One is that the fuel quality is substandard

There is a chemical component in gasoline called olefin, which is prone to oxidation and the formation of gum. Gasoline with an excessively high olefin content is very likely to form carbon deposits on the intake valves and combustion chambers. Its greater hazard is that after combustion, it is prone to form asphalt-like gel-like substances, presenting a shiny black oil appearance, mainly accumulating in the valve heads, valve stems, and valve guide sections.

When the engine is running at high temperatures, it is soft. However, as the engine cools down after it stops, this gel-like substance will solidify. When it is started again, it may cause the valves to bend at best, and at worst, the pistons and valves will be damaged. The top rod machine may experience bending or falling of the top rod, while the chain conveyor may have its upper rocker arm broken, etc.

The second issue is that the fit clearance between the valve and the valve guide is not standard

If it is too small, at high temperatures, due to the different expansion coefficients of the valve and the guide tube, the resistance encountered by the valve when it moves in the guide tube will be too large, causing the valve to break. When the fit clearance between the valve and the guide tube is too large, it can also cause the valve to break at high speed.

The third issue is the quality problem of the guide pipe and the valve

Their uneven expansion at high temperatures can cause the valves to become stuck at high speeds, which may also lead to valve breakage.

The fourth is the weakening of the elastic force of the valve spring

At high speeds, the valves cannot be properly reset in an instant, resulting in valve breakage accidents.

The fifth issue is the detachment of the air lock clamp

When the force of the valve spring is too large, the impact force generated by the valve head and the lock clip during the valve's return to position is too great, which will cause premature wear of the valve head and the lock clip, leading to the valve lock clip falling off. This cannot also rule out the problem of the valve's own quality.

The sixth reason is that the quality of the lubricating oil is too poor or the oil supply to the cylinder head is too small

The quality of the lubricating oil is too poor to play its due role in lubricating and reducing friction at high temperatures. Coupled with a small amount of carbon deposits and sludge, the valves cannot return to their original positions well, causing a series of mechanical accidents.

The seventh issue is excessive carbon deposits on the pistons and valves

A mechanical accident that causes a valve to break.

The eighth point is that some car owners like to slam on the accelerator when the car is cold

This led to insufficient lubricating oil to cool down the exhaust valve and the guide pipe, causing a sharp increase in temperature. As a result, the valve could not move normally inside the guide pipe, causing the piston to hit the valve and resulting in a serious mechanical accident.

The ninth is the misalignment of the valve timing

It leads to the consequence of the valve hitting the piston, causing the valve to break and the piston to be scrapped.

The tenth is that the valve clearance is too large

This results in the CAM and rocker arm being unable to precisely control the opening and closing of the valves at high speeds, leading to serious mechanical accidents.

(The text is from the Internet. If there is any infringement, please contact us for deletion.）