The cylinder head in your engine closes the combustion chamber from the top. So basically the top of your engine is called the cylinder head while the lower part is the engine block. The space between the cylinder head and the engine block is where the head gasket is located. When your cylinder head is working properly it keeps the cylinders in your engine lubricated so that they maintain their temperature and allow for smooth movement as the valves open and close and the pistons rise and fall during the combustion reaction. One of the most common ways that your cylinder head can fail is by cracking and when that happens you could be looking at a repair bill that may cost you anywhere from $500 to $700.
The cost of repairing your cylinder head can vary greatly based on a number of different factors. Obviously, the make, model, and year of your vehicle will have a lot to do with the cost as will the extent of the damage that your cylinder head has suffered. And of course, if you take your car to a dealership it's going to cost more to repair than it will at a mechanic. And do-it-yourself will be even cheaper still. There are a lot of different factors to take into consideration when it comes to getting your cylinder head repaired.
What Causes a Cracked Cylinder Head?
Even though the cylinder head in your car is meant to handle a lot of stress as well as high temperatures, nothing can last forever and accidents as well as manufacturing defects and other problems can eventually cause the cylinder head to go bad on you. For the most part, these are the most common causes of a cracked cylinder head.
Air in the Cooling System: If you have air in your cooling lines instead of just the water and antifreeze mix that is supposed to be in there, you can end up developing hotspots which cause the engine to heat up far greater than it should. This can be hard to detect because there are times when you can check the temperature of your engine and see that it seems normal, but then the air pocket will go through the system and that will cause it to heat up again. Because of that, the sensors may not be able to detect that you have a problem with your engine overheating and the damage can spiral out of control until the cylinder head cracks.
Overheating: In general, the engine overheating is one of the most obvious reasons for a cylinder head to suffer some damage. An overheating engine is probably the most common cause for cylinder heads to crack. The cylinder head is only meant to handle temperatures within a certain range. The lightweight aluminum alloy that it's made of will break when it's exposed to unusually high temperatures for too long.
Broken Water Pump: Much like the air in your cooling lines, a broken water pump will cause the coolant to not circulate the way it's supposed to. When it breaks, coolant can’t circulate the way it's supposed to and that will lead to your engine drastically overheating.
Coolant Leak: Coolant can leak from a number of places throughout the entire cooling system, but regardless of where the leak happens, if you don't have enough circulating through the lines then the engine is overheating and, as we've seen, that can lead to the cylinder head break.
Bad Thermostat: Your engine should be running somewhere between 190 degrees Fahrenheit and 210 degrees Fahrenheit. The temperature is regulated by a thermostat which either allows the coolant to continue flowing or blocks it off depending on the temperature requirements at the time. If it's not able to function properly, if it gets stuck in one position or the other, it can either cause coolant to flow constantly so your engine can't get up to temperature or it can block the flow so that your engine will overheat which in turn causes cylinder head damage.
Signs and Symptoms of a Cracked Cylinder Head
When you develop a crack in your cylinder head there can be a number of symptoms that manifest to let you know that you have a problem. One of these on its own does not necessarily mean a cracked cylinder head for certain, but if you're experiencing several of these then you definitely want to get it checked out before the situation goes from bad to worse.
Coolant Leaks: As we established with the causes for a cylinder head break, coolant can also be a symptom of the cylinder head breaking. If the crack occurs in the wrong place, you'll end up having coolant leaking out at the same time. That means your engine is going to continue to overheat and the situation can get that much worse. If you're lucky the coolant leak will be visible from the outside of your vehicle, dripping underneath your car. However, some coolant leaks can happen inside the engine and end up filling the combustion chamber instead.
Smoke: If you have a large enough crack in your cylinder head, then you're going to notice some smoke coming out of the back of your car when you start to drive. This is the result of coolant leaking into the combustion chamber and oil dripping into the engine components.
Engine Misfires: When your cylinder head breaks badly enough, you can start experiencing engine misfires. That's caused by the fuel and air mixture not being able to burn properly in the combustion chamber.
Poor Engine Performance: There are a number of things that can cause your engine to perform poorly, and this will likely be one of the earliest symptoms of a crack in your cylinder head. That can make it difficult to diagnose right off the bat since it wouldn't be obviously a cracked cylinder head causing it. Still, when you're noticing a lack of power compared to what you're used to when you're driving it's possible that there's a crack in your cylinder head. This is caused by air escaping from the combustion chamber which throws off the precise ratio of fuel to air that is required for an adequate combustion reaction to take place.
Oil Leaks: The cylinder head contains oil which is necessary to keep your engine lubricated as we mentioned earlier. Obviously if there's a crack in the cylinder head then the oil is not going to be contained properly. You may get a check oil light on your dashboard that shows up with this problem because the oil pressure is going to drop significantly as a result. It's possible you'll be able to see this when you lift the hood and just take a look at your engine. Unfortunately, some oil leaks are not visible from the outside and they remain internal issues in the engine. However, if you do have an internal oil leak and it's going into the combustion chamber, you may get warned of this by a bluish grey smoke coming out of the back of your car that indicates you're burning oil as well as fuel.
Can I Fix My Own Cracked Cylinder Head?
Repairing a cracked cylinder head on your own is not the kind of thing that you can really do at home. In fact, if you were to Google it right now and look for a cracked cylinder head repair DIY what you would likely find is a lot of instructions and videos that tell you how to repair a broken head gasket. That's in the ballpark, you definitely have to remove the cylinder head to replace the gasket, but they're not the same thing. The cylinder head itself will either need to be resurfaced or replaced entirely and that's just not the kind of thing you can easily do at home. At least not in the traditional, mechanical sense. However, as we'll see in a moment, there is something that you can do at home that just might be able to fix a broken or cracked cylinder head provided that the problem isn't so bad that it's essentially irreparable.
While you can't just use a wrench and a pair of pliers to fix a cracked cylinder head, there are some compounds you can buy that can help you get the problem fixed that are fairly affordable as well. Let's take a look at what those are and exactly how they work.
Will Stop Leak Fix a Cracked Cylinder Head?
Even though a mechanic can handle fixing cracks in your cylinder head there is also another option available to you if you're looking to get some cracks in your cylinder head fixed. There are compounds such as Stop Leak or K-Seal that have been designed to fix most cracks or leaks in cylinder heads that result in coolant loss. For the most part all you need to do is shake up a bottle and pour it in. Most of these compounds are made with a substance that is antifreeze compatible and made from something called sodium silicate. It’s used for sealing cracked cylinder heads as well as blown head gaskets and cylinder blocks.
If you choose to go this route you definitely need to check the instructions first on how to use the product. Some of these require that you do a complete engine flush before you add the substance and some of them can only handle very fine breaks and cracks. Extensive damage will be beyond their ability to repair. Additionally, some of them can discolor your antifreeze. That might not be a big deal, but it can throw off your ability to diagnose other problems later on if your antifreeze isn't the colour you were expecting it to be.
Depending on the product, some of them have also had a history of issues blocking cylinder tubes in passages or causing thermostat problems. However, they're also fairly affordable solutions compared to what you might have to pay a mechanic to replace a cylinder head. A bottle of K-Seal on Amazon is only going to cost you about $20. Compared to taking your vehicle to a mechanic, that's a pretty attractive option.
Remember however, this solution will not fix every single cracked cylinder head out there. It really depends on the nature of the damage that yours is suffering, and if the compound you bought is meant to deal with a specific kind of damage that you have. That's why it's important to read the label carefully before you make a purchase of anything as there are a number of different options that you to choose from.
The Bottom Line
A cracked cylinder head is one of the most inconvenient things that any driver can deal with. It's going to severely limit your vehicle's ability to perform the way it's supposed to and will eventually lead to much bigger problems in a very short amount of time. Once you realize that you have a crack in your cylinder head you are on a limited time to get it fixed before the cracks get bigger and the repercussions of that crack become more noticeable. If you're leaking coolant or oil it's only a matter of time before your entire engine overheats. The damage that can be caused when that happens can go from the $500 or so you're going to pay to get the cracked cylinder head fixed to upwards of $4,000 for all the damage that can happen as a result of an overheated engine. We're talking things like bent pistons and valves and warped cylinders or even an entire engine replacement.
For those reasons you never want to sit on a cracked cylinder head for too long. Once you realize it's a problem that you're dealing with, you're going to want to either buy a bottle of the sealant and try to get it fixed yourself or take it into a mechanic to make sure that you get the crack fixed and get back to driving with a properly performing engine once again.