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COOLING SYSTEM 7 - 1
COOLING SYSTEM
CONTENTS
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page
DIAGNOSIS .............................
ENGINE ACCESSORY DRIVE BELTS .........
ENGINE BLOCK HEATER ..................
SERVICE PROCEDURES ...................
SPECIFICATIONS .......................
INDEX
page
page
Cooling System ..........................
Cooling System Components ................
General Information .......................
System Coolant Routing ....................
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicle models by alphabetical designation or
by the particular vehicle nameplate. A chart showing
a breakdown of alphabetical designations is included
in the Introduction section at the beginning of this
manual.
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Water pump
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Hoses and hose clamps
SYSTEM COOLANT ROUTING
For cooling system routings refer to (Figs. 1 or 2).
COOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal operat-
ing temperature as quickly as possible. It also main-
tains normal operating temperature and prevents
overheating.
The cooling system also provides a means of heating
the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
An optional factory installed maximum duty cooling
package is available on most models. This package
will provide additional cooling capacity for vehicles
used under extreme conditions such as trailer towing
in high ambient temperatures.
COOLING SYSTEM COMPONENTS
The cooling system consists of:
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A radiator
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Cooling fan
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Thermal viscous fan drive
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Fan shroud
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Radiator pressure cap
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Thermostat
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Coolant reserve/overflow system
Transmission oil cooler (if equipped with an auto-
matic transmission)
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Coolant
Fig. 1 Engine Cooling System—4.0L
Engine—Typical
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 7 - 2 COOLING SYSTEM
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Fig. 2 Engine Cooling System—5.2L Engine—Typical
DIAGNOSIS
PRELIMINARY CHECKS
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer’s specifications.
4. RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been performed
on vehicle that may effect cooling system. This may
be:
²
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause.
1. PROLONGED IDLE, VERY HIGH AMBIENT
TEMPERATURE, SLIGHT TAIL WIND AT IDLE,
SLOW TRAFFIC, TRAFFIC JAMS, HIGH
SPEED, OR STEEP GRADES:
Driving techniques that avoid overheating are:
Engine adjustments (incorrect timing)
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Slipping engine accessory drive belt(s)
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Brakes (possibly dragging)
Changed parts (incorrect water pump rotating in
wrong direction)
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Idle with A/C off when temperature gauge is at end
of normal range.
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Increasing engine speed for more air flow is recom-
mended.
2. TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
3. AIR CONDITIONING; ADD-ON OR AFTER
MARKET:
A maximum cooling package should have been or-
dered with vehicle if add-on or after market A/C is
Reconditioned radiator or cooling system refilling
(possibly under-filled or air trapped in system).
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Rubber and foam air seals not properly installed to
radiator or A/C condenser after a repair.
If investigation reveals none of the above as a cause
for engine overheating complaint, refer to following
Symptom and Action chart.
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COOLING SYSTEM 7 - 3
SYMPTOM AND ACTION—SEE PRELIMINARY CHECKS FIRST
7 - 4
COOLING SYSTEM
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SYSTEM DIAGNOSIS
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COOLING SYSTEM 7 - 5
SYSTEM DIAGNOSIS (CONT.)
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