System For Recirculating Cases Coming From The Engine Crankcase (Blow-By) - Fiat Bravo Service Manual

Engine
Fuel system
10.
S Y S T E M F O R R E C I R C U L A T I N G G A S E S C O M I N G F R O M T H E E N G I N E C R A N K C A S E ( B L O W - B Y )
This system controls the emissions, f r o m the cylinder block/crankcase, of the breather gases made up of
air/petrol mixtures and burnt gases w h i c h escape from the piston seals, in addition to lubricant oil
vapours, recirculating them to the inlet.
The breather gases, directed by special partitions, rise by the engine oil filler, then pass throughthe coils
(7),under the tappet cover, where they lose some of the oil they contain which goes to the camshafts,
through the pipe ( 6 ) , in the form of droplets.
The pipe (6) is shaped like a siphon t o prevent the escape of breather gases and only allow the recircula-
tion of drops of oil.
With the butterfly open, the gases come out of the intake (5) and are sent, via the connector (4) on the
air hose, upstream of the butterfly valve, to be drawn into the manifold.
With the butterfly closed, the vacuum in the inlet manifold draws in the gases through the intake (1) and
they reach the connector (3) on the inlet manifold, via the pipe ( 2 ) , w h i c h contains a PCV (Positive
Crank Ventilation) relief valve (8) w h i c h shutters the inlet.
The PCV valve can, in effect, be modulated and the quantity of gases w h i c h pass through is proportional
to the vacuum in the inlet manifold.
When the butterfly valve is completely open (condition A ) , the vacuum inside the inlet manifold is mini-
mal, the spring (10) is fully extended and the PCV valve allows the maximum flow of breather gases.
Conversely, w i t h the butterfly completely closed (condition B), the vacuum inside the manifold is maxi-
mum, w h i c h causes the movement of the small piston (9) which shutters the section of the f l o w of
breather gases inside the PCV valve thereby limiting the intake of the actual gases into the manifold.
Bravo ^
2 0 v
98 range