1966 FIAT 500 engine

CHAPTER 4
THE COOLING SYSTEM
4:1
4:2
4:3Description
Air outlet thermostat and shutter
Tension adjustment4:4
4:5
4:6Heating system safety device
Maintenance
Fault diagnosis
4:1Description
Sedan:
A l l the Fiat new 500 models covered by this manual are
aircooled by the forced air circulation system from a
centrifugal blower which is mounted on the generator
output shaft. The blower fan has fourteen vanes which are
arranged at various angles to reduce operating noise
during high-speed operation. A specially designed
cowling as shown in FIGS 4 : 1 and 4:2 conveys the air
from the blower and distributes it to the various parts of
the exterior of the engine.
The main components of the air cooling system are as
follows:
1 Air intake compartment at the rear end of t h e body.
2 An elbow pipe for the admittance of incoming air.
3 A flexible air pipe connecting the elbow pipe to the
conveyor.
4 A spiral air conveyor which contains the centrifugal fan.
5 Distribution ducting for directing the air flow to various
parts of the engine.
6 A bellows type thermostat is fitted to the cowling which
operates a butterfly shutter controlling the air outlet
from the engine which ensures control of the engine
operating temperature.
F50053 When the shutter is in the open position, engine heated
air is allowed to disperse to the outside of the engine
cowling. With the shutter in its closed position, the air is
recirculated in the engine cowling so ensuring a quick
engine warm-up period.
It should be noted that by operating the heater lever
which is located on the centre tunnel at the rear seat,
warmed air flowing out from the engine cowling is passed
to the inside of the car for heating and demisting purposes.
Station wagon:
Refer to FIG 4 : 2 where it will be seen that as the engine
is located on its side underneath the luggage compartment
floor the ducting has been modified and the air intakes are
located at the rear of the side windows. A linear blower is
housed in the engine baffles and cowling and is attached
to the drive end of the generator.
The thermostat 'C' (see FIG 4 : 2) is located on the
righthand side of the engine cowling and should start
opening the engine heated air outlet shutter ' D ' when the
temperature of the air rises to 1 7 8 - 1 8 5 ° F and the shutter
should be wide open when the air is at a temperature of
196-207°F.

FIG 4 : 1 Engine cooling air circulation system
Key to Fig4:1 A Engine cooling air intake B Carburetter air suction cleaner C Centrifugal fan and air conveyor
D Oil pan cooling air passage E Warmed air admission hose to car interior F Engine air outlet control shutter, wide open
position (at 178° to 189°F — 81° to 87° C) G Air outlet thermostat
54

55F500
FIG 4 : 2 Cooling air circulation system of engine 120.000
Key to Fig 4 : 2 A Air intakes B Fan C Thermostat, engine air draft shutter control D Shutter enqine air draft
E Carburetter air cleaner F Duct, warmed air-to-car interior G Lever, air-to-car interior valve control

OIL DRAIN PLUG COOLING AIR DUCTS
FIG 4 : 3 Oil sump with blower cowling. Arrows indicate
air outlets
BLOWER
SHAFT GENERATOR ARMATURE
VENT TUBE
FIG 4 : 4 Cooling blower mounted on generator shaft
extension
4 : 2 Air outlet thermostat and shutter
Refer to FIGS 4 :1 and 4 :2 where it will be seen that
the thermostat is located on the righthand side of the
engine cowling. The thermostat should start opening the
engine heated air outlet shutter when the temperature of
the air reaches between 158-165°F (178-185°F station
wagon) and the shutter should be in the wide open posi-
tion when the air has reached a temperature of between
178-189°F (196-207°F station wagon).
When the engine cooling air control system is being
inspected or serviced the following points should be
noted:
1 Check that when the shutter is in the closed
position the edge mates perfectly with the cowling
seating.
2 Ensure that the shutter can swivel freely.
3 Check that the initial thermostat movement is
between .0197 to .0394 inch.
4 Generally check the engine cowling for distortion, bad
jbint sealing or cracks.
56
Key to Fig 4 : 6 1 Circular seat i n cylinders 2 Head
ducts 3 Pierced screws
FIG 4 : 6 Diagram of the heating system safety device
(sedan and station wagon) FIG 4 : 5 Location of cooling air outlet thermostat and
shutter
ENGINE COWLING.
THERMOSTAT
LINK
AIR OUTLET SHUTTER
SHUTTER RETURN SPRING
4 : 3 Tension adjustment, thermostat to shutter
link:
The tension may be varied by using the shims which are
located between the upper shank of the thermostat and
the cover shoulder washer. Before any adjustment is made
ensure that the shutter is able to move freely and that the
return spring has not stretched or fractured. Refer to
FIG 4:5 which shows the location of the shutter and the
return spring.

4 : 4 Heating system safety device
110F series sedan engines and later station wagon
engines incorporate a modification to the cylinder head
designed so that in the event of cylinder head gasket
failure exhaust gases are expelled outside the engine and
not leaked into the heating system.
The safety device comprises a square section circular
seat 1 (see FIG 4 :6) which is formed in the upper face of
the cylinder, a special duct in the cylinder head and a
pierced screw 3 for each cylinder.
The system is so designed that the exhaust gases are
released to the atmosphere from the circular seat in the
cylinder via the duct 2 and the pierced screw 3. It should
be noted that the screw 3 is also used for securing the
conveyor.
4 : 5 Maintenance
Due to the simple design of the air cooling system
maintenance has been kept to an absolute minimum and
should consist of the following checks:1 Inspect all the air conveyor system joints and ensure
that all the joint nuts and bolts are tight and that there
is no distortion between two joint faces.
2 Check that the tension of the generator and fan drive
belt is correct: with a hand pressure of approximately
22 Ib the belt should sag 13/32 inch. Adjust if necessary
as detailed in Chapter 1.
3 Ensure that the shutter can swivel freely and that the
spring is in a serviceable condition.
4 : 6 Fault diagnosis
(a) Engine overheating
1 Generator and fan drive belt slipping
2 Shutter control thermostat defective
3 Shutter unable to swivel freely
4 Shutter return spring broken
5 Leaking joints in conveyor system
F50057

*Dimension to be obtained by
adjusting the throwout lever.
FIG 5:1 Clutch assembly longitudinal section (new
500, 500D sedan and early station wagon)
5 : 2 Removal and installation
To remove the clutch unit from the vehicle proceed as
follows:
1 Remove the engine (Chapter 1) or separate the gear-
box from the engine as described in Chapter 6.
2 Remove the six screws and washers that secure the
clutch cover to the flywheel and gently ease the cover
assembly from the location dowels in the flywheel and
lift away. This will also free the driven plate.
3 Carefully clean the driven plate and clutch cover using a
compressed air jet.
4 To refit the clutch cover assembly to the flywheel
ensure that the driven plate is assembled the correct
way round as shown in FIG 5 :1 and place the cover
onto the flywheel using the locating dowels.
5 To ensure that the driven plate is correctly centred use
Fiat pilot A.62023 (see FIG 5 : 5) or a suitably sized
mandrel. Tighten the clutch mounting screws diagonally
a turn at a time to ensure correct location of the cover
onto the flywheel face. Finally, tighten to a torque
wrench setting of 5.8 to 7.2 Ib ft.
5 :3 Dismantling and inspection of clutch cover
New 500, 500D sedan and early 500 station wagon :
To dismantle the clutch cover assembly proceed as
follows:
60
To assemble the clutch cover assembly proceed as
follows:
1 Place the pressure plate complete with carrier ring bolts
and springs on Fiat fixture 62038 (see FIG 5 : 2).
2 Fit the six pressure springs in their respective seats on
the pressure plate. Insert the cups on the springs and
replace the cover.
3 Compress the clutch cover, continually checking that
the withdrawal lever supporting bolts are properly
guided into their holes in the cover. Onto the bolts, fit
the three withdrawal levers w i t h their relevant nuts and
washers.
4 Replace the carrier ring on the levers and hook up the
retaining springs. 5 :4 Assembly and adjustment
N e w 500 sedan1 Place the clutch cover assembly on Fiat fixture A.62038
as shown in FIG 5 :6 and lock the cover using the three
T-handles provided.
2 Release the w i thdrawal lever carrier ring springs and lift
away the ring.
3 Unscrew the withdrawal lever fixing nuts on the bolts
and lift out the levers and washers. Gradually slacken
the three T-handles so relieving the pressure of the
clutch springs. Remove the clutch cover, springs and
lever mounting bolts. Carefully mark all the components
to ensure that they are assembled correctly so ensuring
that correct balance of the clutch unit is obtained.
Inspection:
Thoroughly clean all parts using a compressed air jet
and proceed as follows:
1 Thoroughly check the springs for signs of overheating
causing loss of tension and compare the effective length
of the springs which when fitted new should have a
length of .9646 inch under a load of not less than 43 Ib.
If the spring length is less t h a n t h e recommended
dimension fit a complete new set of springs.
2 The length of the withdrawal lever carrier ring retaining
springs should be checked which under a normal clutch
load should be .7677 inch whilst the length'of the
expanded spring under a load of 4.85 ± .44 Ib should
be 1.1811 inch. If the springs show sign of heating or
weakening a new set should be fitted.
3 Check the withdrawa l levers and their bolts for exces-
sive wear and fit new parts as necessary.
4 Inspect the pressure plate for an excessively ridged sur-
face or signs of cracking. If the ridges are not too severe
the face may be refaced by turning on a centre lathe.
Also inspect the flywheel friction surface which may
also be refaced providing that the ridges are not too
severe.
5 Whenever the clutch driven plate linings are worn a new
driven plate should be fitted.
6 Inspect the clutch shaft splines and these should not
have a lengthwise clearance in excess of .0039 inch and
side clearance of .0118 inch w i t h respect to the driven
plate hub. Ensure that the driven plate slides easily on
the clutch shaft protruding from the rear of the gearbox
differential unit as any plate drag may be the cause of
d i f f i c u l t y in gear selection.

FIG 5:2 Clutch components (new 500, 500D sedan and early station wagon) DRIVEN PLATE
PRESSURE PLATE
LEVER CARRIER LEVER BOLTSBOLT NUTS PRESSURE SPRINGSWITHDRAWAL LEVERS CLUTCH COVER
LEVER CARRIER RING
SPRING
WASHER
FIG 5:3 Clutch assembly installed on engine (new
500, 500D sedan and early station wagon)
61
F500
To check the correct operation of the clutch cover 500 sedan (110.F) late 500 station wagon :
Inspection—diaphragm clutch: 5 Finally tighten down the cover assembly using the three
T-handles and adjust the clearance between the carrier
ring and its central shoulder by means of the three
adjustment nuts.setting the withdrawal levers stroke to
0039 inch. Check this adjustment using Fiat gauge
C.110 and when correct lock the adjustment nuts by
peining to the lever bolts.
500D sedan and early station wagon:
To assemble the clutch cover assembly proceed as
described above but adjust the withdrawal levers as
follows:
1 Secure the clutch cover assembly to Fiat fixture A.62038
with a ring .5413 to .5433 inch thick placed between
the clutch cover plate and the pressure plate.
2 Adjust the height of the three withdrawal levers so that
the lever tips are 1.9094 inch from the face of the Fiat
supporting plate.

FIG 5:10 Clutch throw-out mechanism
Key to Fig 5:10 1 Clutch throw-out yoke
2 Yoke return spring 3 Rod nut and counternut
4 Adjustable rod 5 Clutch throw-out
onto this shaft the outer operating lever is attached by
means of a key.
A return spring connected to the outer operating lever
is anchored onto the gearbox casing. When the clutch is in
its normal position the spring keeps the central thrust
carbon ring away from the withdrawal levers carrier ring.
The carbon ring is pressed against the carrier ring by the
throw-out ring which is connected to the forked lever as
shown in FIG 5 : 8 .
The clutch pedal must have free travel of 1"3/8 to 1"9/16 inch.
Should any adjustment be necessary release the locknut
from the adjustable tie rod and adjust the position of the
tie rod until the correct adjustment is obtained. Tighten the
locknut.
500F. L and later station wagon:
The free travel of the clutch pedal should be 19/32 to
1"3/16 inch which corresponds to a clearance of .059 inch
between the throw-out sleeve and the ring (see FIG 5 : 7).
Should any correction be necessary release the adjust-
able rod locknut (see FIG 5:10), and reposition the
adjustable rod using the rod nut until the recommended
clutch pedal travel is obtained. Retighten the locknut.
5 : 8 Fault diagnosis
(a) Drag or spin
1 Oil or grease on driven plate lining
64
(g) Driven plate fracture
1 Check 2 and 3 in (a)
2 Drag and distortion due to hanging gearbox in plate hub (f) Tick or knock
1 Worn first motion shaft spigot or bearings
2 Badly worn splines in driven plate hub
3 Release plate out of line
4 Faulty Bendix drive on starter motor
5 Loose flywheel
(e) Rattle
1 Check 3 in (c)
2 Worn release mechanism
3 Excessive backlash in transmission
4 Wear in transmission bearings
5 Release bearing loose on fork (d) Judder
1 Check 1, 2 and 3 in (a)
2 Pressure plate not parallel with flywheel face
3 Contact area of driven plate linings not evenly distribu-
ted
4 Bent first-motion shaft
5 Buckled driven plate
6 Faulty power unit mountings
7 Worn suspension mountings
8 Weak rear springs
9 Loose drive shafts (c) Slip
1 Check 1, 2 and 3 in (a)
2 Check 2 in (b)
3 Weak pressure springs or diaphragm spring (b) Fierceness or snatch
1 Check 1, 2 and 3 in (a)
2 Worn clutch linings 2 Misalignment between engine and gearbox first motion
shaft
3 Driven plate hub binding on first motion shaft splines
4 Binding of first motion shaft spigot bearing
5 Distorted clutch plate
6 Warped or damaged pressure plate or clutch cover
7 Broken driven plate linings
8 Dirt or foreign matter in clutch