CONDITION
POSSIBLE CAUSES
CORRECTION
9. Coolant not flowing through
system
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 area
of obstruction and repair as
necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.
10. Remove insects and debris.
(Refer to 7 - COOLING/ENGINE/
RADIATOR - CLEANING).
11. Radiator core is corroded or
plugged.
11. Have radiator re-cored or
replaced.
12. Aftermarket A/C installed
without proper radiator.
12. Install proper radiator.
13. Fuel or ignition system
problems.
13. Refer to FUEL and /or
IGNITION CONTROL for diagnosis.
14. Dragging brakes.
14. Check and correct as necessary.
(Refer to 5 - BRAKES -
DIAGNOSIS AND TESTING) for
correct procedures.
15. Bug screen or cardboard is
being used, reducing airflow.
15. Remove bug screen or
cardboard.
16. Thermostat partially or
completely shut.
16. Check thermostat operation and
replaces necessary. (Refer to 7 -
COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT -
DIAGNOSIS AND TESTING).
17. Viscous fan drive not operating
properly.
17. Check fan drive operation and
replace as necessary. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING).
18. Cylinder head gasket leaking.
18. Check for cylinder head gasket
leaks. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING). For
repair, (Refer to 9 - ENGINE/
CYLINDER HEAD - REMOVAL).
19. Heater core leaking.
19. Check heater core for leaks.
(Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING/
HEATER CORE - REMOVAL).
Repair as necessary.
20. Hydraulic fan speed too low or
inoperative.
20. Check for
DTC code.
Check fan operation speeds.
Refer to fan speed operation table.
Low power steering pump output.
Refer to power steering pump
diagnosis - 4.7L engine.
7 - 6
COOLING
WK