Engine Block vs Cylinder Block: What’s The Difference?

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The engine block may not be the part of your engine doing the heavy lifting, but it is the most indispensable part of a modern internal combustion motor.

Whether you call it the engine block or the cylinder block, it holds together the cylinders and all the other parts that are essential in transferring power from the pistons to the crankshaft. The addition of the engine block makes the rest of the motor more reliable and more straightforward to repair and replace.

Some people refer to this casing as an engine block, but others see it as the cylinder block. What’s the difference? Keep reading to learn what you need to know about the block that holds your engine together.

​Comparison table

Engine Block vs Cylinder Block

​What Is An Engine Block?

A vehicle’s engine block is the crucial component tying internal combustion engines together. Mechanical engineers call it a “block” because it comes in the form of a solid car part made from cast iron.

While the bulk of engine blocks produced come from cast-iron molds, some cars engineered in the late 1990s might run with an engine block made of plastic or aluminum.

The goal was to create a more efficient vehicle because a cast-iron block often makes up a significant percentage of the engine’s weight and requires a multi-person team for repairs or removal. With a lighter block, drivers receive better fuel economy. However, manufacturers often found that lighter blocks became more complicated and expensive.

So far, the cast iron block continues to dominate.

The block itself is a cooled, lubricated crankcase housing both the engine’s cylinders and the cylinder components.

In popular culture, you might refer to the star player of the team as an engine block because they are strong, sturdy, and indispensable to the machine.

It follows if an engine block fails, so too does the car. You don’t get anywhere until you repair or replace your engine block.

​What Is A Cylinder Block?

The cylinder block is the structure housing the engine’s cylinders and its essential components. It also houses both the intake and exhaust ports and passages as well as the coolant passages.

​There’s No Substantial Difference Between The Engine Block Vs Cylinder Block

If you read both descriptions, you picked up on a significant similarity.

Both the engine block and cylinder blockhouse the cylinders, components, and crankcase. That’s why you hear the two terms used interchangeably or synonymously with each other. They perform what is effectively the same function.

It is possible to dive deep and pick apart the technical distinctions between the two terms or parts. For example, an en bloc cylinder is a discrete unit that doesn’t house the crankcase. Meanwhile, an engine block is an integrated design featuring the crankcase.

The most commonly accepted way of using the two terms allows you to use them interchangeably.

Engine Block vs Cylinder Block

​Image Source: pixabay.com

​Diving Deeper Into The Engine Block: What It Holds, What It Does

The engine block of your car is also known as the car’s cylinder block. Within it lie all the major parts of your motor’s bottom end. What happens in the engine block?

The engine or cylinder block performs three critical functions:

  • Lubricates and maintains stability in the engine
  • Transfers oil via oil galleries to lubricate all critical engine components
  • Cools the engine from the water galleries

Engine Block vs Cylinder Block

In other words, your cylinder block keeps the engine at the optimal operating temperature even when other factors like load or outside temperature vary. It’s also the critical part that lubricates the whole of the engine, allowing it to perform basic functions.

Why does it need to be in a block shape? Cast iron blocks were a vital engineering innovation when the internal combustion engine was still a new invention. Using a sturdy iron block meant that it was possible to cast the cylinders in sets of two or three. Cylinder pairs or triples create a more reliable engine. Engineers also found building the engine was faster with a block.

The engine block evolved significantly over the past hundred years. While old engine blocks featured two or three cylinders, modern undertakings may include eight or more within a single block.

Using a block also makes cylinder repairs and replacements easy. Rather than fiddling with a single cylinder, it’s possible to remove the block, repair it, and then re-install it. It’s also easier to replace. Working this way also means you don’t find yourself repairing one element at a time, which means the longevity of the parts matches rather than creating a piecemeal solution.

Engine Block vs Cylinder Block

​Image Source: pixabay.com

​Why Is Lubrication And Temperature Regulation So Important For Your Engine?

Your engine is the place where fuel combustion happens, which is the process that renders your motor a fuel combustion engine. Combustion, or burning, is a simple chemical process where fuel and air combine to release energy. All this happens in your engine block, and then your engine partially converts the same energy to power the motor.

How? As the combustion expands, the gases push on the pistons. The pressure on them then rotates the crankshaft.

Your car moves because the rotating crankshaft triggers a system of gears known as your powertrain which sends the energy and movement to your wheels.

​Common Engine Block Problems

Engine blocks are sturdy and often last the lifetime of the vehicle. Despite this, engine blocks may encounter problems causing them to fail.

The four most common engine block problems include

  • Internal engine coolant leaks
  • External engine coolant leaks
  • Cracked engine blocks
  • Porous engine block

​​Internal Engine Coolant Leak

Engine Block vs Cylinder Block

​When a faulty gasket allows water and engine oil to mix, you might see the coolant expansion tank levels drop. Another common sign of an internal coolant leak is the build-up of a thick cream under your oil filler cap.

​​External Engine Coolant Leak


​If you move your vehicle and discover a puddle of water where your engine was parked, then you might have an external leak. External engine coolant leaks happen when you have a leaky water pump or house. ​​External EnginePuddles are also a sign of a crack in the engine block.

​Cracked Engine Block

​Spotting large water or oil puddle under the front of your vehicle is a clear sign of a cracked engine block. If you see a pool of oil, check the dipstick. A distinct lack of oil almost confirms it.

If you suspect your engine block now boasts a crack, don’t try to start your car. You enjoy a sound that fatally marries a screeching and grinding noise that you never want to hear again.

​Cracked Engine

Cracked engine blocks are often the result of a deep freeze or overheating. Outside air temperature alone can’t do such severe damage. Excess heat is the result of a lack of coolant, which causes the overheated portions of the block to expand and places stress on the block.

A failed water pump might also lead to a cracked block because it stops the coolant from flowing through the system.

In rare cases, you might find you created a system capable of overheating by adding a turbo- or supercharger to your engine. If your engine wasn’t designed to handle that kind of power, the engine overheats and creates expansion and flexing in the block, which again allows cracking.

Only in rare cases does an engine block fail due to a casting error. Your vehicle or parts warranty should cover casting problems.

Your engine doesn’t just crack. Expect to see symptoms before finding a big puddle of oil. The most common signs of a potential engine crack include:

​Cracked Engine Block

​Image Source: pixabay.com

  • Overheating
  • Decreased engine performance
  • Mixing antifreeze and motor oil
  • Emitting smoke from under the hood

​Porous Engine Block

​Porous Engine Block

Contaminants that infiltrate your casting when it’s still in the factory might contribute to problems down the road. Most of the time, they don’t cause an issue with the block itself. However, they can create issues with gaskets and gasket seals that require some maintenance.

As with a casting error, there’s no fixing a porous engine block. It arrived broken, and manufacturer’s warranties should cover it.

In the case of a porous block causing a broken gasket seal, you’ll likely need to pay for the repair itself because these fall into the category of wear and tear items. The parts themselves are cheap, but labor can be costly.

​Failed Engine Block? Big Problems

​Failed Engine Block

​Image Source: pixabay.com

Without an engine block, you don’t have a car. Fortunately, manufacturers design these heavy, cast iron casings to last across the lifespan of your vehicle as a whole.

The difference between an engine block vs cylinder block is barely perceptible today given the dominant use of the cast iron block casing. If you hear the words interchangeably, the speaker isn’t wrong. It’s correct to use one in place of the other.

Questions about the engine block and engine block repair? Share your questions and thoughts in the comments below.

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