How To Deal With a Blown Head Gasket

Warning: You might have to blow through your bank account.

A mechanic applies a new head gasket.
Depositphotos

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Three words nobody ever wants to hear: blown head gasket. Among the automotive lexicon, the simple phrase is about as bad as it gets for the average consumer because it typically translates to a major repair that will cost the owner thousands of dollars. 

This is usually where we tell you to take a breath, grab your tools, head to the garage, and we’ll walk you through the repair, but head gasket work is a different animal. Unfortunately, this is not a problem you or we can easily resolve with a 1-hour garage session.

Instead, The Drive will arm you with information so you can evaluate how you’d like to proceed. What’s right for you will not be right for another person with a different vehicle. Soak it up, then decide how to deal with your blown head gasket. We’re just going to say sorry now to get it over with.

What Is a Head Gasket? 

A head gasket is the piece of reinforced material that sits between an engine block and an engine head. When the head is screwed onto the block, the gasket creates a seal that maintains the necessary pressure within the engine.

What Does a Head Gasket Do?

The head gasket seals the connection between the head of the engine, which contains the camshaft, and the engine block, which contains the cylinders and pistons. Modern gaskets are designed to adapt to minor surface imperfections and handle vertical and horizontal movement between the block and the head.

Various gaskets on a white background.
Depositphotos

Various types of gaskets.

Does a Head Gasket Need Glue?

In the past, some head gaskets required adhesives or sealants for installation, but that’s no longer the case. Modern head gaskets are designed with the perfect thickness and built-in technology to create a seal with dry installation.

What Are the Holes in a Head Gasket For?

There are a variety of sizes of holes cut out of a head gasket. The large holes are for the cylinders, some of the medium holes are for the bolts, and several small holes are for coolant. 

How Long Do Head Gaskets Last?

Unless you’re a Subaru owner, head gaskets are expected to last a fairly long time. Head gaskets should last at least 10 years, but depending on the vehicle and conditions, they could last 15-plus years.

Symptoms of a Blown Head Gasket

Some symptoms of a blown head gasket are subtle, while others send smoke signals, literally. These tells could indicate a major engine problem.

Oil or Coolant Leaking

If you notice coolant or oil leaking on or around your engine head and block, it could be an indication that your head gasket is no longer sealed. 

Overheating

If a head gasket blows, even slightly, the engine might not be able to cool itself down to acceptable driving levels. Overheating could damage several components within your engine, so immediately turn your vehicle off until you can determine the source of the issue. One thing you should never do when your car is overheating: Remove the radiator cap and check the coolant. That’s how you get a one-way ticket to the ER for a scalded face.

Engine Misfiring

For an engine to work correctly, spark, air, and fuel have to consistently work together with the precision of a Japanese sand artist. It has to be the exact amount of air mixed with the exact amount of fuel ignited with a specific spark voltage at a specific time. If any of these factors are off by a theoretical grain of sand, you could get preignition, knock, or misfiring. More than one of these factors could be affected by a blown head gasket.

Water Vapor or White Smoke Coming From Exhaust

If your head gasket is bad, coolant might work its way into the engine. If this happens, you could see white smoke or water vapor coming out of your exhaust pipe as a result.

Milky Oil

If you notice tan or milky colors in your oil, you might have a blown gasket—the underside of your car’s oil reservoir cap will likely become splattered with the milky oil. This happens when coolant comes in contact with and contaminates the oil. 

Bubbling Inside Radiator 

If you notice bubbling inside the radiator or coolant reservoir, it’s an indication your system has air in it, which could be caused by a leaking or blown head gasket.

Fouled or Wet Spark Plugs

If the gasket is blown, it’s possible for coolant, oil, or gas to get into the cylinders. This could foul or flood the spark plugs.

An engine from an Opel GT.
Tony Markovich

Removing the engine from an Opel GT.

Causes of a Blown Head Gasket

There are several sequences that could result in a failed head gasket seal. Your problem is most likely the result of one of these issues.

Overheating

Heat creates pressure, and when an engine overheats, it puts extra stress on not only the head but the head gasket, as well. If the heat is too much, it could cause the gasket to fail. The reasons for a car overheating are numerous, but it’s most likely the result of a malfunction, failure, or blockage in the radiator and/or cooling system

Warped or Cracked Block or Head

Similar to how heat can damage the gasket, heat could also damage the engine block or cylinder head. Most commonly found on engines with aluminum parts that wear more easily than steel, warped heads interrupt the flat surface needed to create a seal. Without a flat surface, the gasket could fail.

Age

A head gasket is constantly dealing with temperature fluctuations, head and block movement, and intense pressure. After years of wear, the gasket will break down, lose integrity, and naturally fail.

Improper Installation

If anybody has previously tinkered with the head gasket and didn’t install it correctly, it could have had a weakness from the start that finally failed.

How To Test for a Blown Head Gasket

Not all head gasket leaks are immediately catastrophic. At times, a teeny tiny leak will spring and you’ll slowly lose coolant. If you suspect you might have a head gasket leak, there are a few ways to confirm your suspicions.

Check for Radiator Bubbling

This is more of a check than a test, but it’s useful nonetheless. One of the primary symptoms of a leaking head gasket is bubbling radiator fluid due to exhaust gases exiting out of the coolant system. After the car has been sitting, pop the hood, remove the radiator cap, and start it up. If you notice bubbling, that's an indication of a significant leak.

Head Gasket Leak Tester

You can buy head gasket leak testers, also known as compression leak testers. Purchase one online or at your local auto parts store.

Coolant Compression Test

Use a coolant pressure tester kit to check the pressure of your cooling system. If the pressure is lower than its normal operating state, the coolant could be leaking due to the blown head gasket.

How Much Does It Cost To Repair a Blown Head Gasket?

There is no single number we can use to answer this question. Even if there is nothing wrong with your engine and the gasket simply deteriorated, replacing the gasket is so labor-intensive that a professional job will likely cost between $1,000-3,000. Factor in additional engine problems that caused the head gasket to blow and that could quickly climb to $5,000, or more.

A close-up of a head gasket.
Depositphotos

Head gaskets can wear down for a variety of reasons.

Options for Dealing With a Blown Head Gasket

There are only a few options for handling a blown head gasket, and none of them are particularly good, unfortunately. 

You must consider these questions: Does a repair cost more than the car? Does the repair cost more than a replacement engine? Does replacing the engine cost more than the car? If you answered yes to all of these questions, it might be best to accept your car’s death and move on. If you’d like to proceed with repairs, get the credit card ready and pull out the calming lavender bath salts.

Pay For a Repair

Handing over a car with a blown head gasket to a shop is essentially handing the garage a blank check. First, the labor costs begin when the mechanic performs tests to confirm the head gasket is blown. Once confirmed, labor is needed to remove half the engine to access the head gasket. Once it’s open, there are a number of additional problems that could require more time, more labor, and more money. There’s also the potential that you pay the mechanic to tear down the engine only to discover a crack that could total the whole project.

Pay for a New Engine

If you aren’t attached to maintaining your vehicle’s original form with its original engine, an engine replacement is an option. It’s possible to find an engine swap candidate for cheaper than the cost of strictly replacing a head gasket. However, you’ll then need to install the engine yourself or pay a professional to swap it out. 

Attempt To Repair It Yourself

Even if you’ve torn down and rebuilt an engine before, there are still several parts of this process that could require professional repair services such as taking the engine to a machine shop. This is an expert-level job, so only attempt if you have all of the proper tools and a ton of experience.

If you decide to go for it, use a service manual for precise instructions on how to remove parts until you get to the blown head gasket. When replacing the gasket, be sure that the surfaces are clean, smooth, and even. And don’t forget to go beyond replacing the gasket, as well. Inspect everything that could be affected by a blown gasket, including the coolant system, the cylinders, and a million other things. It doesn’t hurt to test, check, and replace old parts while the engine is apart, as well.

Get a New Ride

If you have an old car with a lot of miles that holds no sentimental value and isn’t worth much, it might be time to let it go. It’s tough, we know, that means it’s time to get lost in Craigslist for three weeks straight.

Do Head Gasket Sealants Work?

When you search, “how to repair a blown head gasket,” a bunch of head gasket sealants pop up claiming no-hassle, no-work solutions. Let’s be clear: Head gasket sealers do not fix anything. They temporarily plug a leak and will eventually fail again.

By using a sealant and thinking the problem is fixed, you could be ignoring the real problem that might have caused the gasket to leak in the first place. Ignoring problems can quickly create more problems or bomb your engine. 

We understand not everybody has the money to repair or replace an engine, but your safety is first priority.

Get Help With Head Gasket Repair From a Mechanic On JustAnswer

The Drive recognizes that while our How-To guides are detailed and easily followed, a rusty bolt, an engine component not in the correct position, or oil leaking everywhere can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs. 

So if you have a question or are stuck, click here and talk to a mechanic near you. 

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