1986 FORD SIERRA bonnet

7Remove the clip from the hydraulic unit
pushrod on the brake pedal.
8With an assistant supporting the hydraulic
unit, unscrew the four nuts which secure the
unit to the bulkhead (see illustration).
Withdraw the unit from under the bonnet.
9Recover the gasket fitted between the unit
and the bulkhead.
10Drain the fluid from the reservoir. Do not
actuate the pushrod with the unit removed.
11Dismantling of the hydraulic unit should
be limited to the operations described in the
following Sections (see illustration).
Refitting
12Refitting is a reversal of removal, bearing
in mind the following points.13Do not refill the fluid reservoir until
reassembly and refitting is complete.
14Use a new gasket between the hydraulic
unit and the bulkhead.
15Ensure that the hydraulic pipes are
reconnected to the correct unions.
16On completion, bleed the complete
hydraulic system and check for leaks around
all disturbed components.
Note: A new O-ring must be used between
the accumulator and the hydraulic unit on
refitting.
Removal
1Disconnect the battery negative lead.
2Depressurise the hydraulic system by
pumping the brake pedal at least 20 times, or
until it becomes hard.
3Wrap a clean rag round the base of the
accumulator to catch any spilt fluid.
4Unscrew the accumulator using a hexagon
key. Remove the accumulator, noting the
sealing ring and being prepared for fluid
spillage (see illustration). If fluid isaccidentally spilt on the paintwork, wash off
immediately with cold water.
Refitting
5Fit a new O-ring to the base of the
accumulator, fit the accumulator and tighten
it.
6Reconnect the battery. Switch on the
ignition and check that the hydraulic unit
pump stops within 60 seconds; if not, the
accumulator is likely to be faulty.
7On completion, bleed the complete
hydraulic system and check for leaks around
all disturbed components.
Note: New sealing washers must be used on
the high pressure fluid hose banjo union, and
a new O-ring must be used between the
accumulator and the hydraulic unit on refitting.
Removal
1Remove the accumulator.
2Prepare a suitable container to catch spilt
fluid, and disconnect the high pressure fluid
hose from the pump.
3Remove the securing spring clip and
disconnect the low pressure fluid hose from
the pump. Allow the fluid to drain out of the
hose into the container. If fluid is accidentally
spilt on the paintwork, wash off immediately
with cold water.
4Disconnect the multi-plugs from the
pressure switch and the pump motor.
5Remove the pump mounting bolt (see
illustration).
6Pull the pump and motor assembly off the
mounting spigot and remove it.
7Recover the mounting bushes and renew
them if necessary.
8If a new pump is to be fitted, transfer the
pressure switch to it, using a new O-ring.
18Hydraulic unit pump and motor
(ABS) - removal and refitting
17Hydraulic unit accumulator
(ABS) - removal and refitting
10•16Braking system
16.8 Hydraulic unit-to-bulkhead securing
nuts (arrowed) - ABS
17.4 Unscrew the accumulator and remove
it, noting the O-ring (arrowed)
16.11 Hydraulic unit components - ABS
A Fluid reservoir
B Accumulator
C Main valveD Master cylinder
E Pushrod
F Pump and motorG Booster
H Pressure switch
J Valve block
Caution: Refer to the
precautions in Section 1.
Caution: Refer to the
precautions in Section 1.

4Withdraw the module, and disconnect the
multi-plug (see illustration).
Refitting
5Refitting is a reversal of removal but on
completion check the operation of the ABS
warning lamp as described in the
manufacturer’s handbook.
Note: A new O-ring must be used when
refitting a sensor.
Front wheel sensor
1Apply the handbrake, loosen the relevant
front roadwheel nuts, then jack up the front of
the vehicle and support on axle stands (see
“Jacking and Vehicle Support”). Remove the
roadwheel.
2Working under the bonnet, unclip the ABS
wiring loom from the chassis side member,
and disconnect the wheel sensor wiring plug.
3Unscrew the mounting bolt and withdraw
the sensor (see illustration).
4Refitting is a reversal of removal, bearing in
mind the following points.
5Clean the bore in the hub carrier, and smear
the bore and the sensor with lithium based
grease.
6Use a new O-ring seal when refitting the
sensor.
Rear wheel sensor
7Chock the front wheels, loosen the relevant
rear roadwheel nuts, then jack up the rear of
the vehicle and support on axle stands.
Release the handbrake and remove the
roadwheel.
8Working inside the vehicle, lift up the rear
seat cushion, then remove the side kick panel
and fold the carpet forwards to gain access to
the wheel sensor wiring plug (see
illustrations).
9Remove the wiring plug from its clip, and
disconnect it.
10Prise out the floor panel grommet, then
feed the sensor wiring through the floor panel.
11Free the handbrake cable from its clip on
the suspension lower arm.12Where applicable, disconnect the wiring
to the disc pad wear sensor.
13Unscrew and remove the bolt from the
forward caliper guide pin, while holding the
pin stationary with a spanner.
14Swing the caliper rearwards to gain
access to the wheel sensor.
15Unscrew the bolt securing the sensor to
its mounting bracket.
16Refitting is a reversal of removal, bearing
in mind the following points.
17Clean the bore in the sensor mounting
bracket, and smear the bore and the sensor
with lithium based grease.
18Use a new O-ring seal when refitting the
sensor.
Removal
1The deceleration sensitive valve is located
on the left-hand side of the engine
compartment (see illustrations).
2Place a suitable container beneath the
valve to catch spilt fluid, then unscrew the
union nuts and disconnect the fluid pipes.Plug the open ends of the pipes and valve to
prevent fluid leakage and dirt ingress. If fluid is
accidentally spilt on the paintwork, wash off
immediately with cold water.
3On early models, the valve is secured to the
mounting bracket on the inner wing by a
single bolt. Unscrew the bolt and remove the
valve.
4On later models, the valve is secured to the
mounting bracket by a clip. Remove the clip
and slide out the valve.
Refitting
5Refitting is a reversal of removal, but note
that the early type of valve must be fitted with
the cover bolts facing forwards, and the later
type of valve must be fitted with the smaller
diameter stepped end facing forwards.
6On completion, bleed the rear hydraulic
circuit.
23Deceleration sensitive valve
(all models with conventional
braking system)
- removal and refitting
22Wheel sensor (ABS)
- removal and refitting
10•18Braking system
21.4 Withdraw the module and disconnect
the multi-plug - ABS22.8a Remove the side kick panel
(securing screws arrowed) for access to
the rear wheel sensor wiring plug - ABS
23.1b Later type deceleration sensitive
valve23.1a Early type deceleration sensitive
valve
22.8b Rear wheel sensor wiring plug
(arrowed) - ABS
22.3 Unscrew the mounting bolt and
withdraw the front wheel sensor - ABS
Caution: Refer to the
precautions in Section 1.