Piston and rings explained by expert

Piston and rings are probably the most essential part of an engine. For novice car owners, this might probably be the first time they're hearing about this.

But it's true. Piston rings are responsible for bringing compressions into the automobile engine. This in turn is responsible for generating the power that the engine will need to work at optimum performance. The piston contains parts which are known as rings that assist it during its running.

Damage to these rings can cause irreparable damage to your engine over time. What is a piston ring and how can you prevent this damage? In this article, you'll find out everything you need to know about the piston and ring including its types and how to detect one that has gone bad.

Piston and rings overview

What is a piston?

Before we can get into the discussion of a piston ring and what it does in the automobile engine, the piston must first be discussed in association with the rings. The piston is a moving component of an engine that is contained within a cylinder.

The piston is responsible for compression which produces the power the engine needs to function. This device is made secure and gas-tight by piston rings that are attached to the piston.


It starts down the cylinder drawing in a mixture of air and fuel before coming back up towards the cylinder head and spark plug also compressing the mixture as it goes.

For more information on what a spark plug is, you can check this article for answers. This seemingly simple device is a key component in the internal workings of your vehicle. It is usually made out of an aluminum alloy which is a good material for structural integrity.

And it's major purpose is to transform fuel into the energy that is necessary for moving the car. Basically, a piston converts the linear motion (ie the back and forth movement) in the cylinder into a circular motion that is capable of powering the wheels.

What is a piston ring?

Piston rings

Piston rings are an essential component of your vehicle's engine that ensures that the engine is working efficiently. Piston rings are located in between the cylinder and the piston. Modern-day piston rings are made out of metallic materials.  They are attached to the outer surface of the body of a piston. And by doing this they can:

  • Better the heat transfer from the piston to the cylinder
  • Lower the loss of gases by tightly sealing the cylinder through applied pressure.
  • Regulate engine oil consumption
  • Maintain the right amount of oil between the piston and the wall of the cylinder.

It's important to note that the piston rings vary in terms of size. In fact, the wrong size might render the entire device useless as it would not function as it should. The piston ring needs to provide the perfect fit radially between itself and the cylinder wall

What are the three types of piston rings?

 Types of piston rings

There are three types of piston rings to ensure the job of the piston ring is performed efficiently. The three types of piston rings are:

  • Compression ring
  • Wiper ring
  • Oil ring

Compression ring

The compression ring is the piston ring closet to the piston head. It is located in the ring groove and it has the main responsibility of sealing the combustion chamber. Thus helping to prevent leakage which is one of the core responsibilities of the ring. The failure of your compression ring to seal off the cylinder wall and reduce leakage would result in an engine that is working inefficiently.

Wiper ring

This is the second of the piston rings located between the compression ring and the oil ring. The wiper ring possesses a tapered body which makes it appear different from the rest of the piston rings. But regardless of its physical appearance, it still performs the same function as the rest and that is sealing the cylinder wall and wiping the cylinder wall clean of excess oil.

Oil ring

The oil ring is missing in some types of systems because it's not necessary. But in engines where it is useful, its use is to wipe off excess oil from the combustion cylinder wall during the movement of the piston. The wiped-off excess oil is returned to the oil reservoir through ring openings.

The function of the piston and rings

 A piston with rings attached

The piston rings and rings have four major functions in the combustion engine. And it's in the delivery of these four basic functions that the engine can work as efficiently as it should be. They are:

Sealing functions

The combustion chamber needs to be as gas-tight as it possibly can for there to be enough pressure to move the piston which will In turn generate power.

The piston rings seal the cylinder that way the combustion gas which was released during ignition will not be released. By trapping this gas, enough internal pressure is generated which as we mentioned already causes the piston to create power during its linear motion.

Heat transfer functions

Too much heat accumulating in the piston can damage the engine. That's why the piston rings act by carrying the heat away from the piston into the cooler cylinder wall.

The heat transfer goes thus: from the hot piston, it's carried away by the piston rings into the cylinder wall where it will eventually end up in the coolant system of the engine.

Without this heat transfer, there'll be too much heat around the piston which will impair it from generating enough power and ultimately leading to the engine being damaged.

Piston support functions

The piston rings support a smooth support system for the piston to avoid touching the walls of the cylinder and instead make its up and down movement run seamlessly in the engine.

Oil control functions

Admittedly, the piston requires a certain amount of oil as lubrication to function effectively. By using the right type of engine oil, examples of which can be found in this article, a well-functioning piston is guaranteed.

But an excessive amount of oil can be counterproductive, that's why the piston rings are there to make sure the oil is in a controlled amount within the cylinder. They do this by scraping off the excess oil off the walls in the combustion chamber.

Why do pistons have three rings?

Not all pistons possess three rings. For example, two-stroke engines do not require a piston ring because the oil required to lubricate the piston is produced by mixing oil in the gasoline.

However, the engines which do require a third piston ring, require them to assist in running efficiently to produce power to the engine. In these types of engines, the right type of engine oil which will not overheat is needed, there is a guideline available to help you decide on the best engine oil for your engine and you can find it here.

These rings are used to, support the piston, remove excess oil, regulate the temperature of the piston, and of course to properly seal the piston within the cylinder.

What are the signs and symptoms of a bad piston ring?

The piston rings have four major functions which are imperative to the efficient functioning of your car's engine. Meaning that if anyone goes bad, it could lead to a list of possible problems.

However, because the piston and rings are located within the engine, the symptoms it might show as a result of damage might be similar to symptoms of damage in other parts of the engine. That notwithstanding, these are some good and common indicators that your piston rings might be damaged:

Whitish or grey exhaust smoke

White smoke from the car exhaust

The color of Normal exhaust smoke should be a clear white color. But the instant that your exhaust smoke is a whitish or grey color is a common indication of a damaged piston ring. It could be that too much heat is being generated by the piston as a result of a damaged piston ring. And this causes the engine to burn the coolant producing this color of exhaust smoke.

Low acceleration power

If any of the piston rings is damaged, it means the piston which is the power generating Device in the engine would not work optimally. Meaning simple tasks such as creating enough power for acceleration will prove difficult. If you were to ever notice your car having troubles accelerating, it might be a symptom of a damaged piston ring.

Too much oil consumption

This can go in several different ways but a damaged piston ring can cause overconsumption of oil. This is a result of not enough oil being scrapped off the cylinder wall.

Excessive oil consumption[/caption]Eventually, this excessive use of oil can damage the entire piston and the engine as a whole. Another possibility can be as a result of low-quality engine oil. That's why it's best to buy the best quality engine oils for your vehicle. This article can give you great insight into the procedure.

Poor performance

The piston produces power to the engine. Meaning, if one of its major components ie the rings is damaged that will mean that the piston won't work at peak performance. This will cause overall poor performance to the engine and your vehicle.

What can make your piston ring go bad?

There is an extreme amount of pressure being exerted on the pressure rings. And if the pressure were to ever exceed normal, the rings might suffer damage. The following can cause damage to the piston rings:

  • Poor oil quality

Poor oil quality can lead to bad combustion. This can cause the engine to exert an extreme amount of pressure on the rings causing wear and possible damage over time. Engine oil quality which was discussed in this article is vital in the health of the piston and ring.

  • Carbon sludge deposit

Carbon sludge deposits can result in sticky rings which can result in breaking or cracking of the ring over time.

  • Leaky injector

A leaky injector can lead to the detonation of the rings over time.

Bad fuel injector
  • A narrow ring

The narrower the piston ring the more pressure it is put on and the more likely it's going to wear and out and break over time.

How do you know if your piston ring is bad?

The overall sign of a bad piston ring is loss of power by the engine and low-performance issues. This is because the piston is responsible for compression and generating the power that the engine needs to run efficiently. Any type of damage or indication of a fault can cause an obvious performance problem in how the engine is run. Other signs can be white or grey-colored smoke, excessive oil consumption, etc.

Can you drive with a bad piston ring?

The simple answer is yes, you can drive with a bad piston ring. However, it must be noted that you can only drive for a certain distance before causing irreparable damage to the engine of your car.

Your spark plugs can also be affected too as a result especially if it's one of poor quality. Following the guidelines in this article will teach you how to examine and purchase a higher-quality spark plug. That being said any indication of a bad piston ring must be looked at by a professional as soon as possible.

How often should you replace piston rings?

Except you use your engine on accelerating often, there really isn't a specific time frame to change your piston rings. Rather, let your car engine tell you when it's time to change it.


As we've explained in this article, the piston and rings are invaluable members of the proper and efficient functioning of your vehicle. And they work continuously at high pressure and temperature to ensure the smooth running of your engine.

Bearing this in mind, it's good to be aware of the possibility of damage to help you know how to handle the problem at hand before it gets too serious. With the right-sized rings, however, high-value engine oil, as well as proper maintenance, your piston, and rings, can last you for a very long time.

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