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understanding common causes of piston ring failures

As BISON delve into the common causes of piston ring failures, we’ll shed light on the potential consequences and offer insights into preventive measures.

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In the intricate symphony of a generator’s internal components, piston rings stand as unsung heroes, playing a crucial role in the engine’s performance and reliability. these small yet mighty rings form a vital barrier between the high-pressure combustion chamber and the engine’s crankcase, ensuring seamless operation.

In this article, we embark on a journey to unravel the mysteries surrounding piston ring failures—undoubtedly the Achilles’ heel that can compromise the heartbeat of your generator. As BISON delve into the common causes of piston ring failures, we’ll shed light on the potential consequences and offer insights into preventive measures.

Join us in this exploration to fortify your knowledge and empower your role in maintaining a resilient and reliable power generation system.

understanding common causes of piston ring failures

What are piston rings?

Before discussing piston ring failure signs, we must examine what piston rings are and where they are.

At the heart of a generator’s internal combustion engine lies a critical component— the piston ring. This seemingly humble ring, typically made of durable materials like cast iron or stainless steel, encircles the generator’s piston within the combustion chamber.

The combustion cylinder is where fuel and air mix and ignite, turning the crankshaft and creating an explosion. Turning the crankshaft fills more cylinders with the fuel-air mixture and ignites it. This motion creates the power needed to turn the engine. Piston rings are an integral part of the process. If the seal is not tight, the cylinder cannot be pressurized, and the engine will lose effectiveness. 

Symptoms of piston ring failure

The symptoms of a damaged piston ring are similar to those of a worn or damaged valve seal. Catching signs at an early stage will save your generator’s engine and save you huge bucks.

1. Discoloration or excessive exhaust

The symptoms are apparent. When you turn on your generator, your engine naturally emits exhaust, which should always be a thin white. Bad piston rings can cause drastic color changes or darkening.

When piston rings fail or wear too much to form a seal, the exhaust turns a thick, dark gray or blue. You may also smell burning oil.

When piston rings fail, the seals around the piston rupture during combustion, eroding the barrier between the fuel-air mixture and the oil. When the spark plug ignites the mixture, the leaking oil ignites with the air and fuel, resulting in a dirty burn. Dirty burns produce foul-smelling and smoke.

2. Oil leakage or excessive oil consumption

The engine will naturally consume some oil, but this only happens when the oil needs to be changed.

An engine starts to burn oil when it gets dirty or is overworked. Still, no fuel should be burned during the standard 3,500 to 5,000 miles between oil change services.

When you check your oil level before a scheduled service and find it low, it’s a sign that your engine is overburning or leaking oil somewhere. If you need to add too much oil before your scheduled service, your engine is burning or leaking.

3. Degraded engine performance

Poor engine performance can be the most severe piston ring failure symptom. A decrease in engine performance is easy to notice because your generator is not functioning properly. It stutters, trembles, and even freezes at times.

An engine that is not working properly will be unable to function efficiently. You don’t want to leave the engine in this state too long. Leaving it as it is will cause it to crash.

damaged piston ring

4. Oil in the intake manifold

A small filter in the engine compartment and the air intake draws in air. This air mixes with the fuel in the combustion cylinders and is partly responsible for turning on the engine. The fuel won’t get ignited without air, and the engine won’t start.

When combustion occurs around a failed piston ring, it can sometimes force oil back into the intake manifold. This process is called “blow-by.” You can identify blow-by by a film of oil in the air intake or oil droplets on the air filter.

If this sounds serious, it’s because it is. Oil doesn’t belong in the intake manifold, and it’s dangerous when it’s here. Any static shock can ignite the oil and seriously damage or injure your engine.

5 Low Acceleration

Noticeably sluggish acceleration is a common consequence of piston ring problems. The compromised seal affects the engine’s ability to generate sufficient power during acceleration, resulting in a lackluster performance.

6. Knocking or Thumping Sound

As the engine struggles with compromised piston rings, you may detect unusual knocking or thumping sounds. These noises stem from the irregular combustion caused by the leaking rings.

what are the possible causes of these bad piston ring symptoms?

By understanding what forms the cause of piston ring failure, we can better diagnose the root cause of the problem and recommend appropriate repair or replacement.

The symptoms of a damaged piston ring are similar to those of a worn or damaged valve seal. Catching signs at an early stage will save your generator’s engine and save you huge bucks.


Engine overheating has the potential to cause piston ring deformation. This deformation occurs when metal rings with a specific shape and elasticity change due to prolonged exposure to extreme temperatures.

Deformed piston rings exhibit reduced efficacy in preserving a secure seal, ultimately resulting in compression loss and suboptimal engine performance.

Poor lubrication

Insufficient or improper lubrication can cause excessive wear and tear on the piston rings. As a result they lose their functionality and can cause other engine damage too. It can also lead to piston ring sticking, where the oil fails to provide a sufficient seal, and the rings stick to the piston grooves.

Wear and tear

Normal engine operation gradually wears down the rings over time, eventually requiring replacement. And pushing the engine to its limits for long periods puts tremendous stress on the rings and accelerates wear.

Cylinder scoring

Piston rings sometimes scrape the cylinder wall, causing scoring. This can occur for a number of reasons, including the presence of abrasive particles in the cylinder, poor lubrication, or improper installation of the piston rings.

Intact piston and piston rings

Detonation and pre-ignition

Detonation or pre-ignition can cause an excessive temperature and thermal load on the piston rings, causing failure. It can lead to hot spots that weaken the rings and decrease their lifespan.

Abrasive particles

Dust, dirt, or any abrasive particles can accelerate wear of the piston rings and cylinders. These particles often make their way in the engine through the air intake and can cause significant damage over time.

Improper assembly

Incorrect installation, for example, misalignment during assembly or incorrect ring gap orientation, can cause unnecessary wear and tear, or even immediate failure of the piston rings. It can also cause the rings not to properly seal on the cylinder wall, leading to ineffective combustion and compromised engine performance.


Understanding and resolving piston ring failures is critical to maintaining the health and life of your engine. You can prevent more severe damage and costly repairs later by identifying signs of potential problems early, such as increased fuel consumption, power outages, or excessive smoke.

your trusted piston ring manufacturer

As a professional manufacturer of generator parts, With durability at its core and maintenance simplified, BISON’s generator piston rings offer not just a solution but a promise of sustained performance. And if the need arises to replace your generator spark plug, trust BISON to provide a seamless and compatible solution.

Empower your generator with the reliability it deserves. Act now to prevent, diagnose, and resolve piston ring issues. Choose BISON for quality components and meticulous care. Your generator’s performance is not just a matter of power—it’s a testament to your commitment to excellence.

Take the proactive step—choose BISON for a generator that stands the test of time.

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