How to adjust the valve clearance of 4-cylinder diesel engine? Be careful!

When measuring valve clearance, valve clearance can be divided into cold car value and hot car value, and the measurement should be carried out under the condition of meeting the requirements of vehicle use. Select the plug gauge that meets the specifications and insert it between the valve stem and the valve rocker arm (or cam). Gently pull the plug gauge. If there is slight resistance, the clearance is correct.

The advantages of diesel engine are large torque and good economic performance. The working process of diesel engine has many similarities with that of gasoline engine, and each working cycle has to go through four strokes: intake, compression, work and exhaust.

However, because the fuel used by diesel engine is diesel, its viscosity is higher than that of gasoline and it is not easy to evaporate, but its auto-ignition temperature is lower than that of gasoline. Therefore, the formation and ignition mode of combustible mixture is different from gasoline. The main difference is that the mixture in the cylinder of diesel engine is compression ignition, not ignition.

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Because the valve is in contact with the cylinder, a lot of heat is released when the cylinder moves, and the heat will be transferred to the valve after the valve is in contact with the cylinder, thus increasing the elongation of the valve. If the valve clearance is not reserved in advance, when the car is cold, the valve will be in close contact with the cylinder block. When the cylinder block becomes hot, the extension of the valve will increase due to thermal expansion, which will damage the cylinder block or the valve itself. Therefore, it is necessary to leave a suitable valve clearance.

Exhaust valve is the most common burning loss of valve, and its fundamental reason is valve seat deformation and carbon deposition. In addition, improper adjustment of valve clearance and excessive wear will also cause valve burning.

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