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5 Common Causes Of A Cracked Engine Block

As a car owner, you’ll occasionally deal with problems that need repair for your vehicle to get back on the road. These problems can be minor issues such as blown fuses, worn-out brakes or cracked radiator blocks. It can also be severe complications such as a cracked engine block which is the last thing you’d want to hear.

The issue of a cracked engine block rarely does happen, and when it does, the only option might be to replace the entire engine for your car to be roadworthy again. This repair is expensive because it needs substantial overhaul, labor-intensive, and can take some time to complete. Because of this, it’s best to prevent it from happening in advance by identifying what causes it in the first place. If you’re eager to find out, here are the facts:

What’s An Engine Block?

It’s best first to understand what a cylinder or engine block is before going ahead and identifying the exact cause of this problem. The engine block is an integral part of the internal combustion engine that contains several cylinders and other vital components of a motor’s bottom end. This component provides your car with the power to drive, after an explosion is produced, once air and fuel come together.

When working correctly, the engine block enables the upwards and downwards movement of the pistons inside the cylinders, thereby turning the crankshaft. The revolution of the crankshaft, which is connected to the wheels, is what moves your vehicle.

What Are The Common Causes Of A Cracked Engine Block?

Although the engine block is designed to last for a lifetime, there are instances where it cracks. This usually doesn’t happen unexpectedly, and you should be aware of some warning signs such as:

  • Leaking coolant or oil
  • Visible engine smoke
  • Poor engine performance due to low engine compression
  • Low coolant levels
  • Discoloration of your car’s antifreeze or oil
  • Oil and antifreeze mixing
  • The car is producing too much smoke
  • The car’s engine is overheating due to leaked antifreeze

And because the cracked engine block repair costs are quite steep, it’s best to avoid this issue in advance. Here’s a look at what mainly causes a cracked engine block:

  1. Engine Overheating

Excessive overheating often has a dire effect because the engine block is made out of cast iron or aluminum casting. This happens because very high temperature causes specific parts of your car’s engine to expand. The continued rise of temperature continues to pile on, stressing the engine block beyond what it can handle. When this persists, the metal hits its breaking point, and this causes the engine block to crack. The cracks on the engine block also start to form because of the stress between overheated and cooler engine parts.

  1. Extremely Cold Temperatures

The engine block can also crack due to extreme coldness, and this occurs quite often in areas that experience sub-zero temperatures. This usually happens when the coolant isn’t concentrated enough or is at low levels. If this is the case and you fill the coolant tank with water, the water will eventually freeze when the temperatures fall below freezing point. This freezing causes it to expand in volume, and because there’s no room for expansion, the freezing water piles pressure on the engine walls. When this persists, it eventually causes the engine walls to crack.

The best way to prevent the engine block from cracking due to extreme cold is to use a coolant meant for sub-zero temperatures.

5 Common Causes Of A Cracked Engine Block
the mechanic installs a new piston. Disassemble engine block vehicle. Motor capital repair. Sixteen valves and four cylinder. Car service concept
  1. Water Pump Failure

Another common cause of a cracked engine block is water pump failure. When this happens, the water pump doesn’t effectively pump the coolant as expected throughout the engine block, leading to extreme overheating. The lack of enough coolant circulating will eventually cause the engine block to crack due to extreme heat.

Therefore, you need to keep an eye on the water pump to ensure it’s working correctly. This means checking out for signs such as steam being produced from the radiator and hearing sounds underneath the hood. It’s also helpful to note that water pumps last between 30,000 to 100,000 miles on average. If your water pump has been used for such period of time, then it’s time to have it inspected, to ensure it’s working as expected to avoid future issues.

  1. Manufacturer Defect

Although this is very rare, it’s also likely that a casting failure by the manufacturer might cause the cracking of the engine block.  The engine block during manufacturing is designed into a mold. If there’s a manufacturing defect during this process, other areas might be thinner than the rest or have other flaws. As a result, the engine block becomes more susceptible to cracking.

An excellent example of when manufacturer flaws lead to the engine block cracking is with the 2006 Honda Civics. When the engine block cracks due to the manufacturer’s fault, it’s best to get in touch with the manufacturer to know whether there are possible recalls.

  1. Overpowering

While a cracked engine block, due to excessive stress or overpowering was uncommon in the past, the same can’t be said today. This is because many cars today incorporate additional systems such as turbochargers, superchargers, and nitrous oxide injections to boost a car’s performance. But while these technologies certainly do enhance the engine’s performance, they do place added stress on it due to increased horsepower because of nitrous and forced induction.

Because an engine’s design is meant to operate at an optimal level, extra stress increases the likelihood of the engine block cracking. In addition, you shouldn’t excessively stress your engine by towing a trailer or load that exceeds the recommended weight. Otherwise, this might eventually cause a crack to form on the engine block.


Knowing what causes a cracked engine block is the first step towards reducing the chances of this problem from happening. After all, prevention is better than cure,and to help you avoid such an issue, this helpful guide has outlined the most common causes for a cracked engine block. With this in mind, you’ll be able to implement preventive measures to avoid such a problem from happening.


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