6 Symptoms of a Bad Piston Rings (And Replacement Cost)

Is your engine burning oil, bellowing blue smoke, or lacking power? These are just a few of the signs that failing piston rings could be robbing your engine of power while enabling oil loss and damage.

Losing compression and sealing ability, bad piston rings exhibit identifiable symptoms that signal more serious problems if ignored. Keep reading to learn the distinct warning signs of piston rings losing integrity.

Bad Piston Ring Symptoms

The tricky part about bad piston rings symptoms is that they are similar to the symptoms of bad valve seals. But you should take your vehicle to an auto mechanic and have it checked out either way.

Below are the most common signs you have failing piston rings.

1) Too Much Exhaust Smoke

smoke from exhaust

The downstream effect of piston ring failure permitting oil flow downward is burnt oil smoke bellowing from the tailpipe. This smoke often looks blue/gray in color when oil is being burned in the engine’s cylinders. The emissions worsen upon cold startup or hard acceleration when more oil slips past the defective piston rings.

Not only does the influx of oil elevate oil use, it also hampers optimal air-fuel ratios and combustion inside each cylinder. Incomplete and inefficient burning of the oil-fouled mixture sends more particulate matter out through the exhaust as blue smoke.

Excessive exhaust smoke on acceleration or higher RPMs points to oil contamination in the cylinder stemming from bad piston ring seals. Monitoring tailpipe emissions directly showcases piston ring health and how much blow-by is occurring into the combustion chambers.

2) Excess Oil Consumption

oil pressure check engine light

As the gaps around the pistons grow from failed seals, engine oil is allowed to seep past the piston rings and down into the combustion chambers. This oil is then burned during the engine’s firing, causing an increase in oil consumption.

Even in engines without any visible oil leaks, the drop in ring seal leads to extreme oil loss as the oil quite literally goes up in smoke. Drivers will need to add engine oil much more frequently to keep pace with this type of accelerated consumption.

Oil may need to be topped off every couple weeks or even more in severe leakage cases. Monitoring oil levels becomes critical.

3) Poor Acceleration and Power Loss

car speedometer

One of the most noticeable symptoms of worn piston rings is power loss. As the piston rings lose their seal between the piston and cylinder wall, engine compression drops dramatically. This loss of compression causes the engine to lose power.

Compression in the combustion chamber is vital for generating the force needed to drive the piston down on the power stroke. So as leak-down across the rings increases and cylinder pressures drop, the pressure pushing on the piston face lessens.

This directly diminishes the force available to the connecting rods and crankshaft, delivering less torque and engine power.

Drivers will feel loss of power especially when driving up inclines or pulling heavy loads. Demanding conditions will demonstrate the weakness of worn piston rings earliest. What was once an adequate amount of quick acceleration is now sluggish and lackluster for the driver, regardless of how hard they press the throttle.

Maintenance and diagnosis of pistons rings can hopefully restore normal power levels. But severe damage may require major engine work. Loss of power should prompt immediate inspection of ring integrity and operation.

4) Engine Knocking or Ticking

strange noise

As piston rings wear out, the pistons are no longer held tight against the cylinder wall. This allows more rocking and side-to-side movement of the pistons as the engine runs. This increased piston slap causes knocking or ticking noises from the engine bay.

Loss of the tight seal causes the pistons to rattle loosely and strike the cylinder walls, especially when accelerating or placing the engine under load. This abnormal sound indicates the piston integrity is compromised and too much movement is occurring.

The knocking noises tend to increase as the engine warms up. The noises may come and go as operating conditions change. Bad piston knock can initially come only under hard acceleration but worsen over time. This audible symptom draws attention to the underlying issue of piston ring failure.

Excessive piston slap places more lateral stress on the connecting rod bearings. The bearing wear can become apparent in the form of detectable lower engine knocking. If left unchecked, it can escalate into serious internal engine damage.

5) Excessive Oil in Intake

dirty air filter

Oil in the air intake is often a result of blow by. Blow by is when the air oil mixture in the combustion chamber escapes past the piston rings and creates a positive pressure in the crankcase.

This pressure is vented from the positive crankcase ventilation (PCV) hose back into the intake. When there is a large amount of blow by, you may notice your intake is quite oily.

See Also: 8 Bad PCV Valve Symptoms

6) Engine Overheating

Piston rings keep pressure in the cylinder long enough for combustion. They also play a valuable role in oil control to help properly lubricate the engine. As ring seal and tension decline, this oil control function starts to fail.

With faulty oil control, critical areas can lack enough lubrication. That increased friction and loss of lubricating oil film promotes overheating of engine components. It also creates hot spots meaning less effective heat dissipation with less atmosphere and oil movement.

Additionally, more oil seepage into the combustion chambers thins out the air-fuel mixture and reduces the cooling effects generated by the vaporization of fuel. The fuel can’t properly absorb heat and excessive internal temperatures result.

Finally, loss of compression also means higher peak temperatures in the failing cylinders.

All of these consequences of leaky piston rings lead to overheating and heat-related breakdowns. Bearings wear faster, seals harden and fail, engine parts reach damaging temperatures.

Together these effects can contribute to an engine overheating and lead to permanent damage and even catastrophic engine failure. All that to say, don’t ignore faulty piston rings!

Piston Rings Replacement Cost

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piston rings replacement cost

The replacement cost of the piston rings will be quite expensive. The piston rings themselves only cost between $100 and $200 for the parts. However, most of the replacement cost has to do with the labor behind it.

Since the piston rings are inside of your engine, this means an auto mechanic will need to remove the engine from your vehicle and disassemble the whole thing so they can access the worn-out piston rings.

After they replace the piston rings, they must reassemble the engine and install it back into your vehicle. The book time on an engine rebuild is anywhere from 12 to 20 hours, depending on the vehicle. Note that not all mechanics are able to perform this repair, either. A proper engine rebuild requires specialized tools and a very clean workspace.

With a labor rate around $150-250 per hour, you can see how the labor cost adds up really quickly. The total cost to rebuild an engine and replace the piston rings will be anywhere from $3,000 to $6,000.

Of course, this price range could be even higher if your engine is harder for the mechanic to access. It all depends on the make and model of your vehicle.

What Are Piston Rings?


Most combustion engines have pistons. Pistons, along with the closed valves in the head, are used to seal the combustion chamber while the air fuel mixture is igniting on the combustion stroke. As the air fuel mixture ignites, it forces the piston down the cylinder bore.

The piston is connected to the connecting rod, which also connects to the crankshaft. As the piston travels downward, it rotates the crankshaft which creates the power that propels your vehicle.

Pistons must form a tight seal against the cylinder walls in order to achieve complete and efficient combustion. This seal is created by a series of piston rings that envelop the piston. As the engine wears, the piston rings may not seal as well, or they may even crack over time due to heat or incorrect tolerances.


41 thoughts on “6 Symptoms of a Bad Piston Rings (And Replacement Cost)”

  1. I find it interesting that poor acceleration could be a sign of bad piston rings. My father recently gave his old car to my son for when he goes to college, it seems to be accelerating really slowly and we weren’t sure what was causing it. The car had been in storage for a few years so it probably got worn out there. I’ll have a mechanic look at his piston rings and get the necessary auto parts replacements for it.

  2. I have a 2012 Peugeot RCZ, 70,000 miles. Always been serviced by Peugeot. Burned through an oil change in about 2 months. Took it to mechanic and no pressure from cylinder 2. Best way for this to be repaired?

  3. Hi. My car had been consuming more oil than usual. Changed my piston, crankshaft and the engine block. The engine was mounted and sounded pretty good. I noticed that the number one plug wasn’t responding so well as the others. How do I correct this. Thanks

  4. I changed my oil and the oil filter yesterday and went on a 125 mile journey to fined out there was no oil in my engine. Used to see black blue smoke from the pipe. What is my problem?

    • Sounds like maybe the drain plug or oil filter wasn’t tight and you lost a bunch of oil. Have you checked under the car to see where the oil went?

  5. Heyo i know this thread is Old but i have some of these issues on My bmw e90 328i from 2010, i have had a compression test and it showed 1 of the cylinders had half the compression as the others, but the power delivery is stil solid, but mabye a bit shower when i tried comparing My acceleration to the same model on YouTube videoes, but anyway, when i turn on the car it bounces the revs alot up and Down for like 2-3 second and then idles, and then i smell burned oil for the first 5 mins in idle and then it stops, and when its warm and ive come to an idle then some times it
    Smells and some times not, but the weird thing is i dont lose oil, when it first started occuring i lost oil everytime i drove it very hard for a Long period, but just cruising i could go months without loosing oil, so do guys Think its just the piston ring Thats the problem from all that or is there more to it?

      • A leak down test is where you remove one spark plug, put compressed air into the cylinder on the compression stroke, and see where air is excessively leaking out. You’ll see a little bit of leakage on any vehicle, but if you can’t hold much pressure there’s a problem somewhere. You then repeat this process for each cylinder.

        It’d probably be best to have a mechanic do this if you want to check the piston rings.

  6. Hi there Kevin,

    Great info! So, I have a 2006 Infiniti M35x with 338K miles. I’ve replaced the catalytic converter and according to my mechanic, it has worn piston rings and the cat conv is failing again. Car has symptoms 1-3.

    Also, have a 2013 Infiniti G37s with 204K miles. It has symptoms 3-4. Cat conv is failing in this car, too.

    Both cars are failing emissions due to O2 Sensor & Catalytic converter codes. Are Nissans and Infinities known for bad pistons – or is it just old age? I also had a 1999 Nissan Maxima that made it to 380K. I tore that car up after having the engine clean – dumbest thing ever.

  7. Thanks Sean!
    Yes, I do have something called VCDS by Rosstech. I just don’t really know how to use it. I did a little personal research to find out how to use it and what to look for but I really don’t know much.

    Well, one of the shops I go to told me they ordered replacement hoses for my intercooler and see if that fixes the issue. I’ll update and let you know how it goes. If it’s still having the same issue even after fixing the little leak, then I guess it could be something to do with piston rings going bad and losing compression somewhere or maybe turbo seals that also need to get replaced?

    I will remember to ask them to take a look at the spark plugs and see if it’s fouled up. I am always running rich…somewhere in the -16 to -18 range for LTFT. I wonder what that could give a clue to?

    • A leak down test will tell you a lot more than I could. Since you’re running really rich (-16 to -18 LTFT is a lot), I don’t think the rings are the source of your fueling issues. To my knowledge, worn piston rings won’t change your AFR they’ll just make each power stroke less efficient.

      I think it would be best to lean on your shop(s) for more assistance, since they are already in there helping you diagnose the car. I’d love to hear back with their findings though!

  8. I have 2013 VW Scirocco R, 2.0 L TFIS (ea113), 72,000 km, automatic trans. and it was APR tuned to Stage 2+ (when I bought it used in 2017 with 54,000 km). I don’t drive it much, around 8000 km max per year.

    I’m experiencing loss of acceleration power at low speeds (from 0 to 80 km/h) it seems to stumble or hesitate while lightly speeding up to 80 km/h (I’m only giving it 1700-2000 rpms). I also see my boost readings go up to around 7 psi (0.5 bar) at such light acceleration/speed. It seems to do much better when I’m up to speed (80 km/h +). I don’t see any excessive smoke/white/blue. I do hear a little of a whoosh/air sound when accelerating (could be a boost leak?). One mechanic told me he found a little intercooler hose leak both before the intercooler and after (the two pipes that lead to and out of the intercooler). I believe it is also an aftermarket intercooler (APR) so it’s a bigger diameter hose. Even though it has been re-tightened, he says if you accelerate the engine moves and the movement causes the hose to rub against another object in the engine bay and that is what is causing a leak. There is also some oil that drips out but not excessive but enough to warrant me having to top off my engine oil every few months (as I only drive it about twice a week).

    My question is, is it likely that the leaks in the intercooler hoses (turbo to intercooler and intercooler to engine) is what is causing my loss of acceleration power under load from 0 to 60 km/h? It was suggested to me that I should replace the entire intercooler system to stock, but some have told me I can just replace the hoses with new ones.

    I’m also aware that other potential issues could be: worn piston rings, turbo seals going bad, and lastly bad spark plugs and coils (even though I had new ones installed about 2 years ago when the car was at 58,000 km). I don’t think they’d go bad after just 14,000 km unless all the misfiring has damaged or compromised them?

    But first thing is I should fix the intercooler hose leaks and see if my acceleration returns to normal. No fault codes.

    Also, around the time this first happened was when the car was sitting outside overnight during cold winter season. The next morning I took it to a car emissions center literally right next door to my parking lot so the car wasn’t even warmed up. He started up the car and for whatever reason (probably to warm it up faster) he revved it to redline 1 second after starting the engine while it was freezing cold!! I saw all this white smoke out from the back which I think was just due to condensation of exhaust gases being forced out so strongly, but it startled it me because I always believed you shouldn’t rev the engine to redline when it’s cold especially a winter morning and it hasn’t even had 1 minute to warm up. It made think that somehow him doing that may have caused a seal to go bad or a leak in the hoses because as you know cold objects under pressure have no flex or give so they can snap or break/crack easily vs when they are warmed up and have a lot of give and play to it. The symptom of loss of acceleration started 1 or 2 days after this incident so I don’t think it was a coincidence but I think he somehow caused this issue I have but I can never prove it now since it has been over 18 months ago. Do you think I am correct or am I just being paranoid? Please answer and help! I’ve been struggling for answers for 18 months on this and tried many mechanics and many forums and still haven’t got this resolved.

    • You’re right, you shouldn’t rev to redline like that on a cold engine. However, just doing it once probably didn’t break anything. When your engine is cold, oil is thicker and tolerances inside the engine are different, so the engine may not be lubricated quite as well as it would be while the engine was warm. You can do a compression test if you’re concerned. It’s generally a good idea to do a compression test anyway when you are modifying your car. If your compression test is less than stellar, a leak down test will tell you exactly where you are losing compression.

      Definitely get the boost leak addressed before going too much further; there is a good chance that’s your issue. If you have any real time monitoring software, plug it in while driving around in a safe area away from traffic. A tool like Tuner Studio or a COBB Accessport should help you figure out if you have a leak, and how your ECU is trying to compensate for it. If you notice your air fuel ratio going excessively lean or rich, or you notice large knock events, start there.

      Consider performing a smoke test to find any and all leaks. If you just changed your plugs and coils, that probably isn’t the issue but I would still pull a spark plug or two. Your spark plugs may give you a hint about what’s going on. If they’re fouled you may be running rich, and if they look burnt or white you may be running lean.

      Hope this helps, and good luck.

  9. I have an 03 Infiniti fx 45
    Car doesn’t overheat but white smoke comes from exhaust like in first picture it slows and fastens as the engine does it’s thing. Could it be the valve seals, bad head gasket or piston rings?

    • That’s quite a lot of smoke and a good indicator that you’re burning coolant. I would think about doing a leak down test to determine if there is a head gasket leak.

      Bad valve guide seals mean you’re burning oil, not coolant. Oil probably won’t give you white smoke like that, it’ll have more of a bluish tinge. Check out this article for more info: http://oards.com/valve-guide-seals-symptoms-and-cost/

    • Hi so i bought a scooter recently the lad i bought it of claimed a big hole in the exhaust was causing the engine to be loud asf now further on inspection it is blowing alot of white smoke out when running and its spitting fuel out from between the cylinder block and the cylinder head am i right to think my head gasket has blown and its coolant mixed in with the fuel that spits out everytime its kicked over

  10. I have a 2016 1.2 TSI Polo (hatchback) with 150 000kms.
    The car drove as it normally does with none of the above signs (exhaust fumes, oil leaks/excessive consumption, etc.). We tried to start it, 2 days after moving it from the garage to the driveway, and it just makes a continuous winding noise. It does not shake/shudder.
    The mechanic has checked and found that there is a loss of compression.
    Once he opens the head of the engine, and replaces the valves or pistons (whichever is needed), my question is…will it be worth it to keep my car or should I sell it before I experience further related issues?
    After this large cost, would the engine give me 2 – 3 years further?

    • Those are hard questions to answer. What’s the car worth to you? Are there other components of the car that are near their end of life (shocks or wheel bearings, for instance)?

      If you’re up to date with the rest of your maintenance and you like the car, it might be a good idea to keep it after the engine work has been completed. Personally, I like to stick with the maintenance history I know instead of diving into a new-to-me car with its own set of unknown problems.

      If the engine rebuild is done correctly, you should easily be able to get another 2-3 years out of it, assuming it’s been well taken care of.

  11. I have a 2011 tsi Passat. I have all 4 symptoms above. The car now runs like ****. Had it compression tested and one of the cylinders has no pressure. If I get knew rings will that fix it or does it need a full rebuild ? Using lots of coolant too.

    • I think it depends on what you mean by “full rebuild”. If you’re going far enough to replace the piston rings, I’d replace anything else that looks worn out along the way. You won’t really know for sure what that is until the engine is taken apart.

  12. I just replaced the pistons and rings, but at first start it’s blowing lots of blue smoke. I assume that’s not normal? 🙁 Well, it stopped after about 5 minutes of idling at 2000 to 2500 rpms. Maybe it was just all the oil I dumped into the cylinder bores when tapping in the new pistons to make sure nothing stuck or came out?

    • Blue smoke is usually oil burning. If you dumped a lot of oil in the combustion chamber on reassembly, that could be the cause. I’d keep a close eye on it and see if the issue persists.

  13. I went to both an Audi dealership and a local German repair shop and I was told it would be $6000-8000 by both of them… My 2012 Audi A4 has all of the problems listed above except for the last one. I just replaced my coils and spark plugs in November in the middle of a road trip because my car just started vibrating like crazy (misfiring). It started again around January and the extended warranty has already expired. Now it misfires when I accelerate slowly to 25 mph… I have no idea what to do because no one is going to take it with these issues but the car itself was already $12,000 when we bought it used in late 2017.

      • misfiring and knocking on low acceleration is also a sign of water on the sparkplugs…that happens when you have a blown head gasket and coolant gets in the oil. If that is the case, the car will overheat, the coolant level might drop, and depending on how long that persisted, you might have a milky/peanut butter like look on the oil cap.

    • I had to have my piston seals and gaskets changed and my 2019 Chevy Camaro and I was told by the dealership that if my 36,000 mi warranty runs out it’s still covered under 60,000 mile powertrain. How true is that

      • It’s probably true if your vehicle has less than 60,000 miles. You shouldn’t need heavy engine work like that on such a new vehicle.

        That said, if you starved the engine of oil, modified the engine, or didn’t follow the recommended maintenance interval, it could compromise the warranty.

  14. Getting a really high quote from a local dealer for replacement of all 4 of my piston rings which I am told involves an engine flush and an oil change. $3,900.00 I was told 20 hours of labor and 900-1200 for parts.

  15. Oh ok so I’m using synthetic oil and for the first time of me using synthetic oil my car began blowing out blue light smoke 5 days after me getting a full service including oil change . I am beyond concerned because my has never done that it is a 2016 Toyota Avalon it blows out smoke every few days once or twice throughout the day of me driving , any suggestions

    • Out of curiosity, what made you switch to synthetic? While it does a better job of lubrication, it also has different flow properties. So if you have any wear on your piston rings or valve seals where conventional oil didn’t seep through, synthetic likely will find a way through. Depends how much oil you’re going through. Fixing the problem (leaking rings or seals) is the best thing to do but you can simply live with it (and add oil as necessary) or switch back to conventional oil.

    • This a reply to a post that is more than one year old. Just in case anyone has a similar experience.

      Unfortunately in this case it sounds like something went wrong after it was serviced by the Exxon facility. My guess is that it leaked oil to the point where the engine was being driven with little lubrication causing the piston rings to wear excessively.

      This engine may need to be rebuilt and may cost thousands of dollars to do so.

      The lesson here is to monitor your vehicle after an oil change to verify that your oil level is where it should be.

      A number of things can go wrong at the oil change location:

      1) Oil drained, filter replaced, technician forgets to fill with oil.
      2) Oil drained, filter improperly replaced resulting in slow leak leading to engine damage over time.
      3) Oil drained, drain plug improperly replaced resulting in slow leak leading to engine damage over time.
      4) Any combination of the above.

      • I have used synthetic oil because that’s what it says in the owner’s manual (I have a 2016 Elantra GT). I go through at least a litre of oil a week. I am having a hard time coming to the conclusion that it makes sense to spend $5-10 thousand on a new or rebuilt engine. What would you do if it was your car? Also I am considering a road trip at christmas that would be 9 hours one way. Would it be wise to make a long trip in a car that uses as much oil as mine does? I have no blue or black smoke, and engine isn’t sluggish (or any more sluggish than any other 4 cylinder engine usually is). I hear a rattle, usually when turning left, but haven’t checked to make sure there’s nothing in the wheels. If the owner’s manual says synthetic, can I still use regular oil?

  16. What happens if u have all these signs except the exhaust smoke. I need to put oil in my car more than I have ever done b4. I do not have an oil leak. So could this be about the values? Last time I took my car to the mechanic cause I lost all power cpl years ago. He replaced the points and coils. And it ran fine. I do have the same sluggish engine again now. So I’m unsure on wat it maybe.

    • If it’s not leaking oil on the ground, it’s burning it. Most commonly it’s piston rings or valve guide seals. You may not always see smoke out of your tailpipe if it’s not too severe. Make sure you’re not using synthetic oil since it can get through seals where a conventional oil wouldn’t.

      • Hi Kevin thanks for your advice.
        I’ve been using synthetic oil from when I purchased the car because I always serviced my car at the Toyota dealership to my knowledge they was using synthetic. I had my car serviced by Exxon and they used synthetic oil from what my invoice said and approximately 3 days later I started up my car and smoke came out the exhaust so I kept driving and when I got on the freeway as a result of me accelerating more smoke came out and then my low oil pressure light came on. I took it back to the place they said it was no oil in my car so they put oil again and it still does it . I also have high mileage as well so I’m not sure if that’s the reason or not . I’m not sure if I should change the oil either to a thicker oil .

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