Clutch Hydraulic System; Bleeding Procedure; Conventional Method; Using A One-Way Valve Kit - Opel Zafira B MPV 2006 Owners Workshop Manual

6•2 Clutch
Note: On models equipped with the Easytronic
transmission, the following manual method
of bleeding the clutch is not possible since
the hydraulic control unit is integral with the
transmission. On these models, bleeding is
carried out using the Vauxha/1/0pel TECH2
diagnostic instrument, therefore this work
should be entrusted to
a
Vauxha/1/0pel dealer.
Warning: Hydraulic fluid is
poisonous; wash off immediately
and thoroughly in the case of
skin contact, and seek immediate medical
advice if any fluid is swallowed or gets
into the eyes. Certain types of hydraulic
fluid are flammable, and may ignite when
allowed into contact with hot components;
when servicing any hydraulic system,
it is safest to assume that the fluid is
flammable, and to take precautions against
the risk of fire as though it is petrol that is
being handled. Hydraulic fluid is also an
effective paint stripper, and will attack
plastics; if any is spilt, it should be washed
off immediately, using copious quantities
of fresh water. Finally, it is hygroscopic (it
absorbs moisture from the air) - old fluid
may be contaminated and unfit for further
use. When topping-up
or
renewing the
fluid, always use the recommended type,
and ensure that it comes from a freshfy-
opened sealed container.
General information
1 The correct operation of any hydraulic
system is only possible after removing all
air from the components and circuit; this is
achieved by bleeding the system.
2 The manufacturer's stipulate that the
system must be initially bled by the 'back-
bleeding' method using Vauxhall/Opel special
bleeding equipment. This entails connecting
a pressure bleeding unit containing fresh
brake fluid to the release cylinder bleed
screw, with a collecting vessel connected to
the brake fluid master cylinder reservoir. The
pressure bleeding unit is then switched on,
the bleed screw is opened and hydraulic fluid
is delivered under pressure, backwards, to be
2.8 Clutch bleed screw (arrowed)
expelled from the reservoir into the collecting
vessel. Final bleeding is then carried out in the
conventional way.
3 In practice, this method would normally
only be required if new hydraulic components
have been fitted, or if the system has been
completely drained of hydraulic fluid. If the
system has only been disconnected to allow
component removal and refitting procedures
to be carried out, such as removal and refitting
of the transmission (for example for clutch
renewal) or engine removal and refitting, then
it is quite likely that normal bleeding will be
sufficient.
4 Our advice would therefore be as follows:
a) If the hydraulic system has only been
partially disconnected, try bleeding by
the conventional methods described in
paragraphs 10 to 15, or 16 to 19.
b) If the hydraulic system has been
completely drained and new components
have been fitted, try bleeding by using the
pressure bleeding method described in
paragraphs 20 to 22.
c) If the above methods fail to produce
a
firm pedal on completion, it will be
necessary to 'back-bleed' the system
using Vauxha/1/0pel bleeding equipment,
or suitable alternative equipment as
described in paragraphs 23 to 28.
5 During the bleeding procedure, add
only clean, unused hydraulic fluid of the
recommended type; never re-use fluid that
has already been bled from the system.
Ensure that sufficient fluid is available before
starting work.
6 If there is any possibility of incorrect fluid
being already in the system, the hydraulic
circuit must be flushed completely with
uncontaminated, correct fluid.
7 If hydraulic fluid has been lost from the
system, or air has entered because of a leak,
ensure that the fault is cured before continuing
further.
8 The bleed screw is located in the hose
end fitting which is situated on the top of
the transmission housing (see illustration).
On some models access to the bleed screw
is limited and it may be necessary to jack up
the front of the vehicle and support it on axle
stands so that the screw can be reached from
below, or remove the battery and battery tray
as described in Chapter SA, so that the screw
can be reached from above.
9 Check that all pipes and hoses are secure,
unions tight and the bleed screw is closed.
Clean any dirt from around the bleed screw.
Bleeding procedure
Conventional method
10 Collect a clean glass jar, a suitable length
of plastic or rubber tubing which is a tight fit
over the bleed screw, and a ring spanner to fit
the screw. The help of an assistant will also be
required.
11 Unscrew the master cylinder fluid reservoir
cap (the clutch shares the same fluid reservoir
as the braking system), and top the master
cylinder reservoir up to the upper (MAX) level
line. Ensure that the fluid level is maintained at
least above the lower level line in the reservoir
throughout the procedure.
12 Remove the dust cap from the bleed
screw. Fit the spanner and tube to the screw,
place the other end of the tube in the jar, and
pour in sufficient fluid to cover the end of the
tube.
13 Have the assistant fully depress the clutch
pedal several times to build-up pressure, then
maintain it on the final down stroke.
14 While pedal pressure is maintained,
unscrew the bleed screw (approximately one
turn) and allow the compressed fluid and
air to flow into the jar. The assistant should
maintain pedal pressure and should not
release it until instructed to do so. When the
flow stops, tighten the bleed screw again,
have the assistant release the pedal slowly,
and recheck the reservoir fluid level.
15 Repeat the steps given in paragraphs 13
and 14 until the fluid emerging from the bleed
screw is free from air bubbles. If the master
cylinder has been drained and refilled allow
approximately five seconds between cycles
for the master cylinder passages to refill.
Using a one-way valve kit
16 As their name implies, these kits consist of
a length of tubing with a one-way valve fitted,
to prevent expelled air and fluid being drawn
back into the system; some kits include a
translucent container, which can be positioned
so that the air bubbles can be more easily
seen flowing from the end of the tube.
17 The kit is connected to the bleed screw,
which is then opened.
18 The user returns to the driver's seat,
depresses the clutch pedal with a smooth,
steady stroke, and slowly releases it; this is
repeated until the expelled fluid is clear of air
bubbles.
19 Note that these kits simplify work so
much that it is easy to forget the clutch fluid
reservoir level; ensure that this is maintained
at least above the lower level line at all times.
Pressure-bleeding method
20 These kits are usually operated by the
reservoir of pressurised air contained in the
spare tyre. However, note that it will probably
be necessary to reduce the pressure to a lower
level than normal; refer to the instructions
supplied with the kit.
21 By connecting a pressurised, fluid-filled
container to the clutch fluid reservoir, bleeding
can be carried out simply by opening the
bleed screw and allowing the fluid to flow out
until no more air bubbles can be seen in the
expelled fluid.
22 This method has the advantage that the
large reservoir of fluid provides an additional
safeguard against air being drawn into the
system during bleeding.
'Back-bleeding' method
23 The following procedure describes