我部一辆BJ2020NJ型汽车在行驶3700km后发现发动机动力下降,空气滤清器及化油器内存有不少机油,排气管冒蓝烟。分析其原因:一是气门密封不严,气门导管磨损过甚,造成发动机运行过程中高压气由气门、气门导管进入气门室,将机油吹起被吸入空气滤清器;二是活塞环磨损过甚窜气,致使曲轴箱内压力过高,曲轴箱内高压气在被废气连接管再次吸入进气歧 A BJ2020NJ car of our department, after driving 3700km, found the power of the engine dropped. There was a lot of oil in the air cleaner and the carburetor memory, and the exhaust pipe was blue smoke. Analysis of the reasons: First, lax valve seal, valve guide wear too much, resulting in the engine running high pressure gas from the valve, valve guide into the valve chamber, the oil is blown into the air filter; Second, the piston ring worn very channeling Gas, resulting in high pressure inside the crankcase, crankcase high pressure gas in the exhaust pipe again inhalation intake manifold