Dodge RAM TRUCK 1500 1995 Service Manual page 277

BR COOLING SYSTEM DIAGNOSIS 7 - 7
COOLING SYSTEM DIAGNOSIS—ALL EXCEPT DIESEL—CONTINUED
CONDITION POSSIBLE C A U S E S
CORRECTION
T E M P E R A T U R E GAUGE
READS HIGH OR ENGINE
COOLANT WARNING LAMP
ILLUMINATES. COOLANT
MAY OR MAY NOT B E LOST
OR LEAKING FROM
COOLING S Y S T E M - CONT.
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. Aftermarket A/C installed without
proper radiator.
13. Fuel or ignition system problems.
14. Dragging brakes.
15. Bug screen is being used
reducing airflow.
16. Thermostat partially or completely
shut. This is more prevalent on
high mileage vehicles.
17. Thermal viscous fan drive not
operating properly.
18. Cylinder head gasket leaking.
19. Heater core leaking.
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.
12. Install proper radiator.
13. 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.
14. Check and correct as necessary. Refer to
Group 5, Brakes in the manual text.
15. Remove bug screen.
16. Check thermostat operation and replace
as necessary. Refer to Thermostats in this
group.
17. Check fan drive operation and replace if
necessary. Refer to Viscous Fan Drive in
this group.
18. Check for cylinder head gasket leaks.
Refer to Testing Cooling System For
Leaks in this group. For repair, refer to
Group 9, Engines.
19. Check heater core for leaks. Refer to
Group 24, Heating and Air Conditioning.
Repair as necessary.
J9507-50