Engine ventilation system

The closed-type crankcase ventilation system provides the supply of gases that have broken through the piston rings and collected together with oil vapor in the crankcase into the combustion chambers for subsequent combustion.

OHV engine

OHV crankcase ventilation system

Internal view of the oil cap

Orifice tube (indicated by the arrow in the figure on the right) must always be clean.

To increase the efficiency of ventilation at idle and with partial throttle opening, fresh air partially enters the upper part of the oil filler plug through a wire filter, mixes with crankcase gases, is fed through a hose into the intake manifold and burned.

In the full throttle opening mode, crankcase gases are additionally sucked out through the carburetor. The distribution of gas flows is determined by the diameter of the hole in the oil filler plug, the size of which corresponds to a certain type of engine.


On early engine models, all crankcase breather hoses were connected to an oil filler plug, with the bottom hose providing fresh air directly into the crankcase.

The wire filter of the crater ventilation system, located in the oil filler plug, must be flushed every 20,000 km of the vehicle's run.

CVH engine with carburetor

Crankcase ventilation system CVH

The engine crankcase is ventilated through a valve installed at the bottom of the air filter housing. The valve must be replaced every 40,000 km of the car.

CVH engine with injector

The crankcase ventilation is carried out by a direct connection of the crankcase with the intake manifold. The valve installed on the crankcase must be replaced every 40,000 km of the car.

Diesel engine

Diesel crankcase ventilation system

The check valve on the cylinder head cover and the pipe in the intake manifold are connected by a hose. The tube has 4 calibrated holes, which are located opposite the inlet channels, and through these holes the crankcase gases are removed, which simultaneously lubricate the inlet valves.