How to Check and Repair a Blown Head Gasket

Last Updated: November 13, 2022 References 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.

Part 1

Part 1 of 2:

How to Check for a Blown Head Gasket

1
Look for a high engine temperature. 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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2
Check for lower coolant levels. If your head gasket is blown, coolant may be leaking from the cooling system.

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3
Look out for milky or frothy oil. 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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Beware of light smoke emerging from the exhaust pipe. 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:

How to Repair a Blown Head Gasket

1
Disconnect the negative battery terminal, located at the top of the car battery.^{[4]
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2
Remove the intake hose and airbox.
3
Take off the air conditioner compressor; this will require you to remove several bolts. Once the compressor is free, lay the device on its side in order to access the cylinder head.
4
Disconnect the water pump hose, by using a screwdriver to loosen the clamp.
5
Remove the alternator. You won’t need to take off the entire alternator harness; simply remove the bolts.
6
Drain the radiator and remove the radiator hoses. Disconnect all the lines running to the air conditioner.^{[5]
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The head gasket should now be visible. 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.
8
Remove the old blown head gasket. Be sure to thoroughly clean the cylinder head, so that the new head gasket sits correctly.
9
Once you have fitted the new head gasket into the space, tighten the bolts again in the correct order. 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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10
Replace the components. 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.
11
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.

Community Q&A

Question

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.
Question

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

Community Answer

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.
Question

How can I tell if I need new front shocks?

Community Answer

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.

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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