Jeep Wrangler 1997 Manual page 106

7-14
COOLING SYSTEM
DIAGNOSIS AND TESTING (Continued)
COOLING SYSTEM DIAGNOSIS CONT.
TJ
CONDITION
TEMPERATURE GAUGE
READS HIGH OR ENGINE
COOLANT WARNING LAMP
ILLUMINATES . COOLANT MAY
OR MAY NOT BE LOST OR
LEAKING FROM COOLING
SYSTEM - CONT
POSSIBLE CAUSES
7. Coolant level low in
radiator but not in coolant
reserve/overflow tank. This
means the radiator is not
drawing coolant from the
coolant reserve/overflow tank
as the engine cools.
As the engine cools, a
vacuum is formed in the
cooling system of the engine
and radiator. If radiator cap
seals are defective, or
cooling system has leaks, a
vacuum can not be formed .
8. Freeze point of antifreeze
not correct . Mixture may be
too rich.
9. Coolant not flowing
through system .
10 . Radiator or A/C
condenser fins are dirty or
clogged.
11 . Radiator core is corroded
or plugged .
12 . Fuel or ignition system
problems.
13 . Dragging brakes .
14 . Bug screen is being used
reducing airflow.
15 . Thermostat partially or
completely shut. This is more
prevalent of high mileage
vehicles.
16 . Thermal viscous fan
drive not operating properly .
17 . Cylinder head gasket
leaking .
18 . Heater core leaking .
CORRECTION
7 . (a) Check condition of radiator cap and
cap seals. Refer to Radiator Cap in this
group. Replace cap if necessary.
(b) Check condition of radiator filler neck . If
neck is bent or damaged, replace radiator.
(c) (Check the condition of the hose from the
radiator to the coolant tank. It should fit tight
at both ends without any kinks or tears .
Replace hose if necessary.
(d) Check coolant reserve/overflow tank and
tank hoses for blockage. Repair as necessary
8. Check antifreeze . Refer to Coolant section
of this group. Adjust antifreeze-to-water ratio
as required.
9. Check for coolant flow at radiator filler
neck with some coolant removed, engine
warm and thermostat open . Coolant should
be observed flowing through radiator. If flow
is not observed, determine reason for lack of
flow and repair as necessary.
10. Clean insects or debris. Refer to Radiator
Cleaning in this group.
11 . Have radiator re-cored or replaced .
Refer to Fuel and Ignition System groups for
diagnosis . Also refer to the appropriate
Powertrain Diagnostic Procedures service
manual for operation of the DRB scan tool .
13. Check and correct as necessary. Refer to
Group 5, Brakes in the manual text.
14. Remove bug screen .
15. Check thermostat operation and replace
as necessary. Refer to Thermostats in this
group.
16. Check fan drive operation and replace if
necessary. Refer to Viscous Fan Drive in this
group .
17. Check for cylinder head gasket leaks.
Refer to Testing Cooling System for Leaks in
this group. For repair, refer to Group 9,
Engines .
18 . Check heater core for leaks. Refer to
Group 24, Heating and Air Conditioning .
Repair as necessary.