TRUCK SERVICE MANUAL
Avoid spilling solution on vehicle paint.
Replace radiator cap (if so equipped) and run engine at
moderate speed, covering radiator if necessary, so the
radiator reaches a temperature of 84 degs. C (180
degs. F) or above but does not reach the boiling point.
Allow the engine to run at least two hours at 84 degs C
(180 degs. F) 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 prevent
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 solution.
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 low temperature spots
on the core, is not relieved; radiator core must be
cleaning requires removal of upper and lower tanks
and rodding out the accumulated rust and scale from
the water passage of the core.
D. PRESSURE FLUSHING
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
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
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 snall 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, to soften obstructions.
E. TEST EQUIPMENT
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
SE-1870 Cooling System Pressure Tester
This equipment may be used in detecting the hard-to-
find leaks in the cooling system. Any leak from
cracked or warped cylinder heads or blown gaskets
(internal or external) can be located easily and in a
short time with the pressure tester. Adapters are
available with the tester which permit the testing of
radiators on trucks having the cabover-engine design
(Fig7). Pressure caps can also be tested , with the
CTS-2019P Page 9
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