Hydraulic Lash Adjuster; Action When The Valve Starts To Lift; Action While The Valve Is Lifted; Action When The Valve Stops Lifting - Subaru SVX 1992 Manual

2-3 [M600]
ENGINE
6. Hydraulic Lash Adjuster
The hydraulic lash adjuster is located between the
camshaft and valve stem. The top surface of the hydrau-
lic lash adjuster is always in contact with the cam face.
The cam directly pushes the lash adjuster to open or
close the valve .
The engine oil flows through the cylinder head and goes
into the lash adjuster so as to always maintain zero
valve clearance .
1) Action when the valve starts to lift
When the cam begins to push the lash adjuster, the
bucket and plunger are pushed down . At the same time,
the body is pushed up by the reaction from the valve
stem . This causes the high pressure chamber to com-
press, increasing the oil pressure in the high pressure
chamber.
2) Action while the valve is lifted
As long as the cam is pushed by the lash adjuster, the oil
pressure in the high pressure chamber is held high . The
oil in the high pressure chamber leaks through a very
small clearance between the plunger and body. Since
the high pressure chamber is compressed in a very
short time, almost no change occurs in the oil quantity
inside the high pressure chamber. Accordingly, the
bucket, plunger and adjuster body work as an integral
unit to push down the valve stem to open the valve . The
passage for supplying oil from the cylinder head to the
lash adjuster is closed during this period, and no oil
flows into the lash adjuster.
3) Action when the valve stops lifting
When the cam completes its lash adjuster pressing
stroke, the passage for supplying oil from the cylinder
head to the lash adjuster opens, allowing oil to flow
from the cylinder head into reservoir II of the lash
adjuster . Since the pressure in the high pressure cham-
ber is lower than the pressure in reservoir Il,the check
ball is pushed down by the oil pressure in reservoir II .
Accordingly, oil flows into the pressure chamber until
the oil pressure becomes equal between the high pres-
sure chamber and reservoir II . Under the action of this
oil pressure, the body is pressed against the valve stem
and the bucket against the camshaft .
2)
Overflow recess Reservoir II
Bucket
Plunger
Body
Clip
i
Reservoir 1
Oil feed hole
Retainer
Sleeve
ring \II Ball cage
-
Plunger
Check ball `spring Load
High pressure chamber
Check ball spring
1)
C)
3)
C)
F
- Pressure in
-crTv
Expanded
chamber is
increased
C2-188
Fig . 5
6