Troubleshooting

RENR2696-01 39
Troubleshooting Section
i01798115
Coolant Temperature Is Too
High
Note: This is n
ot an electronic system problem.
Refer to Testing and Adjusting for information on
determining t
he cause of this condition.
Probable Caus
es
•
Radiator fins
•
Coolant level
•
Radiator cap a
nd/or pressure relief valve
•
Combustion gases in the cooling system
•
Engine cooling fan
•
Water tempera
ture regulators
•
Restriction in the coolant system
•
Coolant temperature gauge
•
Coolant pump
•
Excessive load on the system
Recommended Actions
Radiator Fins
Check the rad
iator fins for dirt, debris, and/or damage.
Remove any dirt and/or debris and straighten any
bent fins.
Coolant Level
1. Inspect the c
oolant level. If necessary, add
coolant.
2. Check the coo
ling system for leaks. Repair any
leaks immediately.
Radiator Ca
p and/or Pressure Relief
Valve
1. Pressure te
st the cooling system. Refer to Testing
and Adjusting, “Cooling System” for the correct
procedure.
2. Check operation of the pressure relief valve
and the radiator cap. If necessary, clean the
component
s and/or replace the components.
3. Check that the seating surfaces of the pressure
relief valve an
d the radiator cap are clean and
undamaged.
Combustion Ga
ses in t he Cooling System
Switch off the engine and allow the engine to cool
to below norma
l working temperature. Remove
the pressure cap for the coolant system. Start the
engine and inspect the coolant for the presence
of bubbles. I
f bubbles are present in the coolant,
combustion gases may be entering the cooling
system. Check the cylinder head gasket. Refer to the
recommended
action for the cylinder head gasket
within Troubleshooting, “Coolant in Engine Oil”.
Check the cylinder head for flatness. Refer to the
recommende
d action for checking flatness of the
cylinder head within Systems Operations, “Cylinder
Head - Inspect”. Fit the pressure cap if there are no
bubbles in t
he coolant.
Water Temperature Regulator
Check the water temperature regulator for correct
operation. Refer to Testing and Adjusting, “Cooling
System” fo
r the proper procedure. If necessary,
replace the water temperature regulator. Refer to
Disassembly and Assembly, “Water Temperature
Regulato
r - Remove and Install” for more information.
Restriction in the Coolant System
1. Visually inspect the cooling system for collapsed
hoses and/or other restrictions.
2. Clean the radiator and flush the radiator. Refer to
Testing and Adjusting, “Cooling System”.
Coolant Temperature Gauge
Compare t
he reading for the coolant temperature
from the electronic service tool to the reading for the
coolant temperature from a mechanical gauge.
Coolant Pump
Inspect
the impeller of the coolant pump for damage
and/or erosion. If necessary, repair the coolant pump
or replace the coolant pump.
Excessive Load on the System
Reduce t
he load and verify that the condition does
not reoccur.