coolant temperature JEEP CJ 1953 User Guide

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

G
cation period. It is
good
preventive maintenance to
replace a badly frayed, worn or cracked fan belt
before it breaks in operation.

To
replace the fan belt,
loosen
the attaching
bolts

at each generator or alternator brace-to-engine mounting and pivot the alternator or generator to­

ward
the
engine
to gain slack needed to install the new belt Remove the old belt. Position the new
belt over the fan pulley, over the crankshaft pulley,
then over the generator or alternator pulley.
Pull
the generator or alternator away from the
engine

until
belt tension is
firm.
Then tighten the generator

or
alternator mounting
bolts
and check the tension
as indicated above. Reset the generator or alternator as necessary for correct belt tension.
Finally,
torque
the generator or alternator mounting
bolts
25 to 35 lb-ft. [3,4 a 4,8 kg-m.].

Note:
On the Dauntless V-6
engine
when adjusting
the fan belt tension, the alternator mounting
bolts

should be torqued 30 to 40 lb-ft. [4,14 to 5,53

kg-m.].
If a fan belt tension
gauge
(W-283) is
avail­

able, proper tension should be 80 pounds [36,2 kg.].

G-l
9. Engine Overheating

An
engine
will
not be damaged by high coolant
temperatures unless the coolant boils. The pres­

surized
cooling system on the 'Jeep' vehicles raises the boiling point of the coolant solution. Should
overheating be encountered, and the fault is be­
lieved to be in the cooling system check for the
following:

a.
Proper coolant level. See
Filling
Cooling Sys­
tem Par. G-2.
b. Poor air flow.
Check
for dirty radiator core. (See Radiator Par. G-5).
Check
for faulty belt
pulley operation, worn or
loose
fan belt, or dam­ aged fan.
Clean,
repair, replace or adjust as neces­

sary.

c. Foaming coolant.
Check
for air leaks at water
pump,
hose
connection and filler cap. Tighten, re­

pair
or replace as necessary.

d.
Surging or "after boil".
Check
pressure cap and
replace if valves or gasket are faulty.
e.
External
leaks.
Check
the following for leaks:
Hoses and clamps, water pump, radiator, head gas­
ket, core plugs and drain cocks, as well as the cylin­ der head or block for
cracks.

f.
Internal
leaks.
Check
for faulty head gasket,
cracked
cylinder head or block.
g. Poor coolant flow.
Check
hose
condition, water pump, fan belt, and repair or replace as necessary. Inspect block for rust or scale, and clean and flush
the system, if necessary.

h.
Check
the temperature
gauge.
169

H

ELECTRICAL
SYSTEM
H-124. Testing Indicators and Gauges

Two
gauges
(fuel and temperature) and two in­ dicators (oil pressure and battery charge) that are
located in the instrument cluster are electrically operated.

The
fuel
gauge
is connected by a single wire to a
float-and-slide-rheostat sending unit in the fuel
tank.

The
temperature
gauge
is connected by a single

wire
to a resistance-type sending unit mounted on the engine.

The
battery charge indicator operates when there
is a difference in potential
between
the generator
and
the battery
.The
battery charge indicator lights
when the generator is not charging the battery. The
indicator
light
goes
out when the generator
begins

to charge the battery.

The
oil pressure indicator is connected by a single

wire
to a diaphragm switch located on the engine.
When
engine
oil pressure is low or zero and the
ignition switch is on, the oil pressure indicator
will

light. When
engine
speed is increased slightly above idle speed, raising the oil pressure to approximately 6 psi. [0,2 kg-cm2], the diaphragm switch
will
open the circuit and the indicator light
will
go out.

A
voltage
regulator maintains a constant
voltage
to the
gauges
in normal operation. On early vehicles,
this
voltage
regulator was mounted on the
rear
of
the instrument cluster. On current vehicles, the
voltage
regulator is integral with the fuel
gauge.

Should
trouble
develop
in the
gauges,
first check the regulator (fuel
gauge
on current production vehicle). If the
voltage
to the regulator is below 10 volts system low
gauge
readings
will
result.
Voltage in
excess
of 16 volts
will
not affect
gauge

readings but may result in premature wear of the
regulator contacts. If the
voltage
to the regulator is

within
the above limits, check the electrical con­ nections to the regulator (or fuel gauge), especially
the ground connection. If the readings of all the
gauges
is too high, or they all read too low, replace
the regulator (or fuel gauge).

If
the temperature
gauge
or heat indicator in the
instrument cluster have failed, the cause may
originate from the jumper bar shorting out against the instrument case.
Check
the jumper bar
between

the temperature
gauge
and heat indicator at the

rear
of the instrument case. On later production vehicles, the jumper bar is covered with an in­
sulating
sleeve
to protect it from shorting out
against the instrument case. If the jumper bar

does
not have this
sleeve,
either install one or

wrap
the bar with plastic electrical tape to
half

an
inch [12,7 mm.] from each end. When installing the jumper bar, be sure the curved
segment
is
closest to the fuel
gauge.

Should
only one of the two
gauges
register incor­
rectly,
check the lead wire from the
gauge
to the
sending unit for shorts or open connections. Next disconnect the
gauge
from the sending unit, and
connect the
gauge
to a new fuel tank sending unit

which
has been grounded to the vehicle.
If
the
gauge
registers incorrectly when operating the new unit,
replace the
gauge;
if correctly, replace the sending

unit.

Should
a new fuel tank unit not be available for testing, use a 12-volt
test
light in its place. When
the
gauge
is operating correctly, the pointer
will

move
approximately three-quarters across the
dial.

On
some
vehicles, the temperature
gauge
may
register on or
close
to the H (hot)
mark
when
coolant temperature is
190°F.
to
200°F.
[88°C.
a

93°C.].
In such cases, a 25-ohm,
1-watt
resistor
may be installed on the temperature
gauge
which

will
place the pointer just beyond the center
mark
at a coolant temperature of
190°F.
to
200°F.
Install

the resistor
between
the two terminals on the back
of the
gauge.
Insulate the
exposed
leads of the resistor with electrical tape.

If
the oil pressure indicator
does
not indicate cor­

rectly,
first check the light bulb. Next check all
connections and lead wires. If, after all possible

defects
are corrected, the indicator light
does
not go on and off properly, then the diaphragm type
switch in the cylinder block should be replaced.

H-12S.
LIGHTING SYSTEM The
wiring of the lighting systems is shown in
the wiring diagrams, which indicate the various units in relation to their positions in the vehicle.
The
wires in the various circuits are of different
colors or are marked by tracers to aid when check­
ing individual circuits.

The
lighting circuits of all models are protected by

an
overload circuit breaker mounted on the back of the main light switch and no replaceable fuse is
required.

The
upper and lower headlight beams are con­
trolled by a
foot
switch located on the toe board
to the left of the clutch pedal.
H-126.
Main
Light
Switch

This
switch is a dual functioning unit having two

push-pull
positions and a rotary action. When
pulled out to the first position, the front parking
and
tail
lights are turned on. When pulled all the
way out to the second position, the headlights and
tail
lights are turned on. Rotating the switch to
the right dims the instrument cluster lighting.

The
switch may be removed from the instrument
panel by first loosening the set screw in the control
knob and removing the knob. The retaining nut may then be removed and the switch removed
through the
rear
of the instrument panel.
FIG.
H-51—MAIN
LIGHT
SWITCH
(EARLY)

1—
Battery
4—Parking Lights
2—
Rear
Lights 5—Auxiliary

3—
Head
Lights
212