1983 FIAT UNO clutch

REPAIRS & OVERHAUL
Engine and Associated Systems
Engine (also see Chapter 13)Page 1•1
Cooling and heating systems (also see Chapter 13)Page2•1
Fuel system (also see Chapter 13)Page 3•1
Ignition system (also see Chapter 13)Page4•1
Transmission
Clutch (also see Chapter 13)Page5•1
Transmission (also see Chapter 13)Page6•1
Driveshafts, hubs, roadwheels and tyres (also see Chapter 13)Page7•1
Brakes
Braking system(also see Chapter 13)Page 8•1
Electrical
Electrical system(also see Chapter 13)Page 9•1
Steering and suspension
SteeringPage 10•1
Suspension (also see Chapter 13)Page 11•1
Bodywork
Bodywork (also see Chapter 13)Page 12•1
Additional information
Supplement: Revisions and information on later models Page 13•1
Wiring DiagramsPage 14•1
REFERENCE
MOT Test Checks PageREF•1
Tools and Working Facilities Page REF•5
General Repair Procedures Page REF•8
Fault FindingPage REF•9
Buying Spare Parts & Vehicle Identification Numbers PageREF•12
Glossary of Technical Terms PageREF•13
IndexPage REF•17
Contents

Safety First!0•5
Working on your car can be dangerous.
This page shows just some of the potential
risks and hazards, with the aim of creating a
safety-conscious attitude.
General hazards
Scalding
• Don’t remove the radiator or expansion
tank cap while the engine is hot.
• Engine oil, automatic transmission fluid or
power steering fluid may also be dangerously
hot if the engine has recently been running.
Burning
• Beware of burns from the exhaust system
and from any part of the engine. Brake discs
and drums can also be extremely hot
immediately after use.
Crushing
• When working under or near
a raised vehicle,
always
supplement the
jack with axle
stands, or use
drive-on
ramps.
Never
venture
under a car which
is only supported by a jack.
• Take care if loosening or tightening high-
torque nuts when the vehicle is on stands.
Initial loosening and final tightening should
be done with the wheels on the ground.
Fire
• Fuel is highly flammable; fuel vapour is
explosive.
• Don’t let fuel spill onto a hot engine.
• Do not smoke or allow naked lights
(including pilot lights) anywhere near a
vehicle being worked on. Also beware of
creating sparks
(electrically or by use of tools).
• Fuel vapour is heavier than air, so don’t
work on the fuel system with the vehicle over
an inspection pit.
• Another cause of fire is an electrical
overload or short-circuit. Take care when
repairing or modifying the vehicle wiring.
• Keep a fire extinguisher handy, of a type
suitable for use on fuel and electrical fires.
Electric shock
• Ignition HT
voltage can be
dangerous,
especially to
people with heart
problems or a
pacemaker. Don’t
work on or near the
ignition system with
the engine running or
the ignition switched on.• Mains voltage is also dangerous. Make
sure that any mains-operated equipment is
correctly earthed. Mains power points should
be protected by a residual current device
(RCD) circuit breaker.
Fume or gas intoxication
• Exhaust fumes are
poisonous; they often
contain carbon
monoxide, which is
rapidly fatal if inhaled.
Never run the
engine in a
confined space
such as a garage
with the doors shut.
• Fuel vapour is also
poisonous, as are the vapours from some
cleaning solvents and paint thinners.
Poisonous or irritant substances
• Avoid skin contact with battery acid and
with any fuel, fluid or lubricant, especially
antifreeze, brake hydraulic fluid and Diesel
fuel. Don’t syphon them by mouth. If such a
substance is swallowed or gets into the eyes,
seek medical advice.
• Prolonged contact with used engine oil can
cause skin cancer. Wear gloves or use a
barrier cream if necessary. Change out of oil-
soaked clothes and do not keep oily rags in
your pocket.
• Air conditioning refrigerant forms a
poisonous gas if exposed to a naked flame
(including a cigarette). It can also cause skin
burns on contact.
Asbestos
• Asbestos dust can cause cancer if inhaled
or swallowed. Asbestos may be found in
gaskets and in brake and clutch linings.
When dealing with such components it is
safest to assume that they contain asbestos.
Special hazards
Hydrofluoric acid
• This extremely corrosive acid is formed
when certain types of synthetic rubber, found
in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 400
0C. The
rubber changes into a charred or sticky
substance containing the acid. Once formed,
the acid remains dangerous for years. If it
gets onto the skin, it may be necessary to
amputate the limb concerned.
• When dealing with a vehicle which has
suffered a fire, or with components salvaged
from such a vehicle, wear protective gloves
and discard them after use.
The battery
• Batteries contain sulphuric acid, which
attacks clothing, eyes and skin. Take care
when topping-up or carrying the battery.
• The hydrogen gas given off by the battery
is highly explosive. Never cause a spark or
allow a naked light nearby. Be careful when
connecting and disconnecting battery
chargers or jump leads.
Air bags
• Air bags can cause injury if they go off
accidentally. Take care when removing the
steering wheel and/or facia. Special storage
instructions may apply.
Diesel injection equipment
• Diesel injection pumps supply fuel at very
high pressure. Take care when working on
the fuel injectors and fuel pipes.
Warning: Never expose the hands,
face or any other part of the body
to injector spray; the fuel can
penetrate the skin with potentially fatal
results.
Remember...
DO
• Do use eye protection when using power
tools, and when working under the vehicle.
• Do wear gloves or use barrier cream to
protect your hands when necessary.
• Do get someone to check periodically
that all is well when working alone on the
vehicle.
• Do keep loose clothing and long hair well
out of the way of moving mechanical parts.
• Do remove rings, wristwatch etc, before
working on the vehicle – especially the
electrical system.
• Do ensure that any lifting or jacking
equipment has a safe working load rating
adequate for the job.
A few tips
DON’T
• Don’t attempt to lift a heavy component
which may be beyond your capability – get
assistance.
• Don’t rush to finish a job, or take
unverified short cuts.
• Don’t use ill-fitting tools which may slip
and cause injury.
• Don’t leave tools or parts lying around
where someone can trip over them. Mop
up oil and fuel spills at once.
• Don’t allow children or pets to play in or
near a vehicle being worked on.

0•10Routine maintenance
Maintenance is essential for ensuring safety and desirable for the
purpose of getting the best in terms of performance and economy
from the car. Over the years the need for periodic lubrication has been
greatly reduced if not totally eliminated. This has unfortunately tended
to lead some owners to think that because no such action is required
the items either no longer exist or will last forever. This is certainly not
the case; it is essential to carry out regular visual examinations as
comprehensively as possible in order to spot any possible defects at
an early stage before they develop into major and expensive repairs.
For information applicable to later models, see Supplement.
Every 250 miles (400 km), weekly,
or before a long journey
m mCheck engine oil level
m mCheck brake reservoir fluid level
m mCheck tyre pressures
m mCheck operation of all lights and horn
m mTop up washer fluid reservoirs, adding a screen
wash, and check operation of washers and wipers
m mCheck coolant level
m mCheck battery electrolyte level
Every 6000 miles (10 000 km)
or six months, whichever comes first
m mRenew engine oil and filter (Chapter 1, Section 2)
m mCheck drivebelt tension (Chapter 2, Section 8)
m mCheck carburettor idle speed and mixture
adjustments (Chapter 3)
m mCheck contact points and dwell angle (mechanical
breaker distributors) (Chapter 4, Section 3)
m mCheck tyre tread wear (Chapter 7, Section 7)
m mCheck disc pads for wear (Chapter 8, Section 3)
Every 36 000 miles (60 000 km)
or three years, whichever comes first
m mRenew the timing belt - 1116 and 1299/1301 cc
(Chapter 1, Section 28)
m mCheck exhaust system for corrosion (Chapter 3,
Section 19)
m mRenew contact breaker points and adjust dwell
angle (mechanical breaker distributors) (Chapter 4,
Section 3)
m mCheck and adjust ignition timing (Chapter 4,
Section 4)
m mRenew spark plugs (Chapter 4, Section 11)
m mCheck clutch adjustment (Chapter 5, Section 2)
m mCheck transmission oil level (Chapter 6, Section 2)
m mCheck driveshaft and steering rack gaiters for splits
(Chapters 7 and 10)
m mCheck rear brake shoe linings for wear (Chapter 8,
Section 4)
m mCheck handbrake travel (Chapter 8, Section 16)
m mCheck headlamp beam alignment (Chapter 9,
Section 17)
m mCheck balljoints for wear (Chapter 10, Section 2)
m mCheck front wheel alignment (Chapter 10, Section 8)
m mCheck suspension bushes for wear (Chapter 11,
Section 2)
m mCheck seat belts for fraying (Chapter 12, Section 23)
m mLubricate controls, hinges and locks
Every 24 000 miles (40 000 km)
or two years, whichever comes first
m mRenew coolant anti-freeze mixture (Chapter 2,
Section 3)
m mRenew transmission oil (Chapter 6, Section 2)
m mRenew brake hydraulic fluid (Chapter 8, Section 12)
m mCheck for underbody corrosion and clean out door
and sill drain holes (Chapter 12, Section 2)
Every 12 000 miles (20 000 km) or
12 months, whichever comes first
m mCheck and adjust valve clearances (Chapter 1,
Sections 5 and 26)
m mRenew air cleaner element (Chapter 3, Section 2)

Routine maintenance0•11
Engine compartment (air cleaner removed for clarity) on 55S model
1 Strut upper mounting
2 Washer fluid reservoir
3 Brake fluid reservoir
4 Ignition coil5 Throttle cable
6 Carburettor
7 Battery
8 Timing belt cover9 Distributor
10 Oil filler cap
11 Radiator electric cooling
fan12 Radiator
13 Coolant expansion tank
14 Front mounting
15 Clutch operating cable

Lubricants and Fluids0•13
Component or system Lubricant type/specification
1 EngineMultigrade engine oil, viscosity SAE 15W/40, meeting API-SG or CCMC
G2/G3 specification (or equivalent multigrade engine oil with viscosity
rating suitable for ambient temperature in which vehicle is operated -
see owner’s handbook)
2 Transmission:
1372 cc Turbo ie model FIAT ZC 80/S gear oil
All other models FIAT ZC 90 gear oil
3 Cooling systemEthylene glycol based antifreeze
4 Brake and clutch hydraulic system(s)Hydraulic fluid to DOT 3 or 4, or SAE J1703C
5 Driveshaft CV joints and steering rackLithium based molybdenum disulphide
General greasingMulti-purpose lithium based grease

24Screw in the big-end bolts and tighten to
the specified torque (photo).
25Refit the sump pan (Sec 8) and the
cylinder head (Sec 7).
26Refill the engine with oil and coolant.
10 Oil pump-
removal and refitting
1
1Remove the sump pan as described in
Section 8.
2Unscrew the two bolts which hold the oil
pump housing to the underside of the
crankcase and withdraw the pump. Remove
and discard the pump flange gasket.
Refitting
3Stick a new gasket to the oil pump location
on the underside of the crankcase (photo).
4Locate the oil pump driveshaft in the oil
pump and then offer up the complete
assembly to the crankcase so that the gear
teeth on the driveshaft mesh with those on the
camshaft (photo).
5Fit the securing bolts (photo).
6Fit the sump pan and refill the engine with
oil.
11 Engine mountings-
renewal
1
1The engine/transmission flexible mountings
can be removed if the power unit is supported
under the sump pan or gearbox with a jack, or
a hoist is attached to the engine lifting lugs
and the weight of the power unit just taken.
2Unscrew the mounting bracket bolts and
remove the mounting.
3Fit the new mounting and remove the lifting
gear.
4In the unlikely event of all the mountings
requiring renewal at the same time, renew
them one at a time, never disconnect all the
mountings together.
12 Engine- method of removal
1The engine/transmission should be
removed downwards and withdrawn from
under the front of the car which will have to be
raised sufficiently high to provide clearance.
13 Engine/transmission-
removal and separation
3
1Open the bonnet, disconnect the
windscreen washer tube.
2Mark the hinge positions on the underside
of the bonnet using masking tape and thenwith the help of an assistant to support its
weight unbolt the bonnet and remove it to a
safe place.
3Disconnect the battery negative lead.
4Drain the cooling system and engine oil.
5Disconnect the leads from the rear of the
alternator, the starter motor and the oil pressure
switch also the coolant temperature switch.
6Disconnect the HT lead from the ignition
coil and the LT lead from the distributor.
Disconnect the transmission earth strap.
7Remove the air cleaner.
8Disconnect the clutch cable from the
release lever at the transmission.
9Disconnect the speedometer drive cable by
unscrewing the knurled nut from the
transmission.
903 cc engine 1•13
10.3 Oil pump gasket
10.4 Fitting the oil pump10.5 Tightening an oil pump bolt
9.24 Tightening a big-end bolt
Fig. 1.11 Speedometer drive cable at
transmission (Sec 13)Fig. 1.10 Clutch cable disconnected (Sec 13)
C Reversing switch cablesFig. 1.9 Coolant temperature switch
(Sec 13)
1

31Support the weight of the transmission
and withdraw it in a straight line from the
engine.
14 Engine- dismantling (general)
1Stand the engine on a strong bench at a
suitable working height. Failing this, it can be
dismantled on the floor, but at least stand it
on a sheet of hardboard.
2During the dismantling process, the
greatest care should be taken to keep the
exposed parts free from dirt. As the engine is
stripped, clean each part in a bath of paraffin.
3Never immerse parts with oilways in
paraffin, e.g. the crankshaft, but to clean,
wipe down carefully with a paraffin dampened
rag. Oilways can be cleaned out with a piece
of wire. If an air line is available, all parts can
be blown dry and the oilways blown through
as an added precaution.
4Re-use of old gaskets is false economy and
can give rise to oil and water leaks, if nothing
worse. To avoid the possibility of trouble after
the engine has been reassembled always use
new gaskets throughout.
5To strip the engine, it is best to work from
the top downwards. The engine oil sump
provides a firm base on which the engine can
be supported in an upright position. When the
stage is reached where the pistons are to be
removed, turn the engine on its side. Turn the
block upside down to remove the crankshaft.
6Wherever possible, replace nuts, bolts and
washers finger-tight from wherever they were
removed. This helps avoid later loss and
muddle. If they cannot be replaced then lay
them out in such a fashion that it is clear from
where they came.
15 Engine- removing ancillary
components
1Before dismantling the engine, remove the
engine ancillary components.
Carburettor (Chapter 3)
Thermostat housing (Chapter 2)
Alternator (Chapter 9)
Coolant pump (Chapter 2)
Distributor (Chapter 4)
Exhaust manifold (Chapter 3)
Fuel pump (Chapter 3)
Oil filter cartridge (Section 2 this Chapter)
Clutch (Chapter 5)
903 cc engine 1•15
Fig. 1.21 Camshaft and rocker gear components (Sec 16)
Fig. 1.22 Cylinder head, block and crankcase (Sec 16)
1 Camshaft bush
lockbolt
2 Washer
3 Camshaft front
bearing
4 Exhaust valve
5 Spring cap
6 Valve guide
7 Adjuster screw8 Rocker arm
9 Thrust washer
10 Circlip
11 Locknut
12 Washer
13 Locknut
14 Pedestal
15 Rocker arm
16 Plug17 Rocker shaft
18 Coil spring
19 Stud
20 Split collets
21 Spring cap
22 Valve guide
23 Outer valve spring
24 Inner valve spring
25 Spring seat26 Inlet valve
27 Camshaft bearing
28 Camshaft bearing
29 Camshaft
30 Locating dowel
31 Cam follower
32 Pushrod
33 Washer
1 Washer
2 Cylinder head bolt
3 Gasket
4 Rocker cover
gasket
5 Rocker cover6 Washer
7 Plate
8 Nut
9 Stud
10 Plug
11 Cylinder head12 Plug
13 Cylinder head bolt
14 Washer
15 Dowel
16 Plug
17 Plug18 Dowel
19 Block/crankcase
20 Plug
21 Plug
22 Bolt
23 Plug
1
Do not throw the old
gaskets away as it
sometimes happens that an
immediate replacement
cannot be found and the old gasket is
then very useful as a template. Hang
up the gaskets on a suitable nail or
hook as they are removed.

clearance and end gap. Both clearances
should be checked with a feeler gauge. Check
the end gap when the ring has been pushed
squarely down the cylinder bore for two or
three inches (photos).
25If new rings are being used and the
cylinder bores have not been rebored, always
make sure that the top compression ring has
been stepped to prevent it contacting the
bore wear ridge.
Flywheel
26Check the clutch mating surface of the
flywheel. If it is deeply scored (due to failure to
renew a worn driven plate) then it may be
possible to have it surface ground provided
the thickness of the flywheel is not reduced
too much.
27If lots of tiny cracks are visible on the
surface of the flywheel then this will be due to
overheating caused by slipping the clutch or
“riding” the clutch pedal.
28With a pre-engaged type of starter motor
it is rare to find the teeth of the flywheel ring
gear damaged or worn but if they are, then the
ring gear will have to be renewed.
29To remove the ring gear, drill a hole
between the roots of two teeth taking care not
to damage the flywheel and then split the ring
with a sharp cold chisel.
30The new ring gear must be heated to
between 180 and 220ºC (356 and 428ºF)
which is very hot, so if you do not have
facilities for obtaining these temperatures,
leave the job to your dealer or engine
reconditioner.
31Where such facilities are available, then
the ring gear should be either pressed or
lightly tapped gently onto its register and left
to cool naturally, when the contraction of the
metal on cooling will ensure that it is a secure
and permanent fit. Great care must be taken
not to overheat the ring gear, as if this
happens its temper will be lost. A clutch input
shaft pilot bearing is not fitted on this engine.
Camshaft
32Examine the camshaft bearings for wear,
scoring or pitting. If evident then the bearings
will have to be renewed. The three bearingsare of different sizes and they can be removed
and new ones fitted using a bolt, nut and
distance pieces. When drawing a new bearing
into position, make sure that the oil hole is
correctly aligned with the one in the
crankcase. The centre and rear bearings
require reaming after fitting, the bearing at the
timing chain end is supplied ready reamed
(photo).
33The camshaft itself should show no marks
or scoring on the journal or cam lobe
surfaces. Where evident, renew the camshaft
or have it reprofiled by a specialist
reconditioner.
34Check the teeth of the camshaft sprocket
for wear. Renew the sprocket if necessary.
Cam followers
35Examine the bearing surface of the cam
followers which are in contact with the
camshaft. Any indentations or cracks must be
rectified by renewal. Clean sludge and dirt
from the cam followers and check their fit in
their bores. Side to side rock is unusual
except at very high mileage.
Timing chain
36Examine the teeth on both the crankshaft
sprocket and the camshaft sprocket for wear.
Each tooth forms an inverted “V” with the
sprocket periphery and if worn, the side of
each tooth under tension will be slightly
concave in shape when compared with the
other side of the tooth, ie; one side of the
inverted “V” will be concave when compared
with the other. If any sign of wear is present
the sprockets must be renewed.
37Examine the links of the chain for side
slackness and particularly check the
self-tensioning links for freedom of
movement. Renew the chain if any slackness
is noticeable when compared with a new
chain. It is a sensible precaution to renew the
chain at about 60 000 miles (96 000 km) and
at a lesser mileage if the engine is stripped
down for a major overhaul.
Cylinder head
38This is covered in Section 17.
Rockers and rocker shaft
39Thoroughly clean out the rocker shaft. As
it acts as the oil passages for the valve gear,
clean out the oil holes and make sure they are
quite clear. Check the shaft for straightness
by rolling it on a flat surface. If it is distorted,
renew it.
40The surface of the shaft should be free
from any wear ridges caused by the rocker
arms. If it is not, the shaft will have to be
renewed. Blocked shaft oil holes often
contribute to such wear.
41Check the rocker arms for wear of the
rocker bushes, for wear at the rocker arm face
which bears on the valve stem, and for wear
of the adjusting ball ended screws. Wear in
the rocker arm bush can be checked by
gripping the rocker arm tip and holding the
rocker arm in place on the shaft, noting if
there is any lateral rocker arm shake. If any
shake is present, and the arm is very loose on
the shaft, remedial action must be taken. It is
recommended that a worn rocker arm be
taken to your local FIAT agent or automobile
engineering works to have the old bush drawn
out and a new bush fitted (photo).
42Check the tip of the rocker arm where it
bears on the valve head, for cracking or
serious wear on the case hardening. If none is
present the rocker arm may be refitted. Check
the pushrods for straightness by rolling them
on a flat surface.
Oil pump
43Unscrew the four securing bolts which
connect the two halves of the pump body.
44Clean all the components in a bath of
paraffin and dry them.
45Inspect the gears for wear or damage and
then check for wear in the following way.
46Insert a feeler blade between the tooth
peak and the body. This should be between
0.05 and 0.14 mm (0.0019 and 0.0055 in).
47Now place a straight-edge across the
body flange and check for gear endfloat. This
should be between 0.020 and 0.105 mm
(0.0008 and 0.0041 in). Where the clearances
exceed the specified limits, renew the pump.
48Check that the oil pressure relief valve
spring is in good condition and not deformed.
903 cc engine 1•19
18.41 Rocker components18.32 Camshaft bearing18.24B Checking piston ring end gap
1