(Updated on August 25, 2021)
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?
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
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
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
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
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
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
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.
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.