Subaru Head Gasket Issues: Signs and Solutions You Need to Know

Subarus are known for their durability, reliability, and longevity. However, even the most dependable car needs maintenance and repairs. One of the most common problems faced by Subaru owners is a head gasket leak. The head gasket is a critical component of an engine, responsible for sealing the combustion chamber and keeping coolant and oil from mixing. In this article, we will explore everything you need to know about head gaskets, how to tell if they are leaking, causes, consequences, and repair options.

What is a Head Gasket and its Function?

Before we dive deeper into the head gasket leak issue, let’s first understand what a head gasket is. A head gasket is a seal made of steel, copper, or composite materials sandwiched between the engine block and cylinder heads. It functions to seal the combustion chamber, oil passages, and coolant passages.

In simple terms, the head gasket’s job is to prevent oil and coolant from mixing together or leaking into the wrong part of the engine. If the head gasket fails, it can lead to a range of problems, from overheating to significant engine damage.

Signs That Indicate a Head Gasket is Leaking

Knowing the signs of a head gasket leak is crucial to prevent further damage to your vehicle. Here are the most common signs of a head gasket leak:

  • Overheating engine: A common sign of a head gasket leak is an overheating engine. This is because the head gasket is responsible for keeping the engine’s coolant and engine oil separate. If the head gasket fails, the hot coolant can mix with the oil, leading to significant engine damage.
  • White smoke from exhaust: White smoke coming from the exhaust is another sign of a head gasket leak. This happens when coolant enters the combustion chamber and burns with fuel, producing white smoke.
  • Engine misfire: An engine misfire is when one or more cylinders fail to ignite fuel correctly. This happens when coolant leaks into the cylinders due to a damaged head gasket. The coolant can foul the spark plugs and create a misfire.
  • Milky oil: Inspect your oil dipstick. If you find that the oil appears milky or frothy, chances are there’s a head gasket leak. This is due to the coolant mixing with the engine oil, causing it to turn a milky color.
  • Decreased engine performance: A leaking head gasket will cause engine performance to decrease. It can cause the engine to misfire, result in a loss of power and decreased fuel efficiency.
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Causes of a Head Gasket Leak

Several factors can contribute to a head gasket leak, including:

  • Overheating: Overheating is a common cause of head gasket failure. If the engine gets too hot, the stress put on the head gasket can cause it to break.
  • Age and mileage: A car’s age and mileage can also lead to head gasket failure. Over time, heat cycles will cause the gasket material to weaken and create a leak.
  • Coolant issues: Coolant problems, such as low coolant levels or coolant contamination, can cause a head gasket leak.
  • Poor installation: If a head gasket is not installed correctly, it can result in a leak.

Consequences of Neglecting a Leaking Head Gasket

Ignoring a head gasket leak can lead to severe consequences, including:

  • Engine damage: Engine damage is the most significant consequence of neglecting a leaking head gasket. Coolant and oil mixing together can cause significant damage to your engine, costing thousands of dollars in repairs.
  • Total engine failure: A leaking head gasket can eventually lead to total engine failure if left unattended.
  • Decreased fuel efficiency: Continued driving with a head gasket leak can significantly decrease your vehicle’s fuel efficiency and result in higher gas bills.

Repair Options Available to Fix a Leaking Head Gasket

If you notice any of the signs of a head gasket leak, it’s essential to take your vehicle to a professional mechanic immediately. Here are some of the common repair options:

  • Head gasket replacement: The most effective way of fixing a head gasket leak is by replacing the head gasket. A new gasket will create a perfect seal and ensure that the coolant and engine oil don’t mix.
  • Engine block sealer: Engine block sealer is a temporary fix that can seal small leaks in the head gasket. It is not a long-term solution but can help you get by until you can afford to replace the gasket.
  • Replacing the engine: If the head gasket leak has caused significant damage, replacing the engine may be the best option. This is, however, an expensive repair.
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Tips to Prevent Further Damage to Your Vehicle

Preventive maintenance is crucial to prevent head gasket leaks. Here are some tips to extend the life of your head gasket and prevent further damage to your vehicle:

  • Regular coolant flushes: Regular coolant flushes will keep your cooling system clean and prevent blockages.
  • Watch for warning signs: Keep an eye on the warning signs mentioned above and take your vehicle to a professional mechanic if you notice any of them.
  • Check your oil and coolant regularly: Checking your oil and coolant levels regularly will give you an indication if there is a problem with your head gasket.
  • Regular engine maintenance: Make sure to keep up with your regularly scheduled engine maintenance, including checking and changing your oil and air filter if required.


Q. Can I still drive my Subaru if the head gasket is leaking?

A. It’s not recommended to drive your Subaru with a leaking head gasket. A leaking head gasket can lead to significant engine damage and potentially total engine failure.

Q. Is the Subaru head gasket prone to leaks?

A. The Subaru head gasket is known to be more prone to leaks than other car brands. However, regular maintenance and prompt repairs can help prevent a leaking head gasket.

Final Thoughts

A head gasket leak is a serious problem that needs to be addressed immediately. Knowing the signs, causes, and consequences can help you make informed decisions about your vehicle’s maintenance and repairs. Regular preventive maintenance, keeping an eye on warning signs, and taking your vehicle to a professional mechanic at any sign of a problem can help ensure your Subaru stays running smoothly for years to come.

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Alton Brobst

As a longtime Subaru enthusiast, Alton brings a wealth of knowledge and experience to our blog. From his early days of tinkering with engines to his current role as a certified Subaru technician, Alton has seen it all when it comes to Subarus. When he's not working on cars, he enjoys hiking and exploring the great outdoors.

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