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Bad Piston Rings: Signs, Causes & Solutions

Piston ring replacement cost

Cars need piston rings to regulate engine oil pressure and consumption so bad piston rings also mean bad news to your car’s performance and may eventually lead to total engine failure. How frequently do you truly pay attention to the minor features of your car, in comparison to all the massive, hefty pieces that make up your car? If anything is wrong with practically anything, it is generally due to a huge, separate part that has broken.

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Although piston rings are among the least costly elements of an automobile engine, they are critical to the vehicle's performance. Several signs of faulty piston rings might alert you to the necessity to replace them in order to avert catastrophic engine damage.

Bad Piston Rings: The Basics of Piston Rings


So we could understand better the causes and symptoms of bad piston rings, let us first learn the basics of piston rings. So what is a Piston Ring? A piston ring is a component of your vehicle that can be found inside the engine. It is often a split ring-shaped piece that slips directly into a groove on the outside of your vehicle's piston. Although piston rings are most often found in automobiles, they may also be found in steam engines and other assemblies that incorporate an internal combustion engine.


Cast iron is a common material used in the manufacture of piston rings. This is due to the fact that it includes graphite in the form of lamellar graphite, which works as a lubricant, facilitating the sliding action between the rings and the liner.


The piston rings are alloyed and coated, and this varies depending on the type of ring since the functioning of these rings differs. Chromium, molybdenum, vanadium, titanium, nickel, and copper are the most often used alloying elements in cast iron. To ensure optimum longevity, the piston ring material is maintained tougher than the cylinder lining.


3 Types of Piston Rings


Three piston rings per cylinder are common in modern cars. Two rings keep combustion gases at bay, while the other retains and directs engine oil where it should go in the car. Here are the several types of piston rings and their roles in the engine.


Pressure Compression Rings


It is the role of the pressure compression rings to prevent gas leakage as it seals the top of the piston. These rings are frequently found in the principal piston grooves, though they can be found in a variety of locations depending on the vehicle. These rings help transport heat from the piston to the piston walls. The compression rings shear the oil layer that the oil ring has left behind.


Compression rings in a car engine generally have a rectangular or keystone cross-section. For the peripheral, the upper compression ring normally has a barrel shape, whilst the lower compression ring normally has a taper napier face. Some engines also employ a taper facing for the top ring, while in the past, basic plain-faced rings were employed.


Wiper Rings


The wiper ring, also known as a Napier ring or backup compression ring, is located under the compression ring. Their primary role is to wipe the liner surface of excess oil and to act as a support back up ring on any gas leakage that escapes the top compression ring lower down. 


The majority of wiper rings have a taper angle face positioned at the bottom to provide a wiping motion as the piston advances toward the crankshaft. Bad piston rings when it is caused by inadequately positioned wiper rings result in increased oil consumption because the rings wipe off more oil at the combustion chamber


Scrapper Oil Control Rings


As evident on its name, scrapper oil control rings are responsible for regulating the lubrication oil amount moving through the cylinder walls. The rings spread the oil equally throughout the diameter of the liner. Scrapper rings remove the oil that has been splattered on the cylinder walls. They return the scrapped oil to the crankcase. They also keep oil from flowing through the small area between the ring and the cylinder.


To provide the tension necessary for a close seal, oil control rings are commonly manufactured from a single piece of cast iron, numerous pieces of steel, or steel/iron with a helical spring backing. Cast iron oil rings and rings with helical spring backings feature two scraping regions with varying degrees of intricacy.


Multi-piece steel oil control rings, on the other hand, are often made up of two thin steel rings (called rails) with a spacer-expander spring between them to keep the two rails apart and produce radial pressure. When within the cylinder bore, the gap in the piston ring compresses to a few thousandths of an inch. The following ring gap forms are available: square cut, angle cut, tite joint, step cut, hook step, and mitre step.


In short, piston rings work in three-ring sets, beginning with the top compression ring and progressing to the second groove ring and the oil control ring. Their purpose is to block off combustion gases, help in heat conduction to the cylinder wall, and lubricate and scrape oil from the cylinder wall.

What Causes Bad Piston Rings?


The piston rings are subjected to high pressure in the combustion chamber. If the combustion pressure of the gas produced inside the chamber is higher than typical, the ring performance may suffer resulting in bad piston rings.


This can occur as a result of detonation and pinging of the gasoline from a faulty injector, or when the fuel is combined with filthy air. Contaminated fuel oil or the incorrect quality of cylinder oil will also degrade the ring's performance. As the ring deteriorates, their capacity to seal the combustion gases will be revealed.


The most common causes of piston ring wear include poor fuel or cylinder oil quality, a poor combustion process, incorrect fuel timing, a worn liner, and so on. Gas entering into the crankcase or beneath the piston region, known as blowby, is the most prevalent indicator or indicator of a worn ring. Sticky rings caused by carbon or sludge deposits, as well as ring splitting or cracking, can occur as a result of wear.


What are the Signs of Bad Piston Rings?


Since the piston rings play an important role in the overall operation of an internal combustion engine, forming a seal that prevents the high-pressure gases from escaping, it is important that you can identify or detect bad piston rings. If you know the early signs of bad piston rings, you may be able to prevent severe problems from occurring.


Here are some of the common signs of bad piston rings. 

  • It consumes more oil than usual. 


If you notice that your vehicle is suddenly consuming more oil than it used to, it could be an indication of bad piston rings. Because the piston rings are subjected to high pressure, it becomes worn over time. When this happens, they won’t be able to do their job properly and allow the oil to leak into the combustion chamber. This means that you will be using more oil, spending more since you need to add more oil frequently.


To prevent this from happening, experts recommend checking your engine oil regularly and the moment that you notice that your vehicle is consuming  more oil than usual, have your piston rings inspected. 

  • Excessive exhaust smoke.


Excessive smoke coming from your exhaust is one of the common signs of bad piston rings. If you see a thick, dark gray smoke coming from your vehicle, it can be an indication that the engine oil is leaking to the combustion chamber since the bad piston rings can no longer seal efficiently. The oil leaking and burning can result in incomplete combustion which causes the thick, dark smoke. 

  • Reduced power.


Since the piston rings help control the compression and lubrication, having bad piston rings can result in loss of compression and proper lubrication. When this happens, your vehicle will also suffer loss of acceleration power, making it struggle when you try to step on the gas pedal and accelerate. When you are using the throttle and your engine takes too long to respond when you try to accelerate or speed up, it is also an indication that you have bad piston rings. 


You can do a compression test to test your piston rings since a vehicle with a reduced power can also be caused by bad valve seals. If you get low compressions, it means that you have bad piston rings, if you get higher compressions, it could mean that you have faulty valve seals. It is better that you have it checked by a mechanic to be sure. 

  • Decreased engine performance. 


If the piston rings are already severely damaged, it can cause your engine’s performance to decrease. In extreme cases, it can cause it to completely lose its power. It is because loss of compression causes acceleration delays because of the engine’s inefficient rotation that causes the engine to stall. Decreased engine performance and engine stalling can happen when you still use your vehicle and ignore the symptoms of bad piston rings.  


It is recommended that when you experience any of the signs of bad piston rings, have it checked immediately to get a proper diagnosis so you can correct it. If things get worse, you may lose all your engine power or the engine will malfunction and you will have to call for help and tow your vehicle. 

Bad Piston Rings: How Can You Prevent It?


Bad piston rings are usually caused by dirt contaminations. The dirt can enter the engine through bad air filters or through the oil circuit by contaminated oil. Since dirt contamination is the main reason why piston rings go bad, here are some of the ways that can help keep them from going bad. 


  • Follow the recommended oil change interval. 


If you follow the recommended oil change interval set by your vehicle’s manufacturer, you will increase the lifespan of your piston rings. Doing so makes sure that your engine oil is fresh, clean, and free from any contaminants. 


While it is true that the oil filter sieves out the dirt and that it can help keep the engine oil clean, there are times when the oil circuits are not cleaned thoroughly. There are dirt particles already settled on the clean side of the oil circuit that can reach the vital parts of the engine that can cause wear and tear. 


  • Follow the recommended air filter maintenance. 


An air filter that is long overdue for a replacement can become faulty. When it becomes faulty, it won’t be able to work efficiently which can result in oil leaks that can allow dirt and other debris to enter. If you follow the recommended air filter maintenance and replace your air filter regularly before it goes bad, it can help prolong the lifespan of your piston rings and can keep other problems from occurring. 

Bad Piston Rings: How much does it cost to replace piston rings?


It was mentioned earlier that the piston rings are among the least costly elements of an automobile engine. They are small and they can be bought for around $40 to $ 200 depending on the vehicle’s make and model. It might not sound that much. However, because piston ring replacements involve strenuous labor that can take more than 10 hours to finish, the mechanic can charge you around $1,800 to as much as $4,000 for the labor cost. 


The replacement can go that much because the piston rings are found deep in the engine and the engine will have to be disassembled to locate, remove, and replace the piston rings. The replacement process takes a lot of time and will need precision. After the bad piston rings have been replaced with new ones, the engine will be reassembled and put back in the vehicle. 


Piston rings are vital vehicle components and replacing them can be very expensive. It is for this reason why you need to be mindful of the early signs of bad piston rings so you can correct the problem immediately. To make sure that the life of your piston rings will be prolonged, you need to follow your vehicle’s recommended maintenance and service schedule. 






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