1953 JEEP CJ check engine

Fl

EXHAUST
EMISSION CONTROL SYSTEMS The
air distribution manifold should be installed
after the exhaust manifold assembly is torqued
to the cylinder head. The recommended procedure
for exhaust manifold assembly installation is as follows:
Clean
the mating surface of both the
manifold and cylinder head.
Install
the exhaust manifold to the cylinder head using a new gasket.

Tighten
the manifold to cylinder head, attaching
bolts
down evenly.
Finish
torque tightening to 29
to 35 ft. lbs. [3,4 a 4,8 kg-m.].

Fl-23.
REQUIRED
EQUIPMENT

Each
station licensed to perform repair and main­
tenance on the Exhaust Emission Control System
must be equipped with that equipment necessary
for major
engine
tune-up analysis which shall in­ clude at least the following or equivalent.
Ignition Analyzer Oscilloscope
Ammeter
Ohmmeter
Voltmeter Tachometer
2 Vacuum Gages

Pressure
Gage (0-10 psi.)

Cam
Angle Dwell Meter Ignition Timing
Light

Engine
Exhaust Combustion Analyzer Compression Tester

Fl-24.
REPLACEMENT
PARTS

Parts
necessary to repair and/or maintain the

Exhaust
Emission Control System are available through any Jeep
SALES CORPORATION
ware­
house.

Fl-25.
WARRANTY

All
parts of the Exhaust Emission Control System

are
covered by the Manufacturer's Warranty as stated in the Warranty Service and 'Jeep' Quality
Maintenance Plan booklet.

Fl-26.
EXHAUST EMISSION CONTROL
SYSTEM
DIAGNOSIS GUIDE
Pump Noisy

Hoses Touching Other Parts of Engine or Body (Hood).

Note:
The air pump is not completely noiseless.

Under
normal conditions, pump
noise
rises in pitch as
engine
speed
increases. It is also desirable to
allow for normal break-in wear of the pump prior
to replacement for excessive noise.

Pump Seized

Replace
pump.

Leak
In
Hose

Check
for leaks; using
soap
and water — tighten
clamps or replace
hoses.
Pump
Inoperative

Loose Belt — tighten belt — do not pry on housing.

Filter
Plugged — replace.

Exhaust Backfire

Check
for vacuum leaks — correct as necessary.
Check
air filter for excessive
restriction
— replace as necessary.

Check
anti-backfire valve — replace as necessary.

Induction System Backfire

Verify
engine
timing and distributor dwell.

Verify
accelerator pump charge. 146

'Jeep'
UNIVERSAL SERIES
SERVICE
MANUAL

Fl
Fl-27.
EXHAUST EMISSION CONTROL SYSTEM MAINTENANCE CHART

Efficient
performance of the Exhaust Emission
Control
System is
dependent
upon precise main­tenance. As indicated in the following chart, it is very important that all of the maintenance require­

ments
listed are performed with extreme care at
the specific intervals indicated.

OPERATION
Thousands of miles* or
number of months whichever
occurs first 2
6
12 18
24 30

R R
R R
R R

O O o O
O
o O

R
O
o
o

R
o

o o

o
o

o
O
o
Inspect engine-driven
belts
for condition and tension...
Replace positive crankcase ventilation valve (PCV) Replace filter on exhaust emission control system

Clean
carburetor air cleaner

Engine
tune-up
Check
engine
timing

Adjust
carburetor idle
speed
and mixture

Perform
factory-recommended road
test
for evaluation of overall performance and handling

R
— Required Services
O
— Optional Services
Miles
2,000

6,000

12,000
18,000
24,000
30,000
Kilometers

3,200

9,600

19,200
28,800
38,400 48,000

Fl-28.
EXHAUST EMISSION CONTROL SYSTEM CARBURETOR SPECIFICATIONS

Make
Models

Part
Number
Throttle
Bore
Main
Venturi

Low
Speed Jet

Main
Metering Jet

Idle
Port
Nozzle Bleed in Body
Pump Jet

Float
Level
Dash
Pot Setting

Engine
Idle
RPM:
with Distributor Model
IAY-4401A.
with Distributor Model
IAY-4401B.
Carter
— Single Bore

^ an H
YF
4366S ana 4941S, 6115S

1M"
[3,81 cm.]

IX"
[3,18 cm.]
.035"
[0,889
mm.] .089" [2,26 mm.]
.184" x .030" [4,70 a
0,765]
.028"
[0,713
mm.]
.024"
[0,610
mm.] lW [6,74 mm.]
%"
[3,75 mm.] 650 — 700 700 — 750

Fl-29.
EXHAUST EMISSION CONTROL SYSTEM DISTRIBUTOR SPECIFICATIONS

Engine

Make
Models
Rotation
Point Opening

Breaker
Lever
Tension..
Cam
Angle (Dwell)
Condenser Capacity
Dist.
Degrees and RPM:
Start..

Intermediate

Maximum

TIMING:
Crankshaft

Mark
Location

Firing
Order
F4-134
Prestolite

IAY-4401A

CCW
Rotor End
.020"
[0,508
mm.|
17 — 20 ozs. [482 a 567 gr.l
42°

.25 — .28 mfd.

0°
— 300
3°
— 375

13.5°
— 1700

0°
TDC @ Idle

Crankshaft
Pulley
1-3-4-2
Prestolite

IAY-4401B

CCW
Rotor End
.020"
[0,508
mm.]
17 — 20 ozs. [482 a 567 gr.
42°

.25 — .28 mfd.

0°
— 450

4.5°
— 550

13.5°
— 1700

0°
TDC @ Idle

Crankshaft
Pulley
1-3-4-2

Fl-30.
SPARK PLUG
GAP

Spark
Plug Gap. .030"
[0,765
mm.] 147

Fl

EXHAUST
EMISSION
CONTROL
SYSTEMS
IMPORTANT
NOTICE

The
Exhaust
Emission Systems covered
in
this publication
meet
State and

Federal
requirements for hydrocarbon and carbon
monoxide
emissions.

To
assure continued proper operation,
these
systems
must
be
inspected

regularly,
parts must be replaced
at
factory-recommended intervals and
engine

tune-up services performed at intervals specified in the
Exhaust
Emission
Con­
trol
System Maintenance charts.

For
the
above
reasons,
these
systems
must not, under any circumstances,
be

altered
to anything other than
required
specifications provided in this publication.

Further,
the
Exhaust
Emission
Control
System, or any
of
its components, must
not be physically altered or modified in any respect.

DHTfl
TAG

For
the serviceman's guidance, each vehicle equipped with exhaust emission

control
will
have data
tag
permanently affixed
to the
radiator shroud—-in
example:

VEHICLE
EMISSION
CONTROL
INFORMATION
MODEL
F4-134
C.I.D.

•
ENGINE
AT
NORMAL
OPERATING
TEMPERATURE

•
LIGHTS
AND
ALL
ACCESSORIES OFF

•
IDLE
MIXTURE
. . .
LEAN
BEST
IDLE

•
IGNITION
TIMING
0*
(TDC)
•
SPARK
PLUG
GAP
. . . .030

•
DWELL
...
42* (.020
POINT
GAP)
•
IDLE
SPEED
. . .
700-750 RPM
TRANSMISSION
IN
NEUTRAL
DURING
TUNE
UP

SEE SERVICE MANUAL
FOR
ADDITIONAL INFORMATION
THIS VEHICLE CONFORMS
TO U.S.
DEPT.
OF
H.E.W.
REGULATIONS APPLICABLE
TO
1971 MODEL YEAR NEW MOTOR VEHICLES

Jeep
CORPORATION
14401

Important:
Always refer
to
the data tag when checking or re-adjusting ignition

timing,
idle speed, and idle mixture. 148

'Jeep'
UNIVERSAL SERIES SERVICE
MANUAL

Fl
EXHAUST
EMISSION
CONTROL
SYSTEM

Contents

DAUNTLESS
V-6
ENGINE
SUBJECT
PAR.

GENERAL
.F2-1
HEATED
AIR
SYSTEM.
. F2-2
Testing
Thermo
Air
Cleaner
F2-4
Positive
Crankcase
Ventilation
Valve.
. . .F2-6

Vacuum
Motor Replacement . .F2-8
Air
Cleaner Sensor Replacement F2-9
Replacement Procedures F2-7

AIR
PUMP
.F2-10

AIR
FILTER.
F2-11

AIR
DELIVERY
MANIFOLD.
F2-12

AIR INJECTION TUBES.
F2-13

ANTI-BACKFIRE
VALVE..
.F2-14
ENGINE COMPONENTS
.F2-15
MAINTENANCE
.F2-3
Carburetor
F2-16, F2-17

Distributor
F2-18

Anti-Backfire
Valve . . F2-19
Check
Valve..
F2-20

F2-1.
GENERAL
—V-6
Engine

The
Dauntless V-6
engine
Exhaust
Emission
Con­

trol
System consists of a belt-driven air pump

which
directs compressed air through connecting
hoses
to a steel distribution manifold into stainless steel injection
tubes
in the exhaust port adjacent
to each exhaust valve.
This
air, with its normal
oxygen
content, reacts with the hot but incom­
pletely burned exhaust
gases
and permits further combustion in the exhaust port or manifold.

The
Exhaust
Emission System on V6-225
engines

limits
the hydrocarbon and carbonmonoxide emis­sions from the exhaust system. The system includes

an
engine
designed for low emissions and lean
carburetor
calibration at idle and part throttle.

The
lean carburetion is possible because of the
heated air system that is part of the Emission
System.
See Fig. F2-2.
With
the heated air system
operating, inlet air temperature is around
115°F.
[46°C],
after the first few minutes of operation.

This
makes the use of lean (hot weather)
cali­
bration
possible, and the vehicle
still
responds and

drives
well in cold weather.

The
engine
has a "ported"
spark
advance, with the

vacuum
take-off just above the throttle valve, so that there is no vacuum advance at closed throttle,
but there is vacuum advance as
soon
as the throttle is opened slightly. To reduce emissions at idle and
at lower
engine
speeds, the
engine
timing is such
that the distributor
will
not have centrifugal ad­
vance until about 900 RPM.
F2-2.
HEATED
AIR
SYSTEM

The
heated air system on late model V6 engines,
consists of a manifold heat collector, a heated-air
SUBJECT
PAR.

Air
Pump F2-21
Intake
Manifold F2-22
Carburetor
Air Cleaner F2-5, F2-23

REMOVAL PROCEDURES
F2-24
Air
Pump. F2-25
Anti-Backfire
Valve..
. . .F2-26
Air
Distribution Manifold,

And
Air Injection Tubes F2-27

REQUIRED
EQUIPMENT..
. F2-28
REPLACEMENT
PARTS..
.F2-29

WARRANTY
F2-30
DIAGNOSIS GUIDE
F2-31
MAINTENANCE CHART.
F2-32
GENERAL
SPECIFICATIONS
F2-33

CARBURETOR SPECIFICATIONS.
.... .F2-34

DISTRIBUTOR SPECIFICATIONS
. .F2-35
SPARK PLUG GAP
F2-36
pipe, a adapter elbow and an air cleaner contain­ing temperature control doors operated by vacuum
through a temperature sensor. The heat
stove
is a
sheet
metal cover, shaped to and bolted on with
the right exhaust manifold. Air drawn in along the lower
edge
of the
stove
passes across the mani­
fold surface, picking-up heat. The heated air is
drawn
out from the front of the manifold, through
the heated air pipe and adapter elbow into the
snorkel
of the air cleaner.

The
temperature control air cleaner is designed to mix this heated air with cold air from under the
hood so that carburetor inlet air temperature aver­
ages
about
115°F.
[46°C.].
This
mixing is
done
by two air doors, a cold air door and a hot air door,

which
move
together
so that when the cold air door is closed, the hot air door is open and vice
versa.
Most of the time, both doors
will
be partially
open as required to control the temperature. When
the underhood temperature reaches about 135
°F
[57°C]
the cold air door
will
open wide and the
hot air door
will
close
tight See Fig. F2-3. Ob­ viously, if underhood temperatures rise above
135°F.
[57°C]
the air cleaner
will
no longer be
able to control temperatures and the inlet air tem­

perature
will
rise with underhood temperature.
The
temperature doors are moved by a diaphragm
type vacuum door. When there is no vacuum pres­ ent in the motor, the diaphragm spring forces the
cold air door open and the hot air door closed.

Whenever
the
engine
is running, the amount of
vacuum
present in the vacuum motor depends on
the temperature sensor in the air cleaner which is located in the vacuum line
between
the intake
manifold and the vacuum motor. In the sensor, a 149

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

F2

FIG.
F2-2—DAUNTLESS
V-6
ENGINE
EXHAUST
EMISSION
HEATED
AIR
SYSTEM
1—
Air
Cleaner 4—Adapter
Elbow
and Hose
2—
Vacuum
Motor 5—Manifold Heat Collector
3—
Control
Damper and
Linkage
accelerating the
engine
hard
will
cause the vacuum
level in the intake manifold and in the vacuum motor to drop. Whenever vacuum drops
below
5 inches [12,7 cm.] the diaphragm spring
will
open

the cold air door wide in order to get the maximum

air
flow required for maximum acceleration.
F2-3.
MAINTENANCE

Efficient
performance of the
Exhaust
Emission
System is
dependent
on precise maintenance. In
addition to the heated air system, air pump, con­ necting
hoses
and tubes, it is essential that the

carburetor
and ignition distributor be properly ad­
justed to specifications listed at the end of this section.

Road
test
is a factory-recommended optional serv­
ice every
6,000
miles
[9,600
km.] to evaluate
overall
performance.

The
following procedure is recommended to assist

in
diagnosing performance and/or emission level problems that are peculiar to Controlled Combus­
tion Equipped vehicles.

F2-4.
Testing Thermo
Air
Cleaner Operation
Since
failure of the air cleaner
will
generally result

in
the snorkel cold air door staying open, failure
will
probably go unnoticed in warm or hot weather.
In
cold weather, however, owners
will
complain of
leanness, hesitation, sag, surge or stalling. When any
type
of lean operation complaint is received, always

test
the heated air system for proper functioning
before
doing any work on the carburetor.

Note:
Always perform checks in the same order
as listed
below.
151

F2
EXHAUST EMISSION CONTROL SYSTEMS

<3>
FIG.
F2-3—COLD
AIR
DOOR OPEN

1—
Linkage

2— Motor

3— Air
Cleaner

4—
Sensor
5—
Temp
Sensing Spring

6—
Air
Bleed Valve
7—
Hot
Air
Pip®
8—
Diaphragm
Spring

9—
Diaphragm

10—
Control
Damper

11—
Air
Inlet
12—
Vacuum
Chamber
13—
Snorkel
Tube
Give
the
system
a
general check
as
follows:
1.
Check
all
hoses
for
proper hook-up.
Check
for kinked, plugged
or
damaged
hoses.

2. With
engine
off,
make sure cold
air
door
is
wide open.

3.
With
engine
running, check operation
of
vac­
uum
motor by connecting
a
test
hose
directly

from
intake manifold
to
vacuum motor.
Cold

air
door should close.
If
door fails
to
close, determine
if
motor linkage
is
properly con­
nected
to
door or
if a
bind
is
present;
if
link­
age
is
satisfactory, then vacuum motor must
be replaced.

Give
the
system
a
quick operational check
as

follows: 1. Start
test
with
engines
cold, air cleaner
at a

temperature below 85°
F.
[29.4°
C.].
If the

engine
has been in recent use, allow
it to
cool.
2. Observe
the
cold air door before starting
the
engine;
it
should
be
wide open.

3.
Start
the
engine
and
allow
it to
idle.
Im­
mediately after starting
the
engine,
the
cold
air
door should close.
4.
As the
engine
warms
up, the
cold
air
door should start
to
open
and the air
cleaner should
become
warm
to the
hand.
5.
The
system
is
operating normally
as de­
scribed
above.
If the air
cleaner fails
to

operate
as
above
or if
correct operation
of

the
air
cleaner
is
still
in
doubt, proceed
to

the thermometer check. 152

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

F2

FIG.
F2-4—HOT
AIR
DOOR
OPEN

1—
Linkage

2— Motor
3—
Air
Cleaner
4— Sensor 5—
Temp
Sensing Spring
6—
Air
Bleed Valve 7—
Hot
Air Pipe 8—
Diaphragm
Spring
9—
Diaphragm

10—
Control
Damper
11—
Air
Inlet
12—
Vacuum
Chamber
13—
Snorkel
Tube
To
perform the thermometer check, proceed as
follows:
1. Start
test
with air cleaner temperature below
85°
F.
[29.4°
C.]. If
engine
has been run recently, allow it to cool down. While
engine

is cooling, remove air cleaner cover and

install
a temperature
gage
next to sensor.

Reinstall
air cleaner cover. Do not install wing nut. Let car stand idle for
V2
hour or
more before proceeding to
step
2.
2. Start engine.
Cold
air door should
close
im­ mediately if
engine
is cool enough. When cold air door starts to open (in a few min­
utes), remove air cleaner cover and read
temperature
gage.
It must read 115° F.
[46°
C]
±20°.
3.
If cold air door
does
not start to open at
temperature indicated, temperature sensor is
defective and must be replaced.

F2-5.
Carburetor Air
Cleaner—Dry
Type

Every
24,000
miles
[38,400
km.] (or more fre­
quently in dusty territory) replace the air cleaner element. To do this, remove the wing nut and cover

from
the air cleaner housing.
Lift
out the air cleaner
element. Wipe the inside of the housing clean.
Service
the positive crankcase valve filler as out­
lined in paragraph F2-6. Make sure the air cleaner gasket is in
good
condition and properly located
on the carburetor flange.
Install
a new element, the cover and wing nut. Tighten the wing nut by hand.

Tighten
to make sure the air cleaner remains 153

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

F2

14043

FIG.
F2-6—REPLACING VACUUM MOTOR ASSEMBLY

A—Drill
VW
Hole
B—Sensor
Unit
Replacement Position
1—
Motor
3—Sensor
Unit

2—
Spot
Welds
4—Retaining
Strap
•e.
Drill
a
%j
inch [2,78 mm.] hole in snorkel tube

at
point
"A"
as shown in Fig.
F2-6.
f.
Use the motor strap retainer and the
sheet
metal

screw
provided in the motor replacement kit to secure the retainer and motor to the snorkel tube.
g. Make sure the screw
does
not interfere with the
operation of the damper assembly. Shorten screw
if
required.

F2-9.
Replacement
of Air
Cleaner Sensor

a.
Remove two sensor retaining clips by
prying.
See

Fig.
F2-7.

b.
Pull
vacuum
hoses
from sensor.

c.
Note
carefully the installed position of the sensor so that you can install new sensor in same position.

Then
remove sensor.

d.
Install
sensor and gasket assembly in air cleaner

m
same position as noted in
step
c.
This
is to eliminate the possibility of interference with the air

filter
element.
e.
Install
sensor retaining
clip,
meanwhile support­
ing
sensor at B around the outside rim to prevent 14042

FIG.
F2-7—REPLACING SENSOR ASSEMBLY

1—Sensor
Retaining
Clip
damage to the temperature sensing spring. See

Fig.
F2-7.

f.
Reinstall
vacuum hoses.

F2-10.
AIR
PUMP
The
air injection pump is a positive displacement
vane type which is permanently lubricated and
requires
no periodic maintenance.

The
pump contains an integral relief valve which
controls the
air
supplied to the
engine
exhaust ports

during
high speed operation to limit maximum exhaust system temperatures.

F2-11.
AIR
FILTER
The
air injection system draws clean air from the
carburetor
air filter through an inlet hose, into the

air
pump and from the pump through two
outlets
(one for each cylinder head).

F2-12.
AIR
DELIVERY MANIFOLD

The
air delivery manifolds constructed of cold
rolled
steel with a zinc plating, distribute the air

from
the pump to each of the air delivery tubes in

a
uniform manner.

Two
check valves are included to prevent the
reverse
flow of exhaust
gases
to the pump should
the pump drive
fail.
This
reverse flow would dam­
age the air pump and connecting hose.

F2-13.
AIR
INJECTION TUBES
The
air injection tubes of stainless steel are in­ serted into machined
bosses
of the cylinder head.

The
tubes project into the exhaust ports directing
air
into the vicinity of the exhaust valve stem.

F2-14.
ANTI-BACKFIRE VALVE
The
anti-backfire valve is used to provide a "gulp" of air into the
engine
induction system during
rapid

throttle opening and subsequent closure.
During
rapid
throttle closure, the valve
opens
for approxi­
mately one (1) second and bleeds air into the
intake
manifold through a fitting in the carburetor.

Its
function is to bleed an adequate amount of

air
below the carburetor throttle plate to compen­ sate for the
overrich
fuel mixture normally inducted
into the combustion chamber during
rapid
throttle

closure.

Filtered
air from the pump is provided to the
anti-backfire
valve by means of a connecting hose.

An
exhaust system backfire
will
result if the valve

fails
to function properly.

F2-15.
ENGINE COMPONENTS
The
following item varies in design or specifications

from
those
on vehicles not equipped with the Ex­

haust
Emission
Control
System.

F2-16.
Carburetor

Check
carburetor number for proper application. Specifications are listed in this section.

Proper
carburetor idle mixture adjustment is im­ perative for
best
exhaust emission control.

The
idle adjustment should be made with the en­
gine
at normal operating temperature, lights and accessories off and the air cleaner in place.
Adjust
155