Compulsory crankcase ventilation, suction of crankcase gases into the engine intake gas pipeline through a special valve 3 installed on the intake gas pipeline

From the valve, gases are sucked off through a special tube into the central part of the intake gas pipeline.

To turn off the ventilation system when crossing the ford, a valve 4 is installed between the tubes.

The crane handle must be vertical when crossing the ford.

After overcoming the ford, the handle must be turned to a horizontal position.

ZIL-131 crankcase ventilation scheme and air supply

When the engine is running with a slightly open throttle, under the action of a large vacuum in the intake gas pipeline, valve 3 rises, the upper stepped part of the valve enters the opening of the fitting 5 and reduces the valve flow area to the value necessary for the passage of a small volume of gases breaking into the crankcase.

When the engine is running with a wide open throttle valve, the vacuum in the intake gas pipeline drops, and the valve lowers under the influence of its own weight, opening the full flow area, the value of which corresponds to the passage of a large volume of gases breaking into the engine crankcase.

During maintenance, the valve should be cleaned using acetone or similar solvent.

Before the valve, at the exit from the internal space of the engine, crankcase gases pass through a special trap 2, which separates oil particles from the exhaust gases.

Outside air enters the engine crankcase through air filter 1 integrated with the oil filler.

This filter is cleaned and flushed with every engine oil change.