What Are Pistons and What Can Cause Piston Damage? (2023)

A diesel piston is a very important component of any engine which is why we’ve created a quick guide to explain what a diesel piston is, how it works, what causes damage to piston parts and how to prevent this from happening.

What is a Diesel Piston and How Do They Work?

A diesel piston is a metal cylinder which moves up and down inside the engine cylinder through varying stages of the combustion cycle, which is connected to the engine’s crankshaft via a connecting rod. When a piston moves down, it draws in air and fuel into the cylinder and when the piston moves up this air and fuel is then compressed.
A piston also has the important job of creating an area of low pressure inside the cylinder, opposing the higher level of air pressure that sits outside the cylinder. As a piston forms the lower part of the combustion chamber in a diesel engine, it also has the job of absorbing the heat caused from combustion, conducting it away from the metal temperature to keep it within safe limits.

What Causes Damage to Engine Piston Parts?

So that you can take action before any damage affects the engine, we’ve compiled a list of the most common and specific causes of piston damage to ensure you can easily recognise the problem.

(Video) Piston Failure Analysis-Overheating

Common Causes of Piston Damage

1.Burned Piston
A burned piston can be seen instantly once the top of the engine has been removed. You should be able to recognise visible signs of melting and sometimes a burnt hole in the piston. A burned diesel piston is generally caused by dirty fuel injectors being used.

2.Cracked Piston
Cracked piston causes can include continued use of low-quality fuel. Or, a cracked piston can be a result of the failure of the exhaust gas recirculation system.

(Video) Piston Failure Analysis - Skirt Wear

3. Snapped Timing Belt
The timing belt plays a key role as it keeps the movement of the pistons and the valves in perfect alternating time. Once the belt has snapped, it can cause a collision between the two which can then lead to further damage. To prevent the timing belt from snapping, it’s important to change the timing belt according to the car manufacturer’s instructions.

Specific Causes of Piston Damage

1. Worn Diesel Piston Rings
If you’ve noticed white smoke coming from the tailpipe, low power for acceleration, overall power loss and also a significant drop in engine oil level these are key signs of worn diesel piston rings.

(Video) How To Tell WHY Your Piston is Destroyed

Your engine may experience these signs of piston ring damage as the seal between the piston and cylinder is no longer airtight, meaning the oil will leak into the crankcase and the firing chamber.

Worn diesel piston rings are a very common cause of piston damage, as the diesel rings circle around the piston act as a buffer between the combustion chamber and the crankcase, surrounding the crankshaft. Diesel rings are responsible for moving the heat away to the cylinder wall, whilst regulating the oil temperature.

Unfortunately, piston rings do wear out, and there is little you can do to prevent this. However, if you replace them routinely before they wear, it can play a great part in preventing damage to the engine.

(Video) Intro to Piston Failure Analysis

2. Piston Skirt Damage
The main cause of damage on the piston skirt is caused by rubble coming through the air filtering system. This can cause the piston rock within the cylinder to wear the skirt down, making the skirt thinner and weaker, which can eventually result in the piston breaking.

3. Piston Snap
If your car is starting to make a rattling or knocking noises that remains by the time the car has warmed up, this could mean that there is a large gap between the piston and the cylinder wall.

How to Prevent Diesel Piston Damage and Failure?

Piston damage can be very expensive due to the intensive labour involved to ensure the engine piston parts are fixed. This cost is usually high as the entire engine has to be taken apart for any issue to be resolved.

(Video) Bad Piston Rings - Symptoms Explained | Signs of failing or worn piston rings in your car

To prevent piston damage and failure, whether that’s diesel piston rings or other specific engine piston parts, ensure you are using the correct engine oil and that the oil and filter are changed at the recommended intervals by the manufacturer. You should also make sure the engine coolant is in good condition, which you can check by opening the radiator cap, or you can take a look at the water in the coolant reservoir.

It’s important to remember that diesel pistons are part of the overall engine and all diesel engines are different. Unfortunately, there’s no ‘one size fits all’ solution for anyone experiencing a diesel engine problem or an issue with their diesel rings. It’s also imperative to determine the cause of the problem and address this, before simply replacing damaged parts and re-assembling the engine.

Contact Foxwood Diesel today with your engine number, and exactly what difficulty you’ve had for us to be able to help you. Foxwood Diesel are specialists in the field of diesel engine reconditioning and engine rebuilds, with over 30 years of experience. We hold large quantities of diesel engine spares, many of which are available for same-day dispatch, and which are tailored to a range of car manufacturers, including Mercedes, Volvoand all other major diesel manufacturers. With our expert knowledge of diesel systems, we offer highly effective reconditioning and rebuilding solutions at our engine machining centre to worn-out engines requiring professional care.

(Video) Checking Pistons For Damage With $11 Ebay Borescope


What is the cause of piston damage? ›

The most common causes of piston failures include: their insufficient cooling, insufficient lubrication of the piston guiding part, thermal fatigue of the piston head surface, failures due to an incorrect combustion process, and mechanical damage.

How do you know if pistons are damaged? ›

The symptoms of a piston failure can include engine noise (rattling or knocking noises while the engine is idling), oil burning, misfiring and loss of power.

What are pistons on a car? ›

The piston is an essential part of the internal combustion engine which is key in converting the fuel which you use to fill up your car into energy to drive the car forward. It is a moving component which is used to transfer the force from the gas which expands in the cylinders to the crankshaft to turn the wheels.

What is the most common type of piston breakage? ›

Common Types Of Piston Damage
  • Burned Piston. The usage of unclean fuel injectors is the most common cause of a burnt piston. ...
  • Cracked Piston. Continued usage of low-quality gasoline can lead to cracked pistons. ...
  • Worn Diesel Piston Rings. ...
  • Damage to the Piston Skirt. ...
  • Piston Snap.
Sep 29, 2021

Why do piston engines fail? ›

Reasons that are known to occur include: Preventable fuel problems such as exhaustion, mismanagement, contamination, or misfueling. Structural failures where a broken connecting rod, crank, valve, or camshaft is present account for seventeen percent of engine failures, primarily in Continental engines.

What does piston damage sound like? ›

Sounds like: Continuous muffled, hollow sound. Common causes: Excessive piston-to-wall clearance, worn cylinders or inadequate oil. A continued piston slap noise indicates that the engine needs service. Still, if the sound is only heard when the engine is cold, it is probably not a serious issue.

How often should pistons be replaced? ›

Piston replacement intervals are typically outlined in your machine's factory service manual. Using dirt bikes as an example, many manufacturers outline a piston and ring replacement schedule of every six races or 15-30 hours for a four-stroke, depending on the machine.

Can a damaged piston be repaired? ›

Moreover, the piston is not repaired or changed alone, it requires changing gasket, rubber sealings, valves and engine oil which can increase the overall cost.

What is a piston simple definition? ›

noun. pis·​ton ˈpi-stən. : a sliding piece moved by or moving against fluid pressure which usually consists of a short cylindrical body fitting within a cylindrical chamber or vessel along which it moves back and forth.

What is the main function of a piston? ›

Pistons work by transferring the force output of an expanding gas in the cylinder to a crankshaft, which provides rotational momentum to a flywheel. Such a system is known as a reciprocating engine.

What is piston and its function? ›

It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod.

What does a burned piston look like? ›

Answer: It means the piston failed due to excessive heat in the combustion chamber. A burned piston will typically have a melted appearance, or a hole burned completely through the top of the piston.

What are the signs of piston wear? ›

The Signs. When drivers notice excessive oil consumption, white or gray exhaust smoke, poor acceleration, and/or overall loss of power or poor engine performance, they may be seeing signs of worn piston rings.

What causes a piston to lose compression? ›

Compression loss is a result of a leak in one or more of the cylinders caused by normal engine wear and tear. If you experience compression loss in one cylinder of the engine, it can cause misfiring and poor vehicle performance. A decrease in power output is a sign of worn-out internal parts.

How long does a piston engine last? ›

The number varies from engine to engine, but is generally around 2,000 hours, give or take a few hundred hours. Some owners operate their engines hundreds of hours past TBO with no ill effects. More often, however, the opposite is true.

What is the life of piston? ›

For a large two-stroke piston ring with a bore of approximately 900mm, the overall life of the ring can be up to 24,000 hours and for smaller engines of 500mm bore, it can be up to 16,000 hours. For auxiliary marine 4 stroke engines having high speed, the piston ring life is usually lesser than the 2 stroke engine.

How much piston damage is OK? ›

A minor change in piston-to-wall clearance can be considered normal, but changes in the piston-to-wall clearance of more than 0.002-inch should be considered a good excuse for a change.

How a piston affects engine performance? ›

The piston is at the heart of how an engine creates motion. Adding pistons to an engine or making them bigger increases displacement, which means the engine generates more power because it burns more gasoline.

Why does my piston keep breaking? ›

During engine operation, pistons can break as a result of a forced fracture or can suffer a fatigue fracture. A forced fracture (Fig. 1) is always caused by a foreign body that collides with the piston while the engine is running. These foreign bodies could be parts of the connecting rod, crankshaft or valves, etc.

How do I test my pistons? ›

This can be measured with a feeler gauge between the top of the ring and the groove. Worn ring lands can also exhibit more clearance toward the outboard edge of the groove, creating a bell mouth effect, which will negatively affect ring seal. Ring groove clearance is another measure of the health of a used piston.

How much does it cost to fix pistons? ›

The Average Cost for Piston Ring Replacement Is $75-$3,500, Depending On If You Go to the Mechanic or DIY.

Can you fix a damaged piston? ›

Moreover, the piston is not repaired or changed alone, it requires changing gasket, rubber sealings, valves and engine oil which can increase the overall cost.

How much does it cost to fix a blown piston? ›

A blown piston averages $100 to $200 per hour for your mechanic to replace. Also, a new piston ring costs approximately $100, which you'll have to add to the time it takes your mechanic to finish the job.

Can you repair a damaged piston? ›

Pistons can be replaced, but it is usually cheaper to replace the engine with a re manufactured or used unit.


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