DETROIT DIESEL Engine SysBems Fig. 14 - Typical Mounting of Breather Fig. 13 - Breather Pads and Retainers Installed in Cylinder Block Assemly on Valve Rocker Cover Harmful vapors which may be formed within the engine are removed from the crankcase, gear train, and valve compartment by a continuous pressurized ventilation system. A breather pipe is pressed into or flange mounted on top of the cylinder block to provide an exit for the crankcase vapors. Some engines have an additional breather assembly mounted on the flywheel housing or on one of the valve rocker covers (Fig. 114).
Breathing is through two openings in the rear main bearing bulkhead of the crankcase, which connects to a chamber. Two crimped-steel mesh breather pads, which cover the openings (Fig. 13), filter out the oil as the vapors pass into the chamber. Page 21