11 Signs of a Blown Head Gasket

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A blown head gasket is not an minor issues that you should ignore. If left ignored it can lead to more serious issues and damage to your vehicles. 

But how do you know if your head gasket is blown? 

Don’t worry. I’m here to help. In this post, I will go over the 11 signs of a blown head gasket so that you can act fast and replace your head gasket before any other issues arise. 

Let’s get started. 

1. Issues Starting Your Car

If your car is not starting or having trouble starting, this can signify that you have a blown head gasket.

Starting troubles can be due to a variety of reasons. Some of the most common ones are dead batteries or faulty starters.

To narrow down whether the startup issue is due to a blown gasket, you can look out for some key signs.

Cars with a dead battery will not make any noise when trying to start them. Likewise, if your starter is broken or faulty, you will only hear a click or half ignition attempt.

You can use these signs as a way to narrow down whether your starting issues are due to your head gasket or some other reason.

2. Engine Overheating

Overheating is one of the most common signs that you have a blown head gasket. One of the main reasons that cause the engine to overheat is the coolant leaking into your engine.

When coolant leaks into the engine, it lowers your coolant levels. As a result, when you’re running your engine, it will begin to overheat due to the lack of coolant.

Since a blown gasket can lead to many different issues, overheating can be caused by different reasons.

Another common reason is that your engine is damaged. After a blown head gasket, serious issues that can cause overheating include wrapped or cracked blocks. On the other hand, some more simple issues include a damaged thermostat.

Other reasons that could cause your engine to overheat include contaminated coolant. The blown gasket can also cause damage to other parts of your vehicle, such as the water pump or radiator, causing the engine to overheat.

3. Oil With Coolant In It

head gasket oil

If your gasket is blown, one possibility is that your coolant will leak into the engine and mix with the oil. If there are any coolant traces in your oil, this is a primary sign that your head gasket is blown or on the verge.

One of the easiest ways to check if your oil has coolant is to check your oil dipstick. If there is coolant in your oil, the oil will become beige, milky goo. If you are checking during the early stages of coolant loss, there may be only tiny specs of discoloration in the oil.

You can also drain your oil completely. This will give you a clear view of the contents inside your oil. Typically when draining, you will notice immediately if there is coolant in your oil.

Since coolant and water are heavier than oil, they tend to settle at the bottom and come out first when draining.

4. Coolant with Oil In It

Another common issue that arises when you have a blown gasket is that oil begins seeping into your coolant reservoir.

In severe cases, the end result looks like a beige and milky. Since coolant reservoirs are typically transparent, it’s quite easy to see the chance. 

If your coolant goes from the standard light blue to beige, then you have an issue.

In less severe cases or early in the seepage, you may only see a few specs of oil in the coolant. These specs are quite easy to see since the oil tends to rise to the top.

Whether your coolant reservoir is full of oil or it just has a few specs, this is a key sign that you have a blown head gasket.

5. Milky Build Up Under Oil Cap

head gasket oil

If your oil is running low and you can’t quite see your oil’s quality easily, you can inspect the bottom of your oil cap.

This is one place that you will commonly find leftover oil. Even with low oil, the heat and pressure will cause some to get stuck on the bottom of the oil cap.

If the residue under your oil cap is milky and beige, this is a sign that your head gasket is blown.

6. White or Blue Exhaust Smoke

When the color of your exhaust smoke is changing, this is a sign that there is an inside your engine.

In this case, blue or white exhaust smoke will let you know that either engine or coolant is leaking into the engine.

Thick white exhaust smoke coming from the exhaust system is a clear sign that there is coolant burning inside your engine. This is a key issue caused by a blown head gasket.

After seeing white exhaust smoke, you can confirm that it’s a blown head gasket by inspecting your oil.

If there is coolant inside or if it looks like thick, milky sludge, then coolant has entered your engine due to a blown head gasket.

7. Bubbles in The Radiator or Coolant Reservoir

Another common sign that you have a blown head gasket is bubbles in your radiator or coolant reservoir.

To check this, you want to remove the lids from both these locations first. Then start your car. Let it run for a few minutes, and inspect your radiator and coolant reservoir.

Typically you will see bubbles starting to form where the lid is. If you experience bubbles in either the radiator or coolant reservoir, you likely have a blown head gasket.

When there are bubbles inside your radiator or coolant reservoir, this is a sign that the air pressure is rising inside your cooling system.

This is most likely caused by air blocking the flow of liquid.

When this happens, the air pressure from the engine cylinders is transferred into the cooling system.

This can lead to overheating as well as other more serious engine issues.

8. External Head Gasket Leak

nother clear sign that you have a blown head gasket is if you can see a leak coming from your engine head.

This is sometimes hard to distinguish if there are many tubes and entry points near the leak. To confirm, you can add a dye to your oil and coolant to help you identify where the leak is coming from.

Another clear sign that you have a blown head gasket is if you can see a leak coming from your engine head.

This is sometimes hard to distinguish if there are many tubes and entry points near the leak. To confirm, you can add a dye to your oil and coolant to help you identify where the leak is coming from.

Likewise, it’s also much easier to determine if your engine is clean if the leak is coming from the head gasket.

If you see a leak, I recommend whipping everything down thoroughly so that you can easily monitor where the leak is coming from.

9. Fouled Spark Plug

oil fouling spark plug

Another common issue when you have a blown head gasket is a fouled spark plug.

A fouled spark plug is a spark plug that has been covered in a substance such as oil or coolant. When this happens, the oil or coolant interferes with the spark plug’s ability to ignite the cylinder properly.

This can cause engine misfires and other stating issues for your engine.

A fouled spark plug happens when the blown head gasket leads to an internal leak of coolant or oil into the engine.

When this happens, the excess oil and coolant will enter the spark plugs.

A fouled spark plug will typically be covered in black residue around the insulator tip, threads, and electrodes. 

This is because the oil will cover the spark plug, which will burn off when the car is trying to start.

10. Misfire on startup

If you experience misfires while starting, this can be a result of a blown head gasket. While many issues can cause a misfire, this is an initial sign of a blown head gasket. 

You should inspect your car for other signs on this list to confirm that it’s a blown head gasket and not due to another issue. 

Key signs that you have a blown head gasket if your car is misfiring is 

  • Coolant in your oil 
  • Oil in your coolant
  • Bubbling in radiator or coolant reservoir 
  • White or blue exhaust fumes 
  • Fouled spark plug 

11. Rough Idleing

Rough idling is characterized by jerking or stutters when driving or starting the vehicle. This is especially common if you are driving with a heavy load.

When you see your Check Engine Light cut on, feel a rough idle, a stalling, and a hissing sound from the engine bay – these are all symptoms of a vacuum leak.

You will feel your engine runs at higher RPMs but increases run rough and have difficulty maintaining stable RPMs on idle.

The RPM while idling decreases below the ideal level, resulting in rough idle when there is an uneven supply of fuel. You will need to restart the vehicle if the RPM falls too low because it will stall.

Rough idling can be linked to many other things other than a blown head gasket, such bad spark plugs or lack of oil in the engine.

If you feel rough idling along with any of the other signs on this list, this is a sign that you have a blown head gasket.

What is a head gasket?

The head gasket is the gasket that creates a seal between the cylinders and cylinder head in an engine.

It is located in the upper portion of the engine and sits on top of the cylinders openings. 

The cylinder head is placed on top of the head gasket to seal the cylinders in place. 

What does the head gasket do?

The head gasket is designed to seal your engine shut. 

This seal does several key things for the engine: 

  1. Maintains the pressure inside the engine 
  2. It prevents oil from leaking, combining, or leaking into the engine. 

This gasket is vital to the operation of the engine. 

Frequently Asked Questions (FAQ)

Can you drive on a blown head gasket?

Yes, you can drive with a blown head gasket, but it’s not recommended.

You can complete your trip, and then your next steps should be to fix your head gasket.

Driving on a blown head gasket will inevitably lead to more severe issues.

How Long Can I Drive on a Blown Head Gasket?

It’s hard to predict how long you will be able to drive on a blown head gasket. You can complete a few trips, but it’s not recommended that you drive more than that.

It’s hard to predict what issues your head gasket is causing without inspecting.

As a result, some cars won’t start after the head gasket is blown, while others can drive for months before any serious issues occur.

How much does it cost to fix a blown head gasket?

To replace a blown head gasket, it will typically cost between $1200 and $1500.

It can cost anywhere from $200 – $1,000 depending on the severity of the damage to repair a blown head gasket.

Repairing your head gasket is only possible if the damage is minor. If the damage is severe, it’s recommended that you replace the head gasket even if it’s cheaper to repair it.

The cost to replace a blown head gasket is so expensive due to the labor hours required and not due to the parts.

Depending on your car, you can expect to pay around $200-$400 for a new head gasket. If you are willing to opt to repair yourself, you can save a great deal of money.

Do head gasket sealants really work?

Head gasket sealants are typically temporary fixes to a serious problem.

Over time these sealants will begin to wear down, and you will encounter the same issues as you initially did.

The best course of action for a blown head gasket is typically to replace it or repair it.

Is it worth fixing a blown head gasket?

For newer cars, it’s worth it to fix a blown head gasket. But, it might not always be worth it to repair a blown head gasket for older cars.

To determine if it’s worth it, you need to know the car’s value and the remaining time on the lifespan of the vehicle.

It’s typically not advisable to make repairs that cost more than the value of a car.

Likewise, if your car is not expected to last more than two years, investing in a new head gasket is not an advisable option.

Does a blow head gasket mean engine damage?

No, a blown head gasket doesn’t always suggest engine damage.

To avoid engine damage, you must detect the problem fast and avoid driving on it.

Vehicles that continue to operate on a blown head gasket will inevitably experience engine damage.

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