PCV - Line Routing

REF. NO. MBNA 01/008
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: December 1992

SUBJECT:
MODELS 124.051, 129.061, 140.032
LOCATION OF CRANKCASE VENTILATION AIR CHANNEL AND 2 mm ORIFICE








Following engine repair work to models equipped with engine 104, crankcase ventilation lines attached at the intake manifold must be correctly reinstalled. In order to avoid incorrect installation of crankcase ventilation lines (9, Figures 1 and 2), note the position of the idle air channel (9) and its respective line.

The function of the crankcase ventilation system is shown in Figure 2. The crankcase is ventilated through the vapor separator (4) into the intake manifold (10), and into the idle air channel (9) through a 2 mm orifice (Figures 1, 2). The engine oil in the vapor is separated in the vapor separator (4) and runs back through an oil return pipe (5) to the oil pan (6). The ventilation of the valve cover through the air filter (12) and into the intake manifold (10) prevents formation of oil sludge. Blow-by gases are drawn from the crankcase through the orifice (8) into the intake manifold. If the volume of gas drawn through this system is greater than the amount of blow-by gas past the pistons and piston rings, then the crankcase is ventilated with fresh air from the air filter through the valve cover ventilation system.