5 Symptoms of a Bad Piston Rings (and Replacement Cost)

(Updated on June 16, 2020)

The engine inside of your vehicle contains a series of rings that are called piston rings. These rings help regulate the oil pressure and the amount of oil consumed by the engine.

If the piston rings were to get damaged or worn out, then you will have all kinds of problems happening with your engine. Even though the piston rings are small and inexpensive parts, they are critical for the operation of the engine.

What Are Piston Rings?

pistons

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.

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 top 5 symptoms of bad piston rings.

1) Too Much Exhaust Smoke

smoke from exhaust

If there is a lot of exhaust smoke coming out of your vehicle, this could be an easy sign that you have bad piston rings. This smoke will look very thick and have dark gray and blue colors to it. It is often accompanied with a burning oil smell. 

When you have bad piston rings, engine oil will start leaking into the combustion chamber. Once that happens, the oil will burn and create the thick blue gray exhaust smoke that you see coming out.

2) Excess Oil Consumption

oil pressure check engine light

This symptom has the same result as the first symptom listed here. When you have worn piston rings and oil leaks into the combustion chamber, it will cause a lot more oil to be used up by the vehicle.

This means you’ll have to regularly add oil to your vehicle rather than wait the standard 3,000 to 5,000 miles before you do it. If you find yourself adding oil more often than you should, then have a mechanic inspect your piston rings.

3) Poor Acceleration

car speedometer

When piston rings suffer wear or get damaged, your engine will lose its power because there is less compression taking place.

This means when you put your foot on the gas pedal to accelerate, the vehicle will take a long time to speed up. In this case, you will need to have your piston rings replaced to fix the problem.

4) Poor Vehicle Performance

engine stall

The worst-case symptom of bad piston rings is when you lose all power in your vehicle. You won’t be able to accelerate your vehicle at all and its overall performance will be very poor.

You’ll probably have to tow your vehicle to the nearest mechanic because the performance will be so bad. However, you will only experience this symptom if you’ve ignored the first three earlier symptoms as they occurred.

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. 

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 $30 to $150 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 it 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 whole process will take over 10 hours on average.

Read also: 5 Symptoms of a Brake Fluid Leak and Average Repair Cost

The average auto mechanic charges between $100 to $200 per hour to perform a replacement job of this magnitude. Therefore, let’s say it takes your local auto mechanic approximately 11 hours to perform this task, this means you’ll be paying between $1100 and $2200 just for the labor alone.

Add about $100 in parts and that will come out to $1200 to $2300. 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.

28 thoughts on “5 Symptoms of a Bad Piston Rings (and Replacement Cost)”

  1. 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.

    Reply
    • 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.

      Reply
      • 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 .

  2. 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

    Reply
    • 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.

      Reply
  3. 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.

    Reply
  4. 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.

    Reply
      • 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

      Reply
      • 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.

  5. 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?

    Reply
    • 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.

      Reply
  6. 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.

    Reply
    • 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.

      Reply
  7. 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?

    Reply
    • 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.

      Reply
  8. 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?

    Reply
    • 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: https://oards.com/valve-guide-seals-symptoms-and-cost/

      Reply
    • 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

      Reply
  9. 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.

    Reply
    • 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.

      Reply
  10. 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?

    Reply
    • 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!

      Reply
  11. 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.

    Reply

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