Worn piston rings could be the culprit if your car’s engine isn’t performing as it should. These small components help to maintain efficiency and power. While they typically last over 150,000 miles, replacing them is time-consuming because it involves taking the engine apart.
So, how much does it cost to change piston rings? The price can vary from a few hundred to several thousand pounds. Let’s break it down so you can make an informed decision.
In a nutshell: The average piston ring replacement cost across all makes and models is £877.06.
What are piston rings?
Piston rings create a seal between the piston and cylinder wall, preventing pressurised gases from entering the oil sump. They also prevent excessive oil from entering the combustion chamber and getting burnt.
Click here to learn more about how engines work.
Most pistons in cars have three rings:
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The top and middle rings press tightly against the cylinder wall and seal the combustion chamber.
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The oil ring (at the bottom) scrapes oil off the cylinder wall on the way down the cylinder and deposits it in the oil sump.
Since the cylinder wall and ring interface require a thin layer of oil for lubrication, it’s normal for some oil to burn during combustion.
Oil consumption can vary between different engines and depending on the engine’s age. Older cars tend to go through oil much quicker than new ones.
Average piston ring replacement cost in the UK
According to FixMyCar’s quote data, the average price of a piston ring replacement is £877.06.
| Make | Average Price |
|---|---|
| BMW | £816.51 |
| Mercedes | £1,536.78 |
| Nissan | £1,939 |
| Peugeot | £885.86 |
| Toyota | £1,246.72 |
| Vauxhall | £765.63 |
| Volkwagen | £1,630.36 |
| Volvo | £2,850 |
Our data for piston ring replacements is limited as this job is less common than others on our platform. The best way to get an accurate price estimate for your car is to request quotes on FixMyCar.
What happens when piston rings fail?
Worn piston rings allow a gap to form between the cylinder wall and the ring. This gap allows the pressurised gases that drive the piston to travel further down the cylinder wall and into the oil sump. Not only does this lead to a drop in efficiency, but it also contaminates the engine oil.
A similar outcome happens when piston rings become stuck due to carbon deposits in the ring grooves.
Signs of piston ring failure
Recognising the symptoms of worn piston rings early can save you from bigger engine issues down the road. Here’s what to watch for:
1. Lack of power
When combustion gases escape into the oil sump, they take some of your car’s horsepower with them. Reduced pressure in the cylinders will lead to a significant drop in performance.
Read about other reasons your car might lose power.
2. Discoloured exhaust smoke
Piston ring failure allows engine oil to enter the combustion chamber, where it gets burnt. This upsets the precise mixture of air and fuel required for efficient combustion, creating thick exhaust smoke that may be dark grey or blue-tinged.
3. Excessive oil consumption
If your oil level drops quickly after topping it up, it could mean oil is seeping past damaged piston rings and burning in the engine.
Find out how much an oil change costs.
4. Shuddering or stuttering
Worn piston rings can lead to inconsistent compression, causing your engine to shake or even stall.
Can I drive my car with bad piston rings?
Depending on how worn your piston rings are, it may still be possible to drive – but that doesn’t mean it’s advisable. It can lead to:
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Reduced efficiency
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Loss of power
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Thick exhaust smoke
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Increased emissions
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Engine problems
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Oil leaks
It’s best to get faulty piston rings replaced as soon as possible to keep your engine running smoothly.
Book a piston ring replacement
Think your piston rings are worn out? FixMyCar can help you compare prices from trusted local garages so you get the best deal.
Frequently asked questions
Worn piston rings can cause knocking or pinging noises. If you hear unusual sounds, it’s worth getting your engine checked. Find out what else can cause knocking sounds here: https://www.whocanfixmycar.com/advice/why-is-my-car-knocking
If your car is valuable and you plan to keep driving it, replacing the piston rings is probably a worthwhile investment. However, if your vehicle is older and has a low resale value, you may want to weigh the cost of repairs against the car’s worth.
Piston rings are essential for engine function. Without them, your engine wouldn’t be able to maintain compression, leading to damage.
Both issues can cause similar symptoms, such as burning oil. A compression or leak-down test can help diagnose the problem, or you can take your car to a mechanic for a professional opinion.
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