[77newell]

Robert: Detroit Diesel 2 stroke engines have a mechanical blower that creates positive inlet air pressure necessary for the 2-stroke concept to work. Lubricating oil can seep past the seals in the blower in addition to the possibility that some oil can seep past the rings in the cylinders. This oil could collect in the "air box" that surrounds the base of the cylinders. Normally any oil is blasted out of the air box and into the cylinders by the high airflow. However, at idle the oil may pool in the air box and then be gulped into a cylinder en mass. If enough oil has collected it could exceed the capability of the cylinder to hold it and very loud and expensive noises will occur (those noises would included the cursing of the owner). To preclude this from happening each side of the V-series engines has a drain with an automatic valve that opens only at low air box pressure thus allowing any oil to vent. As soon as engine speed picks up the pressure in the air box rises and the valves close.