skip to Main Content

Media post: Cracked Engine Block Replacement

A cracked engine block is definitely on the list as one of a car owner’s worst nightmares. It ranks right up there with a blown head gasket or failed transmission. Thankfully, engine blocks are designed to last the lifetime of the vehicle, so failures are not very common. When it does happen, it is a major issue and will cost you a hefty sum to get repaired. Here, we will examine the causes and signs of a cracked engine block as well as your repair options.

What Causes a Cracked Engine Block?

The biggest cause of a cracked block is overheating. Engine blocks are made from hard metals such as iron or steel. However, many of the passageways inside the engine block are quite thin. These passageways allow coolant and oil to circulate through the engine to keep it cool and lubricated. As the engine heats, the metal block expands and then contracts again as it cools.

When the engine overheats, these thin passageways expand more rapidly than the thicker portions of the block. This can cause tiny cracks to form. Repeated overheating allows the cracks to get larger and finally break all the way through the metal. Another way that blocks can crack is due to freezing temperatures or over-performance. This occurs when you install aftermarket parts such as a turbo or supercharger and increase the pressure inside the engine past what it can handle. The increased pressure inside the cylinders can cause catastrophic failure.

Symptoms of a Cracked Engine Block

The most obvious sign of a cracked engine block is fluid leaks. If you see oil or coolant pooling under your vehicle, then you should begin inspecting your car for the source. These fluids could be coming directly from the engine block through a crack. If the crack is so bad the fluids are pooled on the ground, then you have a serious problem. It is more likely that the leak would be smaller and visible just on the block around the crack itself.

If your car starts to overheat, this could point toward a cracked block. It might mean that the coolant is no longer circulating properly and removing the heat from the engine. A mixture of fluids is another telltale sign of a crack. If you notice that your coolant is dark and murky or your oil is milky and frothy, then you have a problem! Finally, smoke from your engine compartment can signal a crack. That usually means that oil or coolant is leaking from the block and burning off on the engine. You should get that checked right away.

Cracked Engine Block Replacement

If you have confirmed that you have an issue, then you are likely looking at a replacement of your cracked engine block. While there are some commercial sealants available that can sometimes seal extremely small cracks, many times a replacement of the block is the only option. The other options are to attempt welding of the crack or using a cold metal patch. Either way, you should know up front that this is an expensive repair! These repairs can often take 30+ hours to complete. With mechanics charging anywhere from $50 – $150 per hour, the labor alone will be upwards of $1,500. Add that to the cost of a new engine block, and you might be looking at a $3,000+ repair bill.


If you suspect you have a cracked engine block, stop driving immediately so that you do not do further damage to the car. Have your car checked out by a qualified mechanic to assess whether the engine block truly is cracked. If it is, be prepared for a hefty repair bill as this is a big problem that takes time and expertise to repair. Engine blocks do not fail often, but when they do, it creates a huge problem. You might just consider selling your car to a junk car buyer if you do not have a few thousand dollars sitting around for this kind of repair.

This Post Has 2 Comments
  1. I was run into a medium and cracked the engine block, however the warranty covers everything on the engine. A big Nissan place wanted $8800.00 the only other thing it needs is an oil pan. I think I should make the car place fix the engine. What do you think

Leave a Reply

Back To Top