1. The injector coupling of cylinder is stuck or the positive pressure of injection is too low. A large amount of diesel oil that is not fully atomized enters the cylinder and cannot be completely burned, that is, it flows into the oil pan through the cylinder wall. The elimination method is to determine which cylinder injector coupling is faulty by cutting off the oil one by one, and then replace or clean the coupling according to the regulations.

2. The sealing end face of the cylinder injector is not tight, and the cylinder head and cylinder liner are not tightly attached, resulting in the pressure in the cylinder not reaching the rated value, and the fuel injected into the cylinder cannot burn and flows into the oil pan.

The elimination method is to determine which cylinder is the problem by observing the situation around the injector. Generally speaking, diesel oil seeps around the poorly sealed injector and there are small bubbles, which can be eliminated by replacing the injector gasket or repairing the hinged copper sleeve with a special reamer.

3. Diesel oil leaks in the high-pressure oil pump. The long-term immersion of diesel oil leads to the failure of camshaft oil seal of oil pump, and the diesel oil in high-pressure oil pump enters the oil pan through the aging wheel chamber. The elimination method is to remove the missing oil unloading pump by professionals and replace the oil seal.

Extended data

Guide for the use of diesel engines:

1. According to the national standard (GB 252-87), the specifications of light diesel oil are divided into six grades according to the freezing point, namely 10, 0,-10, -20, -35 and -50, which respectively indicate that the freezing point is not higher than 10℃. The higher the grade, the lower the freezing point.

2. Diesel is a special fuel for compression ignition engines (diesel engines). The appearance of diesel oil is water white, light yellow or brown liquid. Diesel oil is divided into light diesel oil and heavy diesel oil. Light diesel oil is the fuel used by high-speed diesel engines above 1000r/min, and heavy diesel oil is the fuel used by low-speed diesel engines below 1000r/min.

Generally, diesel oil sold at gas stations is light diesel oil. The product standard of light diesel oil is GB 252-2000 Light Diesel Oil. In this standard, diesel brands are divided into 10, 5, 0,-10, -20, -35 and -50, and the classification of diesel brands is based on the freezing point of diesel.

3. The cold filter point is an important index to measure the low temperature performance of light diesel oil, which can reflect the actual low temperature performance of diesel oil and is closest to the actual minimum use temperature of diesel oil. When choosing a diesel brand, users should consider the local temperature and the cold filter point corresponding to the diesel brand.

The cold filter point of No.5 light diesel oil is 8℃, No.0 light diesel oil is 4℃,-10 light diesel oil is -5℃, and -20 light diesel oil is-14℃.

Baidu Encyclopedia: Diesel Engine