1958 FIAT 500 horn

Drain the oil sump to ensure that the oil does not syphon
out. Thoroughly clean the area around the pump body
(see FIG 1 :37).
Remove the end cover plate by releasing the retaining
bolts and washers. Carefully ease t h e driven gear down-
wards followed by the driving gear and shaft
Clean all parts removed and blow clean using a com-
pressed air jet. Inspect the timing gear cover pump area
for cracks or distortion. Check that the inner duct for oil
delivery to the pump is clear of obstruction. If in doubt
remove the drain plug and filler cap and use a com-
pressed air j e t to clean the passage.
Check the gear teeth for damage or excessive wear,
ensure that the drive gear is firmly attached to its spindle
and that the end cover plate is not badly scored or pitted.
Fit new parts as necessary.
Reassembly is the reverse procedure to dismantling,
taking care that all parts are assembled clean and the
end cover plate seating correctly with a new gasket. 5 43 21
1:14 Lubrication, oil filter, relief valve
Description :
The engine is pressure lubricated through a gear type
pump which is incorporated in the timing gear cover and
driven from the camshaft by dogs or gears. The lubrication
circuits are shown in FIGS 1 :36 and 1 : 37.
The pump draws oil from the sump through a suction
horn fitted with a filter screen which is fixed to the crank-
case by a d u c t in t h e timing gear cover. This
supplies oil
to the pump.
Oil passes f r o m the camshaft rear seat o n t o t h e crank-
shaft rear support where it flows into an adjacent chamber.
From here the o i l flows through ducts in the crankshaft
from end to the centrifugal oil filter. The centrifugal filter,
which also acts as a pulley for the generator and blower
drive, rotates w i t h the crankshaft.
Oil from the filter enters a passage in the crankshaft,
where it lubricates the main and connecting rod bearings
and passes f r o m a special groove in the front main
bearing and ducting in the crankcase into which is
inserted the oil pressure warning sender unit, and also
the delivery pipe for oil to the overhead valve gear.
The pushrod sleeves provide the return path for the oil
from the cylinder head and delivers oil to the tappet gear
and the camshaft cams. The tappets are suitably drilled
to allow correct circulation of the oil. The tappets are
located in t w o casting cavities, one of which com-
municates w i t h the timing gear housing and the other
one to the crankshaft front drain support drain.
The oil pressure is regulated by a pressure relief valve 5
(see FIG 1 : 3 8) mounted at the rear end of t h e camshaft.
It comprises a hubbed disc which slides on a guide 6 of
the oil pump drive shaft 7. Under spring load 9 the valve
disc circumferentially closes an annular chamber which
communicates w i t h the lubrication circuit. Excessive o i l
pressure causes the disc to uncover the chamber.
Centrifugal oil filter:
The oil filter is of the centrifugal type comprising of
two flanges and an oil slinger. The filter is attached to the
rear end o f t h e c r a n k s h a f t a s s h o w n i n FIG 1 :38. The
outside diameter of the oil slinger (see FIG 1 :39) is
smaller in diameter than that of the flanges but of such a
F50027
Key to Fig 1:39 1 Drive pulley 2 Rotor hub
3 Seal ring 4 Oil slinger 5 Lockplate
6 Hub-to-crankshaft hollow screw 7, 8, 9 Pulley-to-hub
mounting screws, toothed washers and plain washers FIG 1:39 Centrifugal oil filter components Key to Fig 1 :38 Suction scoop 2 Hole in crankcase
3 Duct in timing sprocket cover 4 Timing sprocket cover
5 Oil pressure relief valve 6 Drive shaft guide and oil
pump cover 7 Oil pump driving gear shaft 8 Camshaft
9 Oil pressure relief valve spring FIG 1:38 Engine longitudinal section through oil pump

5 Using the graduated sector check that all the valve
timing angles are as detailed in Technical Data.
Readjust the valve stem to rocker arm clearance to the
correct setting.
1:16 Valve stem-to-rocker clearance adjustment
It is important that the clearance between the valve
stem and rocker is kept to the recommended figure
of .0059 inch, measured when the engine is cold.
If the clearance is excessive operating noise will occur
and if less than recommended the valves will stay open
too long which will result in damage to the valve face
and its seating.
Inspect the contacting surfaces for scoring or pitting:
if it is excessive, new parts must be fitted. Also check
the condition of the rocker-to-valve and rocker ball
head-to-pushrod contact surfaces are free from wear or
pitting. The faces must have a mirror finish.
The oilway in the rockers and shaft must be thoroughly
inspected and free from sludge, otherwise lubrication
failure will occur.
The assembly clearance between the rocker arm and
shaft should be .00063 to .00217 inch and the clearance
between the rocker shaft and the shaft support should
be .00020 to .00138 inch with a maximum wear limit of
0039 inch.
Turn the engine until the valves of one cylinder are in
balance, that is, the inlet valve opening and the exhaust
valve closing. The other cylinder will now have both valves
fully closed. Adjust the valves on this second cylinder by
loosening the locknut, and turning the
adjuster as shown in
FIG 1 : 43 to obtain the desired clearance measured with
a feeler gauge. Adjust the clearances on the other cylinder
in the same manner.
1 :17 Engine assembly (sedan — all versions)
To reassemble the engine proceed as follows:
1 Thoroughly clean and dry all the parts, ensure that all
drillings are free from dirt or sludge and place on a
clean dry surface.
2 Carefully install the cylinder-piston-connecting rod
assemblies w i t h new paper gaskets between the
cylinders and crankcase seats.
3 Refit the big-end bearing shells to the connecting
rods, ensuring that they are free from any dirt or
metallic particles. Carefully ease t h e crankshaft into
the crankcase, lubricate the main journals with clean
engine oil, place a new paper gasket between the
supporting member and the flywheel end of the
crankcase. Install the supporting member and bearing
assemblies. Secure the supporting members with the
screws and special toothed washers.
4 Locate the connecting rod big-end half onto the
crankpin journals, liberally lubricate the journals with
fresh engine oil, fit the remaining shell half, matching
bearing end cap and tighten the bearing cap nuts to a
torque wrench setting of 23.9 Ib ft.
5 Inspect the camshaft bearing bores and remove any
burrs w i t h a hand scraper wetted with oil. Carefully
slide in the camshaft ensuring the cam lobes or gear
teeth do not score the front bearing bore.
6 Fit a new timing gear cover paper gasket held in
place w i t h a little grease. Install the outer thrust ring,
F50029 inner thrust ring, shoulder washer and slide on the
camshaft drive sprocket, locking it with the Woodruff
key. Assemble the timing chain and driven sprocket,
ensuring that the timing marks on the sprocket are
indexing as shown in FIG 1 :41. Secure the driven
sprocket with six screws and lockplates and care-
fully bend down the lockplates.
7 Install the timing gear cover, the oil pump, oil pressure
relief valve and seal assembly. Secure w i t h nuts,
special toothed washers and plain washers located
in the same manner as was noted on dismantling.
Locate the oil pump suction horn and secure with the
nuts and toothed washers.
8 Install the flywheel in the same relative position to the
crankshaft as was noted on dismantling. Replace the FIG 1 : 4 3 Adjusting the rocker clearances using the
optional service tools. Refer to Technical Data for the
correct clearance on early and late engines FIG 1 :42 Graduated sector C.673 for valve gear
timing
TIMING MARK

CHAPTER 9
THE STEERING SYSTEM
9 : 5 Relay lever and support
9 : 6 Steering rods
9 : 7 Front wheel toe-in
9 : 8 Fault diagnosis 9:1 Description
9 : 2 Steering wheel removal and refitting
9 : 3 Steering box removal and refitting
9 : 4 Steering box dismantling and reassembly
9:1 Description
The steering gear fitted to the new 500 range of
vehicles is of the worm screw and sector type with a
steering ratio of 1:13. The steering gearbox is located on
the front lefthand side of the dash wall on the scuttle as
shown in FIG 9:1. The steering gear comprises a pitman
arm and relay lever pivoting on a pin supported on the
body. A central track rod connects the pitman arm to the
relay lever. T w o track rods connect the pitman arm and
relay lever to the knuckle arms.
9:2 Steering wheel removal and refitting
To remove the steering wheel proceed as follows:
1 Disconnect the battery positive terminal clamp and
remove the horn control from the steering wheel.
2 Remove the cable from the push button seating and the
cable insulation sleeve.
3 Using a suitably sized box spanner or Fiat wrench
A.8279 unscrew the steering wheel to shaft nut as
shown in FIG 9:2.
4 Using the palm of the hands against the back of the
steering wheel rim gently tap the steering wheel
forwards so releasing it from the inner shaft.
F50097 5 Reassembly is the reverse procedure to dismantling.
Care should be taken to ensure that the front wheels
are located in the straight ahead position when the
steering wheel is being replaced otherwise the steering
wheel spokes will not be correctly positioned.
9 : 3 Steering box removal and refitting
To remove the steering box from the vehicle proceed
as follows:
1 From inside the vehicle remove the steering column
clamp bolt 6 (see FIG 9 : 3) after flattening the lock-
washer 7.
2 From the underside of the vehicle remove the t w o
tie rod locking nuts from the pitman arm and then using
Fiat tool A.46006 or a suitable t w o leg puller withdraw
the pins from the seats.
3 Remove the three nuts holding the steering box to the
body panel. Ease out the worm screw from the
steering shaft and lift away the steering box.
4 To refit the steering box is the reverse procedure to
dismantling. The steering box to body mounting nuts
should be tightened to a torque wrench setting of
14 Ib/ft to 18 Ib/ft.

CHAPTER 11
THE ELECTRICAL EQUIPMENT
11:1 Description
11:2 Battery
11:3 The generator
11:4 The starter
11:5 The control box
1 1 : 6 Fuses
1 1 : 7 Flasher unit
11:1 Description
All models covered by this manual have 12 volts
electrical systems in which the negative battery terminal
is earthed. There are three units in the regulator box to
control the charging circuit; a cut-out, a current regulator
and a voltage regulator. These are adjustable but it must
be stressed that accurate moving coil meters are required
when checking or altering the settings. Cheap and
unreliable instruments will make accurate adjustments
impossible.
There are wiring diagrams in Technical Data at the end
of this manual to enable those with electrical experience
to trace and correct wiring faults.
For t h e U.K. Market the headlamps are of the double
filament dipping renewable bulb type with adjustments
for individual beam settings.
The battery is located in the front compartment
forward of the petrol tank and the fuses to the rear o f the
petrol tank.
Detailed instructions for servicing the electrical equip-
ment will be found in this chapter, but it must be pointed
out that it is not sensible to try to repair that which is
seriously defective, electrically or mechanically. Such
equipment should be replaced by new units which can
be obtained on an exchange basis.
F500111
11 :8 Windscreen wipers
1 1 : 9 The lighting system
11:10 Panel and warning lights
11:11 The horn
11:12 Lighting and flasher switch
1 1 : 1 3 Fault diagnosis
11.2 The battery
This of the 12-volt lead/acid type and has to meet
heavy demands for current particularly in the winter. To
maintain the performance of the battery at its maximum
it is essential to carry out the following operations.
Keep the top of the battery and surrounding parts dry
and clean, as dampness can cause leakage between the
securing clamps and the battery terminals. Clean off any
corrosion from the metal parts of the battery mounting
with diluted ammonia and paint them with an anti-
sulphuric paint. If the terminal posts are corroded,
remove the cables and clean w i t h diluted ammonia.
Smear the posts w i t h petroleum jelly before remaking the
connections and fit the terminals securely. High electrical
resistance due to corrosion at the terminal posts is often
responsible for lack of sufficient current to operate the
starter motor.
Ensure t h a t the filler plugs are in good condition and
show no signs of cracks. This may cause leakage of
electrolyte and consequent corrosion. Test the condition
of the cells after topping-up the electrolyte level with
distilled water to just above the tops of the separators as
shown in FIG 11 :2 . Never add neat acid. If it is
necessary to make a new electrolyte due to loss by
spillage add sulphuric acid to the
distilled water.
It is highly dangerous to add water to acid.

Lamp brilliance varies w i t h the speed of t h e car:
Check the condition of the battery. Examine the battery
connections. Make sure they are tight and renew faulty
cables.
11:10 Panel and warning lights:
All the gauges are clustered in a single instrument
mounted on the dashboard above the steering column.
Incorporated in this cluster is the parking light pilot light,
generator charge indicator, fuel reserve supply indicator,
low oil pressure indicator, and the speedometer w i t h
mileage recorder.
The parking lamp indicator glows green when the
ignition lock switch key is in either position 1 or 2 once
the toggle switch on the instrument panel has been
operated.
The generator charge indicator shows red only when
the ignition is turned on. It should be extinguished when
the generator output is sufficient for battery charge
(12.6 ± 0.2 volts) with the engine running at a speed
of 1100 rev/min and the headlights switched off.
The fuel reserve supply indicator shows red only when
the ignition is turned on and the amount of fuel in the
petrol tank has dropped to approximately .8 to 1.1
Imp. gallons.
The low oil pressure indicator shows red only when the
ignition is turned on and should be extinguished when
the oil pressure reaches 7.1 to 21.3 Ib/sq in, and opens
the sending unit contacts. Once the engine is at normal
operating temperature but at a speed below 1000 rev/
min the indicator might light up even the pressure is under
control and with normal operation.
All the bulbs fitted to the above described units are of
the tubular 2.5W type and to renew a bulb extract the
bulb holder from the rear of t h e instrument cluster and
release the bulb which is attached by a normal bayonet
coupling.
Fuel reserve supply indicator sender u n i t:
The fuel reserve supply indicator should be checked for
correct indication by allowing the fuel tank to empty and
then inserting .8 to 1.1 Imp. gallons at which stage the
light should extinguish. Any failure to do so should be
checked as follows:
1 Ensure that the indicator bulb operates correctly.
2 Check for complete circuit between the sender unit and
the indicator bulb.
3 If the sender unit float bracket is distorted the bulb
will
indicate a reserve supply of fuel greater or smaller than
specified. The bracket should be adjusted to give
correct indication of fuel level.
4 The sender unit could have been inadvertantly
damaged in which case the unit must be renewed.
11 :11 The horn
The horn circuit comprises the horn, push button at the
centre of the steering wheel and normal earth return
electrical circuit through the car body. One terminal is
connected to the battery whilst the other to the push
button on the steering wheel which when the button is
depressed the circuit will be closed so causing the horn
to operate.
F500
FIG 11 : 21 Number plate lamp
Key to Fig 11 : 21 A Lens and light cap mounting screws
B Lens
FIG 11 : 22 Horn (opened)
Key to Fig 11:22 1 Body 2 Diaphragm 3 Armature
4,5,6 Core 7 Cable: terminal-condenser-stationary contact
8 Cable: terminal-magnetizing coil end 9 Magnetizing coil
FIG 11 :23 Horn sound adjustment. Obtained by adjust-
ing the armature air gap
123

Before removing an apparently faulty horn check the
wiring and connections. Check that the mounting bolts
are tight and that the horn does not foul any adjacent part.
Removal and installation:
This is a straightforward operation and the only
precaution to be taken is to ensure that the rubber gasket
bonded to the horn body does not become detached. If
the horn is renewed, before installing the new horn bond
the rubber gasket to the new unit with adhesive in
the same position as was on the original horn unit fitted.
Should the horn fail to operate the following points
should be noted.
1 Damaged horn.
2 Broken connection between battery and horn.
3 Broken connection between horn and push button on
steering wheel
4 Damaged push button mechanism.
5 Directional signal and outer lighting changeover
switch blade contact failing to make contact with the
steering wheel hub ring contact.
6 Current lead displaced from the horn blade contact on
the directional signal and outer lighting switch.
7 Distorted or broken diaphragm in horn.
8 Connections or inner windings
broken or burnt.
9 Electro-magnet contact points dirty or excessively
worn.The contacts may be adjusted by the adjusting screw
after the points have been cleaned and refaced.
To adjust the tone of the horn use a ring spanner and
screwdriver as shown in FIG 11 :23.
It is recommended that if the horn unit operation is
unreliable a new unit should be fitted rather than the
original one repaired.
11:12 Lighting and flasher switch
Description:
The two switches provide a directional signal switch
which automatically returns to the rest position once a
turn has been negotiated and the steering wheel is
brought back to the straight-ahead position. The change
over switch controls the outer lights and the headlights
flasher. The complete unit is located under the steering
wheel on the steering column.
Switch unit removal:
1 Carefully pry off the horn push button at the steering
wheel centre using a fine blade screwdriver.
2 Disconnect the positive terminal of the battery.
3 Disconnect the plug in contact in the steering wheel
hub.
4 Unscrew the steering wheel retaining nut from the
inner column and remove the steering wheel from the
shaft.
5 Slacken the bolts securing the steering column support
to the body
6 Remove the plug in contacts from the switch unit
ensuring that their correct location is noted for re-
assembly.7 Remove the switch unit from the steering column.
124
Switch unit installation:
This is the reverse procedure to dismantling. It is
advisable after installation to check that the steering
wheel when in the straight-ahead position and the
directional signal switch lever in neutral, the reference
index on the outer face of the directional signal switch
drum is in line with the index on the steering wheel hub.
This will ensure correct sequence of operation.
11:13 Fault diagnosis
(a) Battery discharged
1 Lighting circuit shorted
2 Terminals loose or dirty
3 Generator not charging
4 Regulator or cut-out units not working properly
5 Battery internally defective
(b) Insufficient charging current
1 Loose or corroded battery terminals
2 Generator driving belt slipping
(c) Battery will not hold a charge
1 Low electrolyte level
2 Battery plates sulphated
3 Electrolyte leakage from cracked casing or top sealing
compound
4 Plate separators ineffective
(d) Battery overcharged
1 Voltage regulator needs adjusting
(e) Generator output low or nil
1 Belt broken or slipping
2 Regulator unit out of adjustment
3 Worn bearings, loose pole pieces
4 Commutator worn, burned or shorted
5 Armature shaft bent or worn
6 Insulation proud between commutator segments
7 Brushes sticking, springs weak or broken
8 Field coil wires shorted, broken or burned
( f ) Starter motor lacks power or will not operate
1 Battery discharged, loose cable connections
2 Starter pinion jammed in mesh with flywheel gear
3 Starter switch faulty
4 Brushes worn or sticking, heads detached or shorting
5 Commutator dirty or worn
6 Starter shaft bent
7 Engine abnormally stiff
(g) Starter motor inoperative
1 Check 1 in (f)
2 Armature or field coils faulty