What is the effect of large valve clearance of diesel engine?

When the diesel engine valve clearance affects the vehicle, it may cause the valve to open late and close quickly, resulting in insufficient intake and poor exhaust, reducing engine power and increasing engine noise. In addition, if the valve clearance is too small, the valve closure will become lax, which will lead to air leakage in the cylinder, insufficient compression, unstable idle speed, reduced power and acceleration, backfire or puncture of the exhaust pipe, easy flameout and deterioration of fuel consumption. The size of the engine clearance varies with the model. Generally, the intake valve clearance is about 0.25 mm ~0.35 mm, and the exhaust valve clearance is about 0.30 mm ~0.40 mm ... The exhaust valve receives a lot of heat when working, and the deformation is also large, so the exhaust valve clearance is generally larger than the intake valve clearance. Valve clearance is an important parameter in automobile design and manufacturing. It has been set at the factory, not too big or too small. Excessive valve clearance will affect the dynamic performance of the engine, while too small valve clearance will lead to the decline of engine power and even burn the valve. The valve and its transmission mechanism will be worn in long-term work, so the valve clearance will also change, and it is necessary to adjust the valve clearance regularly. Most models are adjusted by adjusting screws, but there are also many models that are adjusted by adjusting gaskets. Relatively speaking, it is more troublesome to adjust the partition. Adjusting the valve clearance is a highly technical job, which requires professional technicians. The valve clearance changes with temperature, and gradually increases with the wear of parts during use. If it cannot be adjusted in time, it will affect the performance of the engine. For this reason, smart automobile engineers developed hydraulic tappets. Under the action of oil pressure, the valve clearance can be automatically adjusted to compensate for the change of clearance with temperature and wear, so that the valve clearance is zero, which is helpful to reduce impact, noise and service life of parts. At the same time, the hydraulic tappet can directly operate the valve. Nowadays, hydraulic valve tappets are basically used in automobile engines.