What Are Pistons and What Can Cause Piston Damage?

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. 

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.

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. 

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.

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.

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.

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. 

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.

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.

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.

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. 

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, Volvo 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.