How to Replace a Head Gasket

What Is a Head Gasket?

Your head gasket is responsible for preventing coolant and oil mixing together. It seals the internal combustion process and is located between the cylinder head by the top of the engine and the main structure of the engine.

It has a demanding job as it simultaneously seals oil, coolant and compression from the cylinders, so can often need replacing due to the stress it is under. It can be hard to notice when your head gasket might need replacing as it is out of sight in the assembled engine, but it can become damaged from overheating leading to a perforation or blown head.

The main signs you should look out for are white or milky oil on the dipstick, white exhaust smoke, a loss of engine power, a sweet smell from the exhaust and an overheating engine.

When it becomes apparent you have a faulty head gasket, it’s important to get it repaired sooner rather than later to prevent further engine damage.

How Hard is it To Replace a Head Gasket?

Replacing a head gasket can be a complicated task and ideally needs speciality tools and plenty of experience so should ideally be left to a skilled professional mechanic. As mentioned before, it sits in a difficult to reach position and means removing an engine’s head to get to it.

While the part itself is not expensive, it is the labour involved in getting to it, due to its precarious position deep within the engine system.

We would recommend consulting a professional mechanic such as Power Developments for this task, as our experienced mechanics are well versed in a variety of car repairs and will ensure the issue is fixed properly and your car comes under no further damage from the issue.

However, if you do want to give it a go, here is our definitive guide:

How to Replace a Head Gasket

As you work to reach the head gasket, be sure to mark and index all the parts before removal to ensure you put them back correctly. Ensure you have the service manual to aid with this. As you remove them, check the head and block for flatness, if they are out of specification they will need to be repaired.

Once you have reached the head gasket, prepare the surface carefully and avoid scratching the deck of the block or mounting surface of the head as this can cause issues with the surface such as irregularities and sealing problems further down the road.

Remove build-up in the head bolt or stud holes with a tap or thread chaser, then use compressed air to do a final sweep. Ensure the head bolt torque is correct.

Then prefit the head gasket the right way round, it is not advised to use sealant unless this is a requirement of the manufacturer, they will usually come equipped this way if so and manual will outline the sealant locations and specifications.

Finally, bolt the gasket back, using the correct torque and tightening. Use new bolts if required and coat head bolt threads in engine oil before installing.

Then replace the block and other engine parts in the correct order according to the service manual.