How to Solve the Problem of Valve Erosion and Air Leakage?
2 Answers
If it is caused by excessive carbon deposits, the carbon deposits can be removed. If the valve and valve seat are worn or eroded, the severity of the wear and erosion should be assessed. For minor wear and erosion marks, the sealing can be restored by grinding the valve and valve seat together. If the wear or erosion is severe or the contact ring has significantly widened, and grinding can no longer eliminate the issue, the valve seat ring can be milled, the valve can be polished, and then they can be ground together to restore sealing performance. 1. Incorrect fit clearance between the valve and valve guide. If the clearance is too large, the valve will wobble and tilt when closing, leading to poor sealing. If the clearance is too small, the valve may get stuck in the guide, preventing it from closing properly or at all. In such cases, the cause of the excessive or insufficient clearance should be identified, and the guide or valve affecting the normal fit clearance should be replaced. Insufficient or broken valve spring tension can also prevent the valve from closing or sealing properly. Solution: Replace the valve spring. 2. If the valve clearance is too small, components like the valve stem may not have enough room to expand when heated, resulting in improper sealing. Adjust the valve clearance as required. Valve leakage noise typically occurs outside the valve chamber and is more noticeable under high load and low speed conditions. The noise increases with the load. The main reasons for this noise are improper operation during valve seat reaming or excessive wear of the valve guide bore, causing the valve seat to tilt or the valve clearance to be too small, leading to valve erosion and improper sealing, which results in air leakage noise.
My previous car had valve burning, and the repair was quite complicated. First, the cylinder head had to be removed to check if the valve sealing surface had pitting or deformation. If so, new valves had to be replaced. During installation, it's important to grind the valve seat—this is a skilled job that requires using special grinding paste and repeatedly polishing until the contact surface is even. After that, the valve clearance must be checked; if it's too tight, the burning will worsen faster, and if it's too loose, it affects performance. After the repair, it's best to change the oil and add some engine protectant. By the way, using higher-grade gasoline regularly can prevent this issue, as valve burning is mostly caused by poor fuel quality or excessive carbon buildup.
