Jeep Liberty KJ. Manual — part 1381
COOLING
DESCRIPTION
3.7L ENGINE
The cooling system consists of the following items:
•
2 Speed electric cooling fan - Standard.
•
2 Speed electric cooling fan and mechanical engine fan with viscous clutch - Heavy duty cooling only
•
Radiator
•
Thermostat
•
Combined coolant pressure bottle/overflow system with pressure cap
•
Combination A/C/transmission oil cooler (if equipped with an automatic transmission)
•
Coolant
•
Water pump
•
Hoses and hose clamps
2.8L DIESEL ENGINE
The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temper-
ature as quickly as possible, maintains normal operating temperature and prevents overheating.
The cooling system also provides a means of heating the passenger compartment. The cooling system is pressur-
ized and uses a centrifugal water pump to circulate coolant throughout the system. 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
•
2 Speed Electric Cooling Fan with an engine driven fan with viscous clutch
•
A aluminum-core radiator with plastic side tanks
•
A separate pressurized coolant tank
•
Combined coolant pressure bottle with pressure cap plus an overflow system
•
Fan shroud
•
Thermostat
•
Coolant
•
Low coolant warning lamp
•
Coolant temperature gauge
•
Water pump
•
Hoses and hose clamps
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KJ
COOLING SYSTEM ROUTING - 3.7L ENGINE
For cooling system routing refer to.
HOSE CLAMPS
The cooling system utilizes spring type hose clamps. If
a spring type clamp replacement is necessary, replace
with the original Mopar
T
equipment spring type clamp.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL NUM-
BER 6094. ALWAYS WEAR SAFETY GLASSES
WHEN SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue (1) of constant tension clamps. If replace-
ment is necessary, use only a original equipment
clamp with matching number or letter.
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COOLING
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OPERATION
COOLING SYSTEM
The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temper-
ature as quickly as possible. It also maintains normal operating temperature and prevents overheating.
The cooling system also provides a means of heating the passenger compartment. The cooling system is pressur-
ized and uses a centrifugal water pump to circulate coolant throughout the system.
HOSE CLAMPS
The spring type hose clamp applies constant tension on a hose connection. To remove a spring type hose clamp,
only use constant tension clamp pliers designed to compress the hose clamp.
DIAGNOSIS AND TESTING
ON-BOARD DIAGNOSTICS (OBD)
COOLING SYSTEM RELATED DIAGNOSTICS
The powertrain control module (PCM) has been programmed to monitor certain cooling system components:
•
If the engine has remained cool for too long a period, such as with a stuck open thermostat, a Diagnostic
Trouble Code (DTC) can be set.
•
If an open or shorted condition has developed in the relay circuit controlling the electric radiator fan, a Diag-
nostic Trouble Code (DTC) can be set.
If the problem is sensed in a monitored circuit often enough to indicate an actual problem, a DTC is stored. The
DTC will be stored in the PCM memory for eventual display to the service technician. (Refer to 25 - EMISSIONS
CONTROL - DESCRIPTION).
ACCESSING DIAGNOSTIC TROUBLE CODES
To read DTC’s and to obtain cooling system data (Refer to 25 - EMISSIONS CONTROL - DESCRIPTION).
ERASING TROUBLE CODES
After the problem has been repaired, use the DRB scan tool to erase a DTC. Refer to the appropriate Powertrain
Diagnostic Procedures service information for operation of the DRB scan tool.
PRELIMINARY CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following
may be the cause:
•
PROLONGED IDLE
•
VERY HIGH AMBIENT TEMPERATURE
•
SLIGHT TAIL WIND AT IDLE
•
SLOW TRAFFIC
•
TRAFFIC JAMS
•
HIGH SPEED
•
STEEP GRADES
Driving techniques that avoid overheating are:
•
Idle with A/C off when temperature gauge is at end of normal range.
1. TRAILER TOWING:
Consult Trailer Towing section of owner’s manual. Do not exceed limits.
2. RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been performed on vehicle that may affect cooling system. This may be:
•
Engine adjustments (incorrect timing)
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COOLING
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•
Slipping engine accessory drive belt(s)
•
Brakes (possibly dragging)
•
Changed parts. Incorrect water pump, or pump rotating in wrong direction due to belt not correctly routed
•
Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous items as a cause for an engine overheating complaint,
refer to following Cooling System Diagnosis charts.
These charts are to be used as a quick-reference only. Refer to the group text for information.
COOLING SYSTEM LEAKS
ULTRAVIOLET LIGHT METHOD
A leak detection additive is available through the parts
department that can be added to cooling system. The
additive is highly visible under ultraviolet light (black
light). Pour one ounce of additive into cooling system.
Place heater control unit in HEAT position. Start and
operate engine until radiator upper hose is warm to
touch. Aim the commercially available black light tool
at components to be checked. If leaks are present,
black light will cause additive to glow a bright green
color.
The black light (1) can be used in conjunction with a
pressure tester to determine if any external leaks
exist.
PRESSURE TESTER METHOD
The engine should be at normal operating tempera-
ture. Recheck the system cold if cause of coolant loss
is not located during the warm engine examination.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.
Carefully remove radiator pressure cap from pressure
bottle and check coolant level. Push down on cap to
disengage it from stop tabs. Wipe inside of filler neck
and examine lower inside sealing seat for nicks,
cracks, paint, and dirt. Inspect radiator-to- reserve/
overflow tank hose for internal obstructions. Insert a
wire through the hose to be sure it is not obstructed.
Inspect cams on outside of filler neck. If cams are
damaged, seating of pressure cap valve and tester
seal will be affected.
Attach pressure tester (7700 or an equivalent) to radiator filler neck.
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