1953 JEEP DJ coolant temperature

HURRICANE
F4
ENGINE

D-1.
GENERAL

This
section describes service and repair of the
F4
engine. The
engine
code
number shown in Fig.
A-3
is provided to identify the four cylinder engine.
The
meaning of the coded letters and numbers that

are
stamped on the water pump boss, at the front of the cylinder block, is given below.
Letter
to
Designate
Market

M
—
Military
E
—
Export

D
— Domestic
I
—
Industrial
&
Marine

Letter
to
Designate
Engine
Letter
to
Designate
Year
Built
R
— 1969

S
— 1970

T
— 1971
U—
1972

V
— 1973

W
— 1974

Numbers
to Designate
Compression
Ratio

F
— F4-134
Engine
63
67
•

71
-
6.3 to 1

•
6.7 to 1

-
7.1 to 1

Market
-
D
S F

(Domestic)

(1970)

Engine-
EXAMPLE

123 A B S
(F4-134)

Day- "L

Compression
Ratio

(6.7)
-
Service Engine (S)
Short
Block
(R)

-.010*
Oversize Pistons

(123rd)
-.010*
Undersize
Main

and
Rod Bearings
All
disassembly and assembly procedures are
presented in logical order, assuming a complete

engine
overhaul with
engine
removed from the vehicle. However, many of
these
procedures can
also be performed as on-vehicle services if vehicle
or
engine
components are removed to gain access
to parts involved.

Note:
Some
engines
are equipped with an exhaust
emission control system. Service information on
the components of this system is given in Section

F-l.
D-2.
Description

The
Hurricane
F4-134
engine
is an F-head, four-
cyiinder
engine
of combination valve-in-head and valve-in-block construction.
Large
intake valves
mounted in the head allow
rapid,
unobstructed
flow of fuel and air to the combustion chambers through short, water-jacketed intake passages.The
intake valves are operated by push rods through

rocker
arms. The exhaust valves are mounted

in
the block with through water jacketing to provide
effective
cooling. The exhaust valves are
operated by conventional valve tappets.
The
engine
is pressure lubricated. An oil pump

driven
from the camshaft forces the lubricant
through oil channels and drilled passages in the

crankshaft
to efficiently lubricate the main and
connecting rod bearings.
Lubricant
is also force
fed to the camshaft bearings, rocker arms, timing
gears, etc.
Cylinder
walls and piston pins are

lubricated
from spurt
holes
in the "follow" side of
the connecting rods.
Circulation
of the coolant is controlled by a
thermostat in the water
outlet
elbow cast as part
of the cylinder head.

The
cylinder head assembly when installed on the

engine
consists of the inlet valve guides, inlet valves, inlet valve springs, rocker arm and shaft assemblies, spark plugs, temperature indicator
fitting, water
outlet
fitting, and other assembled

parts.
The carburetor and air cleaner assembly
bolt to the top of the cylinder head. The rocker

arm
cover is attached to the top of the head to
enclose
the inlet valve mechanism.
The
engine
is equipped with a fully counterbalanced
crankshaft
supported by three main bearings. To better control balance, the counterweights are in­
dependently forged and permanently attached to
the crankshaft with dowels and cap screws that are tack-welded.
Crankshaft
end play is adjusted by
shims placed
between
the crankshaft thrust washer

and
the shoulder on the crankshaft.
The
exhaust manifold is a separate unit. The intake
manifold is cast as an integral part of the cylinder
head and is completely water jacketed.
This
con­
struction transfers heat from the cooling system
to the intake passages and assists in vaporizing
the fuel when the
engine
is cold. Therefore, there
is no heat control valve required in the exhaust manifold. Individual exhaust ports in the cylinder
block direct
gasses
into the exhaust manifold for unobstructed flow through the exhaust system.

The
pistons have an extra
groove
directly above
the top ring which acts as a heat dam or insulator.
As
is common practice with manufacturers,
some

engines
are built with oversize cylinder bores or undersize crankshaft journals. These
engines
are
considered standard as replacement parts of the

correct
sizes are supplied. Before ordering parts or
doing any work with a particular engine, it is important to check the
engine
code
number to
determine if oversize or undersize parts are re­

quired.
Definite identification is given by a letter
stamped after the
engine
code
number. See Fig.

A-5
for location. The letters used and their mean­ ings are given here:

A
— .010*
[0,254
mm.] undersize main and
connecting rod bearings.

B
— .010"
[0,254
mm.] oversize pistons.

AB
—
Combination
of A and B.

S
—
Service
engine.

R
—
Short
Block.
Detailed specifications for the
Hurricane
F4
engine

are
at the end of this section.
Torque
specifications
for
engine
service are at the end of this manual in Section U. When adjustments are necessary, refer to
these
specifications so that factory clearances

are
maintained.

D-3.
Engine Mountings

The
front of the
engine
is supported by two rubber
Text continued on
page
41. 38

D
HURRICANE
F4
ENGINE
D-101.
Install
Manifold

If
manifold studs were removed for replacement,
apply sealer on the stud threads
before
installing
a
new stud.
See Section Fl for exhaust emission controlled

engines.
Make
certain that no foreign objects are inside the manifold and that all
passages
are clear. Place a
new set of manifold
gaskets
in position on the side
of the cylinder block.
Then,
carefully slide the manifold
onto
the studs and against the cylinder block being careful not to damage the gaskets.
Torque
all manifold attaching nuts evenly 29 to
35 lb-ft. [4,0 a 4,8 kg-m.].
D-102.
Install
Oil
Filler
Tube

When
installing the oil filler tube, be sure that the
beveled lower end is away from the crankshaft.
Place a
piece
of
hard
wood
over the top of the
tube

to prevent damage to the cap gasket seat.
D-103.
Install
Water Pump

Make
certain that the mating surfaces of the water pump and the cylinder block are clean and smooth.
Install
the gasket on the
flange
of the pump and

install
the pump in position on the cylinder block.
Torque
the water pump attaching
bolts
alternately

and
evenly 12 to 17 lb-ft. [1,7 a 2,3 kg-m.].
D-104.
Install
Water Outlet Fitting

Install
the thermostat and the water
outlet
fitting.
Torque
the water
outlet
fitting attaching
bolts
20
to 25 lb-ft. [2,8 a 3,4 kg-m.].
FIG.
D-42—INSTALLING HURRICANE F4 ENGINE
IN
VEHICLE

1—
Lifting
Sling
2— Hoist
Cable

3—
Hurricane
F4 Engine
4— Dowel Bolt
5—
Flywheel
Housing
D-105.
ENGINE INSTALLATION
a.
Install
lifting sling to
engine
and using suitable hoist raise the
engine
from its blocking or stand

and
then slowly lower it
into
the
engine
compart­ment of the vehicle.

Note:
When installing the
Hurricane
F4 Engine,
two % x 4 inch
guide
bolts
or
dowels
should be
used to properly
guide
and align the
engine
to the
flywheel housing (See Fig. D-42).
b. Slightly tilt the
engine
downward and at the
same time slide the
engine
rearward
while lining up the transmission main gear shaft with the clutch
throw-out bearing and disc spline.

Note
:The
engine
crankshaft may have to be turned
slightly to align the transmission main gear shaft
with the clutch disc spline.
c. Remove the
guide
bolts
or
dowels
and secure
the
engine
to the housing.

d.
Secure the front
engine
mounts to the frame brackets and
bolt
ground cable to
engine.

e. Remove lifting sling from
engine.

f. Connect exhaust pipe to
engine
manifold flange.
g. Connect throttle and choke cables to carburetor.
h.
Install
fan to water pump pulley.
i.
Connect fuel pump line to main fuel line,

j.
Replace starting motor assembly. k. Connect
engine
wiring harness connectors at
front of cowl.

I.
Connect wires to starting motor assembly, water
temperature and oil pressure sending units and alternator.

NOTE:
ON
ENGINES EQUIPPED WITH EX­

HAUST
EMISSION CONTROL,
REPLACE
THE
AIR
PUMP,
AIR
DISTRIBUTOR
MANI­

FOLD,
AND
ANTI-BACKFIRE (DIVERTER)
VALVE.
SEE
SECTION
Fl.
m. Replace radiator and radiator grille support
rods and connect coolant
hoses
to
engine.

Note:
Replace heater
hoses
if vehicle is equipped
with hot water heater.

n. Fill
radiator with coolant and
engine
with oil
(see
Lubrication
Chart).

o.
Install
air cleaner and connect carburetor air
hose.

p. Connect battery cables and start
engine,

q.
Install
hood
and road
test
vehicle.
D-103.
FINAL
IN-VEHICLE
ADJUSTMENTS
a.
Clean
battery terminals and check battery. b.
Check
ignition terminals and check battery.
c. Service carburetor air cleaner.

d.
Service positive crankcase ventilation valve.
e.
Check
fuel lines. f. Gap and install new
spark
plugs.
g.
Check
distributor
points
and capacitor; replace
if
necessary. 68

'Jeep9
UNIVERSAL
SERIES
SERVICE
MANUAL

h.
Check
ignition (distributor) timing; reset if
necessary.

i.
Check
carburetor
adjustments; reset if necessary,

j.
With
engine
fully warmed up, tighten cylinder
head and manifold
bolts
and nuts to specified
torque.
Check
cylinder head gaskets and
bolts
for
air
or coolant leaks.

Note:
Tightness of cylinder head
bolts
should be
checked and corrected after 500 to 600 miles [800

a
960 km.] of normal operation.

k.
Check
fan belt tension; adjust if necessary.

I.
Check
for and correct any oil leak, fuel leak or
coolant leak.
D-107.
VALVE
ADJUSTMENT

Proper
valve adjustment is important to prevent
burning
of valves and poor
engine
performance.

This
adjustment consists of obtaining a specified

lash
in the valve mechanism. The exhaust valve
tappets and the intake valve rocker arms should be adjusted to the proper clearance with the
engine

cold (at room temperature). Valve clearance can
be properly adjusted only when the tappet is on the
heel or low portion of the cam.
INTAKE

OPENS

9°
BTC?

FIG.
D-43-
10270

-VALVE
TIMING
D-108. Valve Adjustment Procedure

The
exhaust valve tappets are adjusted by turning
the adjusting screw in or out of the tappet as neces­
sary
to obtain the proper clearance. Where special
wrenches can be obtained, they should be used to facilitate the adjustment. The proper clearance is .016" [0,406 mm.]
between
the end of the adjusting
screw and the
bottom
of the exhaust valve.

Crank
the
engine
over to
close
a valve and check
the clearance with a feeler
gauge.
To adjust, hold
the tappet with one wrench and
turn
the adjusting

screw,
with the other.
Check
and adjust each of
the tappets in proper sequence.

Adjust
each intake valve by adjusting the rocker
arm
screw at the push rod to obtain .018" [0,457 mm.] clearance
between
the rocker arm and the
valve stem with tappet on the heel of the cam.
D-109.
Check
Valve
Timing

To
check the valve timing, carefully set the intake
valve rocker arm adjustment for No. 1 cylinder to .026"
[0,6604
mm.]
between
the rocker arm and the
valve stem. Rotate the crankshaft clockwise until
the piston in No. 1 cylinder is ready for the intake stroke. The intake valve
opens
9° before top center
(BTC).
Note
the distance
between
the
"TC"
and
"5°"
marks on the indicator on the timing gear
cover and estimate the 9° before top center position.
See
Fig.
D-43.
With
the crankshaft in this position, timing is correct if the rocker arm is just tight
against the intake valve stem. Do not overlook resetting the rocker arm adjustment to the correct

running
clearance.
D-110. Positive
Crankcase
Ventilation

Be
sure there are no air leaks at the tube connec­
tions
between
the air cleaner and the oil filler tube,

and
that the oil filler tube cap gasket is in
good

condition. Always keep the cap locked securely in
place. When tuning the
engine
or grinding valves, remove the control valve and clean it thoroughly.
If
the valve is blocked with carbon, the ventilating
system
will
not operate and, should the valve

fail
to seat, it
will
be impossible to make the
engine

idle satisfactorily. Refer to Par. C-6 for servicing.
D-111. Oil
Filter

The
engine
is equipped with a throw-away type

oil
filter.
This
oil filter must be serviced periodi­
cally
as outlined in the
Lubrication
Section. 69

Dl

DAUNTLESS
V-6
ENGINE
In
addition to the instructions covering operations
for disassembling the
engine
out of the vehicle, special instructions are given to cover different
operations required when disassembly is
done
with
the
engine
installed.

During
disassembly operations, the
engine
should be mounted in a suitable
engine
repair stand.

Where
practicable, modify or adapt an existing re­

pair
stand as necessary to accommodate the
engine.
If
an
engine
repair stand is not used, take care to

perform
disassembly operations in a manner that
will
protect personnel against an accident and the
engine
and its parts against damage.

Dl-6.
Mounting Engine
On
Engine Stand

Refer
to Fig. Dl-4.
a.
With
the
engine
supported by a hoist, remove
the clutch housing and clutch. Match
mark
the flywheel and the clutch cover before disassembly to assure proper reassembly.
b. Position the
engine
on the
engine
stand.
c. Release
some
tension of the hoist cables and secure
engine
to stand.

d.
Make sure the position lock on the
engine
stand
is tight to prevent the
engine
from accidentally
inverting.

e.
Release the hoist cables.
FIG.
D1
-4—ENGINE
MOUNTED
ON
STAND

1—
Spacer
J-8690-6
A—Bolt,
i/2-NC
x 3i/2"

2—
Bolt,
3/a-NC
x 4*/2" 5—Adapter 21316-J 3—
Engine
Mounting Stand
Dl-7.
Remove Intake Manifold
and

Carburetor Assembly

Disconnect crankcase vent
hose,
distributor vacuum

hose,
and fuel line from carburetor. Disconnect two distributor leads from ignition coil. Disconnect

wiring
harness from coolant temperature sending

unit.
Remove ten cap
bolts
which attach intake
manifold to cylinder heads. Remove intake mani­
fold assembly and gaskets from
engine.

Dl-8. Remove Exhaust Manifold
The
engine
has two exhaust manifolds. Remove five attaching screws, one nut, and exhaust mani­
fold from each cylinder head.

Dl-9.
Remove Distributor

Disconnect vacuum
hose
and wiring harness from

distributor.
Disconnect spark plug cables from
spark
plugs. Remove sparks plugs from
engine.
Pull

spark
plug cable retainers from brackets on rocker

arm
covers. Remove mounting screw, retainer

bracket,
and distributor from timing chain cover.
If
timing chain and sprockets are not to be re­
moved from
engine,
note
position of distributor
rotor so that it can be installed in identical position.

Dl-10. Remove
Fuel Pump
Disconnect output fuel line from fuel pump. Re­
move
two mounting bolts, fuel pump, and gasket

from
timing chain cover.

Dl-11.
Remove Alternator
and Fan
Belt

Disconnect wiring harness from alternator. Remove nut and flat washer which fasten alternator to
adjustment bracket. Pivot alternator
inward,
to­

ward
engine
cylinder block, to relieve fan belt
tension. Remove fan belt from pulleys. Remove
two attaching screws, mounting bracket, and alter­ nator from right cylinder head of
engine.

Dl-12.
Remove Cooling
Fan and
Water Pump

Refer
to Fig. Dl-5.
Remove four cap screws, lock washers, cooling fan,

fan
hub, and fan drive pulley from flange of water
pump shaft. Remove nine attaching screws, water
pump, alternator adjustment bracket, and water pump from timing chain cover.

Dl-13.
Remove
Oil
Filter

Unscrew
oil filter from
engine
oil pump.

Dl-14.
Remove Starter Motor

Disconnect wiring harness from starter motor and
solenoid. Remove two attaching screws, starter motor, solenoid, and motor attaching bracket from

engine
flywheel housing and cylinder block.

Dl-15.
Remove
Oil
Pressure Sending Unit

Disconnect wiring harness from oil pressure send­
ing unit. Remove oil pressure sending unit from

engine
cylinder block.

Dl-16.
Remove
Oil
Dipstick

Withdraw
and remove oil level dipstick and dip­

stick
tube
from
engine
cylinder block.

Dl-17.
Remove Crankshaft Pulley

Remove six attaching screws and crankshaft pulley

from
crankshaft vibration damper. 80

Dl

DAUNTLESS
V-6
ENGINE
e.
Connect electrical wiring harness to coolant
temperature sending unit. Connect two distributor leads to ignition coil. Connect fuel line
between

fuel pump and carburetor, vacuum
hose
between
distributor and carburetor, and crankcase vent
hose

to intake manifold
below
rear
of carburetor.
FIG.
D1-46—-INTAKE
MANIFOLD
INSTALLATION

1—Long Bolt 2—Open Bolt Hole
Dl-102.
ENGINE INSTALLATION

Install
the
engine
in the vehicle in the following
procedure listed
below:

a.
Attach suitable sling to
engine
lifting
eyes
and,
using a hoist, lift the
engine
from blocks or
engine
stand.
b. When
engine
is free of the stand lower it slowly

into
the
engine
compartment of the vehicle.

Note:
The
engine
and transmission must be lined
up to
engage
the main shaft and clutch plate spline
while sliding the
engine
rearward
into
the mounting
position.
c.
Install
and tighten up
bolts
securing
engine
to
flywheel housing.

d.
Install
and tighten front
engine
mounting bolts.

e.
Remove sling from the
engine.

I.
Connect exhaust pipes to right and
left
engine
manifolds.
g. Connect choke cable support bracket to
car­

buretor.

h.
Connect
engine
fuel
hoses
and fuel lines at right
frame
rail.

I.
Connect fuel lines.

j.
Mount
engine
starter motor assembly to
engine.
k.
Connect battery cable and wiring to
engine

starter
motor.

I.
Connect
engine
wiring harnesses to connectors
located on
engine
firewall.

Note:
On
engines
equipped with exhaust emission
control, replace the air pump, air distributor mani­
fold, and anti-backfire (gulp) valve. See Section F2.
m. Replace radiator, and secure with bolts,
n.
Replace and tighten right and
left
radiator sup­
port rods.
0. Connect upper and lower radiator
hoses
to the

engine.
p. Connect alternator wiring harness from connec­
tor at regulator,
q.
Replace air cleaner.
r.
Connect battery ground cable from the battery
to the
engine
and the
engine
ground strap,

s.
Replace the hood.

After
the
engine
is installed in the vehicle,
fill
radiator
with coolant and
engine
with oil (Refer to
Lubrication
Section B), then perform an
engine

Tune-up
and road
test
(Refer to Tune-up Sec­
tion C).

Dl-103.
FINAL IN-VEHICLE ADJUSTMENTS

a.
Clean
battery terminals and check battery.
b.
Check
ignition wires and connections.
c. Service carburetor air cleaner.

d.
Service positive crankcase ventilation valve.
e.
Check
fuel lines.
f. Gap and install new
spark
plugs.
g.
Check
distributor
points
and capacitor; replace
if
necessary.

h.
Check
ignition (distributor) timing; reset if
necessary. 1.
Check
carburetor adjustments; reset if necessary,

j.
With
engine
fully warmed up, tighten cylinder
head and manifold
bolts
and nuts to specified
torque.
Check
cylinder head
gaskets
and
bolts
for
air
or coolant leaks.

Note:
Tightness of cylinder head
bolts
should be
checked and corrected after 500 miles [800 km.]
of normal operation and again at 1000 miles [1600

km.].
k.
Check
fan belt tension; adjust if necessary.
I.
Check
for and correct any oil leak, fuel leak or
coolant leak. 104

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

COOLING
SYSTEM

Contents

SUBJECT
PAR.

GENERAL
.G-l Antifreeze Solutions. .G-l6
Cylinder
Block.
..................
.G-8

Draining
Cooling System............... G-3

Engine
Overheating..
.................
.G-19
Fan
Belt.
......... .........
.G-18
Filling
Cooling System.................
G-2

Inhibited
Coolant Solution .G-l7

Temperature
Sending Unit.
...........
.G-l0

Thermostat
.........................
G-9

RADIATOR
.G-5
Radiator
and Heater Hoses.............
G-7
SUBJECT
PAR.

Radiator
Pressure
Cap.................
G-4

Radiator
Removal and Replacement..... G-6

WATER
PUMP.
. . .G-ll
Water
Pump Disassembly. .............G-13

Water
Pump Inspection.
..............
.G-12

Water
Pump Reassembly.
.............
.G-14

Water
Pump Removal and Replacement. .G-l5

SERVICE
DIAGNOSIS.
.G-20

SPECIFICATIONS
. .G-21

ANTIFREEZE
CHART.
..... ... .G-22

G-l. GENERAL
a.
The satisfactory performance of the Hurricane

F4
engine
is controlled to a great
extent
by the proper operation of the cooling system. The
engine

block is full length water jacketed which prevents
distortion of the cylinder walls. Directed cooling
and
large water holes, properly placed in the cylin­
der head gasket cause more water to flow past the
valve
seats
(which are the
hottest
parts of the

block)
and
carry
the heat away from the valves, giving positive cooling of valves and seats.

Minimum
temperature of the coolant is controlled by a thermostat mounted in the
outlet
passage of
the engine. When the coolant temperature is below
thermostat-rated temperature, the thermostat re­ mains closed and the coolant is directed through
the radiator-bypass
hose
to the water pump. When the thermostat opens, coolant flow is directed to
the top of the radiator. The radiator dissipates the
excess
engine
heat before the coolant is recirculated
through the engine.
The
cooling system is pressurized. Operating pres­
sure
is regulated by the rating of the radiator cap

which
contains a relief valve, b. The Dauntless V-6
engine
efficiency and per­formance is controlled to a great
extent
by proper
operation of the cooling system. The cooling system

does
more than cool the engine. It also directs
the flow of coolant to provide the
best
operating
temperature range for each part of the engine.

In
the Dauntless V-6
engine
coolant is forced by
the water pump into two main passages that run the length of the block on each side (Fig. G-l).
FIG.
G-1—COOLANT
FLOW
THROUGH
THE
DAUNTLESS
V-6
ENGINE

161

G
COOLING SYSTEM
engine
connections. Insert flushing gun and flush
heater core.
Care
must be taken when applying air
pressure to prevent damage to the heater core.

G-2.
Filling
Cooling System
To
fill
the cooling system, remove the
fill
cap and

fill
the tank to the top. Replace the cap and run
the
engine
at medium speed for approximately one
minute. Remove the cap and recheck the coolant level. Add more coolant if necessary to bring the level back to the top of the tank. If the cooling system is filled when the
engine
is cold, recheck the coolant level after the
engine
has warmed up.
This

will
ensure that the thermostat has opened allow­ ing complete cooling system circulation.

Always
correct any cooling system leaks before installing antifreeze. A corrosion inhibitor should be used in the cooling system to prevent the forma­
tion of rust and scale. A quality brand antifreeze containing a corrosion inhibitor should be used.

When
the antifreeze is drained in the spring, a
corrosion inhibitor should be added with the water.

Note:
Cooling system components for both V6 and

F4
engines
are shown in
Figs.
G-2 and G-3.

G-3. Draining
Cooling System

To
completely
drain
the cooling system, open the

drain
in the
bottom
of the radiator and also a

drain
on the right side of the cylinder block on the
Hurricane
F4 engine. The Dauntless V-6
engine

has two
drain
plugs, one located on each side of the cylinder block. Both plugs must be removed to
completely
drain
the cooling system.
Remove the radiator cap to break any vacuum
that may have developed.

Should
the cooling solution be lost from the system

and
the
engine
become
overheated do not
refill

the system immediately but allow the
engine
to cool or
refill
slowly while the
engine
is running. If
cold solution is poured into the radiator while the

engine
is overheated there is danger of cracking the

cylinder
block and/or cylinder head.
G-4.
Radiator Pressure
Cap

All
radiators are equipped with pressure caps which
reduce evaporation of cooling solution and make the
engines
more efficient by permitting slightly
higher operating temperatures. When operating
properly,
the pressure cap permits pressure build-up

in
the cooling system during periods of severe heat

load.
This
pressure increases the boiling point of the coolant and thus reduces overflow losses. The

effectiveness
of the cap is limited by its opening
pressure and the boiling point of the coolant (see
note
below). The pressure cap employs a spring-
loaded, rubber-faced pressure seal which presses against a seat in the radiator top tank. Spring pres­

sure
determines the opening pressure of the valve.

A
typical pressure cap is shown in Fig. G-5.

Note:
Refer to cooling system specifications (Par.

G-21)
for opening (relief) pressure when the ve­
hicle is equipped with either the
Hurricane
F4
or
Dauntless V-6 engine. If a new cap is required, always install a cap of the same type and pressure
rating
specified. It should never be altered or re­
placed by a plain cap.

A
vacuum release valve (Fig. G-5) is employed to
prevent undesirable vacuum build-up when the system
cools
down. The vacuum release valve is
held against its seat under light spring pressure.

Vacuum
in the system is relieved by the valve
which
opens
at V2 to 1 psi. [0,035 a 0,07 kg-cm2]

vacuum.
A pressure tester can be used to check and
test
the vacuum pressure rate (see Fig. G-6).
Although the mechanism of the pressure cap re­ quires no maintenance, the cap should be inspected
periodically for cleanliness and freedom of opera­ tion. The pressure cap gasket and radiator filler neck seat should also be inspected to be sure they

are
providing a proper seal. If the rubber face of
the valve is defective, a new cap should be installed.
Filler
neck reseating
tools
are commercially
avail­
able to correct minor
defects
at the surface of the seat. Follow instructions of the reseating tool manu­

facturer.

To
remove the radiator pressure cap when the
engine
coolant temperature is high or boiling, place

a
cloth over the pressure cap and
turn
counter­ clockwise about Vi
turn
until the first (pressure release)
stop
is reached. Keep the cap in this posi­
tion until all pressure is released.
Then
push cap
down and
turn
still
further until cap can be re­ moved. To install the pressure cap, place it in posi­
tion and
turn
it clockwise as far as it
will
go.

Caution:
Use extreme care in removing the radiator
pressure cap. In overheated systems, the sudden release of pressure can cause a steam flash and this

flash,
or the
loosened
cap can cause serious personal

injury.

G-5.
RADIATOR

Maintenance of the radiator consists of keeping
the exterior of the radiator core clean, the interior free from rust and scale, and the radiator free from

leaks.
Check
the cooling system fluid level and for
leaks each
2000
miles
[3.200
km.] or every 30
days, whichever occurs first.
This
exterior of the

radiator
core should be cleaned and the radiator inspected for leaks each
6000
miles
[9.600
km.]
of normal service of the vehicle. Cleaning should be performed by blowing out with air stream or water stream directed from the
rear
of the radiator.

Visual
inspection is not sufficient as the accumula­ tion of small particles of foreign material on core
surfaces can restrict cooling without closing the core openings.

Radiator
leakage occasionally results from cor­
rosion perforation of the metal but most leakage results from mechanical failure of soldered joints
when too much strain has been put on the joint.
Fractures
occur most
often
at the joint where the
radiator
inlet and
outlet
pipes are attached to the

tanks.
When the seams break, the entire soldered

joint
is
exposed
and can corrode, but breakage
rather
than corrosion is the
primary
cause of seam
leakage. Examine the radiator carefully for leaks before and after cleaning. Cleaning may uncover points of leakage already existing but plugged with
rust.
White, rusty, or colored leakage stains indicate 164

G
COOLING SYSTEM and
the outlet
hose
is connected to the water pump
housing.
When
installing a new hose, clean the pipe connec­
tions and apply a thin layer of nonhardening seal­
ing compound. Hose clamps should be properly
located over the connections to provide secure fastening. The pressurized cooling system pressure

can
blow off improperly installed hoses.

G-8.
Cylinder
Block

Any
coolant leaks at the engine block water joints

are
aggravated by pump pressure in the water

jacket
and by pressure developed in the cooling system when the pressure cap is in place.
Small
leaks showing up only as moist
spots
often
cannot
be detected when the engine is hot except by the
appearance of rust, corrosion, and dye stains where
leakage evaporated. Also, expansion and contrac­ tion of the engine block resulting from extreme
temperature changes can aggravate leaks. For
these

reasons, when checking for coolant leaks inspect
the block when it is cold and while the engine is

running.
A
leaking
drain
cock or plug that cannot be stopped

leaking
by tightening should be replaced.
Leaking

core-hole expansion plugs should be replaced.
If
tightening gasketed joints
will
not correct leak­
age, install new gaskets. Use a sealing compound
where recommended.

G-9.
Thermostat
a.
The cooling system of the engine is designed
to provide adequate cooling under most adverse conditions. However, it is necessary to employ
some

device to provide quick warming and to prevent
overcooling during normal operation. Automatic
control
of engine operating temperature is provided
by a water flow control thermostat installed in the
water
outlet of the
Hurricane
F4 engine. The ther­
mostat is a heat-operated valve. It should always
be maintained in working order and the vehicle
should never be driven without one installed as there would then be no control of engine tempera­

ture.
The temperature at which the thermostat
opens
is preset and cannot be altered.

b.
The thermostat on the
Hurricane
F4 engine is
located in a housing on the top front of the cylinder

head.
On the Dauntless V-6 engine it is located
in
the thermostat housing of the air intake manifold.

The
standard engine thermostat for the
Hurricane

F4
and Dauntless V-6 engine has a normal rating
of
190°F.
[87.8°C]
and should begin to open at

a
coolant temperature between
180°F.
[82°C]
to
192°F.
[89°C]
and be fully open at
202°F.
[94°C.].
See Fig. G-7 for method of testing.

When
the thermostat is not operating properly, the engine may
run
too hot or too cold. Overheating

may
damage the thermostat so that its valve
will

not function properly, and a cold engine
will
not achieve
full
efficiency.
Rust
can also interfere with
thermostat operation. To
test
the thermostat, place

it
in water heated approximately
25°F.
[17°C]
above the temperature stamped on the thermostat

valve.
Submerge the bellows completely and agitate
the water thoroughly. The valve should open fully.
Next, place the thermostat in water heated approxi-
FIG.
G-7—THERMOSTAT
TEST

mately 10°F.
[11°C]
below the temperature
stamped on the thermostat valve. Submerge the bellows completely and agitate the water thorough­
ly.
The valve should close completely. If the ther­
mostat fails either of
these
tests, it should be re­ placed with a new one of the same type and rating.

G-10. Temperature
Sending Unit

The
sending unit incorporates a temperature sens­ ing element that when it is surrounded by cold engine coolant, the unit provides the highest resist­
ance in the temperature
gauge
indicator
circuit.
Resultant
low current flow in the circuit causes the

indicator
on the instrument panel to read at the low (C) end of the
gauge.
As engine coolant tem­

perature
increases, the resistance of the unit is
decreased allowing an increased current flow in
the
circuit,
making the instrument panel
gauge

register in proportion to the temperature of the engine coolant.

To
test
the sending unit, first run the engine until

it
has had time enough to warm up.
If
no reading is indicated on the
gauge,
check the
sending unit to
gauge
wire by removing the wire

from
the sending unit and momentarily grounding
the wire. If the
gauge
now indicates, the sending

unit
is faulty. If the
gauge
still
does
not indicate, the wire is defective.
Repair
or replace the wire,

a.
Hurricane
F4 Engine.

The
thermo-couple coolant temperature sending
unit
is mounted in the right
rear
of the cylinder head (Fig. G-8) and is connected by a single wire
to the dash unit of the instrument cluster. 166