The piston rings – being a very small part of the car engine, plays a vital role in the overall working of the engine. It seals the piston and the cylinder wall so that the gases produced in the combustion chamber do not leak out and combustion can happen to generate power to run the engine.

If the piston rings get damaged, several issues can arise with the engine such as insufficient engine power output and increased fuel consumption. However, it is quite inexpensive to buy a piston ring but when it comes to replacement the cost can go very high as it includes the disassembling of the whole engine.

Let’s get to know more about piston rings!

Why Piston Rings Are Used

The piston rings are as essential for the engine as the piston itself. Without piston rings, the engine can’t work with its full efficiency and power. The piston rings are needed for these three important functions-

The piston rings work as a sealant between the piston and the cylinder wall so that the gas compression generated between them does not leak. And the engine can produce enough power. This also contributes to better fuel economy.

When the ignition is on in an engine, the piston has to move up and down several thousand times a minute that causes friction between them. To reduce friction and ensure the smooth working of the piston, a little amount of oil is applied to the piston for lubrication. And piston rings regulate the amount of oil required for lubrication.

The heat generated during the combustion process increases the temperature inside the piston up to 300 C. if this heat is not warded off, the engine may get damaged. The piston rings help release this heat and ensure the smooth working of the piston.

Aside from the piston rings’ three important roles, these are designed and placed in a way that prevents the piston from touching the inside parts of the engine that may cause engine failure.

Different Types of Piston Rings

Generally, the piston rings are used in smaller engines where they fulfill a certain specific purpose.

There are mainly three types of piston rings – compression ring, wiper ring, and oil control ring. Let’s have a look at their dedicated purposes.

#1 – Compression Ring

The compression ring is placed in the top groove that is near the piston head. This ring provides sealing between the piston and the cylinder wall and prevents gas leakage from the combustion chamber.

When the ignition of the air-fuel mixture takes place, the pressure of the combustion gas takes the piston ring against the cylinder wall to prevent the leakage of gas. This ring also helps in transferring heat from the piston to the piston walls.

#2 – Wiper ring

The wiper ring is placed just below the compression ring. The key function of the wiper ring is to clean the surface of the cylinder wall off the excess oil. Further, it supports the sealing of the combustion chamber by blocking any gas leakage from the top compression ring. This ring has a tapered face that is faced towards the bottom to ease the wiping process.

#3 – Oil Control Ring

This oil control ring is located in the groove that is near the crankcase. When the oil is poured on the cylinder wall for lubrication, this ring helps to spread the oil evenly around the piston liner and if there is any extra oil, it wipes off the extra oil and sends it back to the oil reservoir. Thus it also supports reducing the oil consumption with its efficient oil scraping.

Signs and Symptom of Bad Piston Rings

#1 – Exhaust Smoke

The most common and easily noticeable sign of bad piston rings is too much exhaust smoke coming out of your vehicle’s engine. This happens because of leakage of oil in the combustion chamber due to faulty piston rings. When the fuel is ignited, it burns improperly and produces thick gray and white smoke.

However, thick gray and white smoke can be an indication of other engine related issues also therefore you must take your vehicle to a professional mechanic for a thorough inspection.

#2 – Excess Oil Consumption

If you notice a sudden increase in oil consumption, your vehicle may have worn piston rings. The old and worn piston rings cause oil leakage into the combustion chamber that results in more oil consumption than usual. If this is the case with you, get your vehicle inspected by a mechanic.

#3 – Reduced Acceleration Power

When your vehicle has faulty or worn piston rings, the acceleration power of the engine gets reduced significantly. The worn piston rings cause leakage in the gas compression produced in the combustion chamber, the reduced compression means low power.

Thus it affects the engine performance indirectly and in the worst situation, the engine may stop accelerating at all. And you will have to tow your vehicle to the mechanic shop.

Therefore, if you notice any change in the acceleration power of the engine, you should take it seriously and get it inspected on priority.

How to Diagnose Faulty Piston Rings

The easiest way to test the piston rings is compression testing. You need a compression tester to perform this test on your own.

Let’s see how you can do it step by step.

  • Step 1: Disconnect the spark plug wires and also remove the fuses of the fuel pump and fuel injector. Once it is done, remove the spark plugs.
  • Step 2: Screw the threaded end of the compression gauge into the spark plug hole within the cylinder head.
  • Step 3: Now turn on the ignition, have someone to depress the accelerator pedal to block the throttle. And while the accelerator pedal is depressed, crank the engine up to ten revolutions.
  • Step 4: Note down the pressure reading being shown on the compressor. Do the same test for all the cylinders. The cylinder that will have pressure reading below 100 pounds-per-square-inch, it means piston rings are not in good condition.

To ensure, the fault is with the piston rings and not the valve seat, add a little engine oil into the cylinder and retest. If the reading fluctuates and shows improvement, the piston rings are worn out.

How Long Can You Drive With Bad Piston Rings

It is difficult to say how long you can drive with bad piston rings. However, your vehicle will run but with a lot of blue smoke and increased fuel consumption. But we recommend not avoiding the piston ring issues as it can become worse over time.

This is not only about the blue smoke and over fuel consumption, if you keep driving with bad piston rings over a long period, but the piston rings will also start putting stress on other components of the engine. It will affect the overall engine life and in severe conditions, it may lead to engine failure.

The replacement of piston rings is expensive but it is better to go with a replacement rather than getting fix the entire engine that could be many times costly than that.

What Happens When Piston Rings are Worn Out

When you drive with worn or damaged piston rings, several issues come up. The biggest hurdle you face is the poor acceleration that affects your driving experience. And it gradually makes the engine performance poorer. On one hand, you have to deal with excessive oil consumption and on the other hand, the damaged piston ring stops lubricating the piston and cylinder wall properly that result in the metal to metal rubbing with no lubrication.

All of these problems shorten the overall life of the engine that may require the complete rebuilding of the engine. At this point, you will need to look at whether the vehicle is worth spending on reassembling of the engine or it is too old and you should look for a new vehicle.


We would only advise that don’t go for reassembling of the engine until it is absolutely required. When you doubt that your engine has bad piston rings, get it inspected from more than one mechanic. If both mechanics tells you the same problem that piston rings are worn out, then go for the replacement of piston rings.