Burning exhaust valve to the door of the most common, the basic reason is that the valve seat and the distortion of carbon deposition. In addition, the valve clearance adjustment, such as improper, such as excessive wear and tear can cause burning of the valve.

When the valve seat distortion, sealing surface temperature valve and valve seat and between the local pressure to increase at the same time. Valve sealing surface of the trench often, the high-temperature gases will be scouring the formation of burning. When the valve seal and valve seat face serious carbon deposition, so that the heat transfer conditions to deteriorate, there would easily be deformed, resulting in valve burning.