is water jacketed to prevent distortion of the cylinder walls. The hot water surrounding the combustion chambers is forced
by the water pump to the radiator where it is cooled by the slipstream of air created by the ventilator fan. The engine does
not have a thermostat for the control of the water temperature and for this reason it is very important to cover the radiator
in cold weather to avoid overcooling of the engine.
128. Draining and Cleaning Cooling System
a. General. Rust and scale form in every cooling system. The amount of these deposits depends on the water used
for cooling. Avoid the use of water with high mineral content. The cooling system must be flushed at least twice a year.
The cooling system must be drained if the water becomes contaminated with dirt, oil, or sludge.
b. Draining.
(1) Remove the radiator cap to break any vacuum that may have developed in the cooling system.
(2) If the cooling system contains antifreeze, place containers under the radiator and engine block to save the
antifreeze for future use.
(3) Open the draincock (13, fig. 42) on the radiator bottom extension tube. If the draincock is stuck, tap it lightly
with the wooden handle of a screwdriver until it is loose.
(4) Open the draincock on the left side of the engine, slightly above the engine identification plate.
(5) If the engine draincock is clogged, unscrew it from the engine block and clean the opening. Wash the
draincock in cleaning solvent.
c. Cleaning.
(1) Radiator. Disconnect the radiator bottom hose (7, fig. 42). Flush the radiator through the hose (7) until
clean water comes out of the radiator filler (2).
Note. Avoid extreme high water pressure when flushing the radiator, as it may distort or damage
the radiator core.
(2) Engine. Flush the engine block through the water outlet elbow (6, fig. 3). After flushing the block, tighten the
cylinder-head screws. The proper torque wrench reading is 35 to 40 ft-lb.
d. Filling.
(1) Connect the upper radiator hose with the water outlet elbow (6, fig. 3) and the lower radiator hose (7, fig. 42)
with the hose elbow (12). See that the clamps (6) are tight and in good condition. Inspect the rubber hose
and replace if swollen, frayed, cut, or damaged.
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