Pistons: A short intro

Pistons are the very heart of the reciprocating internal combustion engine, which is why they are often called the “piston engine.” The piston is simply a solid cylinder of metal, which moves up and down in the hallow cylinder of the engine block.
The purpose of the pistons is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod. The up and down movement of the pistons converts to a circular motion.

When piston damage occurs, the engine suffers. Damaged pistons also result in poor vehicle performance and many other problems. Luckily, piston failure causes a number of symptoms that can easily be noticed. In many vehicles, a faulty engine part triggers a dashboard light to go on.

The “check engine light” should be the first sign to make you suspect piston damage. The piston has many features, like the piston ring, piston crown and piston skirt.
Piston ring damage: The piston rings seal the gap between the piston and the cylinder, control the oil that lubricate the cylinder, and conduct away heat.

This will cause a noise due to the excessive rocking of the pistons and visible axial and radial wear. The damage of the piston rings can be caused by incorrect installation, improper dimensions, fuel flooding (mixture of fuel and air) and worn ring grooves.

The symptoms of damaged piston rings include: excessive consumption of lubricating oil due to it’s leaking into the combustion chamber, loss of compression and engine power, engine overheating and thick grey smoke coming from the exhaust.

Piston crown damage: The piston head operates in a very hot environment. Sometimes, there is a detonation in the combustion chamber or valve that come too close or even falls on the crown of the piston. This can be caused by a faulty coolant system, wrong fuel grade and faulty cylinder head components. The symptoms of damaged piston crowns include: engine noises, misfiring and reduced compression.

Piston skirt damage: A piston skirt helps to balance the piston within the cylinder. It is usually coated with a low friction material to enable smooth piston operation, but the skirt can wear or deform. Worn or collapsed piston skirts are caused by excessive rocking of the pistons, insufficient compression, bent connecting rod or lack of lubrication.

The symptoms of damaged piston skirts include: piston noise, poor engine performance, overheating and piston skirt seizure in the cylinder.

It is very risky do drive with bad or damaged pistons for it can cause greater damage to the engine. Trust your Audi and VW specialists at V.A.G. Spec Centre to help you identify this problem and take care of your vehicle.


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