How to Check and Repair a Blown Head Gasket

Reviewed by Jason Shackelford

Last Updated: October 9, 2024 Approved

The head gasket is one of the most important components of your car’s engine. It is a mechanical seal that is fitted between the engine block and piston cylinder head. Its purpose is to ensure that the compression process is contained within the combustion chamber, and to prevent the mixing of fluids such as the coolant and engine oil.

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Part 1

Part 1 of 2:

Checking

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High temperatures can cause your gasket to blow, and once this has occurred, your engine temperature will only continue to rise. If your car is constantly overheating, this could be a sign that your head gasket has blown.^{[1]
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If your head gasket is blown, coolant may be leaking from the cooling system.

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Check the colour of your oil. If it’s white and milky looking, or if your oil dipstick reveals a frothy substance, chances are your oil has mixed with the coolant and your head gasket has blown.^{[2]
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If you spot white smoke emerging from your exhaust pipe, this could mean that the coolant has leaked into the combustion chamber.^{[3]
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Part 2

Part 2 of 2:

Repairing

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Once the compressor is free, lay the device on its side in order to access the cylinder head.
You won’t need to take off the entire alternator harness; simply remove the bolts.
Disconnect all the lines running to the air conditioner.^{[5]
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Refer to your service manual and pay close attention to the tightening sequence for the head bolts that hold the head gasket in place, as these must be loosened in the correct reverse order.
Be sure to thoroughly clean the cylinder head, so that the new head gasket sits correctly.
You’ll need a torque wrench to do so, as the bolts must be torqued to a specific tightness, relevant to your particular vehicle. It’s crucial that these bolts are torqued correctly, as otherwise you may cause damage to your new head gasket.^{[6]
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Reconnect the hoses in the order in which you disconnected them, replace the alternator, and ensure that all necessary parts are once again in place.
Fill the cooling system with fresh coolant and turn on the engine, allowing it to idle until it reaches operating temperature.^{[7]
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Research source} Allow the engine to run for several minutes before switching it off and checking your new head gasket for any leaks.

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I have heat while idling, but when driving the car, there is no heat and it turns cold. Replaced water pump and timing belt, which stopped the overheating, but the heat changes while driving car. What could it be?

Community Answer

It sounds like the thermostat is stuck open.

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What should I do first if my car is producing white smoke?

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When you go from hot to cold weather temperatures and encounter humidity, condensation can cause white smoke. This should not happen all the time. If it does, check the motor oil for water. If it's all foamy white, than you have a leaking head gasket.

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How can I tell if I need new front shocks?

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You will see uneven tire wear and the car might bounce excessively. Sometime noise and squeaks may be heard, however that alone is not an indicator of bad shocks. Rubber parts tend to squeak, especially in moist and humid regions or when it rains.

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Warnings

Repairing a blown head gasket can be very difficult, especially if you’re not familiar with the internal workings of your car. Improperly repaired blown head gaskets can cause long-lasting damage, so if you don’t feel confident completing the task yourself, it’s best to have the repair carried out by a professional.

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