Head Gasket Repair Cost: What UK Drivers Pay

A head gasket replacement typically costs between £600 and £1,500 for most cars in the UK. On more complicated engines, the bill can easily climb beyond £2,000.

The surprising part is that the head gasket itself usually only costs around £30 to £80. Most of what you’re paying for is the labour involved in reaching it, along with machining and replacing other parts that have to come off during the repair.

That’s also why head gasket failure can sometimes spell the end for an older car. If the repair costs £1,000 but the car is only worth £1,500, you have to decide whether fixing it makes financial sense.

Why does a £50 head gasket cost £1,000 to replace?

The head gasket sits between the cylinder head and engine block, so getting to it means taking apart a significant amount of the engine.

The mechanic may need to remove manifolds, timing components and the cylinder head itself. Depending on the engine, this can involve anywhere from eight to fifteen hours of labour.

Once the cylinder head is off, a machine shop will usually check it for damage. It may need pressure testing and skimming to make sure the surface is completely flat before everything goes back together. This can add another £60 to £150 to the bill.

You’ll also need fresh oil and coolant, as well as new cylinder head bolts on engines that use single-use stretch bolts.

Depending on the engine and its maintenance history, it can also make sense to replace the cambelt while everything is apart. The labour involved in accessing it has already been done, so replacing an ageing belt at the same time could save money later.

All of this means labour and additional work make up the vast majority of a head gasket repair bill.

What are the symptoms of head gasket failure?

A failing head gasket can cause several different symptoms. Look out for:

• White exhaust smoke with a sweet smell: This can indicate that the engine is burning coolant.

• Creamy or mayonnaise-like sludge under the oil filler cap: Coolant mixing with oil can cause this, although condensation can create a similar appearance.

• Coolant levels dropping without an obvious leak: If you’re regularly topping up the coolant but can’t see where it’s going, it needs investigating.

• Bubbles in the coolant expansion tank: Combustion gases entering the cooling system can cause bubbling.

• Overheating: Head gasket problems can cause the engine temperature to rise, particularly under heavier loads.

• Rough running or misfires: You might notice this most when starting the engine from cold.

It’s important not to diagnose a failed head gasket from one symptom alone. For example, creamy residue under the oil cap is common on cars that mainly make short journeys and can simply come from condensation.

A garage can carry out tests to confirm what’s actually happening. A combustion gas test, often called a sniff test, checks for exhaust gases in the cooling system and can help identify a head gasket problem.

Getting a proper diagnosis before agreeing to a major repair could save you a lot of money.

Should you repair the head gasket or replace the engine?

This depends on the car, its condition and how badly the engine has overheated.

Start by looking at what the car is actually worth. Spending £900 replacing the head gasket on an otherwise reliable £3,000 car might make sense. Spending the same amount on a £1,200 car that already needs several other expensive repairs is harder to justify.

You also need to consider whether the head gasket is the only problem.

Severe overheating can warp the cylinder head or cause additional internal engine damage. In some cases, the garage won’t know the full extent of the damage until it starts taking the engine apart.

Before approving the work, ask the garage for both the expected price and a realistic worst-case figure.

Sometimes fitting a good used or reconditioned engine can work out cheaper than rebuilding the existing one. On a particularly old or low-value car, selling it as a non-runner or for parts might make more financial sense.

A good garage should explain these options rather than automatically pushing you towards the most expensive repair.

Do head gasket sealants actually work?

Head gasket sealants are often marketed as a cheap alternative to a full repair, but they’re not a permanent fix.

In some cases, a sealant may temporarily slow a small coolant leak. That might be useful if you have an old car that’s nearing the end of its life and you simply need to keep it going for a little longer.

However, sealants can’t properly repair significant head gasket damage or replace a failed gasket.

There’s also a risk that some products can cause blockages elsewhere in the cooling system, including the radiator or heater matrix.

If you’re planning to keep the car, getting the problem properly diagnosed and repaired is a much better approach than relying on a bottle of sealant.

How can you prevent head gasket failure?

Overheating is one of the biggest causes of head gasket problems, so looking after your cooling system can make a huge difference.

Check your coolant level regularly and don’t ignore unexplained drops. If you’re constantly topping it up, the coolant is going somewhere and you need to find out where.

Always use the correct type of coolant for your car and replace it according to the manufacturer’s maintenance schedule.

Most importantly, pay attention to the temperature gauge. If your engine starts getting unusually hot, pull over somewhere safe and switch it off rather than trying to make it home.

Continuing to drive an overheating engine can turn a relatively inexpensive cooling system repair into a four-figure engine repair.

Problems with thermostats, cooling fans, radiators and coolant leaks are often much cheaper to fix when you catch them early.

Head gasket FAQs

Can I drive with a failed head gasket?

It’s best to avoid driving with a suspected failed head gasket until you know how serious the problem is.

Continuing to drive can cause the engine to overheat, potentially warping the cylinder head and causing much more expensive damage.

If the temperature gauge starts climbing or you receive an overheating warning, stop somewhere safe and switch the engine off.

How long does a head gasket repair take?

A head gasket replacement can take several days.

The mechanical work itself involves many hours of labour, and the cylinder head may also need to go to a machine shop for pressure testing or skimming.

As a rough guide, expect the car to be at the garage for around two to four days, although complicated repairs can take longer.

What causes head gaskets to fail?

Overheating is one of the most common causes.

Low coolant, a leaking cooling system, failed thermostat, faulty cooling fan or radiator problem can all cause temperatures to climb high enough to damage the gasket.

Age and engine design can also play a part, with some engines having a stronger reputation for head gasket problems than others.

Can a replacement head gasket fail again?

Yes, but a properly completed repair should last if the garage also identifies and fixes whatever caused the original failure.

Simply replacing the gasket without addressing an overheating problem could leave you in exactly the same position again.

The garage should also check that the cylinder head hasn’t warped before putting the engine back together.

Is head gasket failure an MOT failure?

Not directly. The MOT doesn’t specifically test whether your head gasket is working correctly.

However, problems caused by a failed gasket could affect the test. Excessive exhaust smoke, emissions problems or significant fluid leaks may result in an MOT failure.

In reality, if you suspect head gasket failure, getting the engine diagnosed should be the priority rather than waiting for the next MOT.

Download Rooster and start saving.