1988 OPEL CALIBRA sensor

b)Check the throttle cable operation and
adjustment (see above).
c)When reconnecting the vacuum hoses
and pipes, ensure that they are connected
to the front unions as shown in the
accompanying photograph.
d)As no fuel vapour trap is fitted, it is
essential that the manifold absolute
pressure sensor vacuum hose is routed
so that it falls steadily from the sensor to
the throttle body. This precaution will
prevent any fuel droplets being trapped in
the sensor or hose and allowing them to
drain into the inlet port.
e)Ensure that the fuel hoses are correctly
reconnected; the feed hose is on the
injector end of the throttle body.
f)Switch on the ignition and check for signs
of fuel leaks from all disturbed unions; if
any signs of leakage are detected, the
problem must be rectified before the
engine is started.
33Idle air control stepper
motor - removal and refitting
3
Removal
1Remove the air box (see Section 5).
2Disconnect the battery earth lead.3Disconnect the wiring plug from the stepper
motor (see illustration).
4Undo its two screws, then withdraw the
stepper motor. Remove and discard the
sealing ring (see illustrations).
Refitting
5Refitting is the reverse of the removal
procedure, noting the following points.
a)Fit a new sealing ring, greasing it lightly to
ease installation.
b)To prevent the risk of damage, either to
the throttle body or to the stepper motor,
if the motor’s plunger tip projects more
than 28 mm (1.1 in) beyond the motor’s
mating surface, carefully press the
plunger in until its stop is reached. The
stepper motor will then be reset by the
ECU when the engine is restarted.
c)Apply a few drops of a thread-locking
compound to their threads, then carefully
tighten the screws to the specified torque
wrench setting.
34Throttle potentiometer -
removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect the wiring plug from the
potentiometer (see illustration).
3Unscrew the two Torx-type securing
screws (size TX 25) and withdraw the
potentiometer.
Refitting
4Refitting is the reverse of the removal
procedure, noting the following points.
a)Install the potentiometer when the throttle
valve is fully closed, and ensure that its
adapter seats correctly on the throttle
valve spindle.
b)Tighten the screws carefully to the
specified torque.
35Electronic Control Unit
(ECU) - removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Remove the driver’s footwell side trim panel
(Chapter 11).
3Release the unit from its mountings and
withdraw it until the wiring plugs’ locking lugs
can be released and the plugs can be
disconnected (see illustration).
4Note that the unit consists of two parts the
basic control unit and the Programmable
Read Only Memory (PROM). While it is
possible to renew them separately, do not
attempt to separate them. Faults requiring this
degree of attention can be diagnosed only by
an experienced mechanic using the special
Vauxhall test equipment. A previously sound
ECU could be seriously damaged by careless
handling of the contacts between the two
sub-units.
4B•16Fuel and exhaust systems - fuel injection models
32.10 Intake air temperature control -
Multec systems
A Vacuum pipe
B Exhaust gas recirculation valve hose
C Charcoal canister control pipe
D Fuel return hose
33.4A Unscrew retaining screws (second
screw arrowed) . . .
35.3 Withdrawing the fuel
injection/ignition system ECU34.2 Disconnecting the throttle
potentiometer wiring plug - note the
mounting screws (arrowed)
33.4B . . . to remove the stepper motor -
renew sealing ring (arrowed)
33.3 Disconnecting the idle air control
stepper motor wiring plug

Refitting
5Refitting is a reversal of the removal
procedure, ensuring that the wiring plugs are
correctly reconnected and that the unit is
located securely.
36Knock sensor and module
(X16 SZ models) - removal
and refitting
3
Removal
1The knock sensor fitted to the X16 SZ
engine is located on the cylinder block below
the inlet manifold, between cylinders 2 and 3.
2Disconnect the battery negative lead.
3Remove the wiring and unscrew the unit
from the block.
4The module and control unit are located on
the left-hand side of the engine compartment
behind the battery. To remove, disconnect the
wiring multiplug and remove the retaining
bolts (see illustration).
5There is no provision for testing the knock
sensor or module without dedicated Vauxhall
test equipment. Check for external damage
and replace if necessary.
Refitting
6Refitting is a reversal of the removal
procedure, ensuring that the wiring plugs are
correctly reconnected and that the units are
located securely.
37Knock sensor (Simtec
system) - removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect wiring harness plug, from inlet
air temperature sensor and wiring harness
plug, from hot mass air flow meter.
3Remove crankcase ventilation hoses.
4Remove coolant hoses from air inlet hoses,
hot film mass air flow meter complete with air
inlet hoses, from upper part of air cleaner and
throttle body.5Press retaining clip for 1st and 4th cylinder
injectors in plug strip (with screwdriver)
towards fuel distributor pipe - lifting plug strip
at the same time. On the underside of the plug
strip there are a total of 6 plug connections, 4
of which are for the injectors.
6Disconnect wiring harness plug for knock
sensor from the plug strip.
7Connect a 1 metre length of separate cable
to knock sensor wiring harness plug (note
routing).
8Remove knock sensor from cylinder block
(see illustration).
9Disconnect knock sensor cable from
separately attached cable, separate cable
remains in engine compartment.
Refitting
10Refitting is a reversal of removal, but note
the following.
11Before refitting ensure that the sensor is
spotlessly clean. Clean the entire contact
surface of the sensor must lie directly on the
cylinder block. Do not use any form of
washers.
12Carefully refit sensor into the block.
Tighten to the correct torque.
13Guide knock sensor cable between ridges
on inlet manifold using separate cable -
ensure correct routing.
14Remove the cable.
15Insert the wiring harness plug for the
knock sensor, into the plug strip.
16Correctly align the spring clips for theinjectors as they may prevent engagement of
the plug strip. Correct contact between the
plug strip and the injector is essential.
17When connecting plug strip, an audible
‘click’ should be heard.
18Ensure that hoses are in good condition
and installed securely with the two clamps.
38Inlet manifold (SOHC without
Multec) - removal and refitting
3
Note:Refer to warning in Section 2, before
proceeding. Use a new gaskets when refitting.
Removal
1Disconnect the battery negative lead.
2Remove the idle speed adjuster and its
hoses, referring to Section 22, if necessary.
3Release the securing clip, then disconnect
the throttle cable and balljoint from the throttle
valve lever. Slide the throttle cable grommet
from the bracket on the inlet manifold, and
move the throttle cable to one side out of the
way.
4Loosen the clamp screw and disconnect
the air trunking from the throttle body.
5Unscrew the union nut and disconnect the
brake servo vacuum hose from the inlet
manifold(see illustration).
6Disconnect the camshaft cover breather
hose from the throttle body.
7Disconnect the coolant hoses from the
throttle body. Be prepared for coolant
spillage, and clamp or plug the open ends of
the hoses, to prevent further coolant loss.
8Disconnect the wiring plug from the throttle
position sensor.
9Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
10Disconnect the wiring harness housing
from the fuel injectors and move it to one side,
taking care not to strain the wiring. Pull up on
the wiring harness housing, and compress the
wiring plug retaining clips to release the
harness housing from the injectors.
11Disconnect the fuel hoses from the fuel
rail. Be prepared for fuel spillage, and take
adequate fire precautions. Clamp or plug the
open ends of the hoses, to prevent dirt
ingress and further fuel leakage.
Fuel and exhaust systems - fuel injection models 4B•17
38.5 Disconnecting the brake servo
vacuum hose -
SOHC models37.8 Knock sensor and wiring
(Simtec system)
1 Sensor2 Securing bolt
36.4 Knock sensor and module (X16 SZ models)
1 Sensor2 Module3 Sensor securing bolt
4B

12Unscrew and remove the top alternator
mounting nut and bolt.
13Make a final check to ensure that all
relevant hoses, pipes and wires have been
disconnected.
14Unscrew the securing nuts, and withdraw
the manifold from the cylinder head. Recover
the gasket (see illustrations).
15It is possible that some of the manifold
studs may be unscrewed from the cylinder
head when the manifold securing nuts are
unscrewed. In this event, the studs should be
screwed back into the cylinder head once the
manifold has been removed, using two
manifold nuts locked together.
16If desired, the ancillary components can
be removed from the manifold, referring to the
relevant Chapter.
Refitting
17Refitting is a reversal of removal,
remembering the following points.
18Where applicable refit any ancillary
components to the manifold, with reference to
relevant Sections of Chapters 4A or 4B.
19If the alternator mounting bracket has
been unbolted from the manifold, refit it
before refitting the manifold, as access to the
securing bolt is extremely limited once the
manifold is in place.
20Refit the manifold using a new gasket,
and tighten the securing nuts to the specified
torque.
21Ensure that all relevant hoses, pipes and
wires are correctly reconnected.
22On completion, check and if necessary
top-up the coolant level, (Chapter 3).
23Check and if necessary adjust the throttle
cable free play, as described in Chapters 4A
or 4B, as applicable.
24If any of the fuel system components have
been disturbed or renewed, check and if
necessary adjust the idle mixture, as
described in Chapters 4A or 4B, as applicable.
39Inlet manifold (SOHCwith
Multec) - removal and refitting
3
Removal
1Depressurise the fuel system Section 8).
2Remove the air box (see Section 5).
3Disconnect the battery negative lead.
4Either remove the throttle body assembly
(see Section 32), or disconnect the throttle
cable, wiring, fuel and vacuum hoses and
pipes to allow the manifold to be removed
with the throttle body.
5Drain the cooling system (see Chapter 3).
6Continue as described in Chapter 4A,
Section 26, paragraph 4 onwards.
Refitting
7Refitting is the reverse of the removal
procedure; renew all gaskets and seals
disturbed.
40Inlet manifold (DOHC
models) - removal and
refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect the wiring plug from the air
mass meter. Recover the sealing ring.
3Loosen the clamp screw securing the air
trunking to the right-hand end of the air mass
meter.
4Using an Allen key or hexagon bit, unscrew
the four bolts securing the air box to the
throttle body. Lift the air box from the throttle
body, and disconnect the hose from the base
of the air box then withdraw the air box/air
mass meter assembly.
5Disconnect the wiring plug from the throttle
position sensor.
6Slide the throttle cable end from the throttle
valve lever. Then pull the cable end grommet
from the bracket on the inlet manifold and
move the throttle cable to one side out of the
way.
7Disconnect the two breather hoses from the
rear of the camshaft cover. Disconnect the
larger hose from the throttle body, and
remove the hose completely.
8Position a wad of rag beneath one of the
fuel hose unions on the fuel rail, to absorb the
fuel that will be released as the union is
disconnected.
9Slowly loosen the fuel hose union, to
gradually relieve the pressure in the fuel feed
line, then disconnect the hose from the fuel
rail. Be prepared for fuel spillage, and take
adequate fire precautions. Plug the end of the
fuel hose, to prevent dirt ingress and further
fuel leakage.
10Repeat paragraphs 9 and 10 for the
remaining fuel hose-to-fuel rail union.
11Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
12Disconnect the wiring harness housing
from the fuel injectors and move it to one side,
taking care not to strain the wiring. Pull up on
the wiring harness housing, and compress the
wiring plug retaining clips to release the
housing from the injectors.
13Unscrew the union nut, and disconnectthe brake servo vacuum hose from the left-
hand side of the inlet manifold (see
illustration).
14Unscrew the retaining nut, and remove
the fuel hose bracket from the left-hand side
of the throttle body.
15Unscrew the securing nuts, and
disconnect the earth leads from the fuel rail
securing studs at either end of the fuel rail.
16Unscrew the securing bolt, and remove
the cable/hose bracket from the left-hand end
of the inlet manifold.
17Remove the idle speed adjuster, as
described in Section 22.
18Unscrew and remove the top alternator
mounting nut and bolt.
19Make a final check to ensure that all
relevant hoses, pipes and wires have been
disconnected.
20Unscrew the securing nuts, and withdraw
the manifold from the cylinder head. Recover
the gasket.
21It is possible that some of the manifold
studs may be unscrewed from the cylinder
head when the manifold securing nuts are
unscrewed. In this event, the studs should be
screwed back into the cylinder head once the
manifold has been removed, using two
manifold nuts locked together.
22If desired, the ancillary components can
be removed from the manifold, with reference
to the relevant Sections of Chapters 4A or 4B.
Refitting
23Refitting is a reversal of the removal
procedure.
4B•18Fuel and exhaust systems - fuel injection models
38.14A Unscrew the securing nuts
40.13 Brake servo vacuum hose
connection at inlet manifold (arrowed) -
DOHC models
38.14B ...and withdraw the inlet manifold -
SOHC models

Maintenance - component location 1•5
1
Underbonnet view of a 1989 1.6 L model (16 SV engine)
1 VIN plate
2 Air cleaner casing *
3 Suspension strut top
4 Coolant expansion tank
5 Brake fluid reservoir
6 Fuel pump
7 Steering rack
8 Octane rating plug
9 Washer fluid reservoir
10 Battery
11 Ignition coil
12 Distributor (Bosch type)
13 Cooling fan motor
14 Engine oil level dipstick
15 Oil filter
16 Oil filler cap
* Refer to Chapter 4A for
alternative type
Underbonnet view of a 1991 model Cavalier 1.6 L (C16 NZ engine)
1 Air cleaner casing
2 Suspension strut top
3 Coolant expansion tank
4 Brake fluid reservoir
5 Air box
6 Exhaust gas recirculation valve
7 Steering gear
8 Octane coding plug
9 Washer fluid reservoir
10 Battery
11 Ignition coil
12 Distributor
13 Cooling fan motor
14 Engine oil level dipstick
15 Engine oil filter
16 Oxygen sensor
17 Engine oil filler cap

1Introduction
This Chapter is designed to help the home
mechanic maintain his/her vehicle for safety,
economy, long life and peak performance.
The Chapter contains a master maintenance
schedule, followed by Sections dealing specifically
with each task in the schedule. Visual checks,
adjustments, component renewal and other helpful
items are included. Refer to the accompanying
illustrations of the engine compartment and the
underside of the vehicle for the locations of the
various components.
Servicing your vehicle according to the
mileage/time maintenance schedule and the
following Sections will provide a planned
maintenance programme, which should result in a
long and reliable service life. This is a comprehensiveplan, so maintaining some items but not others at
the specified service intervals, will not produce the
same results.
As you service your vehicle, you will
discover that many of the procedures can -
and should - be grouped together, because of
the particular procedure being performed, or
because of the proximity of two otherwise-
unrelated components to one another. For
example, if the vehicle is raised for any
reason, the exhaust can be inspected at the
same time as the suspension and steering
components.
The first step in this maintenance
programme is to prepare yourself before the
actual work begins. Read through all the
Sections relevant to the work to be carried
out, then make a list and gather all the parts
and tools required. If a problem is found, seek
advice from a parts specialist, or a dealer
service department.
2Intensive maintenance
If, from the time the vehicle is new, routine
maintenance schedule is followed closely,
frequent checks made of fluid levels and high-
wear items, as recommended, the engine will
be kept in relatively good running condition.
The need for additional work will be minimised
It is possible that there will be times when
the engine is running poorly due to the lack of
regular maintenance. This is even more likely
if a used vehicle, which has not received
regular and frequent maintenance checks, is
purchased. In such cases, additional work
may need to be carried out, outside of the
regular maintenance intervals.
If engine wear is suspected, a compression
1•8Maintenance - component location
Rear underbody view of a 1990 GSi 2000 model (fully independent rear suspension)
1 Fuel tank securing strap
2 Shock absorber
3 ABS wheel sensor
4 Semi-trailing arm
5 Suspension crossmember
mounting bracing bracket
6 Handbrake cable
7 Suspension crossmember
8 Exhaust expansion box
9 Fuel pump
Maintenance procedures

Valves and guidesInletExhaust
Overall length - production (mm):
20 XEJ and C20 XE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105.0105.0
X20 XEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102.092.0
Overall length - service (mm):
20 XEJ and C20 XE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104.6104.6
X20 XEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101.791.8
Head diameter (mm):
20 XEJ and C20 XE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33.0 ±0.129.0 ±0.1
X20 XEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32.0 ±0.129.0 ±0.1
Stem diameter (mm):
20 XEJ and C20 XE
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.955 to 6.9706.945 to 6.960
0.075 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.030 to 7.0457.020 to 7.035
0.150 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.105 to 7.1207.095 to 7.110
0.250 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.205 to 7.2207.195 to 7.210
X20 XEV
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.955 to 5.9705.945 to 5.960
0.075 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.030 to 6.0456.020 to 6.035
0.150 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.105 to 6.1206.095 to 6.110
Valve guide bore (mm):
20 XEJ and C20 XE
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.000 to 7.015
0.075 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.075 to 7.090
0.150 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.150 to 7.165
0.250 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.400 to 7.415
X20 XEV
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.000 to 6.012
0.075 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.075 to 6.090
0.150 mm oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.150 to 6.165
Valve seat angle (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44°40’
Lubrication system
Lubricant capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .See Chapter 1 Specifications
Oil pressure at idle (engine warm):
20 XEJ and C20 XE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5 bar
X20 XEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 bar
Torque wrench settingsNmlbf ft
Note: Use new bolts (or nuts, if applicable), where asterisked (*).
Alternator to cylinder block bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . .3526
Brake servo line to inlet manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
Camshaft bearing cap to cylinder head (M6) . . . . . . . . . . . . . . . . . . . . .107
Camshaft bearing cap to cylinder head (M8) . . . . . . . . . . . . . . . . . . . . .2015
Camshaft bearing cap to head (X20 XEV) . . . . . . . . . . . . . . . . . . . . . . .86
Camshaft pulley to camshaft (1993-on models):
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5037
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 60°
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15°
Coolant pipe to cylinder block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
Cover to cylinder head (M6 bolts) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
Cover to cylinder head (M8 nuts) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2216
Cover to exhaust manifold (X20 XEV) . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Crankshaft pulse pick-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
Exhaust manifold to cylinder head * . . . . . . . . . . . . . . . . . . . . . . . . . . . .2216
Exhaust pipe to adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Inlet manifold support to cylinder block . . . . . . . . . . . . . . . . . . . . . . . . .2518
Intermediate shaft bracket to cylinder block . . . . . . . . . . . . . . . . . . . . .5541
Knock sensor to cylinder block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2014
Oil cooler lines to adapter/oil cooler . . . . . . . . . . . . . . . . . . . . . . . . . . . .3022
Oil filter to oil pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1511
Oil dipstick flange to cylinder block . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Oil pump safety valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3022
Oil pump, threaded adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2317
Power steering pump to support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Spark plug lead cover to cylinder head cover:
20 XEJ and C20 XE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
X 20 XEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
2B•2DOHC engine procedures

pitting. If evident, the cylinder head and all
bearing caps must be renewed as a matched
set, as there is no provision for refacing if the
bearing caps cannot be renewed individually.
8The camshaft(s) should show no marks or
scoring on the journal or cam lobe surfaces. if
evident, renew the camshaft(s).
9It is advisable to renew the camshaft front
oil seal(s) as a matter of course. Prise the old
seal(s) from the front of the camshaft(s) and
discard them.
Refitting
10Begin refitting by liberally coating the
contact faces of the hydraulic valve lifters and
the camshaft(s) with molybdenum disulphide
paste.
11Coat the mating faces of the front and
rear bearing caps with sealing compound and
refit the bearing caps in their original positions
as noted during removal.
12Tighten the camshaft bearing cap nuts to
the specified torque in half-turn stages, as
when loosening the nuts. Note that when
refitting the exhaust camshaft, the two smaller
rear bearing cap securing nuts should be
tightened after all the main camshaft bearing
cap nuts have been tightened. Note also that
the two smaller nuts should be tightened to a
lower torque wrench setting than the main
nuts.
13Turn the camshaft until the locating peg
for the camshaft sprocket is uppermost, then
lubricate the lips of a rear camshaft front oil
seal with a little grease, and fit the oil seal,
using a tube or socket of similar diameter with
a washer and the camshaft sprocket bolt.
Screw the camshaft sprocket bolt into the end
of the camshaft to draw the oil seal into
position on its shoulder.
14Repeat the procedure for the remaining
camshaft.
15Refit the distributor with reference to
Chapter 5. Fit a new timing belt and the
camshaft sprockets, then adjust the timing
belt as described in Section 4 or 5, as
applicable.
8Cylinder head -removal and
refitting (engine in vehicle)
4
Note: The engine must be cold when the
cylinder head is removed. Do not remove the
cylinder head from a hot engine. New cylinder
head bolts, a new cylinder head gasket and a
new timing belt must be used on refitting.
The torque settings (as shown in Chapter 2A)
are only applicable to latest specification head
bolts, available from Vauxhall. Earlier type or
alternative make, head bolts may require
different torques. Consult your supplier
Removal
1Disconnect the battery negative lead.
2Drain the cooling system, as described in
Chapter 3.3Remove the front section of the exhaust
system, as described in Chapter 4C.
4The cylinder head can be removed
complete with the inlet manifold, or the inlet
manifold can be detached from the cylinder
head before removal, with reference to
Chapter 4B. If no work is to be carried out on
the inlet manifold, it can be unbolted from the
cylinder head and supported to one side out
of the way, thus avoiding the need to
disconnect the relevant hoses, pipes and
wiring.
5If the cylinder head is to be removed
complete with the inlet manifold, disconnect
all relevant hoses, pipes and wiring from the
inlet manifold and associated components,
referring to Chapter 4B, and unbolt the
manifold support bracket from the manifold.
Loosen the alternator mountings with
reference to Chapter 5, then unbolt the upper
alternator mounting from the inlet manifold.
6If the inlet manifold is to be left in the engine
compartment, continue as follows, otherwise
go on to paragraph 17.
7Disconnect the wiring plug from the airflow
meter, and the breather hose from the air box
on the throttle body. Disconnect the air
cleaner trunking and remove the airflow
meter/air box assembly from the throttle
body. Refer to Chapter 4B if necessary.
8Disconnect the end of the throttle cable
from the throttle valve lever, then unbolt the
throttle cable support bracket and remove it
from the inlet manifold.
9Unscrew the two earth lead securing nuts
from the fuel rail (one at each end of the rail)
and disconnect the three earth leads.
10Disconnect the wiring plug from the
throttle position switch.
11Pull up on the wiring harness housing, and
disconnect the wiring plugs from the fuel
injectors by compressing the retaining clips.
Move the wiring harness housing to one side.
12Disconnect the two breather hoses from
the rear of the camshaft cover.
13Loosen the alternator mountings, with
reference to Chapter 5, then unbolt the upper
alternator mounting from the inlet manifold.
14Unbolt the manifold support bracket from
the manifold.15Make a final check to ensure that all
necessary hoses, pipes and wires have been
disconnected, then unscrew the securing nuts
and lift the inlet manifold from the cylinder
head. Ensure that the manifold is properly
supported, taking care not to strain any of the
hoses, pipes and wires, etc., which are still
connected.
16Recover the manifold gasket from the
cylinder head.
17Remove the timing belt, camshaft
sprockets, and timing belt tensioner and idler
pulleys, as described in Section 4.
18Unscrew the upper and middle studs for
the timing belt outer cover screws. Note that
the upper stud simply unscrews from the
cylinder head, but the middle stud is secured
by a bolt.
19Unscrew the two upper rear timing belt
cover securing bolts from the cylinder head.
20Remove the distributor cap and HT leads
with reference to Chapter 5.
21Disconnect the distributor wiring plug.
22Disconnect the coolant hose from the
left-hand end of the cylinder head.
23Unscrew the bolt securing the crankcase
breather tube bracket to the end of the
cylinder head.
24Disconnect the radiator top hose from the
thermostat housing, and disconnect the
wiring plugs from the temperature gauge
sender and the coolant temperature sensor
(both situated in the thermostat housing).
25Make a final check to ensure that all
relevant hoses, pipes and wires have been
disconnected.
26On X20 XEV models, remove the
camshaft, as described in Section 7.
27Using a Torx socket, and working in the
order shown (see illustrations), loosen all the
cylinder head bolts by a quarter of a turn, then
loosen all the bolts by half a turn, and finally
loosen and remove the bolts. Recover the
washers. Note that the loosening sequence
on X20 XEV differs to other DOHC engines.
28Lift the cylinder head from the cylinder
block. If necessary, tap the cylinder head
gently with a soft-faced mallet to free it from
the block, but do not lever at the mating
faces. Note that the cylinder head is located
on dowels.
DOHC engine procedures 2B•7
8.27B Cylinder head bolt loosening
sequence - (X 20 XEV engines)8.27A Cylinder head bolt loosening
sequence - (20 XEJ and C 20 XE engines)
2B

Torque wrench settings (continued)Nmlbf ft
Big-end bearing cap: *
C16 NZ2, 1.8 and 2.0 litre:
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3526
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 45º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15º
Camshaft housing cover to housing . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Camshaft pulley to camshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4533
Camshaft thrust plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Coolant outlet to thermostat housing:
C 16 NZ2, 1.8 and 2.0 litre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Coolant pump to cylinder block:
1.4 and 1.6 litre, (except C 16 NZ2) (M6) . . . . . . . . . . . . . . . . . . . . . .86
C16 NZ2, 1.8 and 2.0 litre (M8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Crankshaft sensor wheel:
C16 NZ2, 1.8 and 2.0 litre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1310
Cylinder head to cylinder block: *
1.4 and 1.6 litre, (except C16 NZ2):
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 60º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 60º
Stage 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 60º
C16 NZ2, 1.8 and 2.0 litre:
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 90º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 90º
Stage 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 90º
Drivebelt (ribbed) pulley/timing belt drive to crankshaft: *
1.4 and 1.6 litre, (except C16 NZ2):
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5541
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 45º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15º
Drivebelt pulley to timing belt drive . . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
Drivebelt (ribbed) tensioner to cylinder block . . . . . . . . . . . . . . . . . . . . .2015
Drivebelt (ribbed) tensioner to support:
1.4 and 1.6 litre, (except C16 NZ2) . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
C16 NZ2, 1.8 and 2.0 litre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1813
Engine bracket to cylinder block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6044
Engine bracket to transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6044
Engine mounting bracket to engine bracket . . . . . . . . . . . . . . . . . . . . . .6044
Engine mounting to engine mounting bracket . . . . . . . . . . . . . . . . . . . .6548
Engine mounting to front axle housing . . . . . . . . . . . . . . . . . . . . . . . . . .4030
Engine mounting to power steering pump support . . . . . . . . . . . . . . . .6044
Engine mounting to side member . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6548
Exhaust manifold to cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2216
Exhaust pipe to manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2518
Flexplate to crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6044
Flywheel to crankshaft: *
1.4 and 1.6 litre, (except C16 NZ2):
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3526
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 30º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15º
C16 NZ2, 1.8 and 2.0 litre:
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6548
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 30º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15º
Front timing belt cover to rear cover . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Fuel pump to camshaft housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1813
Guide sleeve, release bearing to transmission . . . . . . . . . . . . . . . . . . . .2216
Heat shield sleeves to cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . .3022
Inlet manifold to cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2216
Knock sensor to cylinder block (X16 SZ) . . . . . . . . . . . . . . . . . . . . . . . .1310
Main bearing cap: *
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5037
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 45º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle tighten by 15º
Oil filter to oil pump/cylinder block . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
2A•6SOHC engine procedures