Is Your Subaru Suffering from a Blown Head Gasket? How to Diagnose and Repair the Issue.

If you are a Subaru owner, then you probably know how much fun it is to drive one. The car’s unique combination of all-wheel drive, safety, and affordability make it a popular choice for car enthusiasts all over the world. However, like any car, Subarus are not immune to mechanical issues. One of the most common issues faced by Subaru owners is a blown head gasket.

In this article, we will explain what a head gasket is, the common signs of a blown head gasket, how to perform a compression test to confirm the diagnosis, and how to prevent and repair a blown head gasket.

What is a Head Gasket?

The head gasket is a vital component in an engine that sits between the engine block and the cylinder head. Its main function is to seal the combustion chamber and to prevent coolant and oil from mixing into the engine. A blown head gasket is a malfunction that results in oil and coolant mixing. This mixing may result in problems such as overheating, loss of engine power, and excessive smoke from the exhaust.

What Causes a Blown Head Gasket?

Several factors can cause a blown head gasket. Some common causes include:

  • Engine overheating due to a lack of coolant
  • Faulty cooling system components such as the thermostat, water pump, or radiator
  • Engine oil leaks that can contaminate the coolant
  • Use of the wrong type of coolant
  • Increased pressure in the combustion chamber due to hot spots or pre-ignition
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Symptoms of a Blown Head Gasket

If you suspect a blown head gasket in your Subaru, the following signs can help you confirm your diagnosis:

  • Overheating – If you see that the temperature gauge is reading higher than normal, or steam is coming from the engine bay, then there’s a high probability that your head gasket is blown.
  • Coolant loss – Check your coolant level frequently and if you find that it’s low, there could be a head gasket issue. Leaks may occur internally or externally, so check for any signs of leakage around the engine too.
  • White smoke from the exhaust – If you see excessive white smoke coming from your tailpipe, there’s a good chance that coolant is leaking into the combustion chamber, and a blown head gasket is to blame.
  • Reduced engine power – If you’re experiencing a lack of power when accelerating, this may indicate that your engine is not building up pressure properly due to a head gasket problem.
  • Milky oil on the dipstick – If you notice that the oil on the dipstick looks like a milky-white color, then coolant could have leaked into the oil.

How to Diagnose a Blown Head Gasket

If you suspect that your Subaru has a blown head gasket, you can confirm your diagnosis by performing a compression test. Here’s how to do it:

  1. Make sure that the engine is cold.

  2. Remove the spark plugs and the fuel pump fuse.

  3. Attach a compression gauge to the engine’s first cylinder and crank the engine several times until the needle on the compression gauge stops moving.

  4. Record the reading and repeat the process for the remaining cylinders.

  5. Compare the readings for each cylinder. If one or more cylinders show a lower reading than the others, there’s a good chance that your head gasket is blown.

  6. To confirm the diagnosis, you can also perform a "leak-down test". This test will focus on identifying leaks and the location of the leak(s) as well as the compression loss percentage.

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How to Prevent a Blown Head Gasket

There’s no surefire way to prevent a blown head gasket, but regular maintenance of your Subaru’s cooling system can help lower the chances of it happening. Here are a few tips:

  • Check the coolant levels regularly and top up as needed.
  • Check the radiator and coolant hoses for any leaks or damage.
  • Replace any faulty cooling system components before they cause a blowout.

How to Repair a Blown Head Gasket

A blown head gasket is not a cheap repair and sometimes requires replacement of many expensive engine components. However, there are some options available:

  • Replace the entire engine – This is the most expensive option but may be necessary if the head gasket failure is severe enough.
  • Replace the head gasket – This is a more affordable option. However, this will need to be done by a skilled mechanic so as to ensure that there will be no further issues going forward.
  • Use a sealant – One option that some car owners try is head gasket sealant. However, this is not a permanent solution, and may even cause more damage to your vehicle.

Frequently Asked Questions:

Q: Can I still drive my Subaru if the head gasket is blown?

A: It is not recommended to continue driving your Subaru with a blown head gasket as it can result in even more significant engine problems. If diagnosed early, the repair can be addressed immediately.

Q: Can I fix a blown head gasket myself?

A: It is not recommended fixing a blown head gasket yourself as this can be complex and requires specialized mechanical knowledge. This repair should be left to experts.

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Q: How much will it cost to repair a blown head gasket on my Subaru?

A: The price of repairing a blown head gasket can vary widely, but generally it can cost around $1500 for the job depending on the severity of the repair and the extent of any damage incurred.

In conclusion, a blown head gasket is a significant issue that must be addressed promptly to avoid further engine complications in your Subaru. By knowing the symptoms of a blown head gasket, maintaining your cooling system, and having your vehicle serviced regularly, you can help identify and prevent any head gasket issues early on. And even if the problem returns, remember that you have options for repair and can always avoid making the damage worse by addressing it promptly.

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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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