What are the symptoms of excessive valve clearance in diesel engines?

Symptoms of excessive valve clearance of diesel engine: 1, when the valve clearance is too large, impact sound will be generated between transmission parts and between valve and valve seat, which will accelerate wear; 2. At the same time, the duration of valve opening is reduced, and the situation of cylinder inflation and exhaust is aggravated; 3. When the engine is working, the valve expands due to the temperature rise. If there is no gap between the valve and its transmission parts in cold state, or the gap is too small, the thermal expansion of the valve and its transmission parts in hot state will cause the valve to close loosely, and the engine will cause air leakage in compression stroke and power stroke; 4, thus reducing the power, and it is difficult to start in severe cases. In order to eliminate this phenomenon, a certain gap is usually left in the valve and its transmission mechanism when the engine is cold assembled to compensate for the expansion of the valve after heating. This clearance is called valve clearance.