某单位一台TY-180推土机,在使用过程中各部工作均属正常,发动机功率也无明显下降,但停机后再次启动却比较困难,且排气管冒出大量黑烟,如果停机时间较长（3天左右）则机器几乎不能启动,严重影响了正常作业,因此对机器进行了检修。 该推土机配备的是NT855-280型康明斯发动机。开始,我们按照“由表及里、由浅入深”的方法,根据故障现象主要检查了配气机构和发动机燃料系统。经检查,其气门间隙、PT泵、PT喷油器及各部连接处均未发现异常现象;但发现发动机在停机时间较长时,油底壳内油面略有升高,且伴有涩辣味,因此基本断定是油底壳内混入了柴油。当打开缸盖检查时,发现发动机Ⅲ、Ⅳ和Ⅵ缸的燃烧室中都积存 A unit TY-180 bulldozer, the work of the ministries are normal during the use of the engine power has not dropped significantly, but start again after shutdown is more difficult, and the exhaust pipe emits a large number of black smoke, if the downtime is longer (About 3 days) the machine can hardly start, seriously affecting the normal operation, so the machine was overhauled. The bulldozer is equipped with NT855-280 Cummins engine. In the beginning, we mainly inspected the valve train and the engine fuel system based on the symptom according to the method of “from the inside to the inside and from the shallower to the deeper”. After inspection, the valve clearance, PT pump, PT injector and connections between the ministries were found no anomalies; but found that the engine downtime is longer, the oil pan slightly increased oil surface, and accompanied by astringent spicy Taste, so basically concluded that the oil pan mixed with diesel. When opening the cylinder head inspection, found that the engine Ⅲ, Ⅳ and Ⅵ cylinder combustion chamber are accumulated