Head Gasket repair & replacement made easy

What does a head gasket do?

The head gasket on an engine provides the seal between the engine block and the cylinder head to maintain compression and prevent the engine oil mixing with the coolant.

How does the cylinder head gasket work and what are the components?

Cylinder head gaskets are typically made from multiple thin layers, normally steel and elastomer, known as multi-layer steel (MLS) gaskets. Other substances are being used, but this is the most common.

The cylinder head gasket is positioned precisely between the faces of the top of the cylinder black and the base of the cylinder head. The cylinder head is then tightened down onto the block with cylinder head bolts which are torqued to a specific force depicted by the manufacturer. Once this is done, the gasket should seal the top and bottom halves of the engine together.

How do you know when there is something wrong with your cylinder head gasket?

In most cases the symptoms of a cylinder head gasket are pretty apparent, some however take a little know how and some tools to confirm. Typical symptoms though are;

• A cream-like colour and consistency in the oil (usually seen on the engine oil dipstick) or in the cooling system header tank.
• Coolant overflowing out of the cooling system header tank.
• An unexplained loss of coolant.
• Difficulty in starting the engine.
• Evidence of exhaust gasses in the cooling system.
• Poor engine compression.

When should you consider having the cylinder head gasket replaced?

As soon as the efficiency of the cylinder head gasket is compromised, the gasket needs to be replaced prior to the engine being used again.

If the oil and coolant has mixed, the lubricating quality of the oil is non existent and its ability to preserve the internal parts of the engine is lost. Continuing to run the engine will ultimately end in severed damage to it. The same goes for the cooling system, with the water channels and radiators becoming blocked.
Quite simply, it will not get better, only worse.

There are certain products on the market that claim to resolve a cylinder head gasket leak. Whilst in theory they could work, they are not a solution and can add to the issues further down the line and make the correct repair more expensive.

If the coolant is being lost, the engine will overheat. This is not good for the metal components of the engine and the aluminium cylinder head could be damaged beyond repair.

How common is a cylinder head gasket replacement?

Whilst cylinder head gasket replacement is not as common as it was 20 or so years ago, it still occurs. Certain engines are prone to it happening and the use of smaller engines with turbochargers puts increased pressure on the gaskets.

How can I extend the life of my cylinder head gasket?

Physically there is nothing you can do to maintain it, however, continually pushing the engine beyond its capabilities will of course cause more wear and tear on all components, including the head gasket.

Overheating through faulty cooling system components or coolant loss can end up in a failed head gasket. So check your levels regularly and if there is any failing component such as a thermostat or water pump, get these repaired before it causes bigger issues.

What happens during a cylinder head gasket replacement?

There are differences between engines on the exact process and components, but the typical engine will require most of the following basics to be done

• Mechanic will check that the head gasket is faulty.
• The engine will be drained of oil and coolant.
• Components will be removed to allow access to the rocker cover and ultimately, the cylinder head bolts.
• The engine timing will be locked in place using specifically designed pins and locking tools.
• The timing belt will be removed, or the timing chain loosened off and moved off the camshaft sprockets.
• The cylinder head will then be undone in a specific sequence.
• Once all the bolts are out, the cylinder head will be removed and the surface of the engine block and cylinder head will be cleaned of all residue of the old gasket.
• In the case of the majority of cylinder heads, it will need to be pressure tested to ensure it’s structure is sound and then go through a process called skimming. This process ensures that the surface that the new gasket will come into contact with is perfectly flat and clean.
• Once the mechanic has completed the work on the components, the engine is reassembled with a new cylinder head gasket.
• If the engine’s camshaft(s) are driven by a timing belt, this belt will be renewed along with a new water pump if it is on the timing belt circuit.
• Once the engine is back together, the cooling system will be refilled and the oil replenished along with a new filter.
• If the oil has become contaminated with the coolant, an additional oil flush may be required and likewise, if the cooling system has become contaminated, the cooling system will be flushed.
• Once everything is back together, the mechanic will run the engine.
• Finally a road test will ensure that everything works as it should when the engine comes up to temperature and finally any error codes present will be cleared down and re-checked.

As we mentioned previously, this is not a full exhaustive list of what will be done as each engine has its own requirements.

How much does a cylinder head gasket replacement cost?

The cost of a cylinder head gasket replacement depends on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your cylinder head gasket replaced by ClickMechanic, by selecting your car at the top of this page!

One final note, if you are comparing quotations, please ensure that the quotes you have all include the cylinder head pressure test and skimming. Not all companies will include this up front, they will add it to the bill after advising you that it needs to be done once they have commenced the work.