How much to fix a blown head gasket in Australia?

How much does it cost to fix a head gasket?

Well, there are a lot variables at play here, but let’s start with the fine print: You don’t actually fix a head gasket, you replace it. Once it’s broken, there’s no repairing it, you simply swap it for another one. Except it’s not that simple.

Let’s look at what a head gasket does. Nearly all modern engines are made in two main parts. There’s the crankcase which contains the crankshaft, con-rods and pistons, and then there’s the cylinder head which houses the camshafts and valves. Okay, that’s a pretty simplified version, but it holds up.

The thing is, those two main parts are bolted together to complete the engine and make it run. But were they join is precisely where pressurised fuel and air is being ignited to make the engine produce power.

So there’s a huge explosion that has to be contained right at the point where the two engine halves meet. And containing that explosion is the job of the head gasket or, cylinder head gasket to be more precise.

The head gasket is also responsible for keeping oil and coolant separate from each other as they pass from the crankcase to the cylinder head. It also has to seal each cylinder off from its neighbours. Big job, when you think about it.

Think about it like the point at which your garden hose joins the tap. If this joint isn’t sealed properly, water goes everywhere except where it should. So you can see how important a functioning head gasket is to the way an engine works. Or doesn’t.

Like everything in life, the head gasket in an engine can fail. Sometimes this is because of old age, but often it’s because the engine has overheated and the thin, delicate gasket material has failed. At this point, you might have oil and coolant mixing or even the cylinders filling up with coolant because the gasket is no longer doing that sealing job. And that’s when it needs to be replaced.

A good mechanic will be able to perform a couple of simple tests to see if the gasket has failed, but generally if you’re losing coolant and there’s no external leak, or the car is overheating or running poorly and backfiring, then you may be looking at a blown head gasket.

Because of the design of a lot of engines, this is a labour-intensive job. It can take many hours to disassemble the top section of the engine’s valve train and then remove the cylinder head just to get at the failed gasket.

Then, the gasket has to be removed, the crankcase surface it sits on cleaned, the cylinder head checked for straightness (and machined if it’s not straight) and then the whole lot put back together.

Even in the case of an old-school, relatively simple engine like a pushrod engine from the 1960s, this takes many hours, but in a modern car with intricate fuel-injection, double overhead camshafts and maybe even a turbocharger, it takes a lot more labour.

And labour time equals money. Also, this is not exactly a cheap country to have mechanical work done. We’re not saying that mechanics don’t earn their money – because they generally do – but thanks to our generally favourable wage structure, for the average head gasket repair cost Australia is far from a cheap place to have it done.

That’s another reason a blown head gasket repair cost will vary so wildly. Even so, the most basic, simplest gasket repair job is likely to cost at least $1000, because you also need to use new parts.

The head gasket is one of them, obviously, but there are lots of other gasket and seals that must be removed to get to the head gasket, and none of these are generally reusable.

Some engines even have one-use cylinder head bolts that need to be replaced. Just in parts alone, the average head gasket repair cost will be hundreds of dollars.

One of the other major price factors is where you take the car. If you want to use a dealership for this sort of work, you’ll pay more than if you’re using an independent specialist mechanic. And a workshop that knows the make and model in question inside out is probably where you want to be for this type of repair.

Another thing to consider is whether your car is an in-line engine or something with two cylinder heads like a V6, V8 or even a Subaru flat-four engine.

You might find only one head gasket has failed, but it’s actually best practice to replace both gaskets at the same time. You might also find your mechanic recommends replacing the timing chain, tensioners and coolant pump at the same time as insurance against having to open the engine up again later.

Don’t forget to check if there’s a newer head gasket design that is superior to the one that car originally came with. Many Subaru engines, for instance, had gasket problems, but a later gasket design fixed this. It’s a wise upgrade.

The bottom line is you’ll be looking at anywhere from $1000 to, say $5000, for a head gasket replacement. And if it’s a specialist or particularly complex engine the final price might be even higher.

The best advice, of course, is to avoid having to replace the head gasket in the first place. You can do that by servicing the car properly, changing the coolant as recommended and making sure you keep an eye on the temperature gauge to avoid ever overheating the engine.