TM 9-2320-280-20-1
REFERENCE INFORMATION
Change 1 2-159
ENGINE COOLING
Flush cooling system, refer to
(para. 3-60).
For surge tank and radiator support replacement
procedures, refer to (paras. 3-63 and 3-64).
For oil cooler and oil cooler hose replacement
procedures, refer to (paras. 3-7 and 3-8).
Notify DS maintenance to repair radiators.
An external line from the power steering gear brings hydraulic fluid to the clutch fan solenoid
through control valve (normally open) and then to the fan drive, keeping it disengaged. The
action of the valve is controlled by the time delay module and the fan temperature switch.
During normal operation, the fan timer switch is closed. This keeps the control valve in the
open position and the drive disengaged.
As the engine reaches a temperature of 215°F (102°C), the temperature switch opens and the control
valve closes. This engages the fan. If the fan is engaged and the accelerator is floored, the
transmission kickdown system disengages the fan drive for 20 seconds.
The easiest way to determine if the fan is engaged is to stand outside the driver's door and gently
work the accelerator. If the fan is engaged, you will feel a breeze from the engine area. If the fan is not
engaged, you won't feel the breeze.
If the vehicle's serial number is 68555 through 72541 or 100000 through 112867, and you see ADCO
stamped on top of the time delay module, replace the module with part NSN 5945-01-193-7175, refer to
(para. 4-31).
ENGINE COOLING FAN DESCRIPTION OF OPERATION
Replace pressure cap, refer to (para. 3-60).
Check seal and spring on pressure cap.
WARNING
Do not remove surge tank filler
cap before releasing internal pressure
when engine temperature is above
190 °F (88°C). Steam or hot coolant
under pressure will cause injury.
