Jeep XJ. Manual - part 73

(3) Inspect fan assembly for cracks, bends, loose

rivets or broken welds. Replace fan if any damage is
found.

COOLING SYSTEM HOSES

INSPECTION

Inspect the hoses at regular intervals. Replace

hoses that are cracked, feel brittle when squeezed or
swell excessively when the system is pressurized.
The use of molded replacement hoses is recom-
mended. When performing a hose inspection, inspect
the radiator lower hose for proper position and con-
dition of the spring.

SPECIFICATIONS

BELT TENSION

Belt tension must be adjusted. Refer to the follow-

ing Belt Tension chart for specifications.

DESCRIPTION

N·f

Lbs. ft.

New Serpentine Belt*

800-900

180-200

Used Serpentine Belt

623-712

140-160

* Belt is considered new if it has been used 15

minetes or less.

TORQUE SPECIFICATIONS

DESCRIPTION

N·m

Ft.

In.

Lbs.

Trans. Auxiliary Oil
Cooler—Screws

—

Block Heater—Screw

—

Condenser-to-Radiator—
Bolts

—

Electric Cooling Fan—Bolts

—

Fan Blade Assy to Viscous

Fan Drive—Bolts

—

Fan Shroud—Bolts

—

Isolator-to-Crossmember—
Nuts

—

Isolator-to-Radiator—Nuts

—

Radiator—Bolts

4.0L Engine

—

2.5L Engine

—

Thermostat Housing—Bolts

—

Viscous Fan Drive Assy. to

DESCRIPTION

N·m

Ft.

In.

Lbs.

Water Pump or Hub
Bearing—Nuts

—

Water Pump—Bolts

—

SPECIAL TOOLS

COOLING

Hose Clamp Tool—6094

Cooling System Pressure Tester—7700A

3/8” Quick Connect Release Tool—6935

7 - 40

COOLING SYSTEM

CLEANING AND INSPECTION (Continued)

COOLING SYSTEM

TABLE OF CONTENTS

page

DESCRIPTION AND OPERATION

DIAGNOSIS AND TESTING

PRELIMINARY CHECKS . . . . . . . . . . . . . . . . . . . . 8
THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . . 14
RADIATOR COOLANT FLOW CHECK . . . . . . . . . 15
TESTING COOLING SYSTEM FOR LEAKS . . . . . 15
PRESSURE/VENT CAP . . . . . . . . . . . . . . . . . . . . 16
LOW COOLANT LEVEL- AERATION . . . . . . . . . . 16
BELT DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . 17

SERVICE PROCEDURES

COOLANT LEVEL CHECK . . . . . . . . . . . . . . . . . . 18
DRAINING COOLING SYSTEM . . . . . . . . . . . . . . 19
REFILLING COOLING SYSTEM. . . . . . . . . . . . . . 19
COOLANT REPLACEMENT . . . . . . . . . . . . . . . . . 20

REMOVAL AND INSTALLATION

RADIATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
FAN BLADE REMOVAL . . . . . . . . . . . . . . . . . . . . 21
VISCOUS FAN DRIVE . . . . . . . . . . . . . . . . . . . . . 22
THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
DRIVE BELT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
AUTOMATIC BELT TENSIONER . . . . . . . . . . . . . 23
WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . 23

CLEANING AND INSPECTION

WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . 26
RADIATOR CLEANING . . . . . . . . . . . . . . . . . . . . 26
FAN BLADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PRESSURE/VENT CAP . . . . . . . . . . . . . . . . . . . . 27
COOLING SYSTEM CLEANING/REVERSE

FLUSHING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

SPECIFICATIONS

COOLING SYSTEM CAPACITY . . . . . . . . . . . . . . 28
THERMOSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . . . 28

DESCRIPTION AND OPERATION

COOLING SYSTEM

DESCRIPTION

The cooling system regulates engine operating tem-

perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible, maintains
normal operating temperature and prevents over-
heating.

The cooling system also provides a means of heat-

ing the passenger compartment. The cooling system
is pressurized and uses a centrifugal water pump to
circulate coolant throughout the system. A water
manifold collects coolant from the cylinder heads. A
separate and remotely mounted, pressurized coolant
tank using a pressure/vent cap is used.

COOLING SYSTEM COMPONENTS

The cooling system consists of:
• Charge Air Cooler

• Electric Cooling Fan

• An aluminum radiator with plastic side tanks

• A radiator mounted fill vent valve

• A separate pressurized coolant tank

• A threaded-on, pressure/vent cap mounted to the

coolant tank

• Cooling fan (mechanical)

• Thermal viscous fan drive

• Fan shroud

• Thermostat

• Coolant

• Low coolant level sensor

• Low coolant warning lamp

• Coolant temperature gauge

• Water pump

• Hoses and hose clamps

COOLING SYSTEM

7 - 1

2000 JEEP CHEROKEE

COOLANT ROUTING

For cooling system flow routing, refer to (Fig. 1)

Fig. 1 Coolant Flow—2.5L Diesel Engine—Typical

1 – PRESSURIZED COOLANT TANK
2 – PRESSURE/VENT CAP
3 – HOSE
4 – HEATER HOSES
5 – HEATER CORE
6 – WATER MANIFOLD FITTING
7 – WATER MANIFOLD (TOP OF CYLINDER HEAD)
8 – ENGINE (TOP VIEW)
9 – UPPER RADIATOR HOSE
10 – RADIATOR

11 – THERMOSTAT
12 – FILL VENT CAP
13 – WATER PUMP
14 – LOWER RADIATOR HOSE
15 – VENT HOSE
16 – LARGER FITTING TO COOLANT TANK
17 – HOSES
18 – HOSE
19 – ENGINE OIL COOLER
20 – LOW COOLANT LEVEL SENSOR

7 - 2

COOLING SYSTEM

DESCRIPTION AND OPERATION (Continued)

2000 JEEP CHEROKEE

RADIATOR

DESCRIPTION

The radiator used with the 2.5L diesel is con-

structed of a horizontal flow aluminum core with
plastic side tanks.

CAUTION: Plastic tanks, while stronger than brass,
are

subject

damage

impact,

such

wrenches.

ENGINE ACCESSORY DRIVE BELT

DESCRIPTION

The accessory drive components are operated by a

single, crankshaft driven, serpentine drive belt. An
automatic belt tensioner is used to maintain correct
belt tension at all times.

CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to water pump rotat-
ing in wrong direction.

COOLANT TANK

DESCRIPTION

A pressurized, plastic coolant tank is used with

this cooling system (Fig. 2). The tank is located at
the right-rear side of the engine compartment and is
mounted as the highest point of the cooling system.
This allows any air or vapor exceeding the pressure/
vent cap rating to escape through the cap. Coolant
flows through the tank at all times during engine
operation whether the engine is cold or at normal
operating temperature. The coolant tank is equipped
with a threaded pressure/vent cap. Refer to Pressure/
Vent Cap for additional information.

The low coolant level sensor is located near the

bottom of the tank (Fig. 2).

WATER PUMP

DESCRIPTION

centrifugal

water

pump

circulates

coolant

through the water jackets, passages, water manifold,
radiator core, pressurized coolant tank, cooling sys-
tem hoses and heater core. The pump is driven from
the engine crankshaft by a drive belt. The water
pump is bolted to the water pump adapter (Fig. 3).
The water pump adapter is bolted to the engine.

The water pump impeller is pressed onto the rear

of a shaft that rotates in bearings pressed into the
housing. The bottom of the housing is equipped with
a small vent tube (Fig. 3) to allow seepage to escape.

A drain hose is attached to this tube. The water
pump seals is lubricated by the antifreeze in the cool-
ant mixture. No additional lubrication is necessary.

A rubber o-ring (instead of a gasket) is used as a

seal between the water pump and the water pump
adapter (Fig. 3).

A quick test to determine if the pump is working is

to check if the heater warms properly. A defective
water pump will not be able to circulate heated cool-
ant through the heater hoses and the heater core.

COOLANT

DESCRIPTION

Coolant flows through the engine water jackets

and cylinder heads absorbing heat produced by the
engine during operation. The coolant carries heat to
the radiator and heater core. Here it is transferred to
the ambient air passing through the radiator and
heater core fins.

LOW COOLANT LEVEL SENSOR

DESCRIPTION

The low coolant level sensor checks for low coolant

level in the coolant tank (Fig. 4).

OPERATION

When the coolant level gets low a signal will be

sent from this sensor to the powertrain control mod-
ule (PCM). When the PCM determines low coolant
level, the instrument panel mounted low coolant level
warning lamp is illuminated. The sensor is located

Fig. 2 Pressurized Coolant Tank

1 – LOW COOLANT LEVEL SWITCH
2 – COOLANT RESERVOIR
3 – LOW COOLANT LEVEL SWITCH HARNESS CONNECTOR

COOLING SYSTEM

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DESCRIPTION AND OPERATION (Continued)

2000 JEEP CHEROKEE

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