What Are Pistons and What Can Cause Piston Damage?

What is a Piston?

The piston is a very important component of any engine. It moves up and down inside the engine cylinder through varying stages of the combustion cycle, connecting to the engine’s crankshaft via a connecting rod. One role of this piston is to draw air and fuel into the cylinder when the piston moves down then when it moves up, the air and fuel are compressed.

In addition, it 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.

Common Causes of Piston Damage

We have compiled a list of the most common piston problems, as well as their symptoms, to help you recognise these problems and take action before the damage affects the engine. Sections 1-3 cover specific piston parts and the damage which can occur and sections 4-6 are common damages that appear generally in pistons.


1. Worn Piston Rings

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

The result of piston ring damage can cause the seal between the piston and cylinder to become no longer air tight, meaning the oil will leak into the crankcase and into the firing chamber. Worn piston rings symptoms include white smoke coming from the tailpipe, low power for acceleration, overall power loss and you may also see a significant drop in engine oil level too.

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.

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 rattling or knocking noises that still remain by the time the car has warmed up, this could mean that there is a large gap between the piston and the cylinder wall.

4. Burned Piston

A burned piston can be seen instantly once the top of the engine has been removed, with visible signs of melting and sometimes a burnt hole in the piston. This is generally caused by dirty fuel injectors being used.

5. Cracked Piston

Cracked pistons causes can include continued use of low quality fuel, or alternatively they can be a result of the failure of the exhaust gas recirculation system.

6. 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. In order to prevent the snapping of the timing belt, it’s important to change the timing belt according to the car manufacturer’s instructions.


How to Prevent Piston Damage and Failure

The reason piston damage can be so expensive is because the labour involved is intensive, with the entire engine being taken apart in order for them to be fixed.

To prevent piston damage and failure, ensure you are using the correct engine oil and the oil and filter are changed at the recommended intervals by the manufacturer. Furthermore, you should make sure the engine coolant is in good condition, you can check this by opening the radiator cap or you can take a look at the water in the coolant reservoir.

It’s important to remember that pistons are part of the overall engine and all diesel engines are different, with a no ‘one size fits all’ solution existing for any one diesel engine problem. It is 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 been having in order 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, Volvo, DAF and 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. Get in touch so that we can find the right solution for you!