
RENR9348-01 85
Troubleshooting Section
Clamps that are damaged and hoses that are
leaking can usu
ally be discovered during a
visual inspection.
Hoses that hav
enovisualleakscansoften
during operation. The soft areas of the hose
can kink or the soft areas of the hose may
collapse dur
ing operation. This can restrict
the coolant flow. This can cause the engine to
overheat. Check the hoses for soft spots.
Internal cracks can also develop in cooling
system hoses. This type of deterioration usually
produces par
ticles that can build up in the
cooling system. This may cause a restriction in
the coolant flow through components. Check
the hoses fo
r spots that are hard or brittle.
e. Check the water pump. Remove the water
pump and che
ck for damage to the impeller. A
water pump with a damaged impeller will not
pump an adequate amount of coolant through
the system
.
f. Check the operation of the water temperature
regulator
. A water temperature regulator
that does not open, or a water temperature
regulator that only opens part of the way can
cause ove
rheating.
g. If the cooling system for this application is
equipped
with an expansion tank, check the
shunt line for the expansion tank.
The shunt
line must be submerged in the
expansion tank. If the shunt line is not
submerged, air will be introduced into the
cooling
system.
Check the shunt line for a restriction. A
restric
tion of the shunt line from the expansion
tank to the inlet of the water pump will cause a
reduction in water pump efficiency. A reduction
in water
pump efficiency will result in low
coolant flow.
B. High air
inlet temperatures can cause high cooling
system temperatures. Check for a problem in the
engine’s air inlet and exhaust systems.
a. Check for a restriction in the air inlet system.
A restriction of the air that is coming into the
engine
can cause high cylinder temperatures.
High cylinder temperatures cause higher than
normal temperatures in the cooling system.
b. Check for a restriction in the exhaust system.
A restriction of the air that is coming out of the
engin
e can cause high cylinder temperatures.
c. If the air inlet system for this application
is equipped wit
h an aftercooler, check the
aftercooler. A restriction of air flow through the
air to air aftercooler can cause overheating.
Check for debr
is or deposits which would
prevent the free flow of air through the
aftercooler. If the engine is equipped with a
liquid coole
d aftercooler verify that the coolant
flow is unobstructed.
C. The engine’s
operating conditions can also affect
cooling system temperatures. Check the operating
conditions of the engine.
a. Consider high ambient temperatures. When
ambient temperatures are too high for the rating
of the cooli
ng system, there is not enough of a
temperature difference between the ambient
air and coolant temperatures.
b. Consider high altitude operation. The cooling
capability of the cooling system is reduced at
higher alt
itudes. A pressurized cooling system
that is large enough to keep the coolant from
boiling must be used.
c. The engine may be running in the lug condition.
When the load that is applied to the engine
is too lar
ge, the engine will run in the lug
condition. When the engine is running in the
lug condition, engine rpm does not increase
with an in
crease of fuel. This lower engine rpm
causes a reduction in coolant flow through the
system.
Expected Result:
Athorou
gh inspection of the engine revealed the
cause of the high cooling system temperature.
Results
:
•
OK – The cause of the high cooling system
tempera
ture has been identified.
Repair: Repair the problem. Ensure that the repair
elimina
tes the original problem.
STOP.
i024867
16
E362 Engine O versp eed
SMCS Code: 7410-038; 7427-038
Conditi
ons Which Generate This Code:
The Electronic Control Module (ECM) detects
an overs
peed condition. Information on default
settings and ranges for this event can be found in
Troubleshooting, “Event Codes”.