(160-180F). Stop engine, remove radiator cap
carefully (if so equipped) and drain system by
opening drain cocks on radiator and crankcase.
Allow engine to cool, close drain cocks and pour
directions. Fill system with water.
Place a clean drain pan to catch overflow and use to
maintain level in radiator. Avoid spilling solution on
Install radiator cap (if so equipped) and run engine at
moderate speed, covering radiator if necessary, so
the radiator reaches a temperature of 84°C (180F) or
above but does not reach the boiling point. Allow the
engine to run at least two hours at 84C (180F) so
the cleaning solution will take effect. Do not drive
vehicle or allow liquid level in radiator to drop low
enough to interfere with circulation.
NOTE - Stop engine as often as necessary to
With the engine stopped, feel the radiator with bare
hands to check for cold spots, and then observe the
temperature reading. Where there is no change in
temperature for some time, drain the cleaning
If clogging of the core is relieved but not fully
corrected, allow the engine to cool, pressure-flush the
system (see Pressure Flushing), and repeat cleaning
If clogging of core, indicated by cool spots on the
core is not relieved, radiator core must be removed
for mechanical cleaning. Mechanical cleaning
requires removal of upper and lower tanks and
rodding out the accumulated rust and scale from the
water passage of the core.
Disconnect the upper radiator hose which connects
the radiator core to the engine water outlet and
remove thermostat from engine water outlet.
Clamp a convenient length of hose to the radiator
core outlet opening and attach another suitable
length of hose to the radiator inlet opening to carry
away the flushing stream.
Connect the flushing gun to compressed air and
water pressure and clamp the gun nozzle to the hose
attached to the radiator outlet opening.
With radiator cap (if so equipped) on tight, fill core
with water. Apply air pressure in short blasts to
prevent core damage.
Continue filling radiator with water and applying air
pressure in short blasts until the water comes out
Clamp the flushing gun nozzle firmly to a hose
attached securely to the engine water outlet opening.
Fill engine block with water, partly covering water inlet
opening to permit complete filling.
Apply compressed air to blow out water and loose
sediment. Continue filling with water and blowing out
with air until flushing stream comes out clear.
For badly clogged engine water jackets that do not
respond to regular pressure flushing, remove engine
cylinder head and core hole plugs and with a suitable
length of small copper tubing attached to the flushing
gun nozzle, flush the water jackets through the
If the vehicle is equipped with a heater connected to
the cooling system, flush the heater, following the
same procedure as for the radiator core.
After completing the flushing operation, clean out the-
radiator overflow pipe, inspect the water pump, clean
the thermostat and the radiator cap control valve (if
so equipped). Check thermostat for proper operation
before installation. See "Thermostat."
Blow insects and dirt from radiator core air passages,
using water if necessary.
FILLING THE COOLING SYSTEM
To eliminate air being trapped within the engine or heater, the
following procedure should be followed when filling the engine
Set parking brake.
Fill cooling system until coolant reaches bottom of
radiator filler opening. Let stand approximately 5
minutes; recheck level.
Allow engine to operate, without radiator cap, at a fast
idle until the engine reaches its normal operating
temperature, trapped air will be expelled from system.
With engine still running, add sufficient coolant to fill
system. If the radiator has a filler neck extension with
a vent hole near the top, the system is full when the
coolant level is at the bottom of the extension. If the
radiator does not have an extended filler neck, fill the
system to approximately 25.4mm (1 inch) below the
bottom of the filler neck.
To aid the serviceman in maintaining the cooling system at top
efficiency, various items of test equipment are available.
Among these are the Cooling System Pressure Tester and the