TM 5-2420-230-24-2
Troubleshooting Symptoms Charts
B3.9 and B5.9 Series Engines
Page TS-22
Section TS - Troubleshooting Symptoms
Coolant Temperature is Below Normal
This is symptom tree T024.
Cause
Correction
Check the shutters and engine compartment
Engine is operating at low ambient temperature
.......
air. Refer to Cold Weather Operation, Bulletin
No. 3387266.
OK
A
Check and repair shutters, fan clutch, and
irflow across radiator is excessive (nonmarine
.......
viscous fan as required. Refer to OEM service
engines only)
manual.
OK
T
Check or replace the temperature gauge. Refer
emperature gauge malfunction
.......
to the OEM service manual.
OK
E
Close valves to heater cores. Run engine. If
xcessive coolant flow through OEM plumbing
engine operates at normal temperature, refer to
.......
and heater cores
OEM dealer.
OK
T
Check the thermostat for the correct part
number and for correct operation. Refer to
hermostat is not correct or is malfunctioning
.......
Procedure 008-013 and the OEM service
manual.
OK
F
an drive or fan controls are malfunctioning
Check the fan drive and controls. Refer to the
.......
(nonmarine engines only)
OEM service manuals.
OK
C
oolant flow not correct to temperature sensor
.......
Check and clean coolant passages.
L-606
