Yaroslavl Engine Plant YMZ-536, Operation Manual

Page: 104 / 168

104
CRANKCASE VENTILATION SYSTEM
The crankcase ventilation system is a closed-type system (see
Fig. 37).
During the engine operation some amount of exhaust gases
from the cylinders enter the crankcase where they are mixed with oil
mist and sent to the turbocharger suction.
To prevent oil coking in the turbocharger, crankcase gases are
separated from oil in the breather
2
.
The two-stage breather
2
is incorporated into the plastic cover
of the cylinder head 1.
The first preliminary cleaning stage is a complex labyrinth with
swirlers 3 at the inlet and a hydraulic lock
4
at the outlet through
which the separated oil is drained to the cylinder head. The hydraulic
lock is designed as two cylinders
5
and
6
, one inserted into the other,
with a drain pipe
7
in the center. The drain pipe height maintains the
required drain oil column exceeding the pressure of the crankcase
gases.
The second fine cleaning stage is also designed as a complex
labyrinth with swirlers
8
. At the end of the labyrinth there is an oil
sump
9
with a mushroom-shaped drain valve
10
.