Ford Orion. Manual - part 45

Pulse-air check valve (CVH engines)

16 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).
17 Detach the air hoses from the check valve
(see illustration).
18 Hold the lower tube nut at the base of the
valve firm with a suitable spanner, and
unscrew the valve using a spanner fitted on
the upper nut.
19 Refit in the reverse order of removal.
Ensure that the valve is correctly positioned
before fully tightening the tube nut against the
valve nut.

Pulse-air valve, filter and housing
(HCS engines)

20 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).

21 Disconnect the vacuum hose from the
rear of the pulse-air valve assembly (see
illustration).
22 Undo the retaining screws, and withdraw
the air-valve, filter and housing assembly from
the mounting bracket.
23 To dismantle the filter housing, undo the
four screws and separate the top from the
base of the housing; extract the foam filter,
and clean it in a suitable solvent. If any of the
housing’s components are worn or damaged,
the assembly must be renewed.
24 Refitting is the reverse of the removal
procedure.

Pulse-air valve, filter and housing
(Zetec engines)

25 Apply the handbrake, then raise the front
of the vehicle, and support it securely on axle
stands. 
26 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).
27 Disconnect the vacuum hose from the
base of the filter housing (see illustration).
28 Remove the air cleaner air inlet ducting for
access (refer to Chapter 4).
29 Remove the screws securing the filter
housing to the piping, unscrew the mounting
bolt, then withdraw the housing (see
illustration).
30 To dismantle the filter housing, undo the
four screws and separate the top from the
base of the housing. Extract the foam filter,
and clean it in a suitable solvent (see
illustrations). If any of the housing’s

components are worn or damaged, the
assembly must be renewed.
31 Refitting is the reverse of the removal
procedure.

Pulse-air solenoid valve

32 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).
33 Releasing its wire clip, unplug the
electrical connector, then release the valve
from its mounting bracket. Withdraw the
valve, then label and disconnect the two
vacuum hoses.
34 Refitting is the reverse of the removal
procedure; ensure that the hoses are correctly
reconnected.

Pulse-air piping (HCS and CVH
engines)

35 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).
36 Remove the air cleaner if necessary for
improved access (refer to Chapter 4).
37 Disconnect the vacuum hose from the
pulse-air valve.
38 Unbolt and detach the air tube from its
fixing to the exhaust manifold, cylinder head
and transmission, according to engine type.
39 Loosen off the four nuts securing the air
delivery tubes to the cylinder head exhaust
ports, then carefully withdraw the delivery
tubes as a unit (see illustration). Do not apply
undue force to the tubes as they are
detached.
40 Carefully clean the piping, particularly its

6•10 Emissions control systems

6.39  Pulse-air piping retaining nuts

(arrowed) on HCS engines

6.30B  . . . and withdraw the foam filter for

cleaning, if required

6.30A  Remove the four screws to release

the filter housing top from the base  . . .

6.29  . . . then undo screws “A” to

disconnect the piping and mounting 

bolt “B” to release the housing

6.27  Disconnect the vacuum hose from

the base of the filter housing  . . .

6.21  Vacuum hose connection (arrowed)

to pulse-air valve on HCS engines

6.17  Pulse-air check valve and

connections on CVH engines

A  Check valve

C  Check valve upper nut

B  Air hose

D  Lower tube nut

threads and those of the manifold. Remove all
traces of corrosion, which might prevent the
pipes seating properly, causing air leaks when
the engine is restarted.
41 On refitting, insert the piping carefully into
the cylinder head ports, taking care not to
bend or distort it. Apply anti-seize compound
to the threads, and tighten the retaining sleeve
nuts while holding each pipe firmly in its port.
42 The remainder of the refitting procedure is
the reverse of removal.

Pulse-air piping (Zetec engines)

43 Disconnect the battery negative (earth)
lead (refer to Chapter 5, Section 1).
44 Remove the air cleaner air inlet ducting for
access (refer to Chapter 4).
45 Unbolt the exhaust manifold heat shield;
unclip the coolant hose to allow the upper
part to be withdrawn.
46 Remove the screws securing the filter
housing to the piping. Unscrew the four nuts
securing the pipes into the exhaust manifold,
and remove the piping as an assembly, taking
care not to distort it (see illustration).
47 Carefully clean the piping, particularly its
threads and those of the manifold. Remove all
traces of corrosion, which might prevent the
pipes seating properly, causing air leaks when
the engine is restarted.
48 On refitting, insert the piping carefully into
the cylinder head ports, taking care not to
bend or distort it. Apply anti-seize compound
to the threads, and tighten the retaining sleeve
nuts while holding each pipe firmly in its port;
if a suitable spanner is available, tighten the
sleeve nuts to the specified torque wrench
setting.
49 The remainder of the refitting procedure is
the reverse of removal.

7

Positive Crankcase
Ventilation (PCV) system

2

General information

1 The function of the crankcase ventilation
system is to reduce the emissions of
unburned hydrocarbons from the crankcase,
and to minimise the formation of oil sludge. By
ensuring that a depression is created in the

crankcase under most operating conditions,
particularly at idle, and by positively inducing
fresh air into the system, the oil vapours and
“blow-by” gases collected in the crankcase
are drawn from the crankcase, through the air
cleaner or oil separator, into the inlet tract, to
be burned by the engine during normal
combustion.
2 On HCS engines, the system consists of a
vented oil filler cap (with an integral mesh filter)
and a hose connecting it to a connector on the
underside of the air cleaner housing. A further
hose leads from the adapter/filter to the inlet
manifold. Under conditions of idle and part-
load, the emissions gases are directed into the
inlet manifold, and dispensed with in the
combustion process. Additional air is supplied
through two small orifices next to the
mushroom valve in the air cleaner housing, the
object of which is to prevent high vacuum
build-up. Under full-load conditions, when the
inlet manifold vacuum is weak, the mushroom
valve opens, and the emissions are directed
through the air cleaner housing into the engine
induction system and thence into the
combustion chambers. This arrangement
eliminates any fuel mixture control problems.
3 On CVH engines, a closed-circuit type
crankcase ventilation system is used, the
function of which is basically the same as that
described for the HCS engine type, but the
breather hose connects directly to the rocker
cover. The oil filler cap incorporates a
separate filter in certain applications.
4 On Zetec engines, the crankcase ventilation
system main components are the oil
separator mounted on the front (radiator) side
of the cylinder block/crankcase, and the
Positive Crankcase Ventilation (PCV) valve set
in a rubber grommet in the separator’s left-
hand upper end. The associated pipework
consists of a crankcase breather pipe and two

flexible hoses connecting the PCV valve to a
union on the left-hand end of the inlet
manifold, and a crankcase breather hose
connecting the cylinder head cover to the air
cleaner assembly (see illustration). A small
foam filter in the air cleaner prevents dirt from
being drawn directly into the engine.

Checking

5 Checking procedures for the system
components are included in Chapter 1.

Component renewal

Air cleaner components

6 See Chapter 1.

Positive Crankcase Ventilation (PCV)
valve

7 The valve is plugged into the oil separator
on Zetec engines. Depending on the tools
available, access to the valve may be possible
once the pulse-air assembly has been
removed (see Section 6). If this is not feasible,
proceed as outlined in paragraph 8 below.

Oil separator

8 Remove the exhaust manifold (see Chap-
ter 2C). The Positive Crankcase Ventilation
(PCV) valve can now be unplugged and flushed,
or renewed, as required, as described in
Chapter 1.
9 Unbolt the oil separator from the cylinder
block/crankcase, and withdraw it; remove and
discard the gasket.
10 Flush out or renew the oil separator, as
required (see Chapter 1).
11 Refitting is the reverse of the removal
procedure, but use a new gasket between the
oil separator and cylinder block. Refill the
cooling system (see Chapter 1). Run the
engine, check for exhaust leaks, and check
the coolant level when it is fully warmed-up.

Emissions control systems  6•11

6.46  Removing the pulse-air piping on

Zetec engines

7.4  Crankcase ventilation system oil separator and related components on 

Zetec engines

1  Oil separator

3  PCV valve

5  Breather pipe and hose

2  Gasket

4  Cylinder block/crankcase opening

6

8

Catalytic converter - general
information, checking and
component renewal

General information

1 The exhaust gases of any petrol engine
(however efficient or well-tuned) consist
largely (approximately 99%) of nitrogen (N

2

),

carbon dioxide (CO

2

), oxygen (O

2

), other inert

gases and water vapour (H

2

O). The remaining

1% is made up of the noxious materials which
are currently seen (CO

2

apart) as the major

polluters of the environment: carbon
monoxide (CO), unburned hydrocarbons (HC),
oxides of nitrogen (NO

x

) and some solid

matter, including a small lead content.
2 Left to themselves, most of these pollutants
are thought eventually to break down naturally
(CO and NO

x

, for example, break down in the

upper atmosphere to release CO

2

) having first

caused ground-level environmental problems.
The massive increase world-wide in the use of
motor vehicles, and the current popular concern
for the environment has caused the introduction
in most countries of legislation, in varying
degrees of severity, to combat the problem.
3 The device most commonly used to clean up
vehicle exhausts is the catalytic converter. It is
fitted into the vehicle’s exhaust system, and
uses precious metals (platinum and palladium
or rhodium) as catalysts to speed up the
reaction between the pollutants and the oxygen
in the vehicle’s exhaust gases, CO and HC
being oxidised to form H

2

O and CO

2

and (in the

three-way type of catalytic converter) NO

x

being

reduced to N

2

. Note: The catalytic converter is

not a filter in the physical sense; its function is to
promote a chemical reaction, but it is not itself
affected by that reaction.
4 The converter consists of an element (or
“substrate”) of ceramic honeycomb, coated
with a combination of precious metals in such
a way as to produce a vast surface area over
which the exhaust gases must flow; the whole
being mounted in a stainless-steel box. A
simple “oxidation” (or “two-way”) catalytic
converter can deal with CO and HC only, while
a “reduction” (or “three-way”) catalytic
converter can deal with CO, HC and NO

x

.

Three-way catalytic converters are further sub-
divided into “open-loop” (or “unregulated”)
converters, which can remove 50 to 70% of
pollutants and “closed-loop” (also known as
“controlled” or “regulated”) converters, which
can remove over 90% of pollutants.
5 The catalytic converters fitted to models
covered in this manual are of the three-way
open- or closed-loop type.
6 The catalytic converter is a reliable and
simple device, which needs no maintenance
in itself, but there are some facts of which an
owner should be aware if the converter is to
function properly for its full service life:
a) DO NOT use leaded petrol in a vehicle

equipped with a catalytic converter - the lead
will coat the precious metals, reducing their

converting efficiency, and will eventually
destroy the converter; it will also affect the
operation of the oxygen sensor, requiring its
renewal if lead-fouled. Opinions vary as to
how much leaded fuel is necessary to affect
the converter’s performance, and whether it
can recover even if only unleaded petrol is
used afterwards; the best course of action is,
therefore, to assume the worst, and to ensure
that NO leaded petrol is used at any time.

b) Always keep the ignition and fuel systems

well-maintained in accordance with the
manufacturer’s schedule (Chapter 1) -
particularly, ensure that the air filter
element, the fuel filter and the spark plugs
are renewed at the correct intervals. If the
inlet air/fuel mixture is allowed to become
too rich due to neglect, the unburned
surplus will enter and burn in the catalytic
converter, overheating the element and
eventually destroying the converter.

c) If the engine develops a misfire, do not

drive the vehicle at all or at least as little as
possible) until the fault is cured - the misfire
will allow unburned fuel to enter the
converter, which will result in its
overheating, as noted above. For the same
reason, do not persist if the engine refuses
to start - either trace the problem and cure
it yourself, or have the vehicle checked
immediately by a qualified mechanic.

d) Avoid allowing the vehicle to run out of

petrol.

e) DO NOT push- or tow-start the vehicle

unless no other alternative exists, especially
if the engine and exhaust are at normal
operating temperature. Starting the engine
in this way may soak the catalytic converter
in unburned fuel, causing it to overheat
when the engine does start - see (b) above.

f) DO NOT switch off the ignition at high

engine speeds; in particular, do not “blip”
the throttle immediately before switching
off. If the ignition is switched off at anything
above idle speed, unburned fuel will enter
the (very hot) catalytic converter, with the
possible risk of its igniting on the element
and damaging the converter.

g) Avoid repeated successive cold starts

followed by short journeys. If the converter
is never allowed to reach its proper working
temperature, it will gather unburned fuel,
allowing some to pass into the atmosphere
and the rest to soak in the element, causing
it to overheat when a long journey is made
- see (b) above.

h) DO NOT use fuel or engine oil additives -

these may contain substances harmful to
the catalytic converter. Similarly, DO NOT
use silicone-based sealants on any part of
the engine or fuel system, and do not use
exhaust sealants on any part of the exhaust
system upstream of the catalytic converter.
Even if the sealant itself does not contain
additives harmful to the converter, pieces
of it may break off and foul the element,
causing local overheating.

i) DO NOT continue to use the vehicle if the

engine burns oil to the extent of leaving a
visible trail of blue smoke. Unburned
carbon deposits will clog the converter
passages and reduce its efficiency; in
severe cases, the element will overheat.

j) Remember that the catalytic converter

operates at very high temperatures - hence
the heat shields on the vehicle underbody -
and the casing will become hot enough to
ignite combustible materials which brush
against it. DO NOT, therefore, park the
vehicle in dry undergrowth, over long grass
or piles of dead leaves.

k) Remember that the catalytic converter is

FRAGILE. Do not strike it with tools during
servicing work, and take great care when
working on the exhaust system (see
Chapter 4). Ensure that the converter is
well clear of any jacks or other lifting gear
used to raise the vehicle. Do not drive the
vehicle over rough ground, road humps,
etc, in such a way as to “ground” the
exhaust system.

l) In some cases, particularly when the vehicle

is new and/or is used for stop/start driving, a
sulphurous smell (like that of rotten eggs)
may be noticed from the exhaust. This is
common to many catalytic converter-
equipped vehicles, and seems to be due to
the small amount of sulphur found in some
petrols reacting with hydrogen in the
exhaust, to produce hydrogen sulphide
(H

2

S) gas; while this gas is toxic, it is not

produced in sufficient amounts to be a
problem. Once the vehicle has covered a
few thousand miles, the problem should
disappear - in the meanwhile, a change of
driving style, or of the brand of petrol used,
may effect a solution.

m)The catalytic converter on a well-maintained

and well-driven vehicle should last for
between 50 000 and 100 000 miles. From this
point on, careful checks should be made at
regular intervals to ensure that the converter is
still operating efficiently. If the converter is no
longer effective, it must be renewed.

Checking

7 Checking the operation of a catalytic
converter requires expensive and
sophisticated diagnostic equipment, starting
with a high-quality exhaust gas analyser. If the
level of CO in the exhaust gases is too high, a
full check of the engine management system
must be carried out (see Section 3 of this
Chapter) to eliminate all other possibilities
before the converter is suspected of being
faulty.
8 The vehicle should be taken to a Ford
dealer for this work to be carried out using the
correct diagnostic equipment; do not waste
time trying to test the system without such
facilities.

Component renewal

9 The catalytic converter is part of the
exhaust system - see Chapter 4 for details of
removal and refitting.

6•12 Emissions control systems

9

Front brakes

Type  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Solid or ventilated disc, with single-piston sliding calipers

Disc diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

240 or 260 mm

Disc thickness:

Solid disc  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10 mm

Ventilated disc  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

20 or 24 mm

Minimum disc thickness:

Solid disc  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8 mm

Ventilated disc  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

18 or 22 mm

Maximum disc run-out (disc fitted) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0.1 mm

Minimum brake pad thickness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5 mm

Caliper piston diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

54 mm

Rear drum brakes

Type  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Drum with leading and trailing shoes and automatic adjusters

Nominal drum diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

180, 203 or 228.6 mm according to model

Maximum drum diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.0 mm above nominal diameter

Minimum brake lining thickness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.0 mm

Rear disc brakes

Type  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Solid disc with twin-piston fixed calipers

Disc diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

270 mm

Disc thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10 mm

Minimum disc thickness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8 mm

Maximum disc run-out (disc fitted) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0.1 mm

Minimum brake pad thickness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5 mm

Caliper piston diameter  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33 mm

Chapter 9 Braking system

Anti-lock braking system (ABS) - description  . . . . . . . . . . . . . . . . . . 27
Brake check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Brake fluid level check . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Brake fluid renewal  . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Brake pedal - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Brake pedal-to-servo cross-link - removal and refitting  . . . . . . . . . . 15
Brake pressure control valves - removal and refitting  . . . . . . . . . . . 24
Front brake caliper - removal, overhaul and refitting  . . . . . . . . . . . .

3

Front brake disc - inspection, removal and refitting  . . . . . . . . . . . . .

4

Front brake pads - renewal  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2

General information and precautions  . . . . . . . . . . . . . . . . . . . . . . . .

1

Handbrake adjustment  . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Handbrake cable - removal and refitting . . . . . . . . . . . . . . . . . . . . . . 23
Handbrake lever - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . 21
Handbrake primary cable - removal and refitting  . . . . . . . . . . . . . . . 22
Handbrake shoes (disc brake models) - renewal  . . . . . . . . . . . . . . . 20
Hydraulic pipes and hoses - inspection, removal and 

refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Hydraulic system - bleeding  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Hydraulic unit (ABS) - removal and refitting  . . . . . . . . . . . . . . . . . . . 28
Light-laden valve (Van models) - adjustment  . . . . . . . . . . . . . . . . . . 26
Light-laden valve (Van models) - removal and refitting  . . . . . . . . . . . 25
Load-apportioning valve (ABS) - removal and refitting  . . . . . . . . . . . 32
Master cylinder - inspection and overhaul  . . . . . . . . . . . . . . . . . . . . 13
Master cylinder - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . 12
Module (ABS) - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . 29
Rear brake backplate - removal and refitting  . . . . . . . . . . . . . . . . . .

8

Rear brake caliper - removal and refitting . . . . . . . . . . . . . . . . . . . . . 10
Rear brake disc - inspection, removal and refitting  . . . . . . . . . . . . . 11
Rear brake drum - removal, inspection and refitting . . . . . . . . . . . . .

5

Rear brake pads - renewal  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9

Rear brake shoes - renewal  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

Rear wheel cylinder - removal, overhaul and refitting  . . . . . . . . . . . .

7

Vacuum servo unit - testing, removal and refitting  . . . . . . . . . . . . . . 18
Vacuum servo unit vacuum hose and non-return valve - removal, 

testing and refitting  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Wheel sensor (ABS) - removal and refitting  . . . . . . . . . . . . . . . . . . . 30
Wheel sensor ring (ABS) - removal and refitting  . . . . . . . . . . . . . . . . 31

9•1

Easy, suitable for
novice with little
experience

Fairly easy, suitable
for beginner with
some experience

Fairly difficult,
suitable for competent
DIY mechanic

Difficult, suitable for
experienced  DIY
mechanic

Very difficult,
suitable for expert
DIY or  professional

Degrees of difficulty

Specifications

Contents