1988 JEEP CHEROKEE gas type
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1) Drain cooling system. Remove fan shroud and drive belts.
Remove fan assembly.
2) Disconnect heater hoses and lower radiator hose at water
pump. Remove water pump retaining bolts. Remove water pump.
Installation
Clean all gasket surfaces. Install water pump. Tighten bolts
to specification. Ensure pump turns freely. Reverse removal
procedures. Fill and purge air from cooling system.
NOTE: It may be necessary to remove heater hose to remove trapped
air if system cannot be purged using following procedures.
Cooling System Air Purge (Vehicles With Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Install
coolant caps. Operate engine to normal operating temperature. Shut off
engine and allow system to cool. Add coolant to recovery bottle.
Repeat procedure to obtain correct coolant level.
Cooling System Air Purge (Vehicles Without Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Operate
engine to normal operating temperature with radiator cap removed. Add
necessary coolant and install radiator cap.
NOTE: For further information on cooling system capacities and
other cooling system components, see ENGINE COOLING SYSTEMS
article.
ENGINE OILING
CRANKCASE CAPACITY
Crankcase capacity is 4 qts. (3.8 L) with oil filter change.
NORMAL OIL PRESSURE
Normal oil pressure should be 13 psi (.91 kg/cm) at 600 RPM
or 37-75 psi (2.6-5.3 kg/cm) at 1600 RPM.
OIL PRESSURE REGULATOR VALVE
Oil pressure regulator valve is located in oil pump body and
is nonadjustable.
OILING SYSTEM
Engine lubrication is provided by the distributor driven
gear-type oil pump. Oil is supplied through the full-flow oil filter
and into an internal oil passage. Internal passage runs along right
side of block and intersects lifter bores.
Oil is then routed to camshaft and crankshaft bearings. Oil
is supplied to rocker arms from the hydraulic lifters and through the
push rods. By-pass valves are located in oil filter mounting and oil
pump.
OIL PUMP
Removal
Remove oil pan. See OIL PAN REMOVAL article. Remove oil pump
Page 67 of 1378
Removal
Drain cooling system. Disconnect radiator and heater hoses
from pump. Remove drive belt(s). Remove fan shroud. Remove fan
assembly. Remove electric cooling fan (if equipped). Remove power
steering bracket from water pump. Remove water pump and gasket.
Installation
Ensure gasket surfaces are clean. Install water pump. Tighten
bolts to specification. Ensure pump turns freely. Reverse removal
procedures. Fill and purge air from cooling system.
NOTE: It may be necessary to remove heater hose to remove trapped
air if system cannot be purged using following procedures.
Cooling System Air Purge (Vehicles W/Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Install
coolant caps. Operate engine to normal operating temperature. Shut off
engine and allow system to cool. Add coolant to recovery bottle.
Repeat procedure to obtain correct coolant level.
Cooling System Air Purge (Vehicles W/O Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Operate
engine to normal operating temperature with radiator cap removed. Add
necessary coolant and install radiator cap.
NOTE: For further information on cooling systems, see appropriate
article in the ENGINE COOLING section.
LUBRICATION
CRANKCASE CAPACITY
Crankcase capacity for 4.0L is 5 1/2 qts. (5.2L) or 5 qts.
(4.7L) for 4.2L with oil filter change.
NORMAL OIL PRESSURE
Normal oil pressure should be 37-75 psi (2.6-5.3 kg/cm)
maximum above 1600 RPM. Minimum oil pressure should be 13 psi (.9
kg/cm
) at 600 RPM.
OIL PRESSURE REGULATOR VALVE
Oil pressure regulator valve is located in pump body. Valve
is nonadjustable and serviced as an assembly.
ENGINE OILING SYSTEM
Engine lubrication is provided by the distributor driven
gear-type oil pump. Oil is supplied through the full-flow oil filter
and into an internal oil passage. Internal passage provides oil to the
lifter bores. Oil is then routed to camshaft and crankshaft bearings.
Oil is supplied to rocker arms from the hydraulic lifters and through
the push rods.
OIL PUMP
Removal
Remove oil pan. See OIL PAN REMOVAL in this section. Remove
Page 158 of 1378
2000 ....................... 27.82 ........................... 2.1
3000 ....................... 26.82 ........................... 3.1
4000 ....................... 25.82 ........................... 4.1
5000 ....................... 24.92 ........................... 5.0
6000 ....................... 23.92 ........................... 6.0
7000 ....................... 23.02 ........................... 6.9
8000 ....................... 22.22 ........................... 7.7
9000 ....................... 21.32 ........................... 8.6
10,000 ..................... 20.52 ........................... 9.4
(1) - Add correction shown to gauge readings
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OPERATIONAL TEST GAUGE READINGS
Normal System Operating Pressures (PSI) ( 1)
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Low Side High Side
Gauge Gauge
Application (Suct.) (Disc.\
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Jeep 1980-87
(Thermostatic Switch) ........ 5-24 ................... 208-250\
1988
(Accumulator Type) ........... 24-50 .................. 160-250\
( 1) - Pressure readings given are for a system in good operating
condition, at sea level and an ambient temperature of 80
F
(27C). \
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AIR CONDITIONING SYSTEM PERFORMANCE CHECK TABLE \
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PERFORM TESTS: SHOULD BE: IF: \
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Temperature Check Temperature Check is
* Switch to LOW
blower
* Close doors Too warm-Check control lever
* Check outlet 35-45
F (1.7-7.2C) operation, heater water valve,
temperature. cooling system and gauge
readings.
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Visual Check Visual Check Shows:
* Compressor Quiet, no leaks Noisy-Check belts, oil level,
seals, gaskets, reed valves.
* Condenser Free of Blocked-Clean off. Plugged-
obstructions Flush or replace.
* Receiver- Dry and warm to Frosty-Check for restriction,
Drier touch. replace desiccant.
* Sight Glass Clear or few Bubbly, foamy or streaks-
bubbles Check gauge readings.
* High Side Dry and warm to Frosty or very hot-Check for
touch. restriction or overcharge.
* Low Side Dry and cool to Frosty or warm-Check for
Lines touch. restriction, low charge or
bad valve.
Page 162 of 1378
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A/C S YSTE M G EN ER AL S ER VIC IN G
1988 J e ep C hero ke e
1988 AIR CONDITIONING & HEAT
A/C General Servicing
Diagnostic Procedures
Eagle & Jeep
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
INTRODUCTION
This article is to be used for general service and diagnosis.
For specific repair or replacement procedures, use the appropriate
repair article in this section.
R-12 REFRIGERANT - SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
(R-12) is heavier than oxygen, and will displace oxygen in a confined
area. Always wear eye protection when working around air conditioning
systems and R-12. The system's high pressure can cause severe injury
to eyes and skin if a hose were to burst. R-12 evaporates quickly
when exposed to atmosphere, freezing anything it contacts.
2) Use care when handling refrigerant containers. Do not
drop or strike containers. Do not expose refrigerant containers to
excessive heat. Containers must never be heated more than 125
F.
Never expose R-12 directly to open flame.
CAUTION: When R-12 is exposed to an open flame, drawn into a running
engine, or detected with a Halide (propane) leak tester,
poisonous phosgene gas is formed. Keep work areas
ventilated and keep vehicles with running engines away.
USING INDIVIDUAL R-12 CANS
Disposable refrigerant cans (referred to as one pound cans)
have a flat type seal or a screw type seal, and the proper can tap
must be used for each type. Be sure sealing gasket on can tap is in
good condition. A proper safety can tap will prevent refrigerant from
flowing back into open can, as the tap has a one-way flow control.
NOTE: Recent findings by the EPA indicate that R-11, R-12 and
R-113 are harmful to the Earths' protective Ozone layer.
Make every attempt possible, to avoid discharging R-11, R-12
or R-113 into the atmosphere.
USING MULTI-CAN DISPENSING VALVES
A multi-can dispensing valve allows the attachment of
several cans of refrigerant, and is a good substitute when a bulk
container is not available. Cans are installed onto each leg of the
multi-can dispensing valve in the same manner as the individual cans,
and each leg has its own can tap.
Page 163 of 1378
CAN TAP INSTALLATION
FLAT TYPE SEAL CANS
On cam-lock or one-piece can taps, first turn the handle out
to the fully open position. Securely engage the locking lugs over the
flange of the can, and lock them in place by turning the cam lock or
locking nut. Screw the tap assembly into the adapter so the sealing
gasket is fully seated against the can top. Turn the tap inward to
pierce the can and close the tap. DO NOT open the tap until ready to
purge the service hose or dispense refrigerant into the system.
On 2-piece can taps, be certain the tap handle is turned
fully in, so it is closed. Check that the locking base is turned to
its outer limit. Securely engage the locking lugs over the can
flange. Turn the entire tap assembly (without disturbing the closed
setting) down into the locking base to pierce the can. Do not open
the tap until ready to dispense into system.
SCREW TYPE SEAL CANS
Ensure can tap is fully closed. Screw refrigerant can into
can tap fitting until tight. This will pierce the can. Connect tap to
center hose on manifold gauge set. DO NOT open tap until ready to
dispense R-12 into system.
WARNING: DO NOT open high side hand valve while air conditioning
system is in operation. This high pressure could rupture
can or possibly burst fitting at safety can valve,
resulting in damage and physical injury.
COMPRESSOR OIL CHECK
GENERAL PROCEDURES
Some models have compressor-mounted service valves that allow
oil checking by isolating the compressor. On all others, system must
be discharged, using approved refrigerant recovery/recycling
equipment, and compressor may need to be removed to check oil. After
oil level is checked and adjusted, A/C system must be evacuated and
recharged.
ISOLATING COMPRESSOR
1) Connect manifold gauge set to service valves on the
compressor. Close both gauge valves. Open both service valves to
themid-position.
2) Start engine and operate air conditioning. Turn suction
service valve slowly clockwise toward front-seated position. When
suction pressure is reduced to zero or less, stop engine and quickly
close suction service valve (front-seated).
3) Front-seat the discharge valve. Loosen oil check plug
slowly to release any internal pressure. Service valves can now be
removed from compressor and compressor removed from vehicle (if
necessary). Purge compressor after servicing.
PURGING COMPRESSOR
1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
Page 287 of 1378
NOTE: Electro-magnetic interference (EMI) may be caused by
incorrect installation of accessories or components. EMI can
result in improper system operation.
BACKING PLATES
BACKING PLATE INSPECTION \
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Condition Code Procedure
Anchor pin bent ......... B .. Require repair or replacement.
Anchor pin broken ....... A ............ Require replacement.
Anchor pin worn, affecting
structural integrity ... B ............ Require replacement.
Backing plate bent ...... B .. Require repair or replacement.
Backing plate broken .... A ............ Require replacement.
Backing plate cracked ... B .. Require repair or replacement.
Corroded, affecting
structural integrity .... A ............ Require replacement.
Loose ................... B .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Shoe lands worn ......... A .. Require repair or replacement.
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BRAKE FLUID
CAUTION: Most manufacturers prohibit the use of DOT 5 brake fluid
in a system equipped with ABS.
DOT 3, DOT 4, and DOT 5.1 brake fluids are clear or light
amber in color. DOT 5 brake fluid is violet in color. Correct fluid
required for the brake system is stamped on the master cylinder cover.
BRAKE FLUID INSPECTION
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Condition Code Procedure
Beyond service interval . 3 .. Suggest flushing and refilling
with correct fluid.
Brake fluid type
incorrect .............. B .. Require flushing and refilling
with correct fluid.
Contaminated, for example,
fluid other than brake
fluid present .......... A or B ....... ( 1) Require service.
Hydraulic component ..... 3 .. Suggest flushing and refilling
overhaul or replacement with correct fluid.
Rubber master cylinder
cover gasket distorted
and gummy .............. A .......... ( 2) Require replacement
of gasket.
( 1) - If a fluid other than brake fluid is present in the brake
system which DOES affect the rubber parts, the required
service is to:
* Remove all components having rubber parts from the
system.
* Flush lines with denatured alcohol or brake cleaner
* Repair or replace all components having rubber parts
* Flush and fill with correct brake fluid. (Code A)
If a fluid other than brake fluid is present in the brake
Page 478 of 1378
EG R S YSTE M
1988 J e ep C hero ke e
1983-88 Exhaust Emission Systems
JEEP EXHAUST GAS RECIRCULATION
DESCRIPTION
Purpose of the Exhaust Gas Recirculation (EGR) system is to
limit formation of oxides of nitrogen (NOx) emissions. This is done by\
reducing high peak combustion temperatures at which NOx is formed. By
reintroducing some exhaust gas back into combustion chamber, high
temperatures are avoided. Thus NOx emissions formation is reduced.
System consists of vacuum-operated EGR valve and coolant
temperature override (CTO) switch. In addition, some models are
equipped with air cleaner-mounted thermal vacuum switch (TVS), and
some are equipped with an EGR vacuum dump valve.
OPERATION
When the EGR valve receives vacuum signal, through the CTO
switch, EGR valve opens and meters gases from exhaust manifold into
intake manifold. Individual component operation is as follows:
EGR VALVE
EGR valve is mounted on intake manifold. Exhaust gas is drawn
from exhaust crossover passage or exhaust manifold. Two types of EGR
valves are used: valve without backpressure sensor and valve with
integral backpressure sensor.
EGR Valve W/O Integral Backpressure Sensor
EGR valves are calibrated by use of different shapes of valve
pintles or orifices. Valve is normally held closed by spring (above
diaphragm). Valve opens by overcoming spring tension when vacuum is
sensed through coolant temperature override switch (CTO) and
backpressure sensor (if equipped).
EGR Valve W/Integral Backpressure Sensor
Calibration is accomplished by use of different diaphragm
spring loads and flow control orifices. This integral type unit
combines EGR valve and backpressure sensor functions into one
component. Restrictor plate is required with some engines.
Exhaust gas exerts backpressure inside exhaust manifold
whenever engine is running. This pressure is conducted through hollow
pintle stem into EGR diaphragm control chamber. If this pressure is
great enough to overcome spring tension against diaphragm, diaphragm
is moved against bleed valve and exhaust gas flow begins.
COOLANT TEMPERATURE OVERRIDE (CTO) SWITCH
Coolant temperature override (CTO) switch is located in
coolant passage at cylinder head or coolant passage at intake
manifold.
Inner port of switch is connected to EGR port on intake
manifold and outer port is connected to EGR valve, or EGR-TVS. Switch
opens at a preset temperature. Below these temperatures, no EGR is
possible.
Page 574 of 1378
inspection procedures.
A visual inspection is made to determine if any required
emission control devices are missing, modified or disconnected.
Missing, modified or disconnected systems must be made fully
operational before a vehicle can be certified.
POSITIVE CRANKCASE VENTILATION (PCV)
PCV controls the flow of crankcase fumes into the intake
manifold while preventing gases and flames from traveling in the
opposite direction. PCV is either an open or closed system. See Fig. 2
.
Ensure PCV system is installed as required. Verify valve,
required hoses, connections, flame arresters, etc., are present,
routed properly and in serviceable condition.
Fig. 2: Typical Open & Closed Type PCV System
THERMOSTATIC AIR CLEANER (TAC)
The TAC supplies warm air to air intake during cold engine
operation. This system is active during cold engine warm-up only.
Under all other operating conditions, air cleaner function is the same
as any non-thermostatic unit.
Ensure required exhaust shroud, hot air duct, vacuum hoses
and air cleaner components are present and installed properly. See
Fig. 3 . Ensure any required thermostatic vacuum switches are in place
and vacuum hoses are installed and in serviceable condition. Also
ensure air cleaner lid is installed right side up. Check for oversized
air filter elements and for additional holes in the air cleaner
housing.