Ultimate Guide to Head Gasket: Why Does it Fail and What to do

The head gasket is a vital part of the engine and can be an expensive part to replace if it fails. In some cases, the repair and replacement are more than the value of the car which usually means it’s the end of the road for the vehicle. In the article, you’ll find signs to look out for a failing or blown head gasket, what to do next and things you can do to prevent it.

What is a head gasket?

A head gasket is a seal that sits between the engine block and cylinder head in an internal combustion engine. The head gasket’s purpose is to seal the cylinders to prevent coolant or engine oil from leaking into the combustion chamber.

What causes a “blown” head gasket?

A “blown” head gasket is typically caused by extreme engine heat. The head gasket is responsible for sealing the gap between the engine block and the cylinder head. If the head gasket is damaged, it can cause a loss of compression, oil leaks, and coolant leaks.

What are the signs and symptoms that a head gasket has failed?

Common signs that your head gasket is faulty:

Contaminated “milky” oil:

The coolant in the oil is usually the first sign, and is the result of the head gasket leaking coolant into the combustion chamber. Check the engine oil and if the oil is milky or white, then it could be a sign of leaking coolant.

Coolant loss and over-pressurising of the cooling system:

A head gasket fault between the combustion chamber and cooling jacket can result in mysterious coolant loss. The cooling system can pressurise over time when driving and the coolant is forced from the coolant filling cap. The heater can also go hot and cold as the combustion gases air lock the heater matrix and upset the flow of coolant. 

Loss of power: 

A faulty head gasket can cause a loss of power in a few ways. Most commonly, it can cause a loss of compression in the engine, which will reduce the amount of power that the engine is able to produce. Additionally, a head gasket leak can allow coolant or oil to enter the combustion chamber, which can also lead to a loss of power.

Overheating:

An engine overheating consistently (as a result of a clogged radiator for example) can cause the head gasket to fail but ironically, a head gasket failure can lead to overheating.

If the coolant is leaking it means the engine will start overheating. Steam coming from the radiator is a common indication of the engine overheating.

White, sweet-smelling smoke:

A blown head gasket can produce white smoke which has a peculiar sweet smell to it if the engine is running too hot. The white smoke is caused by the coolant leaking into the combustion chamber and burning off. Sometimes you may also find water dripping from the exhaust. 

Can you drive with a blown head gasket?

It is possible to drive a car with a blown head gasket, but it is not advisable. The car will not run as smoothly as it should, you may experience loss of power and the car will often overheat.

Additionally, continuing to drive an overheating engine will inevitably result in disastrous damage to other parts of the engine which is often irreparable. If you want to minimise damage to the engine, the best thing to do is avoid driving with a blown head gasket and get it fixed or replaced as soon as possible.

Can you repair a blown head gasket without replacing it?

As a cheaper alternative to replacing the entire head gasket, it may be possible to use head gasket sealers to temporarily fix developing problems if the problem is caught early enough. However, it is not recommended to use them as a long-term fix. These sealers have also been found to hamper any later repairs as they can clog the cooling system.

There are several head gasket “sealer” products on the market that are designed to repair leaks in a head gasket. If you choose to use a sealer, make sure to double-check the instructions first as the quality, brand and type can make a difference to the final repair job.

How to prevent a blown head gasket?

The best way to prevent a blown head gasket is to keep your engine coolant and oil levels topped off, and to get your vehicle serviced regularly. When the car overheats repeatedly or if you drive after the car overheats, the head gasket can fail, so maintaining a good cooling system is the best way to prevent a head gasket failure. 

If you suspect or notice any of the symptoms pointing to a failing head gasket or come across a coolant leak, get a mechanic to carry out an inspection to find the source of the issue and suggest a fix as soon as possible.

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Marketing at ClickMechanic

Louanne is a marketing and communications professional in the automotive tech industry currently at ClickMechanic, boasting over 5 years of experience.

Louanne’s work at ClickMechanic might revolve around branding and customer engagement, but her passions extend far beyond the marketing sphere. A true foodie at heart, she loves exploring diverse cuisines and talking about her culinary adventures across the world. Her writing prowess shines through in her car-related blog content, where she offers invaluable driving tips and practical car repair advice.

In her Suzuki Jimny 4-wheel drive, Louanne combines her sense of adventure with her automotive know-how, transforming every drive into a lesson and a pleasure.