head gaskets.
What Can Cause Head Gaskets To Fail?
Because of the importance of the function of a head gasket, modern head gaskets should last for at least 100,000 miles. Even though it is made for a long service life, head gaskets can fail prematurely.
Engine overheating is the most common reason why head gaskets fail prematurely.
When engines overheat, the cylinder head expands and presses against the head gasket with greater force than normal. This causes the head gasket to eventually fail between the cylinders because this is the thinnest part of the head gasket.
A micrometer can determine if the head gasket failure was due to overheating when it lost some of its thickness, especially in weaker areas.
After you replace the head gasket, you need to determine the cause of the overheating. Find out the reason behind the overheating. Fix the issue so the new head gasket will not have the same problem and fail prematurely.
Common reasons for overheating are coolant leaks, failing water pumps, non-functioning radiator fans, problematic thermostats, and an exhaust blockage. Blockage in the exhaust is often due to a problem with the catalytic converter or a modification of the exhaust pipe.
Aging Head Gasket
Like all components of your car, a head gasket will age and start to fail. Aging will cause the material of the head gasket to wear down and fail to provide a tight seal.
Car manufacturers always have a mileage point where you should replace the head gasket. Do not ignore this. You should replace the head gasket at the suggested mileage.
The problems that your engine will have if you wait for the head gasket to fail completely will lead to a more expensive repair bill.
Schedule your car for a head gasket replacement as it approaches that mileage where the manufacturer recommends a head gasket replacement.
Faulty Head Gasket Installation
If your engine just had a head gasket replacement but you’re noticing symptoms of a blown head gasket, then the previous replacement was not done properly.
If you don’t install a head gasket properly, it will not be able to create a tight seal between the engine block and the cylinder head. This will lead to symptoms on your engine that is akin to a blown head gasket.
If you do not address the problem immediately, the improper seal will lead to overheating.
An improper seal will cause the coolant to mix with the oil or leak into the combustion chamber. This means that the engine is losing coolant and is not cooling properly. Thus, a bad head gasket seal will eventually lead to overheating.
Bring your car to a mechanic to check the engine. Early diagnosis and repair will prevent the problem from getting worse, leading to a more expensive repair.
Sudden Temperature Changes
The head gasket also expands and contracts following the changes in temperature of the engine and of the environment once the engine stops running. The head gasket—just like the rest of your car and engine—will start to cool down to match the temperature of the environment once you stop the engine.
Thus, when you start your engine in the winter, the head gasket will be at the same temperature as the surrounding air, if not lower.
If you suddenly floor the accelerator pedal as soon as you turn on the engine during winter, the head gasket will undergo a sudden change in temperature that will weaken the material. Eventually, the head gasket will crack and leak.
Let your car slowly reach its operating temperature by taking it easy on the accelerator pedal before you start to push your engine to its limits.
Pre-Ignition And Detonation
Pre-ignition and detonation are two phenomena that can also damage your head gasket.
This is what happens during normal combustion:
Air and fuel enter the combustion chamber, then the piston starts to move upward. The upward movement of the piston compresses the fuel and air mixture. At the perfect moment, the spark plug will ignite the mixture.
The ignition of the mixture will create a large amount of force, pushing the piston downward. Normal combustion creates a natural expansion of the air inside the combustion chamber, creating a downward push.
Pre-Ignition
Pre-ignition happens when the fuel and air mixture ignites before the spark plug fires.
This can be damaging to the engine because the air and fuel will ignite while the piston is moving upward. The force from the combustion will have nowhere to go because the upward movement of the piston is opposing the outward force from the combustion. The opposing forces can damage the piston and the head gasket.
Detonation
Detonation happens when the initial combustion doesn’t consume all the fuel. The leftover fuel will lead to a series of secondary combustions after the first. The effect is the generation of sudden and forceful energy that can damage the pistons and the head gasket.
In Closing
Overheating is only one of the possible causes of a blown head gasket.
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You forgot another very important way that a head gasket can fail without overheating: corrosion. If coolant is not regularly changed and/or tap water is used instead of distilled water, corrosion can occur on the engine block, head, or even the gasket itself. This can undermine or otherwise compromise the gasket, allowing it to leak. And since many people never give coolant a second thought until there is a problem, this sort of head gasket failure is VERY common.
Hello,
There is another cause of cylinder head gasket failure I have experienced 2 times.
One a second hand high performance car I bought, the cylinder head gasket was failing about every year. The cylinder head cover cap was progressively covered with the kind of mustard telling that water was mixed with engine oil, then the sound of the exhaust would change. Then if the gasket was not changed, it would break, always in the same zone. It could happen when driving the car (steamy exhaust) but also when trying to start it. Water would flow inside a cylinder and the compression would blow the gasket. In severe cases, this can even distort a piston wrist pin.
The engine never overheated and the cylinder head was not distorted. The surface of the cylinders sleeves were OK as well. All the surface onto which the cylinder head was bolted was even.
The clue:
The nuts of the studs were supposed to be torqued to 2,5 mKg. After N gasket failures, I decided to torque the cylinder head studs more than recommended (up to 3,5 mkg) using the old style of torque wrench where the torque can be read by a needle that travels over a display. I started by the studs located around the zone where the gasket used to fail. And it turned out that 2 studs could not withstand the torque properly. It was possible to torque them to 3,5 mkg, but when turning the wrench, the speed at which the torque was increasing was much slower beyond a certain value. This means that these studs were torqued beyond their elasticity zone. I replaced the faulty studs and the problem disappeared definitively.
I had the same problem with another engine. It has been fixed the same way.
This might be a rare cause, but you know that it may happen and the check is easy.
To determine if a stud is torqued beyond its elasticity zone, a modern wrench can be used with an angular torque gage to measure the travel of the torque wrench otherwise finding the faulty studs would be difficult.