Informational Guide

What Causes A Blown Head Gasket?

We look at what can cause a blown head gasket, the symptoms, and what to do next.

No one wants to hear that their vehicle has a blown head gasket, mainly because of how expensive the fix can be.

But, what causes a blown head gasket, and how can you prevent it? We look at what can cause a blown head gasket, the symptoms, and what to do next.

The head gasket is located between the engine block and cylinder head. While the part itself is small, it's vital to proper engine function. The head gasket seals the combustion system to allow oil and coolant to freely flow where each belongs.

The head gasket can be made from a variety of materials. Most are constructed of steel, you will also find fiberglass, rubber, cork, silicone, Teflon, nitrile, or felt used.

If the head gasket isn't working the way it should, your engine is in serious trouble. Either coolant or oil will begin traveling where it doesn't belong, leading to other more costly problems.

4 Main Different Types of Head Gaskets Explained

  • Multi-layer steel head gasket 
    This is the most common type of head gasket, consisting of three layers of steel sandwiched together. It is held together with elastomer, which is a flexible adhesive. Then, a coating is applied to resist heat.
  • Copper head gasket 
    Copper distributes heat more evenly, making it less prone to warping. It's also more malleable, so it will easily conform to uneven surfaces. You will find these in high-performance race cars.
  • Composite head gasket 
    The composite head gasket is anchored by graphite or asbestos. These are found in older vehicles from the 1970s and 1980s. These are probably the most prone to a blowout.
  • Elastomeric head gasket 
    Constructed from steel cores combined with rubber beads, this gasket contains just one layer of metal. The die-casting technology used for manufacturing helps to create a better seal.

How to Tell if Your Head Gasket is Blown?

What does a blown head gasket cause? You will notice one or several of these symptoms.

Oil or Coolant Leak

The engine is a closed system, meaning none of the fluids should escape. However, when something goes wrong, you might notice oil or coolant leaking. However, this isn't enough to diagnose a blown head gasket, as many malfunctions can lead to a fluid leak.

Misfire with Cylinder

The misfiring cylinder can occur when a breach between two cylinders happens on the head gasket. To determine if a blown head gasket is the cause, compression and leak tests should be performed.

Engine Too Hot

As oil leaks into the cooling system or vice versa, the ability to cool down the engine decreases. In return, your engine begins to overheat. Ironically, overheating the engine can actually cause a blown head gasket.

White exhaust smoke during start-up

When the car starts up, the antifreeze makes its way into the engine due to the broken head gasket. This causes white smoke to pour out of the exhaust.  This is a tell-tale sign that the head gasket is blown, as nothing else tends to cause white smoke.

Blue Exhaust fumes

You might also notice blue fumes, which come from the oil infiltrating areas where it shouldn't flow. As the car burns more oil, you will notice the smoke become thicker.

Oil contaminated with coolant

The head gasket keeps the coolant from coming in contact with the oil. When it blows, these two substances mix, creating contamination. You might notice a white, milky substance when you are topping off the oil or changing it.

Coolant with oil in it

For the same reason, your coolant might end up with oil inside of it. The only other reason for this to occur is a cracked cylinder head or block. Either way, there is serious engine damage

What Causes a Blown Head Gasket?

What is the cause of a blown head gasket? Many issues can lead to the head gasket blowing, but here are five of the most common.

1. Engine overheating

What is a blown head gasket caused by? Overheating tends to be the most common cause of head gasket failure. When the engine overheats, the head gasket is subject to temperatures it wasn't meant to handle. Even when the extreme temperature doesn't destroy the head gasket, it will weaken it.

Some common causes for engine overheating include:

  • Failing cooling system components
  • Leaking coolant
  • Clogged radiator
  • Bad EGR system
  • Stuck thermostat
  • Failing water pump
  • Loose serpentine belt
  • Old coolant
2. Abnormal combustion mixture/timing

Detonation or pre-ignition is another common reason that the head gasket becomes damaged. When combustion occurs normally, the flame burns the fuel-air mixture in the combustion chamber and spreads out evenly. If the mixture is incorrect or low-octane fuels are used, the combustion becomes erratic.

Detonation occurs when the ignition process develops too slowly in the cylinder. Pressure begins to build up, causing the second ignition to begin against the first. This creates a loud knocking sound. This shock wave causes physical engine damage, including a blown head gasket.

Detonation can be caused by:

  • Advanced ignition timing
  • Poor fuel distribution
  • Lean air/fuel mixture
  • Low octane fuel
  • Defective EGR valve

In comparison, pre-ignition occurs when ignition happens before the spark plug fires. This creates two combustion events, leading to a pinging sound. Typically, this is caused by:

  • Overheated exhaust valve
  • Poor engine lubrication
  • Carbon deposits
  • Glowing spark plug
  • Issues with the cooling system
3. Improper installation

When a new head gasket is installed, many aspects could go wrong, which would lead to failure. What causes a blown head gasket on a car with replacement? Here are a few causes.

  • Using damaged head bolts
  • Reusing old bolts
  • Neglecting to remove dirty areas of the head or block before installation
  • Using the sealant wrong
  • Applying the wrong type of sealant
  • Cleaning the surface with abrasive pads
4. Hotspots (incorrect gasket fitted)

If you use the wrong gasket, it will likely fail. However, even with the right gasket, you might notice some hotspots. These occur on models that have exhaust ports too close to one another, or there is a lack of reinforcement in one area.

To fix this, it's wise to have the cylinder head or block resurfaced to ensure a perfect fit.

5. Old and worn head gasket

Over time, the head gasket simply gets old and worn out, causing it to fail. In fact, the average head gasket life is about 200,000 miles or 10 years.


What to Do When Your Head Gasket Blows (Recommended by a Pro)

You should never drive with a blown head gasket as this could lead to more engine damage. What damage can a blown head gasket cause? It can lead to coolant leaks and damage other parts of the engine.

Some people try to take the cheap way out and pour a gasket sealer into the coolant system. While this is often recommended across the Internet, it's simply a bad decision. More often than not, it will lead to a clog in the cooling system, leaving you with more problems than you started with.

The only real fix for a blown head gasket is to replace it. While this is costly, it's the only way to ensure that no more engine damage occurs.

What is the Average Head Gasket Repair Cost?

Is it worth fixing a blown head gasket? For older vehicles, not usually. The cost can often outweigh the worth of the vehicle.

However, if you have a newer model, you might want to get more life out of it with a head gasket replacement.

Replacing the head gasket can cost $1,000 to $2,000 or more. However, that high cost isn't due to the part, but the amount of time it takes to replace it.

Steps to Help Prevent Your Head Gasket from Blowing

Now that you know what would cause a blown head gasket, you can take steps to prevent it from occurring again.

Take time to:

  • Regularly flush the vehicle's cooling system. Follow the guidance in your owner's manual for the recommended tune-up intervals.
  • Inspect the belts often to ensure the engine doesn't overheat.
  • If the engine does start to overheat, stop driving.
  • Keep the coolant topped off.

People Also Ask (FAQs)

What causes a blown head gasket on a motorcycle?

The motorcycle can suffer from a blown head gasket because of detonation and/or pre-ignition, overheating of the engine, a loss of fluids, or improperly installing the head gasket.

Can you drive a car with a blown head gasket?

You should never drive a car with a blown head gasket. It will only lead to more costly repairs and further engine damage. It can also leave you stranded if the engine decides to quit.

Does a blown head gasket mean a new engine?

It doesn't automatically mean you need a new engine. If you caught the blown head gasket early, it can be replaced. However, once engine damage occurs, you will have no choice but to replace the engine.

Does a blown head gasket make a sound?

If there are performance issues because the seal is broken, you could notice some minor sounds, such as what would be heard with an exhaust leak.

Can you smell a blown head gasket?

If white smoke is coming from the exhaust, it will have a sweet smell. However, a blown head gasket can also cause blue smoke due to the burning oil.

How long do head gaskets last?

The typical head gasket will last around 200,000 miles. However, mistreating the engine or running the coolant low can cause the head gasket to fail early.

What happens if you don't fix the head gasket?

Not only will a failing head gasket lead to further engine problems, but it can also create problems with the cooling system if the oil is infiltrating the coolant.


What would a blown head gasket cause? Nothing good, for sure. If you notice the symptoms of a failing head gasket, you want to have it repaired immediately.