Instructions for replacing car pistons properly

Car piston problems affect the operation of the cylinder and combustion chamber. Car owners need to find the cause to avoid reducing engine power. So how can you tell if your car’s piston is working too hard? Let’s find out with CarOn through this article!

Signs of needing to replace car pistons


Structure of automobile piston divided into 3 parts: top, head and piston body. This part is responsible for coordinating with the cylinder and engine cover to create the combustion chamber engine . Because it often operates in high temperature conditions and is subject to great friction and abrasion, the piston is easily damaged. It can be seen through the following signs:

Emission levels increased suddenly

An unusually large amount of smoke emitted from the exhaust pipe when the vehicle is operating is a sign that the piston ring system is damaged. At that time, lubricating oil spilled into the soil chamber, creating smoke, causing the exhaust gas to turn dark brown, white and thicker than normal.

Xe-ra-khoi-den caron

The amount of lubricating oil is reduced

When the oil system is worn, the amount of lubricant from the engine will flow into the combustion chamber. This not only increases friction between engine parts but also causes more fuel consumption than normal.

Poor performance and low engine power

If the driver feels that the car’s acceleration is poor or it feels sluggish, it may be because the gasket is having problems. Worn piston rings will reduce compression pressure and engine power, causing difficulty in acceleration, fuel consumption, and increased heat accumulation in the combustion chamber.

Causes of piston damage

The main structure of the automobile piston will be divided into 3 parts, which are: top, head, piston body. Each part has an individual function, the cause of a broken car piston will also be affected by each part mentioned above.

*Piston top part:

Piston top is cracked

The piston top has a cracked caron

A cracked piston top causes air leakage, affecting the operation of the combustion chamber and reducing the power of the car engine. The cause of the crack is due to lack of lubricating oil (lubricant oil). In addition, when fuel is injected at the wrong time and in the wrong dosage, it will cause the piston top to overheat. At this time, the piston top surface expands at a rapid speed, while the surrounding positions cannot adapt in time, leading to cracking.

Piston top has a large broken piece

The reason why the Piston top broke in large pieces was due to forces from inside the engine’s combustion chamber.

  • Installing the Piston incorrectly, resulting in the top protruding too much.
  • The cylinder head gasket was installed incorrectly and there was too much carbon deposits on the top.
  • The gap between the valve and the top of the piston is too narrow.
  • The Xupap’s opening/closing time is incorrect, inaccurate, or because the concave contact surface of the Xupap with the top of the Piston is too short.
  • The timing belt inside the engine system has a problem or is slipping.

The top of the piston is melted and covered with soot

With an internal combustion engine, the combustion process in the combustion chamber will create force on the piston, turning the crankshaft to produce work. Therefore, the piston top often melts due to high temperature and friction with other parts.

Melting causes valve opening time to be inaccurate, affecting the efficiency of air intake and exhaust. When the piston does not have enough compression pressure, the combustion process is incomplete, soot will form, affecting the operation of the fuel injector system.

*Piston head:

Piston head reduces in diameter due to overheating

  • Using the wrong gasket on the gasket causes the gap between the cylinder wall and piston to not be sealed properly, causing oil leakage.
  • The injector is leaking and dripping after completing the fuel injection process, the injector is clogged due to the injector body being warped.
  • The fuel injection timing is not accurate or appropriate or the combustion chamber is too hot.
  • Installing the Piston incorrectly can lead to poor cooling and lubrication systems or poor quality oil.

The piston ring ring is broken

pston is worn out

Piston rings are open metal rings located in the grooves of the piston. This part is under great pressure when the piston is always moving forward.

When the inertial force and centrifugal force are too large, causing a pressure difference, the piston ring is pushed to the top of the groove, leading to cracking. In particular, fuel with a reduced octane index is also the cause of broken piston rings and even punctured piston heads. It can also be due to:

  • Piston rings and pistons are not installed correctly, the axial wear of the piston ring groove is too large.
  • The inertial and centrifugal force is too great, causing pressure difference and pushing the piston ring to the upper surface of the groove with stronger pressure than usual.
  • The amount of fuel injected is not appropriate, causing overflow or incomplete combustion, and has a low octane rating.
  • The air intake/exhaust valve process is not tight, causing a leak.
  • The temperature of the intake air or engine is too high, leading to overheating.
  • There is oil mixed in the gasoline engine, causing the octane number to decrease, causing broken piston rings and punctured piston heads.

*Piston body

The piston body is worn and scratched

Piston scratched caron

Responsible for guiding the piston to move in the cylinder, the car piston body is easily worn out after a period of use. When the diameter of the piston body changes, gaps will form between the piston and the cylinder, affecting the piston’s forward motion, creating impact during operation.

In addition, incorrect installation of the connecting rod causes the piston to move to one side, causing the piston ring to tilt and the piston body to wear out faster.

There are also other parts of the piston that require maintenance attention such as:

Cylinder tube is corroded

The cylinder tube is where the piston moves, creating suction and compressing air during operation. With this principle, the cylinder tube helps the piston reduce inertial force, and the vehicle is better balanced.

The combustion chamber is always in a high temperature state. Lack of coolant or antifreeze can cause the cylinder tube to corrode. At this time, the gap between the cylinder and piston is formed, the combustion process is affected, reducing engine power.

Cylinder walls are dented, worn and scratched

  • Due to excessive fuel injection, leakage into the combustion chamber and frequent idling and short driving.
  • The EGR exhaust gas recirculation system has a problem.
  • Cylinder walls are abraded horizontally and vertically due to force from piston rings and pistons.
  • Because the piston is stuck inside the cylinder, in contact with a burning object, the piston pin is not properly removed and the temperature changes suddenly.

Piston test method


Even though it is a small part, when the piston has problems, the performance of the car engine is also reduced. Therefore, as soon as signs of damage are detected, the vehicle owner should check using the following method:

  • Check the clearance between the piston and groove with a ruler
  • Use light to check the back gap
  • Measure the piston mouth clearance with a ruler

Instructions for properly replacing car pistons

How to choose the right piston for your vehicle:

  • Users should choose the piston depending on the diameter and degree of machining of the cylinder wall.
  • You should use a standard piston with wear, taper and deflection suitable for the cylinder. If the taper of the piston ring exceeds the standard, the edge should be re-ground to fit.
  • Do not use machined pistons to avoid expansion causing the bundle to jam in the groove.
  • Car owners choose genuine pistons from reputable and reliable auto parts businesses.

Piston replacement procedure

Step 1: Remove the old piston ring part from the piston head: Use a ruler and specialized pliers to remove the piston ring rings from the piston, but do not let the sharp tips scratch the piston.

Step 2: Clean the piston ring grooves

When the new fuel is replaced and it can work well, the car owner needs to clean the silver rings and piston grooves. Then take a clean cloth and pull it back and forth in the grooves and wipe clean.

Step 3: Apply oil to the piston rings and piston rings: to create smoothness to make installation easier.

Step 4: Install the new piston ring into the groove

Piston rings are the same size as the piston. When attached, the car owner places the side with the letter facing the piston head.

Use specialized pliers or use your hands to install the piston rings: the first piston ring at the bottom is installed first, followed by the middle piston ring and finally the gas piston ring.

Step 5: Position the grooves

Let’s proceed with positioning the piston rings relative to the piston pin shaft:

  • The top piston ring slot is offset at an angle of 45 degrees compared to the piston pin cylinder
  • The second piston ring gap will be 180 degrees away from the top piston ring gap.
  • The 2 oil piston rings are 45 degrees offset from the air piston rings and also 45 degrees offset from the piston pin cylinder

Where is a reputable place to maintain cars and replace pistons?

Although the piston ring is a compact part located on the piston, its role is very important in the air compression process, helping the engine operate stably, smoothly and accelerate easily. Replacing piston rings requires in-depth and meticulous knowledge. So if your car has damaged gaskets, replacement and repair should be done at a reputable warranty center or garage to ensure accuracy during operation and safety during operation.


CarOn Pro is one of the “golden choice” addresses, where your car no longer has to worry about breakdowns. Because the technicians at the store will use their skilled skills to reduce the car’s problems to zero. With quality products, affordable prices and attractive after-sales service, CarOn deserves Worth becoming your trusted car maintenance address. Quickly contact via hotline 0961.247.360 or via website to receive the most surprising offers.

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