What does "pull the cylinder" mean when a car maintenance person says?


Cylinder strain is a very common phenomenon of engine damage in automobile use, which means that the inner part of the cylinder in the automobile engine is scratched, forming various scratches, and reducing the sealing performance of the cylinder.

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Cylinder pulling is a very common phenomenon, which means that the cylinder inside the car engine is scratched, forming this kind of straight lines.

Since the engine is a fairly rigid machine, even such a small amount of friction will lead to a decrease in the sealing performance of the piston, the piston ring and the cylinder wall, resulting in a decrease in the average effective pressure of the cylinder compression stroke, which will affect the performance of the engine. Generally, after the cylinder is pulled, there will be some vibrations in the cold start. When accelerating rapidly, the acceleration will not be strong, the fuel consumption will increase, and the oil will be abnormally consumed. If it is serious, there will be big problems such as abnormal noise in the golden house, combustion knocking, etc., and it needs to be overhauled.

This picture shows that we dismantled the engine of a 400,000 km car, so that the car owner can see the state of the car himself, and some cylinders do have a slight cylinder pull. From the design point of view, due to this metal-to-metal friction condition, it is very normal for hundreds of thousands of kilometers to wear and tear. If it is only slightly worn, it will not affect daily use, and you don't need to see wear and tear. 

What factors will cause the cylinder to pull? Based on my own experience doing engine fatigue tests:

1.Oil: In order to save fuel, some car owners use oil with a lower viscosity than the specified requirements. For example, OW-30 is required but OW-16 is used. The viscosity is too thin and the oil film is not enough, which will lead to increased wear and tear. Only 100,000 km will show obvious wear and tear of the engine, and visible wear will appear at 100,000 km. Some people do not change the oil at the specified time. In the first few years, it may be changed every year, and then it will be changed every two years, which will also cause wear and tear.

2.Air filter element: Some people only pay attention to the air filter element, not the air filter element of the engine. In fact, the air filter element of the engine is more important. Even if the filtering effect of the air-conditioning filter element is not good, it is at most the same as the air quality of the normal road. However, if the air filter element is not replaced, a lot of air dust will enter the engine combustion chamber. This thing is extremely hard and can be easily removed. Piston rings and cylinder wall scratches.

3.Cold start: A full throttle on a cold start will also lead to increased wear. At this time, the temperature of the combustion chamber is not high, the gap between the cylinder and the piston is relatively large, the lubricating oil film on the cylinder wall has not been fully established, and the dry friction of the full throttle will aggravate the wear. . However, you don't need to worry too much. After starting normally, you can directly go to 3000rpm°, and there is no problem with half-throttle.

4.Violent driving: It will not appear for ordinary consumers, mainly if the family car is taken off the track without modification, then the cylinder is almost certainly pulled. If you want to go off the track, you must use high-viscosity oil and strengthen the cooling system. In order to control the wear of the detonation piston wall.

5.Carbon deposition: Carbon deposition itself will not worsen wear, but carbon deposition will lead to low-speed pre-ignition and knocking, which will lead to a sharp increase in the load of the combustion chamber, and cylinder pulling will occur.

6.Abnormal cooling system: The engine is overheated and undercooled, and abnormal wear will also occur. It is mainly due to the designer matching the dimensional tolerances of the cylinder, piston ring, and cylinder wall according to the complete warm-up. If the engine is overheated, then the piston and cylinder The wall also has an interference fit; if it is too cold, then there is a gap and the piston will keep hitting the wall. will cause abnormal wear and tear.

There is also a very critical factor, and even the pull cylinder of most grocery carts is affected by this: whether the size of the cylinder liner used during assembly matches the cylinder block and piston. Generally, the cylinders and cylinder liners of the engine are made by the car companies themselves, which tests the manufacturing accuracy and assembly process of each car company. But the car company will definitely not admit this...

What should I do if the cylinder is pulled?

Pulling the cylinder is really hard to handle. First of all, we must find the cause. After finding the cause, we will deal with it first. For example, if there is a problem with the oil circuit, then change the oil; if there is a problem with the cooling system, repair the cooling circuit; and then deal with the combustion chamber, because the cylinder is worn and irreversible. Deformation, generally this kind of thing only needs to be replaced but not repaired, such as pistons, piston rings, cylinder liners, etc. Now many cars have adopted the honing process, and there is no traditional cylinder liner, so the cylinder block needs to be replaced, which is very expensive.

There is no other good solution for the time being. The effect of some repair shops' repair fluids is debatable, and it is a no-do solution.

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