Located between the cylinder head and the engine block, you’ll find the head gasket. This small yet vital component is used to seal the internal combustion process allowing coolant and oil to travel throughout the engine to cool and lubricate.
Which means, when it “blows,” it could spell big trouble for the engine. Blown head gasket symptoms are pretty easy to identify and need to be rectified pretty quickly to prevent damage to your engine. This article will help you understand the head gasket, what it does, and how to know when it fails.
What is a Head Gasket?
In addition to sealing the combustion portion of the engine to allow oil and coolant to circulate, the head gasket also seals the combustion chamber in the engine.
This allows the vehicle to produce enough power to move forward, as well as keep harmful gases from exiting the combustion chamber by directing them through the exhaust system. The head gasket in modern vehicles is comprised of several layers of steel material entwined with elastomer, making them more durable and longer lasting.
Vehicles produced in the past were equipped with gaskets created by graphite or asbestos. In comparison, today’s gaskets are better as they are less prone to leakage and have little to no health risks as opposed to asbestos produced gaskets.
The head gasket is a vital component within the combustible engine. The head gasket ensures the pressure created from the spark plug’s ignition of fuel vapors remains within the combustion chamber.
The combustion chamber contains the pistons and needs a high amount of pressure to ensure the pistons continue to fire appropriately. Additionally, oil and coolant have equally important jobs but, in order to perform their tasks efficiently, they cannot mix. The head gasket keeps the chambers separated to ensure there is no cross-contamination of fluids.
What Does a Head Gasket Do?
A head gasket serves as a seal between the engine block and cylinder head, preventing engine fluid leaks and pressure losses.
A head gasket is an essential component that is located between the cylinder head and the engine block. A vehicle’s engine is split into two parts, the engine block where the pistons and cylinders live and the cylinder head which houses parts such as the valves, spark plugs, etc.
Situated between these two engine parts, the head gasket is designed to seal the internal combustion process and keep any fluids from leaking and mixing. The head gasket plays a crucial role in sealing the engine’s combustion chamber so that your car can build the appropriate compression that is needed to maintain your engine power. It also keeps coolant or oil from leaking anywhere else, preventing your engine from overheating and catching fire.
For these reasons, when building a head gasket, most manufacturers use thin layers of steel, making them more durable and sustainable. As an important component of your car frame, it serves a similar role to the skeleton of your car’s body. As engine downsizing is one of the most noticeable trends in modern cars, the head gasket also tends to be more light and rigid these days.
How Does a Head Gasket Work in a Car?
Comprehending how a head gasket works means first understanding how the engine works as a whole. In the engine block reside pistons that move up and down in cylinders. The pistons are connected to a rotating crankshaft from which your car gets its power. At the top of the engine is the cylinder head where the valves open and close to let the air-fuel mixture in and out of the combustion chamber.
The head gasket ensures the compression generated by the ignition of the air-fuel mixture remains inside the combustion chamber. This allows your engine to operate correctly, thus creating enough power for the car to push forward. Additionally, the head gasket keeps coolant or engine oil from leaking into the cylinders so that your engine runs properly and doesn’t overheat.
Accurate operation of your engine requires that these two fluids don’t leak or mix at the juncture of your cylinder head and engine block. As a seal between these two main engine parts, the head gasket stops the leaks and maintains the pressure.
What Causes a Blown Head Gasket?
Head gasket failures are usually the result of engine overheating, so ensure the coolant is topped up and the coolant system is in good working condition, with no leaks and an efficient radiator.
A properly installed head gasket will also prevent future damage. Ensure you use bolts that are in good condition and are suitably tightened. Too loose and a seal won’t form, too tight and you risk crushing the gasket.
Everything undergoes failure after enough time and use, but factors like these can cause head gaskets to fail sooner rather than later:
- Poor Maintenance: A lack of cooling system maintenance can lead to overheating — the most common cause of head gasket failure.
- Overheating: When your engine overheats, the cylinder head or engine block can warp or expand. When this happens, your head gasket may no longer seal properly.
- Pre-Ignition: Sometimes known as detonation, pre-ignition occurs when air and fuel ignite in the combustion chamber before it is supposed to. When this happens, combustion temperatures and pressures rise. Higher combustion temperatures and pressures can compound overheating and further test the head gasket(s).
- Installation Errors: If you’ve recently had your engine rebuilt or replaced, it’s possible that your head gasket was installed incorrectly. Don’t be too hard on the installer, though — head gasket installation can be tricky. Simply over tightening cylinder head bolts can lead to head gasket failure.
5 Symptoms of Head Gasket Blown
Once a head gasket has failed it can cause all manner of problems, including:
#1. Overheating.
A head gasket failure may have been caused by excessive engine overheating (as a result of a clogged radiator, coolant leak, defective fan, etc.). However, a blown head gasket will also overheat the engine.
Hot exhaust gases can leak into the cooling system, or coolant can leak into the cylinders and be burned as vapor. In either case, the end result is overheating of the engine.
If the car is driven while overheating, the alloy cylinder head can also warp, or steam can damage the catalytic converter, significantly increasing repair costs.
#2. Loss Of Power.
If the head gasket fails to allow compressed air/fuel to escape, the compression on that cylinder will be reduced. This loss of compression results in rough engine running and a noticeable decrease in engine performance. This type of failure is usually accompanied by noise such as an exhaust leak.
#3. Oil Contamination.
One of the most common signs of head gasket failure is the milk sludge on the bottom of the oil filler cap or dipstick, sometimes jokingly referred to as a “milkshake”. This is caused by coolant getting into the oil and vice versa.
While this is not conclusive evidence of head gasket failure, it is generally a good indicator and a sure sign that your engine must fall apart in order to find the source of the contamination.
If the oil becomes contaminated with antifreeze, the motor’s bearings are quickly destroyed with every trip. The repair will require at least an engine oil flush, replacement oil filter, and often a complete disassembly of the bottom end of the engine to ensure the bearings are not damaged and to remove any contaminated oil.
#4. White Smoke.
A faulty head gasket usually results in large clouds of sweet-smelling white smoke coming out of the exhaust. This is caused by antifreeze that gets past the seal into the cylinders and is converted into steam as part of the combustion process.
Less common, but still possible, is a leak from an oil passage to the cylinder, which would cause bluish smoke.
Each of these types of seal failure also allows for combustion pressure in the cooling system or the oil vent system. If a radiator hose suddenly blows its water outlet or the dipstick does not stay in place, this could be the cause.
#5. External Leaks.
If a head gasket fails between the water or oil passage and the outside of the engine, it can result in a simple coolant or oil leak. This is the least bad version of a blown head gasket, but it’s still serious.
This may not manifest itself as an immediate problem (other than causing a mess), but allowing the coolant level to drop too far can lead to serious engine problems. The other problem is that leaking oil can get into the hot exhaust and lead to acrid smoke and possible fire.
How To Prevent A Blown Head Gasket?
Prevention is the name of the game. Here’s how you can help prevent your head gasket(s) from a premature demise:
- Perform Regular Maintenance: Change your oil, replenish coolant when needed, and keep an eye on the temperature gauge. A well-maintained engine is less likely to suffer a head gasket failure.
- Use Fuel with an Appropriate Octane Level: You’ve probably noticed that gasoline is organized by numbers like 87, 89, and 91 — these are octane ratings. The higher the octane, the less likely your fuel is to detonate before it should. Higher compression engines require higher levels of octane. Check the inside of your gas cap or your owner’s manual for information on what octane level your vehicle requires.
- Pay Attention to Warning Signs: Do your best to notice unusual symptoms like overheating, strange noises, or smoke from the tailpipe. Catching problems early can be easier on your engine and your wallet!
What Should You Do If You Suspect A Blown Head Gasket?
If you think you have a blown head gasket, you should get it repaired as quickly as possible. Stop driving the vehicle immediately. A blown head gasket left alone can cause additional engine damage that will only add to your repair costs.
Coolant mixing with oil will destroy bearings and any other parts that rely on engine oil for protection. Exhaust gases entering the cooling passages can over-pressurize the cooling system leading to coolant loss and accelerated overheating. Don’t wait it out if you suspect a failed head gasket.