Guide

Pistons in the engine

In a motorized system, the crankshaft must rotate to convert combustion energy into mechanical energy. Here is the piston that moves to rotate the crankshaft. As it pushes the piston with expanding gas and then the crankshaft, it begins to rotate.

The piston is a component connected to the crank system in motor vehicles. It is possible to extend the life of an engine by minimizing wear on the piston. The material of the piston and its shape are clues that support this service life. Although it looks like a simple component, the piston, the sizing of which requires engineering expertise, is one of the most important parts of a motor vehicle.

We offer pistons for engines, including agricultural and construction engines, with diameters ranging from 64.0mm to 140mm. From small compactors or aggregates, to huge 12-cylinder engines.

Issues addressed in the article:

1. The role of pistons in an engine 
2. Piston faults – common piston problems 
3. Piston pin clearance: symptoms
   1. Too much play on the piston pin
   2. Too little play on the piston pin 
4. Piston cracked or burned out? 
5. How to select a piston for a cylinder?

The role of pistons in an engine

Pistons play a key role in an internal combustion engine. Their main task is to convert the explosive energy of the fuel into mechanical energy by generating rotational movement of the crankshaft. Here are some of the key functions that pistons perform in an engine:

Movement in the cylinders

Pistons move up and down in the engine’s cylinders in response to the exhaust gas pistons and the pressure generated by the burning fuel. It is the movement of the pistons in the cylinders that generates the rotational motion of the crankshaft, which is transmitted to the drive wheels or other drive mechanisms of the vehicle.

Cylinder sealing

The pistons are equipped with sealing rings to prevent exhaust gases from leaking into the crankcase and to maintain adequate pressure and compression in the cylinders.

Energy transfer

During the downward stroke of the piston, the energy generated by combustion of the fuel mixture is transferred to the piston through the exhaust gas tract. This mechanical energy is transferred to the crankshaft through the connecting rod, which causes the crankshaft to rotate and ultimately generates power.

Vibration reduction

The pistons are designed to minimize vibration and oscillation during engine operation, which affects driving comfort and engine durability.

Heat dissipation

Pistons need to be cooled effectively to maintain proper operating temperatures. Therefore, pistons are usually made of aluminum or aluminum alloys, which are lightweight and conduct heat well.

In short, pistons play a key role in the energy conversion process in an internal combustion engine, converting the energy of a fuel explosion into mechanical energy that propels the vehicle. Their precise operation and durability are essential to the proper functioning of the engine.

Piston faults – common piston problems

The most common piston malfunctions in an internal combustion engine can be caused by a variety of factors, including increased wear, design defects, improper handling or vehicle operation. Here are some of the most common piston failures.

Worn pistons and rings

Worn pistons and sealing rings can lead to a decrease in cylinder compression, which can result in loss of power, increased fuel consumption and increased exhaust emissions. Piston wear can be caused by normal wear, but also by abnormal engine operating conditions or improper lubrication.

Piston cracks

Cracks in pistons can occur due to excessive load, sudden temperature changes, vibration or inadequate lubrication. Cracked pistons can lead to exhaust or oil leaks, loss of engine power and damage to other engine components.

Seal ring wear

Worn or damaged sealing rings can lead to a decrease in cylinder compression, which can cause a loss of power and an increase in fuel consumption. Seal ring wear can be caused by normal wear or contaminants in the engine oil.

Piston seizure

Piston seizure occurs when pistons and cylinders are not properly lubricated, leading to metal surfaces coming into contact and creating seizure. Piston seizure can result from low oil levels, improper lubrication or high engine loads.

Piston overheating

Excessive heating of pistons can lead to deformation or thermal damage, especially in engines operating under high loads or high temperature conditions. This can lead to damage to pistons and other engine components.

Contaminants

Contaminants in engine oil or fuel can lead to increased wear on pistons and damage to sealing rings, which can result in reduced engine performance.
Regular maintenance, proper lubrication, and attention to fuel quality can help prevent many piston failures. If you have any worrisome symptoms regarding engine operation, it is recommended that you consult a professional mechanic as soon as possible to diagnose and repair the problem.

Piston pin clearance: symptoms

Piston pin clearance, also known as piston play, is the distance between the piston pin and the hole in the piston bark where the pin moves. This clearance is an important design element that allows the piston to move freely in the engine cylinder.

Assessing and adjusting piston pin clearance is part of routine engine maintenance and repair. Excessive clearance on the pin can be corrected by replacing the piston or piston seals, while too little clearance may require cylinder reconditioning or some other type of repair. Therefore, if there are suspicions of abnormal piston pin clearance, it is recommended to consult an experienced mechanic for diagnosis and possible repair.

Too much play on the piston pin: symptoms

Too much play on the piston pin can be a problem that can lead to various problems in the engine. Here are some potential consequences of too much play on the piston pin:

• Noise: Too much play on the piston pin can lead to excessive noise when the engine is running. The piston may make a clattering or thumping sound, which can be a nuisance to the driver and indicate improper engine operation.
• Excessive piston mobility: Excessive piston pin clearance can cause excessive piston movement in the cylinder. This can lead to unstable engine operation, difficulty achieving adequate compression, and even damage to the piston, piston rings and cylinder.
• Decrease in performance: Too much piston pin clearance can lead to a decrease in engine performance through loss of compression in the cylinder. This can result in loss of power, increased fuel consumption and increased exhaust emissions.
• Piston wear: Excessive piston pin clearance can lead to excessive wear on the pistons, piston rings and cylinder. Excessive piston mobility can lead to faster wear of the piston and cylinder surfaces, reducing engine life.
• Drop in oil pressure: Too much piston mobility can cause a drop in oil pressure, which can lead to improper lubrication of the piston and cylinder. This, in turn, can lead to increased wear and damage to the engine.

Too little clearance on the piston pin: symptoms

When the clearance on the piston pin is too small, various problems can also occur that can adversely affect engine performance. Here are some potential symptoms of too little piston pin clearance:

• Piston seizure: Too little clearance on the piston pin can lead to contact between the piston and the cylinder or other engine components, which can cause seizure. Piston seizure can result from excessive friction and pressure on the surface of the piston or cylinder.
• Noise: Too little clearance on a pin can cause excessive noises during engine operation, such as knocking, creaking or banging. These noises result from improper contact between the piston and other engine parts.
• Decrease in power: Too little clearance on the piston pin can lead to a decrease in engine power due to increased friction and resistance in piston movement. This can result in difficulty accelerating, loss of power and an overall deterioration in engine performance.
• Increased fuel consumption: Too little piston pin clearance can increase resistance to piston movement, which can result in increased fuel consumption. The engine may consume more fuel than usual, which may be noticeable on fuel consumption charts or during refueling.
• Increased temperatures: Too little piston pin clearance can also lead to elevated engine temperatures. Excessive friction and pressure can generate additional heat, which can increase engine temperatures and lead to overheating.

Piston cracked or burned out? Symptoms will help in diagnosis

A cracked piston and a burnt-out piston can produce similar symptoms, but they can also have some differences depending on the severity of the damage and how they affect engine performance. Here is a comparison of the symptoms of a cracked piston and a burnt piston.

In both cases, there is a risk of more serious damage to the engine, so it is important to diagnose the problem as soon as possible and take appropriate corrective action. If piston damage is suspected, it is advisable to consult an experienced mechanic who can thoroughly examine the engine and recommend appropriate corrective measures.

How to select a piston for a cylinder?

Choosing the right piston for your cylinder is crucial to the proper operation of your engine. Here are some steps to take to properly select a piston for a cylinder:

Step 1: measure the diameter of the cylinder

The first step is to accurately measure the diameter of the engine cylinder in several places, both at the top and bottom of the cylinder. This measurement should be accurate because the piston must be the right diameter to ensure proper sealing and operation in the cylinder.

Step 2: measure the piston clearance

Measure the piston clearance, which is the distance between the diameter of the piston and the diameter of the cylinder. This measurement helps determine whether the piston will fit properly in the cylinder.

Step 3: choose the right piston

Based on accurate measurements of the cylinder diameter and piston clearance, select the right piston with the correct diameter. The piston should be selected to provide the minimum clearance to ensure proper sealing and minimal movement in the cylinder.

Step 5: install and check the fit

It’s also a good idea to make sure that the piston meets the proper tolerances for shape, finish and material. The piston should be made of high quality materials and match the engine specifications.

Krok 5: montaż i sprawdzanie dopasowania

Once the right piston has been selected, it should be properly installed in the cylinder, and then the fit and clearance of the cylinder should be checked. It’s worth carefully checking that the piston moves freely in the cylinder without excessive resistance, but also without too much slack.

Step 6: inspect the piston rings

It is also worth checking the condition and fit of the piston rings to the cylinder. Piston rings must fit the cylinder properly and ensure proper sealing and minimal wear.

Selecting the right piston for the cylinder requires accurate measurements and careful fitting. It should also be remembered that piston selection may vary depending on the specific engine and manufacturer’s recommendations. If in doubt or inexperience, it is recommended to consult a professional mechanic or engine specialist.