You’re driving along, and suddenly, your check engine light comes on. The power may decrease. You may lose power altogether. You might see smoke. Or none of the above. Still, the engine light is worrisome. What could it be?

While blowing a head gasket isn’t a common, everyday occurrence, for some makes and models, it’s more commonplace than others.

What is a head gasket?

First of all, let’s talk about what a head gasket is. It’s a simple mechanical seal that separates your engine block and your cylinder head. Every car has one, but they do change shape and size based on manufacturers’ design.

The head gasket has two primary purposes:

1. It seals the combustion chamber, ensuring you have a properly functioning engine

2. It also separates the different liquids flowing into the engine block. Fuel, oil, and coolant all serve a purpose, but it’s important to keep them separate to function properly.

Sounds like a tough job, right? It is. That’s why you could argue that the head gasket is one of the most important parts of your engine block.

Because a head gasket is part of the combustion process, it must be tough. A lot of pressure occurs as your car burns fuel and releases energy. It can’t melt, change, or weaken under pressure. That’s why most head gaskets today are made from a variety of composite materials, steel, or even copper with high-performance vehicles.

Why head gaskets blow

A head gasket’s job is to create a seal between the engine block and the cylinder head. Because it comes in contact with extremely hot, high pressure combustion, as well as varying temperatures from the coolant, it has to perform well under extremes. This can create a lot of tension over time. Eventually, the head gasket can develop a leak. It doesn’t matter the make or model of your car, or how well you care for it. The pressure can eventually build.

What’s more, it’s not a part you can easily see, which means it could very well have a problem and continue operating that way for a long time. Until it eventually blows.

Since you can’t readily see it, it’s important to understand the warning signals so you can accurately diagnose the problem before it turns into something significant.

Things to watch for that signal a blown head gasket

Because a head gasket’s job is critical, it’s crucial to replace it at the first sign something is wrong. Watch for these signs, and see your mechanic right away.

An overheating engine – If you watch the temperature gauge on your vehicle, you might start to see temperatures moving up. That’s because the coolant is no longer doing its job. If the coolant leaks or burns away, there isn’t enough left in the engine to cool it properly. Eventually, the engine overheats. Hopefully, the warning light on the dashboard lights and gives you enough time to turn off your vehicle and fix your car before further damage can occur.

A poorly operating engine – Because head gaskets don’t always go from working to broken overnight, you’ll often see engine performance declining first. Watch for things like decreased power or a rough idle. This can signal fuel is reaching the combustion chamber and isn’t firing correctly.

Low coolant – A part of your maintenance routine should be to check your fluid levels. If your coolant starts to lower without any visible signs of a leak, it could be a problem with your head gasket.

White, milky oil – Remember, your head gasket separates the different fluids as they enter the engine block. Even a small leak can allow these fluids to intermix. If your oil starts to look white or milky, it’s been compromised. Coolant is leaking in and making the lubricating process less effective.

White smoke – As the vehicle runs, you might start to notice white smoke flowing from the tailpipe. Leaking coolant produces steam. It’s water and burned glycol flowing from the combustion chamber. Keep in mind that other than seeing the white smoke, your car may appear to operate normally until the coolant is all gone.

Leaking coolant – If the coolant begins leaking below the exhaust manifold, you’ll see a small puddle forming on the ground. This is the easiest way to diagnose a problem with your head gasket. Always look at the ground of your regular parking spaces to keep an eye out for potential problems.

Bubbles in the radiator or overflow tank – If the head gasket between the coolant line and the combustion chamber is compromised, it can allow air to push into the system. While bubbles might not seem like a bad thing, if allowed to continue, they eventually can form a large pocket of air and stop the coolant from flowing. This can stop your car in its tracks.

Spark plug problems – If coolant flows into the combustion chamber, it can cause problems with the spark plugs. If you notice your car misfiring, this could be one of the reasons.

Is it okay to drive with a blown head gasket?

As you can tell from the above symptoms, it can be quite tricky at times to determine if you do have a blown head gasket. Therefore, you might drive with it for quite a while.

The key is in watching for the symptoms and fix problems before they are allowed to fester and grow. It’s easier and cheaper to fix minor issues than it is to do a complete system overhaul.

Pay attention to how your car operates. You can even keep a log as your car ages.

If there are problems with the head gasket, hot gases and liquids, and cold coolant are moving through the mechanics and can quickly erode or warp the metal of the engine block. The longer it goes unnoticed, the more damage can occur. That leaves you with costly repair bills when you do finally bring your car in for servicing.

Are there ways to prevent a head gasket from blowing? 

One of the simplest ways to prevent the head gasket from blowing is to ensure your engine doesn’t overheat. Frequent maintenance can help with that. Regular oil changes will ensure your system always has fresh oil and is properly topped off. Checking your coolant levels will ensure it’s properly filled as well. Watch for evidence of leaks as well.

Try to keep from pushing your car on a regular basis. Avoid aggressive driving. This increases RPMs and increases stress on your engine. Likewise, if your car has a turbocharger or supercharger, keep the combustion pressures as low as possible. More stress means more heat, which can push the deterioration process of different parts.

Have you ever experienced a blown head gasket?