Symptoms of Bad Piston Rings [Causes and How to Prevent and fix]

A car’s piston rings regulate engine oil consumption and oil pressure. Therefore, when the piston rings fail, the car will experience a myriad of problems that may ultimately damage the entire engine. Although piston rings are some of the least expensive parts of a car engine, they are essential to the effective operation of the vehicle. Several symptoms of bad piston rings can let you know when you need to replace them to avoid critical engine damage.

Different Types of Piston Rings

Modern vehicles are commonly installed with three piston rings per cylinder. Two rings to hold back combustion fumes and the other holds and direct engine oil where it should go in the vehicle. Here are the different piston ring types and their functions in the engine.

Pressure Compression Rings

Compression rings prevent gas leakage by sealing the top of the piston. These rings are commonly on the primary piston grooves but different car models can have them located differently. These rings also transfer heat to the piston walls from the piston. The compression rings shear the oil layer left by the oil ring.

Wiper Rings

Wiper rings provide a backup to the pressure compression rings. They are below the compression rings and are responsible for cleaning the excess oil from the liner surface. They also help the compression rings to stoop any possible gas leakages. Wiper rings are tapper angle faced directed towards the bottom to adequately wipe oil simultaneously with piston and crankshaft motion. Improper positioning of the wiper rings causes excessive oil consumption because the rings wipe off more oil at the combustion chamber.

Scrapper Oil Control Rings

According to their name, oil control rings regulate the lubrication oil amount that moves through the cylinder walls. The rings evenly distribute the oil around the liner circumference. Scrapper rings scrub off the oil splashed on the cylinder walls. They disburse this scrapped oil back to the crankcase. They also prevent oil from passing the narrow space between the ring and the cylinder.

Common Symptoms of Bad Piston Rings

Several things can help you identify if your piston rings are wearing out. The most common symptoms are listed below.

bad piston rings sound

An Increase in Exhaust Smoke

One of the obvious symptoms of bad piston rings is having too much smoke coming out of the exhaust of your car. In addition to an increase in the amount of exhaust smoke, this smoke will have a somehow burning smell and will appear darker than usual. It has a dark grey appearance because engine oil is leaking to the combustion chamber because the piston rings have failed to seal efficiently.

Read Also: White Smoke from Exhaust: Reasons and How to Fix it

Excess Oil Consumption

The moment your check engine light turns on because of excess oil consumption, it is highly likely that your piston rings need replacement. Worn-out piston rings will lead to oil leaks in the combustion chamber which automatically will manifest themselves as more oil consumption by the vehicle. So check the Engine oil Level Regularly.

Therefore, your car will require you to regularly add oil more frequently than the average 4000 miles before refill. Immediately inspect your piston rings when your car begins consuming more than the regular amount of oil.

Decreased Acceleration

Piston rings regulate compression and lubrication. Therefore, when your piston rings wear out and you lose compression and you have inadequate lubrication, the vehicle will lose its acceleration power. The car will struggle to accelerate when you step on the gas pedal and the engine will take longer to respond and speed up your maneuver.

Decreased acceleration can also be due to spoilt valve seals. Therefore perform a compression test to distinguish whether you have bad piston rings or valve seals. Higher compressions are symptoms of bad valve seals while low compression means your piston rings are damaged.

Poor Engine Performance

As mentioned above, loss of compression delays acceleration due to inefficient engine rotation which leads to engine stall. In extreme cases, you may lose all engine power and you may need to tow your vehicle when the engine malfunctions on the road due to bad piston rings. Minor cases only lead to poor engine performance.

Complete engine stall will only occur if you ignore the early symptoms of bad piston rings and continue to use the car without taking it to the mechanic for inspection.

Dirty Air Filters

An increase in the oil intake is often because of blow-by when the air-oil mixture in the combustion chamber leaks past the installed piston rings to create more pressure in the engine crankcase.

When pressure vents from the positive crankcase ventilation (PCV) hose back to the crankcase then there will be a large amount of blow-by and the air intake will be very oily. Oily intake will also result in increased oil consumption.

How to prevent worn-out Piston Rings

The two main causes of wearing out of piston rings and most engine parts are dirt contamination. Dirt enters the engine through faulty air filters. Similarly, dirt can make its way to the engine through the oil circuit by contaminated oil. Therefore here are the easiest ways to increase your piston rings lifespan.

Regularly change your engine oil. Changing your oil regularly ensures that the oil running in your engine is clean and free from residue. That prevents sedimentation and corrosion of useful metal parts like piston rings. Although the oil filter sieves off dirt, sometimes the oil circuit is not adequately cleaned. The dirt particles already on the clean side of the oil circuit reach crucial engine parts causing wear and tear.

Perform regular air filter maintenance. When the car air filter doesn’t work efficiently it leads to oil leaks that can give easy entrance to dirt and debris. When you timely replace your air filter before it malfunctions you increase the chances of your piston rings serving you for a longer period.

How Do You Fix Piston Rings?

Take the following steps to fix your piston rings when you notice the symptoms of bad piston rings.

  • You should first carefully clean the used pistons to remove any dirt stuck on them. Clean the ring grooves and make sure they are free from any carbon residue. Try not to damage the groove sides when cleaning them. Any damage will lead to high oil consumption and increased blow-by gas emissions when you run your vehicle. Also, use piston ring pliers and not screwdrivers or pliers to avoid damaging the piston rings.
  • Unless you are dealing with steel cup segment type double-beveled oil control rings, don’t pull the rings by hand. The rings may break due to excess strain and also cause you injury. Pulling the rings by hand damages the rings and may cause difficulties when mounting them. If the ring bends, it can no longer lie flat in the groove; therefore, it won’t rotate and will wear out on one side and lose its sealing ability. The sliding layer will loosen and will damage the piston and cylinder. The piston will proceed to eat up the cylinder bore due to the hot combustion gases blowing through the piston and the cylinder wall. The loose parts damage the entire piston and cylinder sliding surfaces.
  • Only pull out piston rings when you have no choice because the rings slightly bend with every mounting. Inspect whether the rings can be easily rotated in the grooves. Also, check whether the ring fits completely into the ring groove and holds up the entire circumference. The sliding parts of the ring shouldn’t protrude over the piston skirt to allow efficient sealing.
  • When setting up the two-part oil control rings, pay attention to the position of the spiral expander. The ring joint should always be opposite the ends of the spiral expander.
  • The right position of the expander spring in three-part rings is important to ensure oil scraping occurs efficiently. Before you install the piston, check the position of the expander springs because they are untightened and might slip one above another as you transport them. Check that both markings at the spiral ends are visible. If you cannot see them, the spiral has overlapped and the ring might not work.
  • Now turn the piston ring joints of the piston ready for installation so that the ring joints are 120° towards each other. This will help the piston and the piston rings when you first start the engine. That is because the compression is relatively lower during the first engine start because the piston rings are not yet run in. Turning the ends towards each other lowers the blow-by gas creation which may lead to poor starts.

How To Replace Piston Rings YouTube

Frequently Asked Questions – FAQs

Most people ask, how long can I drive with bad piston rings? It all depends on the extent of their damage. However, here are the answers to the most frequently asked questions by car owners with piston ring problems.

Q: Can you just replace piston rings?

After performing piston ring failure analysis, ideally, you should replace piston rings together with the ring spacer. That is because bad piston rings hone and de-glaze the cylinder leaving the grooves damaged. Remove the top ring ridge on the bore to avoid the ring smashing with the ridge.

Since you already have the engine out, you can also check and replace bearing shells and check for lapping in the valves.

Q: What does a broken piston sound like?

A broken piston causes a rattling and knocking sound when running. The rattling sound of a broken piston is difficult to miss. Bad piston rings sound will be accompanied by misfiring and engine knocking.

Q: Is it cheaper to rebuild an engine or replace it?

Depending on the kind and extent of the problem on your hands, it is unlikely that rebuilding an engine can be less expensive than replacing it. Most engine parts are quite costly and require you to purchase other parts simultaneously when they malfunction.

You can avoid having to replace or rebuild your engine by regularly servicing your vehicle to fix what causes piston rings to fail before waiting for them to wear out.

Q: Can bad piston rings cause a misfire?

When you have bad piston rings or the valves, cylinder walls, or a head gasket leak, the vehicle engine will stall causing misfiring. You will notice white smoke from the engine that means that the worn-out and damaged piston rings can no longer seal the cylinder adequately.

Final Words

Piston rings are crucial parts of a vehicle’s engine. They may easily be ignored but can cause major damage to the vehicle because the engine will lose the compression necessary for avoiding oil leaks. You will notice failing piston rings by the increase in oil consumption by the car and the increase and change in smoke color. Ensure you visit a mechanic regularly to check and replace your piston rings as soon as you sight any of the symptoms of bad piston rings, motorcycle, or car as soon as possible.

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Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

One thought on “Symptoms of Bad Piston Rings [Causes and How to Prevent and fix]

  1. Salamm very informative article about cars .I am very impressive u high knowledge of vehicles. I want to repair my car please mentioned u address regards shahzad Ahmed

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