Provision be made for ventilation of an enclosed diesel engine crankcase by means of a small breather or slight suction not exceeding 25mm of water. By ventilating the enclosed crankcase of a diesel engine, the pressure inside the crankcase can be reduced. Thus preventing the excess pressure developed which may cause the leakage in the crankcase doors and crankcase oil may finds its way out. At the same time, it will prevent the development of high concentration of oil mist in the crankcase. Thus reducing the possibility of crankcase explosion. In modern engines mostly, the crankcase external fans are not provided but crankcase weld is provided which is led to a remote plate which prevents the excessive built up of pressure inside the crankcase. This pressure should not be above 25mm of water gauge otherwise the leakage from the crankcase and the loss of oil will be very much.