
Welcome to our comprehensive guide on cylinder head cracks and how to fix a leaking cylinder head. If you’re experiencing issues with your engine, such as loss of power or overheating, it could be a result of a cracked cylinder head.
In this guide, we’ll cover everything you need to know about cylinder head cracks and provide professional tips on repairing cracked cylinder heads and detecting cylinder head cracks.
First, we’ll explore the symptoms and causes of cylinder head cracks, so you can accurately diagnose the problem. We’ll also provide guidance on identifying a leaking cylinder head through common signs and leak tests. Once you’ve diagnosed a cracked cylinder head, we’ll provide step-by-step instructions on how to repair it, including the best repair methods and tools needed.

Even if you’re not experiencing cylinder head issues right now, it’s important to understand the preventive measures and regular maintenance required to avoid cylinder head cracks in the future. We’ll cover these preventive measures and recommend the best maintenance practices for your cylinder head.
By following the guidance in this guide, you’ll be able to effectively address cylinder head issues and keep your engine running smoothly. So, let’s dive into the topic of cylinder head cracks and learn how to fix a leaking cylinder head.
Understanding Cylinder Head Cracks
Your car’s engine is a complex machine that relies on many different components to function correctly. One of the most critical parts of your engine is the cylinder head, which sits above the cylinders and helps to seal them. Unfortunately, cylinder head cracks can occur, causing leaks and other engine problems. In this section, we will explore cylinder head cracks in detail, including their symptoms and causes, and how to repair them.
What Are Cylinder Head Cracks?
Cylinder head cracks are fractures or breaks in the cylinder head’s metal structure. These cracks can occur due to a variety of factors, including overheating, age, or improper installation.
What Are the Symptoms of Cylinder Head Cracks?
One of the most common symptoms of cylinder head cracks is oil leaking from the engine. Other symptoms may include white smoke coming from the exhaust, loss of power, and a decrease in fuel efficiency.
What Causes Cylinder Head Cracks?
There are several potential causes of cylinder head cracks. These can include overheating, which can cause the metal to expand and contract rapidly, leading to fractures. Other causes may include improper installation, age-related wear and tear, or issues with the engine’s cooling system.
Table: Comparing Cylinder Head Crack Causes
Cylinder Head Crack Causes | Description |
---|---|
Overheating | Causes rapid expansion and contraction of the metal, leading to fractures |
Improper Installation | May put undue stress on the cylinder head, leading to cracks over time |
Age-Related Wear and Tear | The metal may weaken and become more prone to cracks as the engine ages |
Cooling System Issues | Can cause the engine to overheat and put stress on the cylinder head |
As you can see, there are several potential causes of cylinder head cracks. Understanding the root cause of the problem is crucial for addressing the issue effectively and preventing it from happening in the future. In the next section, we will discuss how to identify a leaking cylinder head and diagnose cylinder head cracks.
Identifying a Leaking Cylinder Head
If you suspect that your cylinder head is leaking, it’s crucial to identify the problem as soon as possible. Ignoring this issue can lead to severe engine damage, which can be expensive to repair. Below are some common signs of a leaking cylinder head:
- White smoke coming from the exhaust
- Engine overheating
- Coolant loss
- Milky oil
- Decreased engine performance
If you notice any of these symptoms, it’s essential to check your cylinder head for leaks. You can perform a basic leak test to determine if your cylinder head is leaking. Here’s how:
- Make sure that your engine is cold and turned off
- Remove the radiator cap
- Start your engine and let it idle
- Observe the coolant level in the radiator
- If the coolant level drops and bubbles appear in the radiator, it’s likely that your cylinder head is leaking
Once you have determined that your cylinder head is leaking, it’s important to take immediate action. In the next section, we will discuss how to fix a leaking cylinder head.
Diagnosing Cylinder Head Cracks
Diagnosing cylinder head cracks can be tricky, as the symptoms may not always be immediately apparent. However, there are several signs that can indicate a crack in your cylinder head.
Visual Inspection
The first step in detecting cylinder head cracks is performing a visual inspection of the engine. Look for any visible cracks or damage to the cylinder head itself. You may also notice damage to the gasket, which can indicate a crack in the cylinder head.
Leaking Coolant
If you notice a loss of coolant without any visible leaks, it could be a sign of a cylinder head crack. The coolant may be leaking into the combustion chamber or mixing with the engine oil, so be sure to check your oil to see if it appears milky or foamy.
Overheating
An overheating engine can also be a symptom of a cylinder head crack. If the crack is allowing coolant to leak into the combustion chamber, it can cause the engine to overheat and potentially cause further damage.
Testing Equipment
There are also specialized testing kits available that can help you detect cylinder head cracks. These kits typically involve pressurizing the cooling system and looking for drops in pressure, which can indicate a leak. You can also use dye to help identify any leaks.
By paying attention to these symptoms and performing a thorough inspection of your engine, you can accurately detect and diagnose cylinder head cracks. Once you have identified the issue, you can move on to repairing the crack.
Causes of Cylinder Head Cracks
Understanding the causes of cylinder head cracks is crucial for preventing future issues. The following are some of the common causes of cylinder head cracks:
- Overheating: The most common cause of cylinder head cracks is overheating. When an engine overheats, the aluminum head expands more than the cast iron block, causing the head to warp and crack. Overheating can be caused by several things, including a malfunctioning cooling system, a clogged radiator, a faulty water pump, or a stuck thermostat.
- Cooling System Problems: A damaged or worn-out cooling system can also lead to cylinder head cracks. Any restrictions or blockages in the system can cause hot spots and uneven cooling, which can result in warping and cracking.
- Improper Installation: Poor installation techniques can also cause cylinder head cracks. Improper torquing of the head bolts, using incorrect gaskets, or not properly cleaning the gasket surfaces before installation can lead to leaks and eventually cause cracks.
- Manufacturing Defects: Although rare, manufacturing defects can also cause cylinder head cracks. Porosity in the metal or incomplete casting can create weak spots that can eventually crack under pressure.
By identifying the root causes, you can take proactive steps to avoid cylinder head cracks in the future.
Repairing Cracked Cylinder Heads
If you’ve diagnosed a cracked cylinder head, it’s time to start thinking about repairing it. While there are temporary fixes available, a permanent repair is the best option for ensuring that your engine runs smoothly. Here are some steps to follow:
- Remove the cylinder head: The first step is to remove the cylinder head from the engine. This can be a complex process, so be sure to follow the manufacturer’s instructions carefully.
- Assess the damage: Once you’ve removed the cylinder head, you’ll need to assess the damage. Depending on the severity of the crack, you may need to replace the entire cylinder head.
- Clean the cylinder head: Before you can repair the crack, you’ll need to thoroughly clean the cylinder head. Use a degreaser and a wire brush to remove any dirt, grime, or corrosion.
- Apply the epoxy: Once the cylinder head is clean, you can apply the epoxy. Be sure to follow the manufacturer’s instructions carefully, and make sure the epoxy you use is designed specifically for cylinder head repairs.
- Let the epoxy cure: After applying the epoxy, you’ll need to let it cure for the recommended amount of time. This can take several hours or even overnight, so be patient.
- Reinstall the cylinder head: Once the epoxy has cured, you can reinstall the cylinder head. Again, be sure to follow the manufacturer’s instructions carefully.
- Test the repair: Finally, it’s important to test the repair to make sure it’s holding up properly. Perform a leak-down test or a compression test to verify that there are no leaks or other issues.
While repairing a cracked cylinder head can be a complex process, it’s not impossible. With the right tools, materials, and instructions, you can repair the crack and get your engine back in top shape.
Temporary Fixes for Cylinder Head Cracks
If you need a quick solution for your cylinder head cracks, there are a few temporary fixes that can help buy you some time. Keep in mind, these are not permanent solutions and should only be used as a last resort.
Sealants and Adhesives
One option is to use sealants and adhesives to temporarily patch up the cracks. These products can help prevent further leaks and buy you some time until you can perform a more permanent repair. Be sure to choose a product that is specifically designed for engine repairs and closely follow the manufacturer’s instructions.
To use a sealant or adhesive, first clean the area around the crack thoroughly. Apply the product directly to the crack and surrounding area, covering it completely. Allow the product to cure for the recommended amount of time before refilling the coolant and testing for leaks.
Steel Epoxy
Another temporary fix is to use steel epoxy. This two-part epoxy can be mixed and applied directly to the crack, where it will harden and provide a temporary seal. Again, be sure to choose a product that is appropriate for engine repairs and follow the manufacturer’s instructions carefully.
Steel epoxy can be applied by mixing the two parts together, and then directly applying it to the crack and surrounding area. Use a putty knife or similar tool to spread the epoxy evenly over the area. Allow the epoxy to cure for the recommended amount of time before refilling the coolant and testing for leaks.

While these temporary fixes can help stop the immediate problem of a leaking cylinder head, they are not meant to be a long-term solution. Eventually, you will need to perform a more permanent repair to prevent future issues.
Professional Cylinder Head Crack Repair
If you are not confident in repairing a cracked cylinder head yourself, it’s best to seek professional assistance. A skilled mechanic or engine builder will have the expertise and specialized tools required to ensure a successful repair.
Professional cylinder head crack repair typically involves the following steps:
Inspection and Diagnosis
The first step in professional cylinder head crack repair is a thorough inspection and diagnosis of the issue. The mechanic will look for cracks and other damage, and evaluate the extent of the damage to determine whether repair or replacement is necessary.
Pressure Testing
Next, the mechanic will perform a pressure test to identify any leaks or other issues. This test can help pinpoint the specific areas that need repair and ensure that the cylinder head is functioning properly before any repair work begins.
Machining and Repair
The next step is to machine and repair the cylinder head. This process involves removing any cracks and other damage, as well as reconditioning or replacing any parts that are worn or damaged beyond repair.
There are several techniques for repairing cracked cylinder heads, including welding, pinning, and stitching. A skilled mechanic will be able to determine the best repair method based on the extent and location of the damage.
Reassembly and Testing
Once the cylinder head has been repaired, the mechanic will reassemble the engine and conduct a final testing to ensure that the cylinder head is functioning properly.
Professional cylinder head crack repair can be expensive, but it is often the best option for ensuring a successful repair and avoiding future issues. It is important to choose a reputable mechanic or engine builder with experience in cylinder head repair to ensure the best possible outcome.
Whether you decide to tackle the repair yourself or seek professional assistance, it’s important to address cylinder head cracks as soon as possible to avoid more significant engine damage.
Preventing Cylinder Head Cracks
If you want to avoid dealing with cylinder head cracks and repairing cracked cylinder heads, there are several preventive measures you can take. By following these tips, you can ensure that your cylinder head stays in good condition and your engine runs smoothly:
Perform Regular Maintenance
Regular maintenance is the key to preventing cylinder head cracks. Be sure to follow the manufacturer’s recommended maintenance schedule, including regular oil changes and coolant flushes. Checking for leaks and maintaining proper torque settings can also help prevent cylinder head cracks.
Monitor Cooling System
The cooling system is vital to keeping your engine at the proper temperature and preventing overheating, which can cause cylinder head cracks. Regularly check the level and quality of your coolant, and ensure that your radiator cap and thermostat are functioning correctly.
Proper Installation
Make sure that your cylinder head is installed correctly. Improper installation can cause stress on the cylinder head, leading to cracks. If you are unsure how to install a cylinder head correctly, seek the assistance of a professional.
Avoid Overheating
Overheating is one of the primary causes of cylinder head cracks. Be sure to monitor your engine’s temperature and avoid driving with an overheated engine. If your engine is overheating, take immediate action to determine and fix the cause.
Monitor Engine Performance
If your engine is not running smoothly, it can put stress on your cylinder head and other engine components. Be sure to monitor your engine’s performance, including unusual vibrations, sounds, or loss of power. If you notice any issues, address them promptly to avoid further damage to your engine.
Use High-Quality Parts
Using high-quality parts in your engine can help prevent cylinder head cracks and other issues. Be sure to use parts that meet or exceed the manufacturer’s specifications, and avoid using cheap or inferior parts.
By following these preventive measures, you can minimize the risk of cylinder head cracks and ensure that your engine stays in good condition. However, if you do encounter a cracked cylinder head, follow the tips provided in this guide for repairing cracked cylinder heads.
Regular Maintenance for Cylinder Heads
Regular maintenance is essential for keeping your cylinder head in good shape and preventing issues such as cracks and leaks. By following these recommended maintenance practices, you can help extend the life of your engine and avoid costly repairs.
Performing Regular Coolant Flushes
One of the most important maintenance tasks for your cylinder head is performing regular coolant flushes. Over time, coolant can become contaminated with dirt and debris, which can cause corrosion and other damage to your engine. By flushing the coolant system regularly, you can help prevent these issues and keep your engine running smoothly. It’s recommended to flush the coolant system every two years or as recommended by the manufacturer.
Checking for Leaks
Regularly checking your engine for leaks is another important maintenance task for your cylinder head. Leaks can be caused by a variety of factors, such as worn gaskets or loose bolts. By catching leaks early, you can prevent further damage to your engine. Make sure to check for leaks regularly, particularly after long trips or periods of heavy use.
Maintaining Proper Torque Settings
Ensuring that all bolts are tightened to the proper torque settings is essential for preventing damage to your cylinder head. Over-tightened bolts can lead to stress and cracking, while under-tightened bolts can cause leaks and other issues. Always refer to the manufacturer’s specifications and use a torque wrench to properly tighten all bolts.
Keeping the Engine Clean
Maintaining a clean engine can help prevent issues such as corrosion and contamination. Regularly cleaning your engine can also help you spot potential issues early on. Make sure to use a gentle cleaning solution and avoid getting water or other liquids on electrical components.
By following these recommended maintenance practices, you can help prevent cylinder head cracks and other issues. If you do experience a cracked cylinder head or other problems, it’s important to address them as soon as possible. Follow the repair and prevention tips we’ve provided to keep your engine running smoothly for years to come.
Troubleshooting Cylinder Head Issues
If you are experiencing issues with your cylinder head, it’s essential to troubleshoot the problem accurately to find the appropriate solution. In this section, we will explore common cylinder head issues and provide guidance on how to troubleshoot them.
Valve Issues
Valve issues are a common problem with cylinder heads and can cause a range of symptoms, including misfires, rough idling, and reduced power. If you suspect valve issues, start by checking the valve clearance and adjusting it if necessary. If the valve clearance is correct, then you may need to inspect the valves themselves for any damage or wear. Use a valve spring compressor to remove the valves and check them for any signs of wear or damage. If the valves are damaged, they will need to be replaced.
Gasket Failures
Gasket failures can cause oil leaks, coolant leaks, and even combustion leaks in severe cases. If you suspect a gasket failure, start by checking for external leaks. Use a flashlight to inspect the engine for any signs of leaks around the cylinder head. If you don’t find any external leaks, perform a combustion leak test using a tester kit. This will help you determine if there is a combustion leak, which could be caused by a blown head gasket or a cracked cylinder head.
Warping
Cylinder head warping can cause a range of problems, including coolant leaks, reduced power, and poor fuel economy. If you suspect cylinder head warping, start by inspecting the head surface for any signs of warping using a straight edge and feeler gauge. If you detect any warping, take the cylinder head to a machine shop for resurfacing or replacement.
FAQ
What are cylinder head cracks?
Cylinder head cracks refer to fractures or breaks in the cylinder head of an engine. These cracks can cause various issues, including coolant leaks, loss of compression, and engine overheating.
What are the symptoms of cylinder head cracks?
Some common symptoms of cylinder head cracks include white smoke from the exhaust, engine misfires, engine overheating, coolant leaks, and oil contamination.
What causes cylinder head cracks?
Cylinder head cracks can be caused by factors such as overheating, cooling system problems, improper installation, and excessive pressure or stress on the cylinder head.
How do you identify a leaking cylinder head?
To identify a leaking cylinder head, look out for signs such as coolant leaks, white smoke from the exhaust, low coolant levels, and engine overheating. Performing a basic leak test can also help determine if there is a leak in the cylinder head.
How do you diagnose cylinder head cracks?
Diagnosing cylinder head cracks can be done by examining the symptoms, performing a cylinder leak-down test, using a pressure tester to check for leaks, and inspecting the cylinder head for visible cracks or damage.
Can cylinder head cracks be repaired?
Yes, cylinder head cracks can be repaired. The repair process involves removing the cylinder head, performing a thorough inspection, cleaning the cracks, and using professional repair techniques such as welding, stitching, or epoxy to fix the cracks.
Are there temporary fixes for cylinder head cracks?
While a permanent repair is recommended, there are temporary fixes available for cylinder head cracks. These include the use of sealants or adhesives to temporarily stop coolant leaks and reduce the impact of the crack until a permanent repair can be arranged.
Should I attempt to repair a cracked cylinder head myself?
Repairing a cracked cylinder head requires expertise and specific tools. If you are not comfortable or confident in performing the repair yourself, it is best to seek professional assistance to ensure a proper and long-lasting repair.
How can I prevent cylinder head cracks?
Preventing cylinder head cracks involves regular maintenance practices such as maintaining proper coolant levels, ensuring the cooling system is in good working condition, avoiding overheating, and following proper installation techniques when replacing the cylinder head.
What maintenance should I perform on my cylinder head?
Regular maintenance for cylinder heads includes performing coolant flushes, checking for coolant leaks, maintaining proper torque settings for cylinder head bolts, and addressing any signs of issues promptly.
What other cylinder head issues should I be aware of?
In addition to cracks, cylinder heads can also experience issues such as valve problems, gasket failures, and warping. Understanding these potential issues will help you troubleshoot and address any problems that may arise.
Conclusion
Cylinder head cracks can be a frustrating and costly problem for any engine owner. However, with the guidance provided in this comprehensive guide, you can effectively diagnose, repair, and prevent cylinder head cracks.
Remember to regularly maintain your cylinder head and engine to minimize the risk of cracks and leaks. If you do encounter a cylinder head crack, follow the step-by-step instructions for repairing cracked cylinder heads or seek professional assistance if needed. And for any other cylinder head issues, such as valve problems or gasket failures, refer to the troubleshooting section for guidance.
By taking the necessary preventive measures and timely repairs, you can keep your engine running smoothly and avoid the frustration and expense of cylinder head cracks. Here’s to a well-maintained and leak-free engine!