Think You Got Engine Block Cracks? 5 Signs You Can’t miss

When it comes to the most essential components of any vehicle, nothing comes before the engine. It is the one thing that must always be in the best condition. 

Any flaws can significantly affect the performance or efficiency of your car and in some cases become extremely dangerous.

Engine blocks are the primary foundation where all the components rest and are prone to damage. 

The following text takes a look at some of the most prevalent methods of checking that damage and preventing complete engine failure.

5 Giveaway Signs of a Cracked Engine Block

It’s highly unlikely that you won’t notice a cracked engine block because it’s hard to miss and usually the last thing to get affected. Generally, the cylinder heads are the first engine component to have a flaw that many users catch and rectify early.

However, if you are building an engine from the scratch or are salvaging parts, there are chances that you must have missed a crack in the block. 

Sometimes engines also operate normally despite having multiple flaws in the cylinders or other components which propagate towards the block.

The following 5 signs are a sure indication that you might be dealing with a cracked block.

  • Overheating: A cracked engine block can cause the coolant to leak and may overheat the engine. If your engine temperature gauge is constantly showing high readings and you’re also topping up your radiator with coolant, there is a high chance that you’re dealing with a cracked engine block.
  • White Exhaust Smoke: White smoke from the exhaust is another giveaway sign of a cracked engine block. Exhaust leak like this usually happens because the coolant is being burned along with fuel in the engine cylinders.
  • Coolant Leak: If you notice coolant leaking from the engine, it could be a sign of a cracked engine block. If you see a puddle of coolant under your car or notice the coolant level dropping rapidly, the problem is most likely going to be a vacuum or coolant leak.
  • Engine Misfire: A cracked engine block can cause problems with the engine’s cylinders, leading to an engine misfire.
  • Engine Oil Contamination: Milky or foamy substances in the engine oil could be another sign of a cracked engine. This happens when coolant mixes with the oil and can cause engine damage if left unchecked.

Why do Engine Blocks Crack?

Engines are complicated assemblies and there are several reasons why they might have a particular flaw. 

From the way they are being used to the way they were manufactured, there are several reasons why an engine component might have a flaw. 

Even everyday driving can eventually damage and crack the intake manifold gaskets or even the intake and exhaust ports.

For cracks in engine blocks, the following reasons are the most common:

  • Overheating: When an engine gets too hot, the metal can expand and contract rapidly, which can cause stress fractures and cracks to develop.
  • Freezing: Freezing can also cause engine block cracks. If the coolant in the engine freezes, it can expand and cause the metal to crack.
  • Manufacturing Defects: Sometimes engine blocks can have manufacturing defects that make them more susceptible to cracking. This can include things like porous metal, weak points in the casting, or uneven cooling during the manufacturing process.
  • Age and Wear: Over time, engine blocks can weaken and become more susceptible to cracking. This is especially true if the engine has been subject to heavy use or has not been properly maintained.
  • Improper Installation: If an engine block is not installed correctly, it can cause stress in certain areas of the block, which can lead to cracks.

Common Ways to Check for Cracks in an Engine Block

Depending on the car you have and the condition of the engine, there are multiple ways to check for cracks. 

The suitable way depends on whether the engine is mounted or not.

Similarly, it’s absolutely necessary that whatever test you conduct should be a non-destructive one. There is no point in carrying out the test if doing so can introduce cracks in a perfect engine.

1. Visual Inspection

As its name suggests, this is the primary method that can help you identify the most obvious cracks easily. 

Look for signs of coolant or oil leaks, as well as any visible cracks or damage to the exterior of the block. Most of the time, combustion or coolant leak can easily be identified through a visual inspection.

Another advanced method of visual inspection is through a borescope. 

In essence, it’s a small camera on a long and flexible arm that can go inside the engine and allow you to visually inspect the condition without dismounting anything.

2. Pressure Testing

A pressure test involves filling the cooling system with air and pressurizing it to the manufacturer’s specifications. 

If the pressure drops, it could indicate a leak, which could be caused by a crack in the engine block.

You can also conduct the same test with water which would allow you to identify the location of the crack by checking out the point of leakage. 

This method can also be utilized for identifying a cracked plastic intake manifold.

3. Magnetic Particle Inspection

This is another non-destructive testing method that involves applying a magnetic field to the engine block and then adding iron particles to the surface. 

The particles will stick to any cracks or defects, making them easy to identify.

4. Dye Penetration Test

Dye testing involves adding a special dye to the coolant system, which will flow through any cracks or leaks. 

A UV light can identify the dye, which can help to pinpoint the location of any cracks.

5. Ultrasonic Testing

This method uses high-frequency sound waves to detect cracks and other defects. 

It involves using a handheld wand to send sound waves into the engine block, which are then reflected back and analyzed to identify any cracks or other issues.

Engine Block Testers: What are They and How to Use Them?

One of the easiest ways to check for engine block cracks is through a device called a block tester

The device can detect the presence of combustion gases in the coolant system, which is a clear indicator of a cracked block or a damaged gasket.

Here’s how you can use an engine block tester:

  • Drain the Coolant: The first step in using an engine block tester is to drain the coolant from the radiator and the engine block. This is necessary to ensure that no coolant in the system could interfere with the testing.
  • Attach the Tester: Next, the engine block tester is attached to the radiator or coolant reservoir using a special adapter. The tester consists of a clear plastic cylinder with a rubber bulb on one end and a chemical chamber on the other.
  • Suck in Air: The rubber bulb is used to suck air from the coolant system and into the chemical chamber. The chemical in the chamber reacts with the combustion gases in the air, causing a color change.
  • Interpret Results: Depending on the tester, the color change may indicate the presence or absence of combustion gases in the coolant system. Some testers use a liquid that changes color, while others use a test strip that changes color. The instructions that come with the tester will explain how to interpret the results.

While block testers are really easy, they have some limitations as well. Most importantly, they won’t tell you if it’s the head gasket or the block itself that’s damaged. 

You’ll have to carry out further tests or approach an experienced mechanic to get a better idea of the issues and start the repair process.

Frequently Asked Questions About Cracked Engine Blocks

Will the car run with a cracked engine block?

Yes, but it’s not recommended to delay the repairs. Cracked engine blocks can negatively affect performance and may even be dangerous on the road.  

Can a cracked engine block be fixed?

Yes, cracked engine blocks are fixable if the flaw is small. Your mechanic will be a better judge of your car’s condition and present you with the right options.

What does a cracked engine block look like?

On visual inspection, it’s very hard to identify a crack unless it’s on the bolt or another easier location. Instead, the correct practice is to look for signs of leakages and other flaws to identify the cracks in the engine block.

Key Takeaways

Engine blocks are one of the most important components of the assembly that hold the entire engine together and regulate its performance.

Cracks and flaws in engines are common and can be easily repaired if caught on time. 

Delaying repairs can cause the issue to propagate and become unmanageable, which requires more time and resources to fix. 

As a car owner, knowing how to do basic checks can help you ensure that your car remains in the best condition for the longest time possible.


Dean Alvarez, TireForge Head Author

Thanks for reading our article! We've written this article with a lot of thought and care. If you're interested in seeing more of our content, please check out our Tires section and find an answer to your questions!

Tire Forge