As a vehicle owner, you need to be very aware of all the things that could go wrong with your engine. To help you out, this post by Syntex Lubricants in Austin & Kyle, TX will give you an overview of everything there is to know about a cracked engine block.

A cracked engine block is one of the worst problems a vehicle can experience. As the core structure of the engine, the block houses the cylinders, pistons, and other key components. When a crack develops, it can lead to severe consequences. Let’s dive into everything you need to know about this serious engine problem.

Call Syntex Lubricants in Austin & Kyle, TX at (800) 890-0220 or visit AMSOIL's online shop to buy the right products for your engine's maintenance.

What Is an Engine Block?

The engine block is the main part of your engine, usually made of cast iron or aluminum. It contains the cylinders, which house the pistons that generate power. Inside the block, there are also passageways for coolant and oil, which help regulate engine temperature and reduce friction.

Since the engine block holds everything together and allows the engine to function, any damage to it can cause significant performance problems.

What Causes an Engine Block to Crack?

1. Overheating

One of the biggest causes of a cracked block is extreme engine overheating. When an engine gets too hot, the metal expands. If it expands too much, it can crack under pressure. Low coolant levels, a faulty thermostat, a bad water pump, or a clogged radiator can all lead to overheating.

2. Freezing Temperatures

Cold weather can also cause cracks in an engine block. If the coolant inside the engine freezes, it expands, putting pressure on the metal. If this pressure becomes too great, the engine block can crack. Using the correct antifreeze-to-water ratio in your coolant system helps prevent this problem.

3. Manufacturing Defects

Although rare, some engine blocks have structural weaknesses from the factory. Poor casting or low-quality materials can make a block more prone to cracking over time.

4. Excessive Stress or Towing

Pushing your engine too hard—such as towing heavy loads, aggressive driving, or running at high RPMs for extended periods—can create excessive stress. Over time, this stress can cause small fractures in the block that eventually grow into larger cracks.

Signs of a Cracked Engine Block

A cracked engine block often starts with small, subtle signs before leading to major engine failure.

1. Overheating Engine

If coolant is leaking due to a crack, your engine may overheat frequently. Even if you top off the coolant, the temperature may still rise abnormally.

2. Coolant or Oil Leaks

A visible coolant or oil leak under your car could mean a cracked block. Look for green, orange, or blue coolant or dark brown engine oil pooling under the vehicle.

3. White Smoke from the Exhaust

If coolant is leaking into the combustion chamber, it can burn and produce thick white smoke from the tailpipe. This is a major warning sign of internal engine damage.

4. Milky or Foamy Oil

A crack in the engine block can allow coolant and oil to mix. If you check your dipstick and notice milky or foamy oil, it means coolant has contaminated the oil supply, which can lead to severe engine damage.

5. Loss of Engine Power

A cracked block can cause a loss of compression, making your engine run poorly, misfire, or stall. If your car suddenly lacks power, a cracked block could be the culprit.

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Can a Cracked Engine Block Be Fixed?

Fixing a cracked engine block depends on the size and location of the crack.

1. Engine Block Sealant (Temporary Fix)

For small cracks, some sealants can temporarily stop leaks. However, this is only a short-term solution and won’t work for major damage.

2. Welding or Machining (Possible but Expensive)

A skilled mechanic may be able to weld or re-machine an engine block, but this depends on the material (cast iron vs. aluminum) and severity of the crack. Welding an engine block is complex and costly.

3. Engine Replacement (Most Reliable Option)

In many cases, replacing the entire engine is the only viable solution. While expensive, it’s often more reliable than attempting to repair a severely cracked block.

How to Prevent a Cracked Engine Block

While not every crack can be prevented, taking care of your engine can greatly reduce the risk:

• Monitor Coolant Levels – Always check and maintain proper coolant levels to prevent overheating.
• Use the Right Coolant Mix – In cold climates, ensure you’re using the correct antifreeze-to-water ratio to prevent freezing.
• Address Overheating Immediately – If your car starts overheating, pull over and shut it off before permanent damage occurs.
• Avoid Heavy Stress – Don’t overload your engine with excessive towing or high-RPM driving.

Call Syntex Lubricants in Austin & Kyle, TX at (800) 890-0220 or visit AMSOIL's online shop to save time and money on your engine's maintenance.